One Health Meets the Exposome: Human, Wildlife, and Ecosystem Health 9780323898737, 0323898734

Citation preview

ONE HEALTH MEETS THE EXPOSOME Human, Wildlife, and Ecosystem Health Mary Ann Ottinger Department of Biology and Biochemistry, University of Houston, Houston, TX, United States

Cullen Geiselman The Cullen Trust for Health Care, Houston, TX, United States

Academic Press is an imprint of Elsevier 125 London Wall, London EC2Y 5AS, United Kingdom 525 B Street, Suite 1650, San Diego, CA 92101, United States 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom Copyright © 2023 Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-323-89873-7 For information on all Academic Press publications visit our website at https://www.elsevier.com/books-and-journals Publisher: Nikki P. Levy Acquisitions Editor: Anna Valutkevich Editorial Project Manager: Andrea R. Dulberger Production Project Manager: Kiruthika Govindaraju Cover Designer: Miles Hitchen Cover Art: Nicole Ami Ray Typeset by TNQ Technologies

Dedication To our families and friends, their love of nature and the world. We could not have accomplished this journey without their love and support. To my amazing husband, our awesome children and their spouses, and beautiful, talented grandchildren. Mary Ann To my mother for being my teacher and companion in so many facets of our lives. Cullen

v

Preface

sustaining human and wildlife populations, and improving the world as an interrelated entity.

Our beautiful world is in jeopardy from multiple challenges including human population growth, pollution, land use change, sea level rise, climate change, and sharp declines in wild flora and fauna. These challenges are interconnected, so disruptive change in one is likely to alter another with rippling effects. This means that humanity must seek global solutions in a coordinated and constructive manner that transcends international, national, and regional boundaries. These solutions must consider culture and social drivers while recognizing the linkage of human, domestic animal, and wildlife health with their environment. Myriad organizations, citizen groups, research centers, and consortia have put countless hours into describing issues and many have produced valuable insights and approaches to resolve specific challenges facing humanity. Because the dimensions and drivers of these global challenges are complex, it is often necessary to address pieces of an issue instead of its entirety. As global consortia and summits coalesce information and activities, long-term solutions are beginning to emerge, but often they are exceedingly difficult to implement. A coordinated approach is needed so that all parties communicate and move in synchrony while informing and engaging all constituents and stakeholders, including scientists, public officials, decision makers, educators, and the public. Accordingly, many essential pieces and cooperative programs are required to implement programs for restoring global ecosystems,

The Opportunity This book brings together two conceptual frameworks, One Health and the Exposome, to address these challenges within the context of human health in our global society and to provide approaches toward achieving solutions. Although many conceptual frameworks exist, they often have been created for a specific purpose, such as assessing risk from pollutants or the global decline in wildlife. The One Health and the Exposome conceptual frameworks both offer structured approaches to addressing issues that follow a logical path of recognition, characterization, and implementation. These two frameworks have additional attributes making them applicable across a range of global challenges. The foundational basis for One Health can be found throughout human history in which the broadest definition describes humanity in delicate balance with nature and all aspects of our global environment. The concept incorporates humans, domestic animals, wildlife, ecosystems, and physical components of the global environment. One Health conceptualizes this interrelationship in a way that is both understandable and accessible to the public, ultimately creating a framework that characterizes the challenges

ix

x

Preface

as well as develops programmatic actions. The most recent usage of One Health has been in the context of disease transmission from wildlife to humans though it continues to broaden to encompass more aspects of the environment. The Exposome concept emerged more recently and at its core recognizes the effects of environmental exposures on an individual human’s health. It initially focused on environmental chemicals from a variety of sources, such as food and pollutants, and now also incorporates social and cultural environmental factors. This conceptual framework can be applied at any point in an individual’s lifetime. Its practitioners make use of rich datasets linking biomarkers of exposure and characteristics of an individual’s Exposome that could affect healthy aging as well as onset of diseases known to be associated with exposure to environmental chemicals and other factors. The One Health and Exposome conceptual frameworks each has strengths and weaknesses. As mentioned above, the One Health concept has been successfully utilized worldwide to address local, regional, and national issues. It is a concept that considers relatively high-level interactions and interrelationships among human, domestic animal, and wildlife populations that affect the health of all. Furthermore, the health and sustainability of ecosystems depend on these interactions and the health of all components. In contrast, the Exposome focuses on individual humans and characterizing biomarkers of exposure and health over the lifespan. The sharp increase in the number of publications and the conversation around both these conceptual frameworks, discussed in detail in Chapter 1

with an accompanying reference list (see online appendix), reveals their growing adoption. However, an opportunity seems to be lost in that the merits of these two lines of thought run in parallel and have not yet benefited from cross-fertilization. Practitioners and advocates of One Health and the Exposome generally do not interact meaning the attributes of one do not benefit the existing gaps of the other conceptual framework. Herein, we offer some solutions to both visualizing global challenges on an individual to global scale and directly comparing the views of each concept. Our intended audience is all stakeholders ranging from scholars and practitioners to the public. Many figures are provided that are intended to visualize the concepts and points. The overall organization of this book is from introducing both concepts, their frameworks, and history to in-depth consideration of the health of humans, domestic animals, wildlife, and ecosystems. Case studies offer details of specific events and issues with discussion of how each of the concepts would produce both shortand long-term resolutions. We have included a terminology for ease of describing and comparing the challenges facing humanity and all living beings. These “ingredients” are essential for health and sustainability of individuals and populations and are used to identify and link essential components for life to the challenges that compromise our health and life itself. Our goal is to provide a merged concept and framework that incorporates assets of both One Health and the Exposome as well as a unifying voice that will help link together nomenclature and understanding.

Acknowledgments

and the introductory facing image for each chapter that captured the essence of our ideas. This work includes many graphs and figures from Our World in Data (https://ourworldin data.org/) that illustrate many of the global challenges addressed. This open access resource is invaluable for compiling and visualizing extensive datasets in a concise and understandable way. We are grateful to the many consortia and organizations that have shared discussions, innovative concepts, and passion for the health of humankind, wildlife, and global ecosystems. Thankfully, they are too numerous to list and are a harbinger for optimism for the future of our planet. Finally, a huge thank you to the SESYNC Team and especially to Drs. Andre Botha, William Bowerman, Brent Coverdale, Nicholus Funda, Meredith Gore, Reggie Harrell, Sonja Kr€ uger, Humbu Mafumo, Jennifer Mullinax, Eric Reson, L. Jen Shaffer, Hanneline SmitRobinson, Lindy Thompson, and Linda van den Heever. Their work with the endangered vultures of Africa is truly inspirational. A special thanks to the Anna Valutkevich, Andrea Dulberger, Kiruthika Govindaraju, and many others at Elsevier Press for their time and efforts, and for working with us to problem solve throughout this journey.

This book would not have been possible without our “village” of family, friends, and colleagues, who reviewed, discussed ideas, and provided valuable insights. Heartfelt thanks to Beth Robertson and Sarah Flournoy for reviewing the entire volume. Dr. Paul Ottinger read every chapter, often multiple times, and imparted his exceptional logic and clarity. We are grateful to Dr. Bryan Brooks for his candid feedback and synthetic view of the complexities that greatly helped us unify our ideas. Thank you to many colleagues and friends that provided critical input to our proposal and to multiple chapters including Tasneem Bawa, Auriel Fournier, Andrew Geller, Jeffrey Gleason, Jean Harry, Emma Lavoie, Martin Nunez, Katey Pelican, Catherine Propper, Stephen Spann, Lani Wheeler, and Diane Wiernasz. Special thanks to Gabriela Chaverria, Deborah January-Bevers, Sue Lamont, Kristen Malecki, Shailaja Mani, Claudia Neuhauser, Heather Patisaul, Tom Porter, Amy Sater, and Ralph Stahl for essential discussions about the complex topics that we were attempting to wrangle and valuable advice. The design and artwork in our volume could not have happened without talented artists. Megan Farias, our gifted design illustrator, was our partner throughout this process; we thank her for great patience and innovative solutions. Nicole Ray, our creative and innovative artist, conceptualized and produced the cover artwork

xi

C H A P T E R

1

Introduction their origins, and scope and specifics about the One Health and Exposome conceptual frameworks. The next four chapters go into detail about the threat of global challenges to health, examining their effects on essential ingredients needed for health in each of the major realms (human health-Chapter 2, domestic animal health-Chapter 3, wildlife health-Chapter 4, and ecosystem health-Chapter 5). In Chapter 6, three case studies are presented to examine if/ how One Health and/or the Exposome conceptual frameworks are reflected in actions taken to resolve the threat. Each case illustrates a significant challenge to humans, wildlife, and ecosystem health on global or regional scales. The final chapter (Chapter 7) coalesces what we have learned throughout the chapters and evaluates the utility of these conceptual frameworks to effectively grapple with today’s complex challenges, alone and as a merged framework that integrates the best of both. The content of each chapter is based on findings from the peer-reviewed published literature that provides the science needed to understand the interrelated nature of humankind to our environment. This approach achieves a primary objective of providing consumable and useful information for a general audience, with additional material available to those who wish to examine pertinent scientific evidence and datasets. There are diagrams and supporting examples throughout the chapters to help visualize

Recognizing the interconnected nature of the challenges faced by humanity in the 21st century is essential for implementing solutions that move global society forward in a mutually constructive and cohesive manner. To effectively resolve the globe’s most prickly issues, it is important to first identify and articulate their dimensions as well as understand their drivers, modulators, and triggers. This volume brings together two current conceptual frameworks, One Health and the Exposome, to address these challenges within the context of human health in our global society and provide approaches toward achieving solutions. These frameworks are complementary, albeit starting from different perspectives, timings, and scales. Ultimately, it is a merger of these two concepts that will provide the most encompassing framework to realize local and regional solutions. Once enacted, these solutions can be implemented on larger scales to enable communities and society as a whole to successfully tackle incredibly complex and challenging issues. This volume presents an in-depth view of these conceptual frameworks, by (1) providing a review of the foundational work that underpin each, (2) pointing out overlapping as well as differing perspectives, (3) considering existing gaps in our knowledge and needs, and (4) proposing scenarios that could effectively merge the best of both. Accordingly, the introduction in this chapter explains each of the concepts,

One Health Meets the Exposome https://doi.org/10.1016/B978-0-323-89873-7.00003-X

1

© 2023 Elsevier Inc. All rights reserved.

2

1. Introduction

BU

I LT

E N VIRO N ME

LDLIF

ST

M

ALS

E

Since the inception of our species, humans have altered their environments in ways that serve their current needs. Prior to the industrial revolution (1760e1820), the positive and negative effects of most of these modifications were felt locally or regionally. However, today, our anthropogenic activities impact all corners of the earth. Fig. 1.1 provides a way to visualize where humans and their activities fit into this global context in a way that can be used at local, regional, or global levels. As depicted in Fig. 1.1, all humans, no matter where they reside on Earth, live within one or more ecosystems in our shared biosphere. Within these ecosystems, humans have created pockets of human-dominated “built” environments that we share with domestic animals and plants as well as wildlife. Throughout this volume, realms denote the different “spaces” occupied by humans, domestic species (Zeder, 2015; animals bred and adapted to human needs), wildlife (nondomesticated animals), and ecosystems (see

WI

M AN S HU

E

Humanity in context

ECOSYSTEM

DOM

the information and perspectives for the two conceptual frameworks. Resources and references are provided at the end of each chapter containing topical literature and pertinent supporting information. The scientific method, contributions from new technologies, metadata, and big data provide the inputs necessary for these frameworks to deliver accurate solutions that inform policy makers, the public and to combat misinformation. Making scientific findings understandable reinforces the critical roles of science, technology, engineering, and math (STEM) and the arts (STEAM) for our young people as they learn about and appreciate our world. Accessible science also informs more general audiences about how evidence-based decisions can improve their lives and is critically needed to bring together diverse communities to address global challenges.

IC AN

I

NT

FIGURE 1.1 Interconnecting realms showing our shared world with humans, domestic species, and wildlife, both within and outside of the built environment, all within and affected by and having effects on the larger ecosystem.

Chapters 2e5 for definitions and detailed information). Humans, wildlife, and domestic species may also reside outside of the human-built environment. Recognizing these interconnected realms will be helpful when considering the origins and solutions to some of our greatest global challenges. Fig. 1.2 shows some of the many pathways and examples of how activities and elements of one realm spillover, interact with, and affect factors in other realms. Examples include the movement of diseases from wildlife to domestic animals and then further to people, disruptive effects of habitat fragmentation from road building and highways on wildlife populations, movement of invasive species through transport of goods internationally, migratory birds carrying pathogens to domestic counterparts, and pollution of waterways from agricultural or industrial chemicals. There are many situations, including the COVID-19 pandemic, that illustrate the transmission of infectious disease from wildlife to humans as well as the risk of wildlife exposure to human pathogens. The anthropogenic

3

Global challenges

ECO

SYSTEM

Loss of habitat causing stress to wildlife

Deforestation

WILDLIFE

HUMANS

Sick domestic animals can pass viruses on to humans

DOMESTIC ANIMALS

Stressed wildlife shed more viruses that can spillover to domestic animals

FIGURE 1.2

Conceptual map of interconnection between humans-domestic species-wildlife and the global ecosystem. The example shows how deforestation exacerbates disease spillover from wildlife to domestic animals and to people.

influences of humanity have led to a plethora of effects on wildlife and humans, not the least of which is the movement of invasive species, with resulting changes in the distribution of native versus potentially aggressive nonindigenous species moving into an ecosystem. Moreover, the impacts of pollutants and varied environmental chemicals modify the resilience of human, wildlife, and ecosystems. These interactions are nonlinear and dynamic resulting in positive and negative feedback loops that must be considered when addressing the origins and solutions to our greatest global challenges.

COVID-19, extreme weather events and other negative outcomes of climate change, loss of biodiversity and ecosystem function, pollution, expanding wealth inequality, and the impacts of all of these on human health. Selected major pressures on human communities and the ecosystems they rely upon are discussed below; these pressures are felt worldwide with varying degrees according to geolocation, population, industrialization, and other factors.

Global challenges

The human population has grown exponentially in the last 100 years from about 2.6 billion in 1950 to 6 billion in 1999 with an estimated 9.7 billion projected for 2050 (Fig. 1.3). However, human population is not evenly distributed throughout the world. As shown in Fig. 1.4, the

The interconnected world in which we live requires that we have coordinated approaches to achieve long-term solutions to complex problems like emerging infectious disease such as

Human population growth, resource use, and migration

4

1. Introduction

FIGURE 1.3

Human population annual growth rate (purple) overlaid with world population (green) by year 1700e2100. From: Roser et al. (2013), revised 2019, Data based on HYDE, UN, and UN Population Division.

current highest population in terms of sheer numbers is in Asia, with lower percentages of the global population in Africa, Europe, South America, and North America. The largest proportion of future population growth, however, is projected for sub-Saharan Africa, whereas European countries are projected to have decreasing population numbers through 2050 (Fig. 1.5). The differences in population growth rates and current population numbers must be considered within the backdrop of the inherent variability across the world in natural resources, climate, terrain, culture, and geopolitical and governmental system that dictate how populations can meet their growing needs. All humans have similar basic requirements, including a safe environment, housing, nutrition, employment, and basic resources, and, when these are limited, people

will move to meet their needs. Often migration occurs locally, specifically from rural to urban areas. However, these movements can spill across political borders and over oceans. For example, the first 20 years of the 21st century saw mass migrations of people out of North Africa and the Middle East to Europe to seek resources and improve their quality of life.

Human health and its determinants The rapid increase in the human population, mass migration to urban centers, vast expansion of the built environment, and improvements in technology have resulted in substantial changes to the various drivers affecting the health of individuals and their communities. For example, in

FIGURE 1.4 Human population by region from 1820 to 2021 showing the large increase in the numbers of people in Asia compared to the rest of the world. From: Roser et al. (2013); revised 2019, Source data from Gapminder (V6), HYDE (v3.2), UN 2019.

FIGURE 1.5

Population growth rate across the world shows areas of rapid increase and others that have no growth or negative growth. From: Roser et al. (2013), revised 2019, Source, UN Population Division, 2019.

6

1. Introduction

the United States, the leading causes of disease and death in 1900 were infectious diseases, trauma, cancer, and organ failure, whereas in the 21st century, these have been replaced by heart disease, diabetes, and stroke (Jones et al., 2012). “Health” as defined by the World Health Organization is “the state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.” As shown in Fig. 1.6, the primary determinants of a person’s health are their physical environment, genetics and biology, behavior/lifestyle, access to medical care, and social and economic circumstances. All these determinants vary based on an individual’s location within the interconnected realms shown in Fig. 1.1 (e.g., rural vs. urban,

living in proximity to livestock or wildlife vs. proximity to industrial plant).

Biodiversity loss and land use change Among the most catastrophic outcomes from the interrelated and dynamic changes to our planet is the loss of biodiversity, which includes all forms of life from animals and plants to fungi and microorganisms. The underlying causes are complex, and many are linked to anthropogenic impacts, such as overharvesting, deforestation, habitat fragmentation, and pollution, over the past few centuries with many of these impacts accelerating since 1900. For example, one third

Weather Conditions & Local Climate

MENTAL DETERMINA NTS IRON ENV

Air Quality

Heat Severe Storms Drought Climate Change Allergens

Indoor Outdoor

IAL DETERMINANTS SOC

Pollution Industrial Agricultural Non-point source Noise

Clinical Care

Health Behaviors Alcohol & Tobacco Use Drug Use Nutrition Sexual Activity Exercise Coping Skills

Housing Transportation/Mobility Green space & Parks Safety Sanitation

10%

10%

Education Employment Income Family & Social Support

L DETERMI NA NA N SO R

Sex Genetics Age & Biology Genetics

10%

Proximal Factors

FIGURE 1.6

Water Quality & Availability

Social-Political Context/ Discrimination

40%

TS

Built Envir.

PE

30%

Access to Care/Insurance Quality of Care

Social & Economic Factors

M ON VIR S -EN TION C I C LOG TERA O I B IN

Intermediate Factors

EN

T

Distal Factors

Determinants of health for individuals in the 21st century, including personal, social, and environmental health determinants. Percentages show average contribution of personal (sex, age, genetics) and social determinants to a person’s health. Social determinants are set within the environment, which has its own health determinants, including local climatic conditions, water and air quality, and pollution of various kinds. Some determinants are inherent to the person (personal) and are thus proximate factors, while others are further removed and can vary depending on a person’s external conditions, referred to as intermediate and distal factors.

Global challenges

of the earth’s forests have been felled since the last ice age as half of the world’s habitable land has been converted to agriculture (Fig. 1.7). The loss of habitat and impacts of land use change have resulted in declines in biodiversity not only in terms of decreasing numbers of individuals per species but also the complete extinction of species. As shown in Fig. 1.8, the Living Planet Index, which calculates the average rate of population change among vertebrate groups, estimates a 68% decline in wildlife populations since 1970. In terms of loss of species, researchers

7

have determined that recent extinction rates are 100 to 1000 times higher than the natural background rate (Fig. 1.9; Pimm et al., 2014). These losses directly and indirectly affect humans through damage to ecosystem function resulting in reduced ecosystem services. Diminished biodiversity affects not only the viability of species but also the food web. Ultimately, the lack of a full complement of species in ecosystems leads to declining ecosystem resiliency and productivity, consequently impairing current and future generations to meet their needs.

FIGURE 1.7 The loss of forests and grasslands since the last ice age reflects the conversion of land to agricultural use with the accompanying dramatic loss in forests, wild grasslands, and shrubs. From Ritchie and Roser (2019); Data from UN Food and Agriculture Organization, Williams 2003; History Database of the Global Environment.

8

1. Introduction

FIGURE 1.8

Global Living Planet Index compiles abundance data of 20,000 populations of mammals, birds, reptiles, amphibians, and fish monitored since 1970. When considered together, there has been a 68% average decline in these wildlife populations over the last 50 years. Ritchie and Roser (2021); Data from World Wildlife Fund, 2020.

Climate change, ecosystem health, and sustainability The ecosystems within which humans and all other living things exist are changing in sometimes chaotic and rapid ways due to climate change brought on by alterations to atmospheric composition, namely, the increase in greenhouse gases from fossil fuel use and land conversion. These changes are increasing the frequency of droughts, wildfires, and floods, causing sea level rise as polar ice melts, and resulting in species range extensions/contractions, among many other outcomes. As shown in Fig. 1.10, these changes can result in positive and negative feedback loops that can exacerbate and/or accelerate climate change and its effects. A prime example is the likelihood that wildfires and destruction of

Amazonian forests in 2020, partially driven by climate change, not only released more carbon into the atmosphere but also may have affected atmospheric oxygen levels (Ellwanger et al., 2020). Several notable concepts related to climate change will be emphasized throughout subsequent chapters, including: (1) underlying causes of climate change and geophysical outcomes; (2) complexity of feedback loops and interrelated factors that compound problems, such as greater frequency and intensity of weather events; (3) loss of ecosystem services; and (4) human health effects. In terms of human health, the immediate impacts of climate change include increased risks of heat stroke, infectious disease, allergies, asthma, and malnutrition. Climate change also affects how people can access the resources

Global challenges

9

FIGURE 1.9 Recent extinction rates compared to background across various vertebrates. The background rate is 0.1 extinctions per 1 million species per year, whereas the current extinction rates for well-studied vertebrates are 132, 183, and 587 per million per year for birds, mammals, and amphibians, respectively, since 1900. From Ritchie and Roser (2021); Data source Pimm et al. (2014).

they need to sustain themselves now and into the future (Fig. 1.11). Beyond these direct impacts, climate change also exacerbates other environmental issues leading to a loss of ecosystem services, such as water filtration by naturally occurring ecosystem processes. Restoration and adaptive management can mitigate some of the damage associated with environmental pressures though most projects require substantial monetary investments for sustaining recovery and staff to implement effective, longer-term management programs.

Culture, society, science, and policy Human interactions with domestic species, wildlife, and their environments are grounded in attitudes, values, cultural practices, and societal norms that have been shaped by history, economics, religious beliefs, and the environment itself. Some practices honor the interconnectedness of life on earth and the circularity of energy and nutrient flows, which inform their behaviors toward their environment and other species. Many of these recognize that actions in the

10

1. Introduction

FIGURE 1.10

Climate change feedback loops showing how rising temperatures accelerate the release of additional greenhouse gases or hamper their uptake by plants. From Climate Emergency Institute.

present will affect the ability to pursue future endeavors. Others do not, waiting until it is too late to reverse negative feedback loops associated with overharvesting, resource extraction, land conversion, and pollution before they harm their own (or other/future) human communities. Lack of understanding of science and skepticism toward the scientific community hinders the development and incorporation of newer practices that have fewer deleterious effects on other species and ultimately humans. Nonetheless, humans appear to have innate fondness for the natural world (“biophilia”), and most societies have practiced some form of conservation, whether it is the establishment

of protected areas or the collective agreement to conserve species, such as the enactment of the US Endangered Species Act. On a global scale, international treaties have attempted to tackle issues that transcend national boundaries, such as whaling, biodiversity loss, and climate change. These endeavors are not selfsacrifice but instead are in the long-term best interest of all human populations. Effective changes in policy used to direct future actions require (1) agreement on the existence of a problem and availability of solutions, (2) collaboration and willingness to make shortterm sacrifices, and (3) ability to take collective action for the betterment of current and future generations. As noted earlier, this book does

11

Defining the conceptual framworks

CLIMATE IMPACTS

Extreme Weather

Rising Sea Levels

Increasing CO2

Rising Temperatures

Air pollution

Increasing allergens

Water and food supply impacts

Extreme heat

Poor water quality

Environmental degradation

Severe weather

EXPOSURES

Vector-borne diseases

ENVIR. & INSTITUTIONAL CONTEXT

Increasing allergens

Land-use change

SOCIAL & BEHAVIORAL CONTEXT

Water borne pathogens

Clinical Care

HEALTH OUTCOMES

Ecosystem change Infrastructure condition Geography Agricultural production & livestock use

Respiratory allergies

Respiratory allergies, asthma

Malnutrition, diarrheal disease

Asthma, cardiovascular disease

Cholera, cryptosporidiosis, campylobacter, leptospirosis

Forced migration, civil conflict, mental health impacts

Malaria, dengue encephalitis, hantavirus, Rift Valley fever

Heat-related illness and death, cardiovascular failure

Social & Economic

Injuries, fatalities, mental health impacts

Genetics and Biology

Built Environment

Health Behaviors

Diarrheal disease

Injuries, fatalities, mental health impacts

FIGURE 1.11 Climate change impacts on human health. Extreme weather, rising sea levels, increasing CO2 levels, and rising temperatures increase exposures to negative elements resulting in poor health outcomes. All are nested within the environmental, institutional, social, and behavioral contexts in which a person lives. Modeled after EPA: https://www.epa.gov/sites/default/ files/2016-07/8129_intr_pathwaysweb.png.

not focus on the role of policymaking to tackle these interconnected global challenges but instead outlines two frameworks that can inform courses of action that can be incorporated into policies and laws once they have been shown to be effective.

Defining the conceptual framworks Two concepts have emerged as humanity attempts to tackle the negative outcomes to human and ecosystem health caused by these

intertwining complex global challenges. Although numerous concepts and approaches exist, most are specifically focused on a very specific or restricted issue or task. For example, a chemical spill may happen in a sequestered area, which then may endanger living organisms. An EPA Risk Assessment (EPA/630/R-92/001, Norton et al., 1992) can provide actionable information for public safety and management of the affected area. This volume focuses on two concepts that share some characteristics and differ in other perspectives. Both concepts look at threats and challenges to the health of living

12

1. Introduction

organisms and establishing an approach to mitigate adverse outcomes. In addition, both concepts look to the underlying causes and factors driving the demise of health, albeit from an integrative view (One Health) or from an individual human-oriented view (The Exposome). The One Health concept is defined by the US Centers for Disease Control and Prevention as “a collaborative, multisectoral, and transdisciplinary approachdworking at the local, regional, national, and global levelsdwith the goal of achieving optimal health outcomes recognizing the interconnection between people, animals, plants, and their shared environment.” The second concept is The Exposome, which considers external and internal exposures from the environment, including chemical pollutants, noise, and living conditions, and lifestyle/behaviors, such as diet, exercise, and sleep, as they affect the health of an individual throughout their lifespan (Wild, 2012). The background and associated frameworks for each concept are detailed below.

One Health The idea that human health is linked to that of animals and the larger environment is not new. In fact, a fundamental tenant of the One Health concept is that there is an immutable interrelationship between human health and our surroundings, notably the environment. The interdependence of communities and healthy ecosystems has been integrated into human cultures across the world from the Inka of Peru to the Taoist of ancient China. Writings by early Greek and Roman scholars emphasized the importance of the environment and well-being of the earth on the health and prosperity of communities. The inclusion of veterinary medicine and the link between the health of domestic animals and humans arose in the 1800s as people began to understand the movement of pathogens between people and domestic animals (Fig. 1.12). However, the term “One Health” was not coined until 2004 when the focus shifted

specifically to acknowledging our shared evolutionary history with other animals and how our conserved physiological characteristics making us susceptible to their pathogens. This concern led to efforts aimed at preventing circumstances in which those pathogens overcome multitude of barriers to move from animals to people, termed “spillover events.” As depicted in Fig. 1.13, the potential for spillover events to occur increases as human communities and/or their domestic animals come into increasing contact with wildlife, often instigated by habitat loss from encroaching agricultural, developments into wildlife areas, and other economic drivers. These “zoonoses,” diseases from pathogens with origins in other animals, became the predominant focus of One Health and broad the concept into the mainstream as the world grappled with the emergence of novel viruses, such as Ebola virus, Avian influenza, and the coronaviruses SARSCoV-1 that caused severe acute respiratory syndrome, and more recently SARS-CoV-2 that caused COVID-19. The critical role of ecosystem health was incorporated into the One Health concept as it became evident that disease spillover events from wildlife to people often are precipitated by stress caused by environmental degradation. There are numerous examples of humanewildlife conflicts, particularly land use change resulting in habitat loss, bringing wildlife and humans in closer proximity. Humans, domestic animals, and wildlife must also contend with the effects of climate change that may alter their environments in unpredictable ways, such as increasing or decreasing rainfall resulting in floods, droughts, and more conflict over water and foraging resources. Coincident with habitat loss, increasing presence of environmental pollutants impacts wildlife and humans alike. All contribute to the deterioration of the health of humans, wildlife, and the ecosystem, and all are now considered in the current One Health framework. As the incidence of novel diseases and the necessity for ongoing surveillance to identify them

Defining the conceptual framworks

BRIEF TIMELINE OF

ONE HEALTH Dr. Rudolf Vinchow, a pathologist in Germany, recognizes 1821- the link between human and animal health, coins the term 1902 “zoonosis”, advocates for improved veterinary education.

1876

Dr. William Osler, a Canadian medical doctor and first Physician in Chief at Johns Hopkins Hospital, authors “The Relation of Animals to Man” highlighting comparative pathology and the concept that humans and animals require the same approach to medicine.

1947

Center for Disease Control and Prevention (CDC) establishes the Veterinary Public Health Division to respond to public health threats such as rabies, brucellosis, etc.

1964

Calvin Schwabe coins the term “One Medicine” and calls for a unified approach against zoonoses that uses both human and veterinary medicine.

2004

The Wildlife Conservation Society publishes the 12 Manhattan Principles, calling for an international interdisciplinary approach to prevent disease and forming the basis of the “One Health. One World” concept.

2008

One Health becomes a recommended approach and a political reality. “Contributing to One World, One HealthA Strategic Framework for Reducing Risks of Infectious Diseases at the Animal-Human -Ecosystems Interface” is officially released during the International Ministerial Conference on Avian and Pandemic Influenza in October in Sharm el-Sheikh, Egypt.

2009

Key recommendations for ‘One World. One Health’ are developed. United States Agency for International Development (USAID) establishes the Emerging Pandemic Threats program while the CDC launches the One Health Office.

2010

The Hanoi Declaration recommending broad implementation of One Health is unanimously adopted by 71 countries. CDC, World Organization for Animal Health (OIE), the Food and Agriculture Organization of the United Nations (FAO), and the World Health Organization (WHO) convene a meeting entitled “Operationalizing ‘One Health’: A Policy Perspective –Taking Stock and Shaping an Implementation Roadmap” to operationalize global One Health collaborations. The United Nations and the World Bank recommend adoption of One Health approaches.

2012

The Global Risk Forum sponsors the first One Health Summit.

2013

The Second International One Health Congress welcomes over 1,000 participants and encourages collaboration across disciplines to develop effective policies related to human, animal, and environmental health.

FIGURE 1.12

History of the One Health concept from 1820s to 2013.

13

14

Transmission

1. Introduction

HU MA NS

Contact

Biology

Social Norms Livelihood Systems Settlement Patterns Governance/ Politics

HUMAN

Type Intensity Frequency Duration

ANIMALS

Movement

W ANI ILD MAL

Land Use Climate Change

Pathogen Ecology Density Diversity

Disease Transmission

Biology

C STI ME ALS O D NIM A

S

ENVIRONMENT

FIGURE 1.13

Disease transmission from animals to humans occurs when a combination of factors coincides, such as land use change by people resulting in closer contact of stressed infected wildlife with people or domestic animals. Major factors that influence the outcomes of these interactions include (1) human activities, such as cultural practices, settlement patterns, and land use; (2) wildlife, such as density, diversity, and pathogen ecology of animals; and (3) contact situation with variation in type, intensity, frequency, and duration of contact. Based on Woldehanna and Zimicki (2015).

early has become a focus of national and international organizations, the One Health framework has been adopted to provide the needed structured and multidisciplinary approach while also having the capability to express quantitative outcomes to measure success. Disciplines as diverse as Zoology, Human Medicine, and Earth Sciences come together to find the origins of and treat the disease while also exploring ways to prevent its reemergence (Fig. 1.14). National efforts in Ethiopia, Rwanda, and Nepal (see Additional resources for details) have used a One Health approach and international organizations, including the Wildlife Conservation Society, have developed One Health plans coalescing these more coordinated approaches to predict, prepare for, and ideally prevent

future crises instead of reacting to them. As the world gains insight into the complexity of factors impacting human health, One Health has emerged as a conceptual framework useful in developing and implementing approaches to manage the potential for transmission of pathogens from wildlife to human populations, especially as habitat decreases driving human and wildlife populations in closer juxtaposition. The concept has also been used to address antibiotic-resistant germs, vector-borne diseases, diseases in food animals, human-animal bond, and contamination of water. All these areas benefit from One Health’s recognition of the essential need for sustaining healthy wildlife and ecosystems to keep human communities healthy.

15

Human Medicine

&

dividual & co n | in mm ptio un a ity ad

man Health Hu

g ein ll b we

res ilie nc e

Defining the conceptual framworks

Social Sciences & Humanities

Agriculture & Engineering

Comparative Medicine he a he

th

y, w

ildl if

e po p u

E nv i r o

s afe

lations

s a n it a ti o n

, sh

nm

od

lt h

fo

le ,

al

r

,

ab

ea

en

lH

tal

A ni m a

e s t ic a n i m a l s | s t

Zoology

H e alt h

do m

Veterinary Medicine

elter,

lth y

ONE HEALTH

air,

wa

te

Ecosystem & Earth Sciences or Geosciences

Biology (Ecology)

FIGURE 1.14

One Health concept embraces the interrelation of humans, animals, and environment. Given this breadth, many disciplines are brought together under this framework.

KEY ELEMENTS OF THE ONE HEALTH CONCEPTUAL FRAMEWORK 0 One Health embraces the interconnection and interdependence of health and wellbeing of humans, animals, and the environment, its three key domains. 0 Understanding the origin of zoonoses and the drivers of their emergence are as important as treating the disease because this allows for developing strategies to prevent future spillover events. 0 Human activities of the 21st century, particularly global trade, international travel, and greater accessibility of all places on earth, are increasing the potential for global effects of disease spillover events.

0 The current One Health framework accepts that old solutions and practices may not be effective when applied to today’s complex problems. 0 One Health looks beyond the specific disease to improve health despite underlying health factors that may predispose individuals to disease. 0 One Health not only considers infectious disease but also other exposures related to health and is open/willing to engage scientists from all disciplines, policy makers, and public advocacy groups to produce better health outcomes.

16

1. Introduction

Putting the One Health concept into practice begins with determining if a problem or program contains elements from each of the three One Health domains: humans, animals, and the environment. Fig. 1.15 outlines the flow and provides specific examples of how to determine if each of the areas is represented. Once the criteria shown in Fig. 1.15 have been established and the decision to pursue a One Health approach has been made, then the actionable framework shown in Fig. 1.16 is followed in a stepwise manner using structured decision-making to prioritize the sequence and scope of each activity. Opportunities for feedback and reassessment are imperative to adapt programmatic goals and refine activities. An overall One Health conceptual framework can be envisioned as a process that is triggered by an unusual event that brings attention to the potential of a significant problem (Fig. 1.16). This observation could serve as an early warning signal, which would then require more in-depth assessment to evaluate the magnitude of the potential problem. Technology is valuable both to assess the problem and to establish measures and metrics that can be used throughout to monitor change. At its core, the One Health conceptual framework engages existing assets and milestones for actions through enlisting input from stakeholders from many disciplines and the community. As shown in Fig. 1.17, coordination, communication, and collaboration among diverse stakeholders are key to success. Implementation of the program is an iterative process involving reassessments and adjustments as needed until the interventions become permanent. Finally, successful programmatic elements of the framework can be upscaled for applications to other challenges to human-

animal-environmental health on local, regional, national, and international scales.

The Exposome While the One Health approach brings together human, animal, and ecosystem perspectives, the Exposome conceptual framework is decidedly human-centric and stems from a biomedical viewpoint. It primarily considers the influence of exogenous exposures on the health of an individual at a point in time or over their lifespan. Following the complete sequencing of the human genome and subsequent mapping of genes and studying their functions by the Human Genome Project, Wild (2005) urged the initiation of a Human Exposome Project to link geneeenvironment interactions, which account for cancer and other chronic diseases that are not solely genetic in nature. This line of inquiry is particularly compelling given only a small percentage of diseases result from genetics alone, and the incidence and progression of disease often arise from environmental effects on the genome. In essence, the Exposome is the missing complement to the genome (Fig. 1.18). The Exposome framework provides an inclusive approach to human health risk assessment linking causal agents, or combinations thereof, with disease incidence. A person’s Exposome was originally defined as “encompassing life-course environmental exposures (including lifestyle factors), from the prenatal period onwards” (Wild, 2005). Early work focused on exposures to environmental chemicals and pollutants through a variety of sources, including diet, air, water, contact with contaminated materials and soils, containing both parent

Defining the conceptual framworks

17

FIGURE 1.15 Flow chart with key components of an overall One Health conceptual framework. These include the three main domains of One Health: human, animal, and environmental health. From Lebov et al. (2017).

18

1. Introduction

Outside Force Disrupts Natural State (e.g., Land use change, Human encroachment into natural areas, humans eating wildlife, domestic animals sharing space with wildlife, chemical spill)

Intervention

Biological Repercussions from Disruptions (e.g., Disease spillover events, fires, animal die-offs)

Intervention

NO

Abnormal Event from Disruption Observed by Surveillance Team (e.g., more dead animals found than normal)

Intervention

NO

Event Assessed for Risk Potential by Experts (e.g., does it meet threshold?)

YES

Background State of Surveillance

Larger Cross Disciplinary Stakeholder Groups Engaged (e.g., local, regional, global)

Intervention

YES

Intervention Effectiveness Assessed

Stepwise Program (developed to monitor, respond, and intervene)

Effective Programs Upscaled

FIGURE 1.16 One Health conceptual framework is used for identifying, assessing, and implementing an actionable program. The process is as follows: (1) external disruption to the current natural state results in (2) biological repercussions, such as disease spillover (3) that are witnessed as abnormal events by the surveillance team; (4) experts assess if the event reaches a risk threshold; (5a) if yes, a cross disciplinary team develops a stepwise program to monitor, respond, and/or intervene, (5b) if no, background surveillance continues, (6) effectiveness of intervention from (5a) is assessed, (7) if effective (yes), the program is upscaled; and (8) if not effective (no), the program is revised.

Defining the conceptual framworks

ONE HEALTH APPROACH Medical professionals Veterinarians Social Scientists Community Members Government Officials

Coordinating

Wildlife Biologists Disease Ecologists Industry Representatives Other Stakeholders

Collaborating

Communicating

Optimal Health and Well-being for people, animals, and the environment

FIGURE 1.17 Stakeholder engagement and collaboration among different disciplines are key components to the One Health framework. Based on CDC and Prevention, National Center for Emerging and Zoonotic Infectious Diseases, C5302365-A.

19

and secondary metabolites. In addition, lifestyle, diet, physical activity, sleep, and stress all play important roles in exacerbating or mitigating the potentially deleterious effects of exposures to chemicals and other environmental factors. More recently, the Exposome concept has expanded to consider environmental exposures associated with living conditions and the built environment down to a person’s microbiome (symbiotic microbiota in an organisms; often differing with bodily area, i.e., intestines, skin, nasal passages, etc.), transcriptome (entire range of all messenger RNA expressed in a cell and organism), and metabolome (inclusive set of small molecule chemicals produced by cells), making it extremely valuable in visualizing the multitude of external factors with which an individual must cope as well as articulating the range of potential physiological responses to these exposures as depicted in Fig. 1.19. Similar to Genomics, or the study of a person’s entire set of genes (genome), Exposomics provides the metrics for describing this suite of molecular, epigenetic, endocrine, immunological, and other physiological responses indicative of environmental exposures and stressors. To account for such a diverse number of interactions over the course of a lifetime, an individual and their exposures would potentially need to be monitored at many scales and extensively over time. Scaling the Exposome up to population level requires extensive data sets on multiple cohorts and intensive computational capacity. Exposomics, the study of the Exposome, attempts to do just that. Interest in this concept has coincided with rapid technical advances in biology and the sequencing of the human genome; thereby providing an opportunity to link exposures and geneeexposure interactions that may account for most cancers and other chronic diseases. More recently, the Exposome conceptual framework bridged the gap to novel infectious diseases when applied to understanding COVID-19-associated mortality in the United States (Gebreyes et al., 2021).

20

1. Introduction

GENE ENVIRONMENT INTERACTION EXPOSOME

Your Health

GENOME

Chemicals

Air, noise

Water

Diet

Exercise

Sleep

Stress

FIGURE 1.18 Geneticeenvironmental interactions showing the impacts of lifestyle, diet, and environment exposures from conception to senescence.

KEY ELEMENTS OF THE EXPOSOME CONCEPTUAL FRAMEWORK 0 The Exposome concept is focused on understanding the internal pathways triggered by internal and external exposures and their physiological consequences in humans. 0 The Exposome incorporates the concept of early exposure leading to later disease as well as a cumulative view of lifetime exposures. 0 The Exposome concept seeks to understand the mechanisms involved in producing the adverse effects from these cumulative

exposures over time for individuals and associated communities. 0 Contaminants and other environmental stressors are important contributors to an individual’s Exposome. 0 The Exposome places high value on medical research to determine how exposures affect humans on a molecular or cellular level, and only then can public health workers turn to interventions to reduce exposures and disease risk.

21

Defining the conceptual framworks

Gut Microbiome

Gene Expression

Biological Responses

Stress/Aging

Metabolomics Epigenetics

Inflammation

THE EXPOSOME Diet & Exercise

Work & School

Internal & Personal Choice

Pollution

Habits

Urban Envir.

Social

Climate

Light & Noise

Green Spaces

Sleep Toxic Chemicals

External & Situational

Community

FIGURE 1.19

An individual’s Exposome incorporates impacts from internal conditions and personal choice, external and situational exposures, and the biological responses to these over the course of a lifetime.

Putting the Exposome concept into practice at the simplest level begins with determining if (1) there has been an exposure and if (2) it resulted in a biological response that may or may not go one to cause disease. As shown in Fig. 1.20, there are multiple steps in which interventions can occur that will effectively limit exposure to

environmental chemicals, reduce adverse effects, or treat existing diseases. However, the exposomics needed to diagnose a specific disease relies on the development of additional tools and capabilities to establish linkages of exposure and adverse effects/diseases as well as to develop effective treatments

22

1. Introduction

Intervention Block pathway to exposure

Interventions can happen at multiple stages to curb physical response or even cut the exposure entirely once it has been identified

Exposure

Intervention Block pathway to response

Physical Response

Intervention Block pathway to process

Outcomes & Disease

Intervention Treat disease

FIGURE 1.20 The Exposome conceptual framework provides a stepwise functional path for assessing and implementing actions, with potential for intervention at multiple steps in the process.

to curtail and, if possible, reverse any pathogenic processes arising from one-time or chronic exposures. Some of these measures are shown in Fig. 1.21 in which multiple physiological and disease indicators occur with exposure to

specific toxins. Having both the metadata (environmental factors) and spatio-temporal information are important in developing reliable models of effect, both for an individual and a community at large. With these data in hand, the Exposome conceptual approach can be effectively used to map a specific disease constellation, with the contingencies and risk factors that promote and exacerbate disease onset and progression. This approach is proving to be an excellent way to visualize the multiple interrelated internal and external environmental challenges that each of us experiences as individuals. The challenge of cataloging a person’s exposome is that exposures and experiences over the lifespan vary with time and age. Fig. 1.22 captures each of these life stages with a subset of the challenges confronted at that time in life. Over time, some of the effects of some stressors will diminish while others may pose cumulative risk to the individual’s health. As one ages, chronic effects from the body’s burden of contaminants can accumulate with potential impacts on healthspan, meaning the “healthy years” that an individual experiences and, in the worst case, lifespan. These stressors may also make an individual more susceptible to disease and to other challenges in their environment as well as exacerbate any preexisting vulnerability from genetic predisposition to some conditions and diseases, such as cancer or neurodegenerative diseases. It is then possible to upscale from individual to population level outcomes that may be impacting an entire community confronted with similar exposures (Fig. 1.23). When scaled up, the Exposome framework and exposomics become powerful tools for biomedical and public health applications. However, the identification of risks must follow a logical sequence that can be customized for every situation and issue. Thus, development of an Exposome Conceptual Framework is complex, must be customized or limited in scope to individual(s) and/or communities, and the metadata that accompany the

Comparing the two concepts through the literature

23

FIGURE 1.21 Complex inputs from varied sources of external exposure are modulated by individual susceptibilities that are expressed in measures provided by exposomics. Developing an Exposome framework includes these sources of exposure and methods to assess the level(s) of exposure and impact indicators. From Huhn et al. (2021).

exposomics analysis for a specific situation must be as complete and inclusive as possible.

Comparing the two concepts through the literature Although both concepts tackle the interrelationship of human, animal, and ecosystem health at some level, they have significantly different vantage points. The results of a Web of Science search for peer-reviewed articles with either

“One Health” or “Exposome” in their titles from 2006 to early 2021 illustrates the areas of overlap and divergence between the two concepts. The search resulted in 2007 items, which after culling out news articles and other nonscientific texts, produced 929 related to “One Health” and 277 for “Exposome,” the lower number of articles indicative of the recent coining of the term. As shown in Fig. 1.24, the subject areas assigned by the search engine to each article reveal four areas of overlap between the two concepts: Public, Environmental, Occupational Health; General

24

1. Introduction

FIGURE 1.22

An individual’s Exposome is subjected to multiple environmental factors over the course of their lifetime, affecting the resilience and overall response to stressors as one ages.

and Internal Medicine; Ecology and Environmental Sciences; and Pharmacology and Pharmacy. Other areas, such as Veterinary Science and Infectious Disease, were exclusively found in One Health citations, whereas Toxicology

and Biochemistry and Molecular Biology are exclusively found in the Exposome literature. In addition to subject area, we categorized each citation by the level of study (molecular, cellular, individual, species, community),

Comparing the two concepts through the literature

25

FIGURE 1.23

An Exposome approach takes into consideration the multiple routes of exposure and stressors affecting the susceptibility of an individual to disease. The health of individuals (personal health outcomes) and that of multiple individuals in the community culminate in health outcomes for the population. From Juarez et al. (2020).

organism (human, nonhuman), point of intervention (origin/driver, intermediate, receiver), and realm (human, domestic animal/agriculture, wildlife, built environment, ecosystem) with the option of including all categories if a citation did indeed study all aspects (Fig. 1.25). Comparing One Health and Exposome in this way reveals a few key differences. In terms of level of study, One Health has a strong bent toward the levels of species and community while the Exposome literature encompasses many more molecular studies as well as those focused on individuals within a population. When examining the points of intervention, both One Health and Exposome studies address intermediate or origin/drivers of problems with less attention paid to the proximate/receiver end. In terms of organism of study, the Exposome is exclusively focused on humans while One Health studies range into nonhuman subjects. The organism of study appears to dictate the realm, with the Exposome literature almost entirely focused on

humans and the built environment whereas the One Health literature also includes numerous studies involving domestic species/agriculture, wildlife, and ecosystems. In many ways the two conceptual frameworks complement each other while having some overlaps, particularly in terms of understanding the impacts of environmental conditions on the health of living organisms. Given their attention to environmental impacts on health, both frameworks have the potential to develop solutions that prevent exposures or take other proactive public health measures. Smoking cessation, as a type of preventative measure, is an example of the power of proactive interventions developed through evidenced-based science and spread through education and other behavior change mechanisms to curb disease progression or even stop it from happening in the first place (see Chapter 6 for more details). As revealed in Fig. 1.25, neither concept focuses extensively on prevention. The strength of both frameworks is

26

1. Introduction

LITERATURE COMPARISON SUBJECT OVERLAP EXPOSOME

ONE HEALTH

No. of Pubs

No. of Pubs

58

Public, Environmental & Occupational Health

Public, Environmental & Occupational Health 257

6

General & Internal Medicine

General & Internal Medicine

15

7

Pharmacology & Pharmacy

Pharmacology & Pharmacy

34

75

Environmental Sciences & Ecology

Environmental Sciences & Ecology 190

NO OVERLAP No. of Pubs

No. of Pubs

60

Toxicology

Veterinary Sciences 244

27

Biochemistry & Molecular Biology

Infectious Diseases 219

24

Chemistry

Microbiology

66

18

Genetics & Heredity

Parasitology

53

11

Respiratory System

Tropical Medicine

85

11

Science and Technology- Other Topics

Biomedical Social Sciences

25

11

Dermatology

Science and Technology- Other Topics

25

11

Engineering

Environmental Sciences & Ecology

23

10

Endocrinology & Metabolism

Dairy & Animal Agriculture

16

9

Allergy

Biodiversity Conservation

75

9

Immunology

Health Care Sciences & Services

27

8

Psychiatry

Immunology

27

8

Pediatrics

Social Sciences- Other Topics

15

5

Neuro- sciences

Education & Educational Research

13

5

Oncology

Life Sciences & Biome

11

5

Medical Informatics

Health Policy & Service

10

4

Computer Science

Food Science & Technology

12

4

Gastroenterology & Hepatology

Virology

10

FIGURE 1.24 Results from Web of Science title search for “Exposome” and “One Health” by subject area showing areas of overlap (top) and divergence (bottom).

27

Comparing the two concepts through the literature

Exposome 226

LEVEL OF STUDY

Molecular

64 68

Cellular

11

Individual

POINT OF PREVENTION ORGANISM

136

20

130

Species

674 3

Community

483 66

Origin/Driver

519 241

Intermediate

665 6

Reciever

130 262

Human

REALM

812

19

Non-Human

474 270

Human Domestic Animal

11

Wildlife

17

923 794 652

231 248

Built Envir. 51

Ecosystem

280 950

900

850

800

750

700

650

600

550

500

450

400

350

300

250

200

150

100

0

50

FIGURE 1.25

One Health

Comparing One Health and Exposome articles by level of study, organism, point of intervention, and realm.

their abilities to unearth the causal mechanisms driving poor health and both could benefit from further transformation to include solutions that prevent these exposures. As will be discussed throughout this volume, preventative measures can be difficult to implement when the drivers

of poor health outcomes are far removed in space and time from their effects. This chapter provides an overview of One Health and the Exposome concepts. The next four chapters will go into detail about these concepts and their associated frameworks as applied to human health

28

1. Introduction

(Chapter 2), domestic animal health (Chapter 3), wildlife health (Chapter 4), and ecosystem health (Chapter 5). In Chapter 6, case studies are used to test the applicability and utility of these conceptual frameworks. Although both conceptual frameworks consider human health, their approaches and views differ. It is these similarities and differences examined in this volume that will guide us to achieving global solutions for environmental and human health.

References and additional resources Acharya, K.P., Karki, S., Shrestha, K., Kaphle, K., 2019. One health approach in Nepal: scope, opportunities and challenges. One Health 12 (8), 100101. Allen-Scott, L.K., Buntain, B., Hatfield, J.M., Meisser, A., Thomas, C.J., 2015. Academic institutions and One Health: building capacity for transdisciplinary research approaches to address complex health issues at the animalehumane ecosystem interface. Acad. Med. 90 (7), 866e871. Amuguni, H., Bikaako, W., Naigaga, I., Bazeyo, W., June 2019. Building a framework for the design and implementation of One Health curricula in East and Central Africa: OHCEAs One Health training modules development process. One Health 7, 100073. https://doi.org/10.1016/ j.onehlt.2018.08.002. Published online 2018 Sep. 8. Andrianou, X.D., Pronk, A., Galea, K.S., Stierum, R., Loh, M., Riccardo, F., et al., January 2021. Exposome-based public health interventions for infectious diseases in urban settings. Environ. Int. 146, 106246. https://doi.org/ 10.1016/j.envint.2020.106246. Epub 2020 Nov 9. PMID: 33181410. Antoine-Moussiaux, N., Janssens de Bisthoven, L., Leyens, S., Assmuth, T., Keune, H., Jakob, Z., et al., 2019. The good, the bad and the ugly: framing debates on nature in a One Health community. Sustain. Sci. 14 (6), 1729e1738. Baum, S.E., Machalaba, C., Daszak, P., Salerna, R.H., Karesh, W.B., 2017. Evaluating one health: are we demonstrating effectiveness? One Health 3, 5e10. Bolon, B., Haschek, W.M., August 2020. The exposome in toxicologic pathology. Toxicol. Pathol. 48 (6), 718e720. https://doi.org/10.1177/0192623320912403. Epub 2020 Mar 19. PMID: 32191165. Buck Louis, G.M., Smarr, M.M., Patel, C.J., March 2017. The exposome research paradigm: an opportunity to understand the environmental basis for human health and disease. Curr. Environ. Health Rep. 4 (1), 89e98. https://doi.org/10.1007/s40572-017-0126-3. PMID: 28194614; PMCID: PMC5363405.

Canali, S., April 22, 2020. What is new about the exposome? Exploring scientific change in contemporary epidemiology. Int. J. Environ. Res. Publ. Health 17 (8), 2879. https://doi.org/10.3390/ijerph17082879. PMID: 32331256; PMCID: PMC7215638. Capua, I., Cattoli, G., 2018. One health (r) evolution: learning from the past to build to a new future. Viruses 10 (12), 725. Cui, Y., Balshaw, D.M., Kwok, R.K., Thompson, C.L., Collman, G.W., Birnbaum, L.S., August 1, 2016. The exposome: embracing the complexity for discovery in environmental health. Environ. Health Perspect. 124 (8), A137eA140. https://doi.org/10.1289/EHP412. PMID: 27479988; PMCID: PMC4977033. Cunningham, A.A., Daszak, P., Wood, J.L.N., 2017a. One Health, emerging infectious diseases and wildlife: two decades of progress? Philos. Trans. R. Soc. Lond. B Biol. Sci. 372 (1725), 20160162. https://doi.org/10.1098/rstb.2016.0167. Cunningham, A.A., Scoones, I., Wood, J.L.N., 2017b. One Health for a changing world: new perspective from Africa. Philos. Trans. R. Soc. Lond. B Biol. Sci. 372 (1725), 20160162. https://doi.org/10.1098/rstb.2016.0162. Davis, M.F., Rankin, S.C., Schurer, J.M., Cole, S., Conti, L., Rabinowitz, P., COHERE Expert Review Group, 2017. Checklist for One Health epidemiological reporting of evidence (COHERE). One Health 4, 14e21. de Moraes, K.F., Santos, M.P.D., Gonçalves, G.S.R., de Oliveira, G.L., Gomes, L.B., Lima, M.G.M., July 17, 2020. Climate change and bird extinctions in the Amazon. PLoS One 15 (7), e0236103. https://doi.org/10.1371/ journal.pone.0236103. PMID: 32678834; PMCID: PMC7367466. Destoumieus-Garzon, D., Mavingui, P., Boetsch, G., Bossier, J., Darriet, F., Duboz, P., et al., 2018. The One Health concept: 10 years old and a long road ahead. Front. Vet. Sci. 5, 14. https://doi.org/10.3389/fvets.2018.00014. Published online 2018 Feb 12. Ellwanger, J.H., Kulmann-Leal, B., Kaminski, V.L., ValverdeVillegas, J.M., Veiga, A.B.G.D., Spilki, F.R., et al., April 17, 2020. Beyond diversity loss and climate change: impacts of Amazon deforestation on infectious diseases and public health. An. Acad. Bras. Cienc. 92 (1), e20191375. https://doi.org/10.1590/0001-3765202020191375. PMID: 32321030. Errecaborde, K.M., Pelican, K.M., Kassenborg, H., Prasarnphanich, O.O., Valeri, L., Yuuzar, E., et al., 2017. Piloting the One Health systems mapping and analysis resource toolkit in Indonesia. EcoHealth 14 (1), 178e181. Errecaborde, K.M., Macy, K.M., Pekol, A., Perez, S., O’Brien, M.K., Allen, I., et al., 2019. Factors that enable effective One Health collaborationsda scoping review of the literature. PLoS One 14 (12), e0224660.

References and additional resources

Escher, B.I., Hackerm€ uller, J., Polte, T., Scholz, S., Aigner, A., Altenburger, R., et al., February 2017. From the exposome to mechanistic understanding of chemical-induced adverse effects. Environ. Int. 99, 97e106. https:// doi.org/10.1016/j.envint.2016.11.029. Epub 2016 Dec 8. PMID: 27939949; PMCID: PMC6116522. Evans, B.R., Leighton, F.A., 2014. A history of One Health. Rev. Sci. Tech. 33 (2), 413e420. Falzon, L.C., Lechner, I., Chantziaras, I., Collineau, L., Courcoul, A., Filippitzi, M.-E., et al., 2018. Quantitative outcomes of a One Health approach to study global health challenges. EcoHealth 15 (1), 209e227. Gebreyes, W.A., Dupouy-Carnet, J., Newport, M.J., Oliveira, C.J., Schlesinger, L.S., Saif, Y.M., et al., January 7, 2021. An external exposome-wide association study of COVID-19 mortality in the United States. Sci. Total Environ. 768, 144832. https://doi.org/10.1016/j.scitotenv.2020.144832. Epub ahead of print. PMID: 33450687; PMCID: PMC7788319. Huhn, S., Escher, B.I., Krauss, M., Scholz, S., Hackermuller, J., Altenburger, R., 2021. Unravelling the chemical exposome in cohort studies: routes explored and steps to become comprehensive. Environ. Sci. Eur. 33, 17. https://doi.org/10.1186/s12302-020-00444-0. Jiang, C., Wang, X., Li, X., Inlora, J., Wang, T., Liu, Q., Snyder, M., September 20, 2018. Dynamic human environmental exposome revealed by longitudinal personal monitoring. Cell 175 (1), 277e291.e31. https://doi.org/ 10.1016/j.cell.2018.08.060. PMID: 30241608; PMCID: PMC6472932. Jones, D.S., Podolsky, S.H., Greene, J.A., 2012. The burden of disease and the changing task of medicine. N. Engl. J. Med. 366 (25), 2333e2338. Juarez, P.D., Hood, D.B., Song, M.A., Ramesh, A., August 12, 2020. Use of an exposome approach to understand the effects of exposures from the natural, built, and social environments on cardio-vascular disease onset, progression, and outcomes. Front. Public Health 8, 379. https:// doi.org/10.3389/fpubh.2020.00379. PMID: 32903514; PMCID: PMC7437454. Karlsson, O., Rocklöv, J., Lehoux, A.P., Bergquist, J., Rutgersson, A., Blunt, M.J., Birnbaum, L.S., December 8, 2020. The human exposome and health in the Anthropocene. Int. J. Epidemiol. https://doi.org/ 10.1093/ije/dyaa231. Epub ahead of print. PMID: 33349868. Kazwala, R., Tekola, B., Shryock, T., Biseisi, M., Patchanee, P., Boonmar, S., King, L.J., 2014. The global one health paradigm: challenges and opportunities for tackling infectious diseases at the human, animal, and environment interface in low-resource settings. PLoS Negl. Trop. Dis. 8 (11), e3257. https://doi.org/10.1371/journal.pntd.0003257.

29

Kelly, T.R., Karesh, W.B., Johnson, C.K., Gilardi, K.V., Anthony, S.J., Goldstein, T., et al., 2017. One Health proof of concept: bringing a transdisciplinary approach to surveillance for zoonotic viruses at the human-wild animal interface. Prev. Vet. Med. 137 (Pt B), 112e118. Kock, R., Haider, N., Mboera, L.E.G., Zumia, A., 2019. A OneHealth lens for anthrax. Lancet Planet. Health 3 (7), e285ee2286. https://doi.org/10.1016/S2542-5196(19) 30111-1. Lavorel, S., Locatelli, B., Colloff, M.J., Bruley, E., March 16, 2020. Co-producing ecosystem services for adapting to climate change. Philos. Trans. R. Soc. Lond. B Biol. Sci. 375 (1794), 20190119. https://doi.org/10.1098/ rstb.2019.0119. Epub 2020 Jan 27. PMID: 31983325; PMCID: PMC7017776. Lebov, J., Grieger, K., Womack, D., Zaccaro, D., Whitehead, N., Kowalcyk, B., MacDonald, P.D.M., 2017. A framework for One Health research. One Health 3, 44e50. Lerner, H., Berg, C., 2017. A comparison of three holistic approaches to health: One Health, EcoHealth, and Planetary Health. Front. Vet. Sci. 4, 163. https://doi.org/10.3389/ fvets.2017.00163 eCollection). Macapagal, E., 2020. One Health: an extensive work in progress that includes animals in the human health picture. Animal Scene. Manila Bulletin Publications, Inc. https://animalscene.ph/2020/10/02/one-health-anextensive-work-in-progress-that-includes-animals-in-thehuman-health-picture/. Mackenzie, J.S., Jeggo, M., 2019. The One Health approachd why is it so important? Trop. Med. Infect. Dis. 4 (2), 88. https://doi.org/10.3390/tropicalmed4020088. Maitre, L., de Bont, J., Casas, M., Robinson, O., Aasvang, G.M., Agier, L., et al., September 10, 2018. Human Early Life Exposome (HELIX) study: a European population-based exposome cohort. BMJ Open 8 (9), e021311. https://doi.org/10.1136/bmjopen-2017-021311. PMID: 30206078; PMCID: PMC6144482. Mi, E., Mi, E., Jeggo, M., 2016. Where to now for One Health and ecohealth? EcoHealth 13 (1), 12e17. Miller, G.W., Jones, D.P., 2014. The nature of nurture: refining the definition of the exposome. Toxicol. Sci. 137 (1), 1e2. https://doi.org/10.1093/toxsci/kft251. Misra, B.B., November 23, 2020. The chemical exposome of human aging. Front. Genet. 11, 574936. https://doi.org/ 10.3389/fgene.2020.574936. PMID: 33329714; PMCID: PMC7732411. Niedzwiecki, M.M., Walker, D.I., Vermeulen, R., ChadeauHyam, M., Jones, D.P., Miller, G.W., January 6, 2019. The exposome: molecules to populations. Annu. Rev. Pharmacol. Toxicol. 59, 107e127. https://doi.org/ 10.1146/annurev-pharmtox-010818-021315. Epub 2018 Aug 10. PMID: 30095351.

30

1. Introduction

Nieuwland, J., Meijboom, F.L.B., 2020. One Health: how interdependence enriches veterinary ethics education. Animals (Basel) 10 (1), 13. https://doi.org/10.3390/ ani10010013. Norton, S.B., Rodier, D.J., Gentile, J.H., van der Schalie, W.H., Wood, W.P., Slimak, M.W., 1992. A framework for ecological risk assessment at the EPA. Environ. Toxicol. Chem. 11, 1663e1672. Nyatanyi, T., Wilkes, M., McDermott, H., Nzietchueng, S., Gafarasi, I., Mudakikwa, A., et al., 2017. Implementing One Health as an integrated approach to health in Rwanda. BMJ Glob. Health 2, e000121. https://doi.org/ 10.1136/bmjgh-2016-000121 for additional material published online only, see. O’Brien, E., Xagoraraki, I., 2019. A water-focused one-health approach for early detection and prevention of viral outbreaks. One Health 7, 100094. https://doi.org/ 10.1016/j.onehlt.2019.100094. Pelican, K., Salyer, S.J., Barton Behravesh, C., Belot, G., Carron, M., Cava, F., et al., 2019. Synergising tools for capacity assessment and One Health operationalization. Rev. Sci. Tech. 36 (1), 71e89. Peters, A., Hoek, G., Katsouyanni, K., February 2012. Understanding the link between environmental exposures and health: does the exposome promise too much? J. Epidemiol. Community Health 66 (2), 103e105. https://doi.org/10.1136/jech-2011-200643. Epub 2011 Nov 11. PMID: 22080817. Pieracci, E.G., Hall, A.J., Gharpure, R., Haile, A., Walelign, E., Deressa, A., et al., 2016. Prioritizing zoonotic diseases in Etheopia using a one health approach. One Health 2, 131e135. Pimm, S.L., Jenkins, C.N., Abell, R., Brooks, T.M., Gittleman, J.L., Joppa, L.N., et al., 2014. The biodiversity of species and their rates of extinction, distribution, and protection. Science 344 (6187). https://doi.org/10.1126/ science.1246752, 1246752e1246752. Rabinowitz, P.M.G., Pappaioanou, M., Bardosh, K.L., Conti, L., 2018. A planetary vision for one health. BMJ Glob. Health 3 (5), 3001137. https://doi.org/10.1136/ bmjgh-2018-001137. Rappaport, S.M., JanuaryeFebruary 2011. Implications of the exposome for exposure science. J. Expo. Sci. Environ. Epidemiol. 21 (1), 5e9. https://doi.org/10.1038/jes.2010.50. Epub 2010 Nov 17. PMID: 21081972. Ritchie, H., Roser, M., 2019. Age Structure. Published online at. Retrieved from: OurWorldInData.org. (Accessed 26 June 2022) https://ourworldindata.org/age-structure. Accessed on. Ritchie, H., Roser, M., 2021. Biodiversity. Published online at OurWorldInData.org. Retrieved from. https:// ourworldindata.org/biodiversity.

Roser, M., Ritchie, R., Ortiz-Ospina, E., 2013. World Population Growth. Published online at OurWorldInData.org. Retrieved from. https://ourworldindata.org/worldpopulation-growth. R€ uegg, S.R., Nielsen, L.R., Buttigieg, S.C., Santa, M., Aragrande, M., Canali, M., et al., 2016. A systems approach to evaluate One Health initiatives. Front. Vet. Sci. 5, 23. https://doi.org/10.3389/fvets.2018.00023. Rwego, I.B., Babalobi, O.O., Musotsi, P., Nzietchueng, S., Tiambo, C.K., Kabasa, J.D., et al., 2016. One Health capacity building in sub-Saharan Africa. Infect. Ecol. Epidemiol. 6. https://doi.org/10.3402/iee.v6.34032. Sille, F.C.M., Karakitsios, S., Kleensang, A., Koehler, K., Maertens, A., Miller, G.W., et al., 2020. The exposomeda new approach for risk assessment. ALTEX 37 (1), 3e23. https://doi.org/10.14573/altex.2001051. PMID: 31960 937. Siroux, V., Agier, L., Slama, R., June 2016. The exposome concept: a challenge and a potential driver for environmental health research. Eur. Respir. Rev. 25 (140), 124e129. https://doi.org/10.1183/16000617.0034-2016. PMID: 27246588. Sleeman, J.M., DeLiberto, T., Nguyen, N., 2017. Optimization of human, animal, and environmental health by using the One Health approach. J. Vet. Sci. 18 (S1), 263e268. https://doi.org/10.4142/jvs.2017.18.S1.263. Spencer, J., McRobie, E., Dar, O., Rehman-Shephert, A., Hasan, N., Hanefeld, J., Khan, M., 2019. Is the current surge in political and financial attention to One Health solidifying or splintering the movement? BMJ Glob. Health 4 (1), e001102. https://doi.org/10.1136/bmjgh-2018001102. Stingone, J.A., Buck Louis, G.M., Nakayama, S.F., Vermeulen, R.C., Kwok, R.K., Cui, Y., et al., March 20, 2017. Toward greater implementation of the exposome research paradigm within environmental epidemiology. Annu. Rev. Publ. Health 38, 315e327. https://doi.org/10.1146/annurev-publhealth-082516012750. Epub 2017 Jan 6. PMID: 28125387; PMCID: PMC5664945. Subramanian, A., Khatri, S.B., March 2019. The exposome and asthma. Clin. Chest Med. 40 (1), 107e123. https:// doi.org/10.1016/j.ccm.2018.10.017. Epub 2018 Dec 20. PMID: 30691706. Vermeulen, R., Schymanski, E.L., Barabasi, A.L., Miller, G.W., January 24, 2020. The exposome and health: where chemistry meets biology. Science 367 (6476), 392e396. https://doi.org/10.1126/science.aay3164. PMID: 31974245; PMCID: PMC7227413. Vesterinen, H.M., Dutcher, T.V., Errecaborde, K.M., Mahero, M.W., Macy, K.W., Prasamphanich, O.-O., et al., 2019. Strengthening multi-sectoral collaboration

References and additional resources

on critical health issues: One Health systems mapping and analysis resource toolkit (OH-SMART) for operationalizing One Health. PLoS One 14 (7), e0219197. https:// doi.org/10.1371/journal.pone.0219197. Vineis, P., Robinson, O., Chadeau-Hyam, M., Dehghan, A., Mudway, I., Dagnino, S., October 2020. What is new in the exposome? Environ. Int. 143, 105887. https:// doi.org/10.1016/j.envint.2020.105887. Epub 2020 Jun 30. PMID: 32619912. Vrijheid, M., Fossati, S., Maitre, L., Marquez, S., Roumeliotaki, T., Agier, L., et al., June 2020. Early-life environmental exposures and childhood obesity: an exposome-wide approach. Environ. Health Perspect. 128 (6), 67009. https://doi.org/10.1289/EHP5975. Epub 2020 Jun 24. PMID: 32579081; PMCID: PMC7313401. Wild, C.P., August 2005. Complementing the genome with an “exposome”: the outstanding challenge of

31

environmental exposure measurement in molecular epidemiology. Cancer Epidemiol. Biomarkers Prev. 14 (8), 1847e1850. https://doi.org/10.1158/1055-9965.EPI05-0456. PMID: 16103423. Wild, C.P., February 2012. The exposome: from concept to utility. Int. J. Epidemiol. 41 (1), 24e32. https://doi.org/ 10.1093/ije/dyr236. Epub 2012 Jan 31. PMID: 22296988. Williams, M., 2003. Deforesting the earth: from prehistory to global crisis. University of Chicago Press. Woldehanna, S., Zimicki, S., March 2014. An expanded One Health model: integrating social science and One Health to inform study of the human-animal interface. Soc Sci Med 129, 87e95. https://doi.org/10.1016/j.socscimed.2014.10.059. Epub 2014 Nov 1. PMID: 25464873; PMCID: PMC7115783. Zeder, M.A., 2015. Core questions in domestication research. Proc. Natl. Acad. Sci. USA 112 (11), 3191e3198. www. pnas.org/cgi/doi/10.1073/pnas.1501711112.

C H A P T E R

2 Human Health Humans have changed and continue to change the planet in complex ways, such as by deforestation, industrialization, urbanization, and domestication of animals, and these changes have both improved and compromised human health over the centuries. The panorama shown

One Health Meets the Exposome https://doi.org/10.1016/B978-0-323-89873-7.00008-9

in the artwork captures the use of land for cities, towns, farms, and transportation conduits, humanewildlife proximity, and the close interrelationship of humans and domestic animals. This chapter explores these changes and their resulting challenges to human health through

33

© 2023 Elsevier Inc. All rights reserved.

34

2. Human Health

the lens of both One Health and the Exposome specifically addressing (1) population growth and demographic transition, (2) novel diseases, (3) anthropogenic pollution, (4) climate change, and (5) social and economic determinants of health. This exploration is intended to show root causes of human health issues and their interconnections with the environment and other species while uncovering areas for further study.

Humans: history, distribution, and demographics Humans (Homo sapiens) are the only extant species of primate in the genus Homo. Our species was born in Africa over 300,000 years ago, and today we inhabit every continent, including Antarctica, where researchers maintain a permanent presence supported with supplies from

more temperate climates. Prior to the development of agriculture 11,000 years ago, which arose independently nearly a dozen times throughout the world, humans lived in small family groups of hunter gatherers. With the rise of agriculture came a surplus of food and fiber, which allowed for labor to be used for other endeavors, such as trade, building infrastructure, and artisanry that culminated in the development of urban centers, including cities in Egypt (Thebes), China (Xi’an), and Iraq (Babylon) that each hosted populations of w100,000 people over 3000 years ago. Fig. 2.1 illustrates where these urban centers and dense populations have occurred over the last 5000 years. These snapshots of the distribution of humans over the centuries reveal areas of migration and preferable zones for habitation. Along with the increase in the population

FIGURE 2.1 Progressive change in the distribution of humans throughout the world over the last 5000 years. These changes are seen through snapshots beginning at 3000 BCE with 1000-year intervals, then with 550-year intervals, and finally with 100year intervals. Compiled by Roser et al. (2013b), adapted from Klein et al. (2010).

Humans: history, distribution, and demographics

worldwide, the final snapshot highlights the concentration of human communities throughout the continents today, including the megatropolises of 20e37 million people in Japan, China, India, South Korea, Mexico, Brazil, and Egypt. As shown in Fig. 2.2, global human population rose gradually from 10,000 BCE to year 0, at which point, there were approximately 190 million people on the planet. The number of humans has swelled from 190 million to over 7 billion today, with a steep exponential increase after the loss of life from the Black Death in the mid-14th century. Over the last 150 years, the move from rural to urban areas has dramatically shifted where and how the majority of humanity lives (Fig. 2.3). Prior to modern sanitation systems, building

35

and environmental regulations, and understanding of infectious diseases, cities were population sinks, meaning more people died than were born there. With today’s transportation and supply networks and proper sanitation and housing, people benefit from city life’s access to jobs, education, and cultural institutions without the health and safety risks from prior centuries. In fact, by 2007, over half of the world’s people were living in urban areas (Fig. 2.3). The most densely populated areas are city states (Macao: 21,000 people/km2; Monaco: 19,000 people/km2; Singapore: 8000 people/ km2) (Fig. 2.4), while larger countries vary greatly in population density, ranging from Bangladesh’s > 1000 people/km2 to Mongolia’s two people/km2. This great variation in density is driven by many factors including availability

FIGURE 2.2 Rate of increase in the estimated global population beginning at 10,000 BCE to the present day, with approximately 190 million at year 0 and increasing to over seven billion today, with a steep exponential increase after the loss of life from the black death in the mid-14th century (Roser et al., 2013b; updated 2022).

FIGURE 2.3 Distribution of people living in urban and rural areas worldwide between 1960 and 2020 showing a continued rapid increase in urban population and diminishing rural population. Ritchie and Roser (2018), updated 2020; data from UN World Urbanization Prospectus (2018).

FIGURE 2.4 The distribution of the global population, showing areas of greater concentrations of human communities in 2022. Roser et al. (2013b), updated 2022.

Humans: history, distribution, and demographics

of inhabitable/arable lands, cultural practices, availability of resources, and climate. The data shown in Fig. 2.5 provides an alternate view of human population density by adjusting the size of the landmass to reflect population totals per country. It graphically depicts the significant heft of India, China, Indonesia, Japan, the Philippines, and Nigeria in contrast to the small populations within relatively large landmasses of Russia, Australia, Canada, and Mongolia. Similar to population density, life expectancy, which denotes the average age of death in a population, is a critical metric for population health. As may be expected, life expectancy varies greatly across the world. The average life expectancy in premodern times (w1700 s) was 26e35 years, reaching a worldwide average of 29 years of age by 1800. Thanks to access to adequate nutrition, clean water, medical care, and other resources associated with industrialization that decreased childhood mortality, life expectancy worldwide has more than doubled over the last 120 years. As shown in Fig. 2.6, gains in life expectancy accelerated after 1900 and have continued to climb, with worldwide life

37

expectancy reaching 72.6 years in 2019. Africa has the lowest life expectancy (63.2 years) while Oceania has the highest (78.5 years). Rising life expectancy has in many cases been followed by a decrease in birth rate (shown in Fig. 2.7 as number of children born per woman), a phenomenon known as the demographic transition. This phenomenon results in great variation in the median age of each country’s current population with those countries experiencing a recent rise in life expectancy having younger populations and higher birth rates. Considering Figs. 2.6, 2.7 and 2.8 together illustrates this correlation. For example, average life expectancy in Italy in 2015 was 83 years where 1e1.5 children were born per woman (2019) and the median population average was 40e45 years (Fig. 2.8). In contrast, average life expectancy in Kenya was 67 years where 3-4 children were born per woman (2019), and median population age range was 14e20 years in 2015. As the global population lives longer, there may be increasing pressure on healthcare and social systems. Ideally, the healthspan, or part of a person’s life during which they are generally in good health, will increase along with greater longevity.

FIGURE 2.5 Human population per country expressed as relative landmass in 2018. Highly concentrated populations, such as China and India, are compared to low density populations of Russia and Australia and other countries. Roser (2018), data from United Nations Population Division Version 3 (2018).

38

2. Human Health

FIGURE 2.6 Estimated life expectancy worldwide in 1800 compared to 1950 and 2015. Data compiled from various sources and visualized by Roser et al. (2013a), updated 2016.

Humans: history, distribution, and demographics

39

FIGURE 2.7 Number of children born per woman in 2019 worldwide showing areas with higher or lower relative birth rate per country. Roser (2014), updated 2020.

This great variation in human population density, median age range, and growth rate has far-reaching implications for each country’s economic growth, political stability, resource needs, and ultimately the health of its populations, which is not only an outcome of but also a critical contributing factor to these complex interdependent systems. More specifically, the rapid increase in human population, mass migration to urban centers, and technological innovations have resulted in substantial changes to the various drivers affecting human health. This is brought into stark relief when considering the leading causes of mortality in the United States in 1900 compared to 2010. In 1900, the top three causes of death were infectious diseases (pneumonia/influenza, tuberculosis, and gastrointestinal infections), whereas by 2010, these had

been replaced by heart disease, cancer, and noninfectious airway disease (Jones et al., 2012, also see Fig. 2.23). This substantial shift reflects not only the increasing average age of the population but also the substantial changes to lifestyle and environment over the last century.

Human health and burden of disease “Health” as defined by the World Health Organization (WHO) is “the state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.” This inclusive definition does not lend itself easily to measurement. There are many metrics used to assess the health of an individual, including weight (body mass index), systolic/ diastolic blood pressure, LDL/HDL cholesterol

40

2. Human Health

FIGURE 2.8 The median age of the population by country in 2015 showing a relative proportion of younger people in Africa compared to North America. Ritchie and Roser (2019), data from UN Population Division (2018).

levels, and blood sugar levels, though these vary with stage of life and from person to person due to genetic differences. Population health, on the other hand, often considers life expectancy as estimated by the WHO’s Healthy Life Expectancy (HALE) according to country. However, HALE does not include causes of poor health as expressed by the “Disability Adjusted Life Years” (DALYs) that combines mortality and morbidity into one metric, called “burden of disease,” and then adjusts life expectancy for years lost due to premature death and years lived with a disability. Table 2.1 shows the relative disease burden from communicable

diseases, noncommunicable disease, and injuries. Improved nutrition, communicable disease control measures, maternal education, and equity have lowered infant and childhood mortality resulting in increasing lifespan worldwide. Accordingly, there has been a shift of disease burden to noncommunicable diseases, such as cardiovascular disease and cancer, which account for more than 25% of the world’s disease burden (Fig. 2.9). In fact, since 1990, there has been a 40% decline in global burden of communicable diseases (Global Burden of Disease Collaborative Network, 2021). However, parts of the world that still suffer greatly

TABLE 2.1

Share of total worldwide disease burden (DALYS) by cause (2019) in percentages categorized by communicable diseases, noncommunicable diseases, and injuries.

Communicable, maternal, neonatal, nutritional diseases

Noncommunicable diseases (NCDs)

Neonatal disorders

7.33% Cardiovascular diseases (stroke, heart disease, heart failure

Tuberculosis and respiratory infections

Injury

15.52% Unintentional injury (falls, drowning, fires, etc.)

4.08%

6.04% Cancers

9.93% Road and other transport injuries

3.06%

Diarrhea, lower respiratory, and other common infections

3.82% Mental and substance use disorder

6.30% Self-harm

1.35%

Malaria and neglected tropical diseases

2.46% Other NCDs

6.02% Interpersonal violence

1.06%

HIV/AIDS/STIs

2.22% Musculoskeletal disorders

5.89% Conflict and terrorism

0.25%

Nutritional deficiencies

1.95% Respiratory disease

4.09% Natural disasters

0.04%

Maternal disorders

0.50% Diabetes, blood and endocrine diseases

4.44%

Neurological disorders (including dementia)

3.84%

Digestive diseases

3.06%

Sense organ diseases

2.59%

Roser and Ritchie (2021), data from Global Burden of Disease Collaborative Network (2021).

FIGURE 2.9 Share of total disease burden by cause (DALYs) worldwide in 2019; blue ¼ noncommunicable disease, red ¼ communicable, gray ¼ injury. Roser and Ritchie (2021), data from Global Burden of Disease Collaborative Network (2021).

42

2. Human Health

FIGURE 2.10 Disease burden (DALY) by country in 2019. One DALY equals one lost year of healthy life. Countries in Africa has the highest burden of disease. Roser and Ritchie (2021), data from Global Burden of Disease Collaborative Network (2021).

from them, such as sub-Saharan Africa, carry the largest disease burden per capita as shown in Fig. 2.10. Finally, it should be noted that these data are pre-COVID-19 pandemic and analyses of these variables may look very different for 2019e22. Disease burden is both a result of economic factors and a driver of them. For instance, countries with low gross domestic product (GDP) have less to spend on measures to combat communicable diseases, such as improved sanitation infrastructure or vaccination programs,

while these same diseases result in a workforce that falls ill more often and thus is not available to work to increase GDP. Other countries, like the United States, spend far more on health expenditures per capita (w$9000 per year) without realizing any additional reductions in disease burden (Fig. 2.11). Examining this figure begs the question: where should countries be investing to decrease disease burden if increased health expenditures above w$2000 per person per year do not appear to result in better outcomes?

Overview of One Health and the Exposome

43

FIGURE 2.11 Relative disease burden (DALYs) and health expenditures per capita in 2014 showing little improvement above a $2000 per capita investment. Roser and Ritchie (2021), data from Global Burden of Disease Collaborative Network (2021) and The World Bank (2017).

Overview of One Health and the Exposome For this reason, this volume takes a broader view of human health and its determinants, which include a person’s genetics and biology, physical environment, behavior/lifestyle, access to medical care, and social and economic circumstances. This book addresses the major challenges affecting human health by considering this larger context. Often environmental factors

that drive health are not considered within the traditional domains of health and healthcare. This chapter focuses on human health and improving health outcomes by bringing together two concepts, the Exposome and One Health, that systematically identify, study, and address the underlying factors and challenges to achieving optimal health for individuals and populations in somewhat separate but complementary pathways (Boxes 2.1 and 2.2).

44

2. Human Health

BOX 2.1

One Health overview

man Health Hu

ea

en

lH

tal

A ni m a

H e alt h

ONE HEALTH

lt h

One Health is defined as a “collaborative, multisectoral, and transdisciplinary approachd working at the local, regional, national, and global levelsdwith the goal of achieving optimal health outcomes by recognizing the interconnection between people, animals, plants, and their shared environment.” At its roots, One Health recognizes humanity’s shared evolutionary history with other animals and how this translates into conserved physiological characteristics that make us susceptible to each other’s pathogens. This basic insight underpins One Health’s proactive efforts to prevent circumstances in which pathogens overcome multitude of barriers to move between animals and people. These “spillover” events are more likely to occur where human communities and/or their domestic

E nv ir o

nm

animals come into increasing contact with wildlife, often instigated by habitat loss from encroaching agricultural, developments into wildlife areas, and other economic drivers. The scope of One Health has evolved beyond a singular focus on infectious disease into a much broader examination of the interrelationship of human populations with their surroundings and the importance of healthy ecosystems in sustaining the health of human communities. The One Health framework provides not only insight into the consequences of exposures, but also develops structured approaches, which bring together diverse disciplines and stakeholders, to confront the complex underlying causes driving poor health in humans, animals, and ecosystems.

BOX 2.2

Exposome overview

Gut Microbiome

Gene Expression

Biological Responses

Stress/Aging

Metabolomics Epigenetics

Inflammation

THE EXPOSOME Diet & Exercise

Work & School

Internal & Personal Choice

Pollution

Habits

Urban Envir.

Light & Noise

Green Spaces

Sleep Toxic Chemicals

External & Situational

Social

The Exposome concept emerged following the sequencing of the human genome when it became apparent that gene-environment interactions account for most cancers and other chronic diseases that are not solely genetic in nature. While a person’s genome is the w3 billion DNA base pairs which code for w25,000 genes that provide the instructions for all cellular functions, a person’s “Exposome” encompasses all environmental exposures a body encounters from conception to senescence. Early work focused on exposures to environmental chemicals and pollutants and later the role of lifestyle, diet, physical activity, sleep, and

Climate

Community

stress were recognized in exacerbating or mitigating the potentially deleterious effects of these exposures. More recently, the Exposome has expanded to consider environmental exposures associated with living conditions and the built environment as well as a person’s microbiome, transcriptome, and metabolome. These Exposomics are extremely valuable in visualizing the effects of multitude of external factors with which an individual must cope. Workflows for gathering and analyzing data from the Exposome are still in process and focus on elucidating the physiological pathways that link exposures to human disease.

46

2. Human Health

Ingredients necessary for human health Before delving into both conceptual frameworks in the context of large challenges to human health, it is important to consider the basic elements necessary for humans to be healthy (Table 2.2). In the simplest form, healthy human beings require these ingredients: access to appropriate nutrition, clean water, clean air, appropriate shelter, healthcare, nature, and community while limiting exposures to toxic substances, infectious diseases, and trauma. The ingredients originate in and are obtained from complex systems that can be disrupted resulting in poor health outcomes for individuals and communities. The focus of this chapter is on the threats that face humans from environmental factors that disrupt, contaminate, or disturb the systems that deliver these ingredients and how both the Exposome and One Health frameworks help us to conceptualize the complex interrelationships of factors and drivers of human health. We will use these ingredients as important assets to assess the potential deleterious effects of the challenges addressed below (Box 2.2). To better visualize where and how humans obtain the ingredients they need and limit exposures to those that cause harm, one must consider the interconnecting worlds in which humans reside within their environment, as simply depicted in Fig. 2.12. Humans live within their societies while sharing their world with domestic animals and wildlife, both within and outside of the built environment, all within and affected by and having effects on the larger ecosystem. Complex interactions take place not just along the edges where the various realms intersect, but within each, where a multitude of interactive factors affect a person’s ability to access the ingredients critical to sustaining health.

Global challenges to human health Traditional approaches targeting human health issues typically focus on proximate causes, such as high cholesterol, with the goal of correcting the imbalance through medication and medical interventions to counter internal ill

effects. Instead, this book pans out to consider the larger backdrop driving human health issues at their sources. This chapter addresses five major challenges to human health: (1) population growth and demographic transition, (2) novel diseases, (3) anthropogenic pollution, (4) climate change, and (5) social and economic disparities. These challenges are considered from the views both of Exposome and One Health with specific emphasis on where the frameworks overlap, the potential targets for intervention to change the trajectory of their effects on human health, and critical areas that neither framework addresses.

Challenge #1: Population growth and demographic transition The steep increase in the global human population, which grew to six billion in 1999 and is projected to reach 9.7 billion by 2050, presents a major challenge to human health as it relates to availability of resources, such as nutrition, clean water, materials, and fuel, and the negative environmental impacts associated with their extraction, use, and disposal. The projected increase in population is not evenly distributed in all areas of the globe; the current highest population resides in Asia while rapid population growth is projected for sub-Saharan Africa through 2050. As noted in the beginning of this chapter, as the global population has grown so has average worldwide life expectancy, which was 45.7 years in 1950 and reached 72.6 years in 2019 (Roser et al., 2013a; data updated in 2020). Increasing age and affluence result in different health issues with older populations typically suffering from noncommunicative diseases associated with lifestyle as opposed to communicable diseases that result in higher childhood mortality. Coincident to the growing uneven distribution of the world’s population and its varied geopolitical landscape is the uneven distribution and consumption of resources. This is largely driven by economic inequities and facilitated by global trade, resulting in pressure to meet local community requirements, which in turn drive land use to satisfy agricultural, housing,

Global challenges to human health

TABLE 2.2

47

Critical ingredients for human health. Unshaded rows indicated ingredients that humans require for health while shaded sections indicate negative ingredients that should be avoided.

Ingredients

Definition and role in human health

Adequate nutrition

Adequate nutrition provides the protein, fats, carbohydrates, vitamins, and minerals needed to grow and fuel the human body. Active adults require on average 2000 calories per day. Globally, 45% of deaths of children under five are linked to malnutrition and an estimated 149 million children under five have stunted growth due to lack of adequate nutrition. 1.9 billon adults are overweight or obese, which comes with its own health impacts, such as heart disease, stroke, diabetes, and some cancers (World Health Organization, 2021; factsheet on nutrition).

Clean water

Clean water is accessible, free of pollutants at harmful levels, with no or low levels of pathogens that cause disease, and in adequate quantities for drinking, bathing, and other household needs. While 74% of the global human population has access to a safely managed drinking-water service on premises, an estimated 785 million people lack basis drinking-water services that can be collected within a 30-minute round trip. At least 2 billion people use a drinking water source contaminated with fecal material. Worldwide an estimated 485,000 deaths each year are attributed to water-borne diarrheal diseases (World Health Organization, 2022; factsheet on drinking water).

Clean air

Clean air is free of harmful levels of contaminants, such as chemicals, fine particulate matter, and biological agents. Worldwide an estimated 7 million people die each year from exposure to indoor (mainly from smoke from cooking fires) and outdoor/ambient air pollution that cause stroke, heart disease, lung cancer, and chronic respiratory diseases. 99% of the world’s population lives in places where air quality levels exceed WHO limits (World Health Organization, 2021; factsheet on household air pollution; factsheet on ambient air pollution).

Shelter

Adequate housing is structurally sound; provides shelter from the elements and from excess moisture, facilitates comfortable temperatures; has adequate sanitation, illumination, space, safe fuel, or connection to electricity; and lacks pollutants, injury hazards, mold, and pests. In high-income countries, people spend 70% of their time at home. Globally, 3.8 million people die each year from complications from living with poor indoor air quality. Exposure to lead from paint and other housing elements causes w850,000 deaths per year (World Health Organization, 2018).

Healthcare

Healthcare is the maintenance or improvement of health via the prevention, diagnosis, treatment, or cure of disease, illness, injury, and other physical and mental impairments delivered by health professionals and/or allied health fields. Nearly half of global population lacks access to healthcare because of financial constraints. Worldwide, 800 million people spend at least 10% of their household budgets on health expenses for themselves or other family members. For almost 100 million people these expenses are high enough to push them into extreme poverty (World Health Organization and The World Bank, 2017).

Nature

Access to parks, recreational areas, and green space are known to enhance both physical and mental health of individuals. Recent studies show that spending at least 120 min per week in nature improves self-reported health outcomes (White et al., 2019). Natural areas also decrease urban heat while plants within them clean the air. In the United States, people of color are three times more likely than whites to live in places with no immediate access to nature driven by racial and economic disparities (Rowland-Shea et al., 2020).

Community

Living in supportive community results in greater safety, resilience, connection, and access to goods and resources, which enhance healthspan and lifespan.

Toxic substances Toxic chemicals are individual chemicals or mixtures of chemicals and their by-products that originate from human activities. They pose both health hazards (irritation, asthma, cancer) and physical hazards (fires, corrosion, explosions) to people and their toxicity depends on the duration and intensity of the exposure. Toxic compound exposure accumulates over the lifespan and contributes to both short-term and chronic illness, such as Alzheimer’s disease. Infectious disease

Infectious disease, also known as communicable disease, is an illness caused by an infection by pathogens, such as viruses, bacteria, fungi, or parasites, which are introduced to the body either directly through food, water, surface, and air contact or through a vector, such as a mosquito. Millions of people die each year from infectious diseases including diarrheal disease (1.53 million), tuberculosis (1.18 million), HIV/AIDS (863,837), malaria (643,381), meningitis (236,222), and hepatitis (79,176) (2019 numbers from Global Burden of Disease Collaborative Network, 2021). Novel infectious diseases mostly come from animal hosts.

Trauma

Trauma can include bodily harm from physical injury or in some cases mental health impacts from traumatic situations. Worldwide, unintentional and violence-related injuries kill 4.4 million people per year. Trauma also causes physical and mental disabilities costing billions of dollars each year in healthcare costs, lost productivity, and law enforcement (World Health Organization, 2021; factsheet on injuries and violence).

2. Human Health

FIGURE 2.12 Interconnecting realms showing where humans live within their societies while sharing their world with domestic animals and wildlife, all within and affected by and having effects on the larger ecosystem. The sizes of the circles reflect relative interrelationships and are not meant to indicate scale.

ECOSYSTEM

LDLIF WI

DOM

ALS

E

MANS HU

E

ST

BU

and resource needs for local use, and for export for income. The complexities of the global distribution of resources, wealth, and trade are also exacerbated by other factors associated with demographic transition as detailed in Box 2.3. Though all humans have the same basic requirements, access to specific resources will vary across regions/countries and between urban and rural communities as do the community structures dictating resource distribution within the population. Table 2.3 explores how population growth indirectly affects a human’s ability to obtain these basic ingredients for health. For example, densely populated areas have higher risk from infectious disease because of overcrowding and its limitations on social distancing. Environmental quality, including air and water quality, may also suffer due to increasing infrastructure associated with population

I LT

EN VIRO N ME

M

48

IC AN

I

NT

growth. However, population growth may also come with some benefits of scale with larger populations able to collectively afford municipal water systems thus increasing access to clean water. In sum, population growth negatively affects access to clean air and nature/recreation while increasing exposures to toxic substances and infectious diseases in most circumstances. The effect of population growth on some ingredients, including access to clean water, nutrition, adequate housing, medical care, and human community, however, is more nuanced and depends on the specific circumstances of individual communities. One Health and Exposome views on population growth, demographic transition, and human health Both the One Health and Exposome concepts deal with the results of increasing human

Global challenges to human health

BOX 2.3

Population growth, demographic transition, economic opportunities, and consumption of natural resources (illustration from Roser et al., 2013b)

Demographic transition is both a product and driver of population growth, economic opportunities, and consumption of resources. Dynamics are listed below: ➢ Improved hygiene and nutrition result in more children living past the age of five. ➢ More children living past the age of five results in women having fewer children. ➢ More women having fewer children means better health outcomes for women and a greater chance for them to work and improve their economic circumstances. ➢ Fewer children per household results in more resources available per child leading to better health and economic outcomes for children.

➢ Increased affluence results in greater consumption of resources thus greater environmental impact per capita. ➢ Fewer children born per woman results in fewer young people to pay into social security systems in countries with more developed economies to care for a large aging population. In summary, there are complex underlying factors that drive local, regional, national, and international distribution of populations and resource consumption.

49

50 TABLE 2.3

2. Human Health

Population growth and demographic transition affect our ability to obtain the ingredients necessary for Human Health. (

¼ combination of positive and negative effects;

¼ negative effects only;

NA ¼ not applicable). Population growth Cumulative effects on:

Ingredients for human health

Explanation

Access to clean water

• Larger populations may have municipal water and sewage systems allowing greater access to clean water for more people, but without these systems, access to clean water will decrease with increasing population as human waste and refuse contaminate water bodies and waterways causing waterborne diseases (communicable). • Large populations require more food, meaning more water is needed for agriculture so less may be available for drinking, cleaning, etc. Agricultural runoff can deteriorate water quality. • More affluent populations (result of demographic transition) consume more water per capita.

Access to nutrition

• Larger populations require more food, which requires land and water to produce. If these are lacking to accommodate more people, there will be fewer calories available per person. • The green revolution and mechanization of agriculture have resulting in more food produced by fewer producers meaning more calories available per work effort allowing more people to be employed outside of agriculture. • More people can grow a greater diversity of crops, which could increase diet diversity through trade thus increasing nutritional quality with increasing population. • More affluent populations (result of demographic transition) consume more calories per capita meaning more food is required per person.

Access to clean air

• Larger populations produce more fires (agricultural, home kitchen, etc.), transportation exhaust, and pollution from energy production for heating, cooling, light resulting in more air pollution with increasing populations. • More affluent populations (result of demographic transition) consume more resources, many of which are created using fossil fuels and chemicals that contaminate the air.

Access to appropriate shelter

• Larger populations may be able to collectively afford more robust housing that provides greater protection from the elements closer to other amenities. • Larger populations can result in overcrowding in urban areas without appropriate sanitation or safety.

Access to medical care

• Larger populations may be able to afford a larger medical sector that can service a denser population resulting in lower per capita costs and more efficient care delivery. • Institutions may not be able to produce the needed professionals as quickly as needed by the growing populations resulting in fewer healthcare workers per capita. • Healthcare workers may seek employment where pay is highest leaving areas/ countries of need to service areas that can pay more leaving gaps in the local medical system.

Access to nature/ recreation

• Larger populations require more resources extracted from nature resulting in fewer natural areas/less nature in proximity to large populations. • Larger populations tend to congregate in urban areas, which are farther from natural areas and thus more difficult to reach for most urbanites.

51

Global challenges to human health

TABLE 2.3

Population growth and demographic transition affect our ability to obtain the ingredients necessary for Human Health. (

¼ combination of positive and negative effects;

¼ negative effects only;

NA ¼ not applicable).dcont’d Population growth Cumulative effects on:

N/A

Ingredients for human health

Explanation

Access to human community

• Larger populations result in more people living in closer proximity to each other allowing for more human connections and larger human communities to develop. • Larger populations congregate in urban environments, which tend to have more transactional/anonymous human relationships resulting in increased loneliness and less sense of human community. • Larger populations in urban areas with greater density tend have more social services than rural areas.

Limit toxic substances

• Larger populations consume more resources, live in urban areas in closer proximity to industry so are exposed to more toxic substances.

Limit infectious diseases

• Larger populations mean more people living and working close together which increases contact among individuals increasing the spread of infectious diseases (also see above about clean water). • Larger populations push into wild areas where they have greater likelihood of encountering animals with infectious diseases. • Larger populations produce more livestock meaning more opportunities for livestock to be infected by diseases from wildlife.

Limit trauma

• Larger populations have greater density so more likelihood for trauma and violence.

Promote healthy behaviors

populations, albeit from differing viewpoints. One Health approaches the subject of human health from the macro level focusing on the complex interconnected relationship between humans as organisms and their environment. For example, individuals in all communities need housing, nutrition, and other resources and fulfilling these needs is dependent on the local climate and surrounding environment. As the human population grows and demand for resources increases, so does the strain on the environment, which can lead to human health effects from limited resource availability, water pollution associated with increased human presence, encroachment into wildlife habitats and its

associated risks of zoonotic disease spillover events, among other impacts. Specifically, from the historic perspective of One Health, a growing human population means a growing number of people and domestic animals coming into contact with wildlife, which greatly expands the potential for zoonotic disease spillover events. Recent examples of these events include Avian influenza, Ebola, MERS, SARS, and the SARS CoV-2 pandemic. The risk of spillovers to humans is exacerbated by the loss and deterioration of habitat for wildlife related to the expansion of agriculture, growth of communities, and other changes in land use associated with industry and resource

52

2. Human Health

extraction. As habitat becomes more limited, there is not only increasing opportunities for humans and wildlife to come into contact, but also increasing stress on wildlife, which weakens their immune systems making them more prone to diseases outbreaks that could potentially jump to humans. The Exposome framework addresses the growing global human population indirectly in the proximate issues that arise from more people using more resources with its associated increase in pollution, urbanism, and overcrowding. The Exposome focuses on the health effects of an individual’s exposures, both at a moment in time and accumulated exposures over the lifespan, with its main thrust in uncovering the physiological mechanisms involved in the individual’s response to exposures at the cellular and molecular levels. It espouses the value of medical research to explain these effects and importance of gaining an in-depth understanding of the physiological targets as the basis for developing diagnostics that public health workers can use to diagnose and then apply interventions to reduce the disease risk following an exposure. However, there has been much less emphasis on preventing exposures in the first place. The Exposome builds on a wealth of literature that clearly shows the physiological effects of overcrowding and limited resources result in chronic stress that culminate in reduced health span (Sapolsky et al., 2000). What is not captured in either framework? At this point, neither conceptual framework thoroughly treats the impacts of age distribution as an important variable. Changes in age distribution of populations and how human health issues differ by age must be considered in both frameworks when developing indicators of health to understand the effects of environmental challenges on the health of individuals, the community, and the ecosystem. More broadly, neither framework addresses the role of exponential human population growth on

driving many of the environmental issues that affect human health. Specifically, neither framework focuses on preventing additional population growth through education and economic development, both of which are negatively correlated with population growth rate as seen in Fig. 2.13. Neither framework addresses demographic transition and ways to accelerate it in places that have high birth rates but low availability of natural resources.

Challenge #2: Novel diseases Unlike population growth, which indirectly affects human health by disrupting or compromising one’s access to resources or ability to limit negative exposures, novel diseases are a direct assault on the body. Prior to the development of vaccines, antibiotics, and access to proper sanitation and hygiene, infectious diseases were the main causes of mortality worldwide. The increasing threat of novel diseases to global human health, as evidenced by the recent COVID-19 pandemic, has long been recognized even while many other infectious diseases have been reduced or eradicated due to better understanding of their vectors and the development and uptake of preventative measures. Most of these novel infectious diseases arise from animal hosts, diseases referred to as “zoonoses.” In fact, an estimated 60% of infectious diseases in humans and 75% of emerging infectious diseases are zoonoses. The probability of spillover of viruses and other pathogens from animals to people continue to rise, facilitated by society itself. The opposite can also take place with wildlife being sickened from pathogens spread to them from humans and domestic animals. There are multiple contributing factors to the rise and spread of zoonoses as humans and domestic animals come into increasing contact with wildlife due to human encroachment into wildlands, bushmeat trade, and intensive livestock production, among others

53

Global challenges to human health

FIGURE 2.13 Population growth rate by level of development in countries and regions. In 2020, more developed regions had growth rates less than 0.5% whereas least developed countries have growth rates above 2%. Roser et al. (2013b), data from UN Population Division (2019).

outlined in Fig. 2.14. These contributing drivers of spillover events are discussed in more detail in Chapter 4, with consideration of the effects of poaching, illegal wildlife trade, and other factors. Once a spillover event has occurred, it is unclear which factors are the primary drivers for

Illegal & poorly regulated wildlife trade

Deforestation

future spread. Rather, in each case it is a “perfect storm” of selection pressures acting on a subset of microbes that allow them to mutate so they can infect an intermediate host. This mutated form can then infect humans and subsequently spread person to person as depicted in Fig. 2.15.

Intensified agriculture & livestock production

Antimicrobial resistance

FIGURE 2.14 Human activities resulting in increasing zoonosis emergence shown in the context of overlapping human, domestic animal, and wildlife points of contact, which is more likely to occur in situations involving wildlife trade, deforestation, intensified livestock production, and antimicrobial resistance.

54

2. Human Health Stage 1: Original Host Natural species reservoirs typically contain low levels of the pathogen. However, the pathogen may transfer to a new species, a phenomenon known as zoonotic spillover. Stage 2: Intermediate Host In the new host species, the pathogen is present in much higher levels, with increased replication raising the risk of further mutation. Species outside of the native population ranges of the original hosts are especially susceptible to zoonotic spillover.

N1 H5

H7N 9

Stage 3: Human Host Amplification from the intermediate hosts increases the opportunity for the pathogen to mutate and infect humans. With enough exposure, mutation may allow for human-to-human transmission. Virus

He nd ra

RS ME

viru s

Influenza

ah ip en H

Coronavirus

SA RS

us vir ah Nip

FIGURE 2.15 Examples of zoonotic spillover through intermediate hosts by virus type including influenza (N7N9, H5N1), coronavirus (MERS, SARS), and hemipah (Nipah virus, Hendra virus). The stages reveal how a virus moves from original host to intermediate host to humans. Adapted from Bean et al. (2013) and Spevack (2021).

Emerging infectious diseases have taken a great toll on human health since modern recordings of these events. Fig. 2.16 shows the number of cases and deaths in the 20th and 21st centuries, beginning with the Flu of 1918 through the recent COVID-19 pandemic. These numbers do not include the economic burden of these events. For example, the SARS outbreak that

killed 774 people inflicted over $50 billion in economic losses from canceled travel and decreased economic output during lockdown measures (Lee and McKibbin, 2004). As of this writing, there have been 452 million cases of COVID-19 with approximately 6.02 million deaths, though the World Health Organization is estimating the numbers could be as high as 15 million

55

Global challenges to human health

19862019

1918

Mad Cow Disease

1968 1937

Hong Kong Flu

1918 Flu ~20-50M Deaths

~1-4M Deaths

Nipah virus

Swine flu (H1N1 Influenza)

Deaths > 106

Deaths > 150,000 575,000

Deaths > ~232

(H3N3 Influenza)

West Nile virus

(H1N1 Influenza)

2009

1999

1976

? Deaths

2002-2003

Ebola virus

SARS

Deaths > ~15,000

Deaths 774

Coronavirus

1900 1994

Asian Flu (H2N2 Influenza)

~1.1M Deaths

HIV

Hendra virus

2013

Deaths 4

Avian flu (H7N9 Influenza)

27-47M Deaths 19571958

Deaths 610

COVID-19 Coronavirus

Deaths ~6M

2012

1981

1997

Avian Flu

MERS Coronavirus

2020

(H5N1 Influenza) Deaths 812 Deaths > 371

FIGURE 2.16 Timeline documenting the emergences of significant zoonoses noting their original hosts, vectors, intermediate hosts, and human death tolls. Based on United Nations Environment Programme and International Livestock Research Institute (2020) and Bean et al. (2013).

(Adam, 2022). It will take years to retrospectively tabulate the full consequences of the COVID-19 pandemic on economic loss, damages to communities from loss of homes and livelihoods, and the movement of people seeking work. Although the direct impacts of novel diseases on human health are devastating, their indirect impacts are numerous, wide-ranging, and potentially more damaging. Table 2.4 explores how novel diseases can indirectly affect a human’s ability to obtain the basic ingredients for health. For example, novel diseases may cause a surge of patients afflicted with it resulting in decreased

capacity of the medical system to treat those with chronic diseases and suffering from other health crises. The effects on environmental quality, including air and water quality, could be mixed depending on how the novel disease and containment measures affect local economies and the workforce. Novel disease’s effect on access to nutrition and adequate housing is overwhelmingly negative while its effect on our abilities to limit toxic exposures and other infectious diseases is more nuanced and depends on the specific circumstances of individual communities.

56 TABLE 2.4

2. Human Health

Novel diseases affect our ability to obtain the ingredients necessary for Human Health (

¼ combination of positive and negative effects;

¼ negative effects only).

Novel diseases Cumulative effect on:

Ingredients for human health

Explanation

Access to clean water • Economic disruptions due to novel diseases may result in decreased economic activity resulting in less water pollution from agriculture and industry. • Economic disruptions due to novel diseases may result in fewer people being able to afford clean water. Access to nutrition

• Economic disruptions due to novel diseases may result in worker shortages and supply chain issues that decrease the availability of food. • Economic disruptions due to novel diseases may result in fewer people being able to afford food, especially fresh foods.

Access to clean air

• Economic disruptions due to novel diseases may result in decreased economic activity resulting in less air pollution from transportation and industry sectors. • Controlling vectors of novel diseases may require the spray of chemicals resulting in local air pollution.

Access to appropriate shelter

• Economic disruptions due to novel diseases may result in fewer people being able to afford rent resulting in their losing appropriate shelter. • Economic disruptions due to novel diseases may result in worker shortages and supply chain issues that decrease the rate of new buildings coming to market resulting in a decrease in housing supply.

Access to medical care

• Patients ill with novel diseases may surge in hospitals thus decreasing the health system’s capacity to treat patients with chronic disease resulting in a loss of access to medical care. • People may avoid treatment because of fear of being exposed to the novel disease while in the medical system. • Health workers may also fall ill to the novel disease resulting in fewer providers to care for the sick.

Access to nature/ recreation

• Social distancing to avoid a novel disease during an outbreak may result in fewer people leaving their homes thus decreasing their access to nature/recreation. • Social distancing to avoid a novel disease during an outbreak may result in more people recreating outdoors instead of using indoor facilities thus increasing time in nature.

Access to human community

• Containment of novel infectious diseases require limiting human interactions, which in turn limit building and sustaining human community.

Limit toxic substances

• Novel diseases that result in serious disruptions to local and global economies may halt some industrial operations thus decreasing the creation and use of some toxic substances. • Novel diseases may prompt the use of some toxic substances, such as DDT, to control vectors of disease resulting in more potential harmful exposures.

Limit infectious diseases

• Social distancing to avoid contracting a novel disease during an outbreak may limit the spread of other infectious diseases. • Novel diseases are not well understood so it can be difficult to determine ways to limit exposures to them.

57

Global challenges to human health

TABLE 2.4

Novel diseases affect our ability to obtain the ingredients necessary for Human Health (

¼ combination of positive and negative effects;

¼ negative effects only).dcont’d

Novel diseases Cumulative effect on:

Ingredients for human health

Explanation

Limit trauma

• Disruption of lives from a novel disease event can cause trauma, anxiety, and depression. • Domestic violence increases during novel disease events when victims are stranded at home. • Physical trauma events from automobile accidents and workplace injuries may decrease with economic disruptions associated with novel diseases.

Promote healthy behaviors

• Novel diseases may limit people’s ability to exercise and access to healthy foods. • Isolation from social distancing may also result in increased use of addictive substances. • Personal hygiene (hand washing) may increase as a way to combat a novel disease with other positive repercussions.

One Health and Exposome views on novel diseases and human health The primary focus of One Health on disease transmission from wildlife to humans, which gained momentum three decades ago, has received considerable traction as humanity grapples with the COVID-19 pandemic and recognizes the potential for future pandemics. As shown in Fig. 2.17, there are multiple primary and secondary factors that influence the incidence and spread of novel diseases, many of which are considered by One Health’s more comprehensive view of human-wildlifeecosystem health. Habitat loss, climate change, and other stressors not only cause declines in wildlife populations but also induce stress in wildlife, which compromises their health making them more susceptible to disease. At the same time, these same drivers increase the probability of sick animals encountering humans resulting in greater opportunities for disease transmission from stressed wildlife to people. While the One Health framework does not directly address how novel diseases affect one’s ability to obtain the ingredients necessary for

human health, its focus on understanding root causes and developing interventions and ultimately preventive programs, which take an upstream approach, make downstream measures unnecessary. To do this, One Health practitioners enlist multidisciplinary collaborators on surveillance, changes in livestock and hunting practices, and community engagement to limit exposure to and spread of novel disease. The success of this approach can be seen in its adoption by entire nations, such as Rwanda, that have developed their own One Health programs, which integrate managing the potential risk from disease transmission with tangible steps to mitigate the underlying causes, as for example habitat loss and other environmental challenges. Wildlife trade has been identified as a significant contributor to regional and global spread of novel diseases. While wildlife and wildlife products are sold locally and globally through legal distribution routes, there is substantial illegal trade that can spread novel diseases (Gore and Bennett, 2021). During the COVID-19 pandemic, One Health practitioners focused extensively on closing wet markets, where live animals and

58

2. Human Health

ECO

SYSTEM

Loss of habitat causing stress to wildlife

Deforestation

WILDLIFE

HUMANS

Sick domestic animals can pass viruses on to humans

DOMESTIC ANIMALS

Stressed wildlife shed more viruses that can spillover to domestic animals

FIGURE 2.17 One Health conceptualization of how the human, wildlife, and domestic animal realms interact. In this example, deforestation caused by humans precipitates in loss of wildlife habitat resulting in stress causing wildlife to shed more viruses that can then spill over to domestic animals or people.

wildlife products are sold, as a preventative measure to stave off future pandemics by decreasing the potential for disease spillover events. It should be noted that the environments, such as wet markets and other situations in which different species of stressed wild animals are housed in close proximity to each other and to people, heighten the risk of disease vulnerability and transmission. However, effective measures to reduce this risk must address the economic and cultural drivers that encourage wildlife markets and global wildlife trade. From the perspective of the Exposome framework, individuals vary in their risk of exposure to microorganisms and pathogenic zoonotic diseases depending on their socioeconomic, cultural, and regional situations, among other

factors. However, the Exposome framework does not look beyond the effects of the actual infectious disease on human biology and the route of human-to-human transmission to tackle the underlying mechanisms that result in spillover events. It does have the potential to aid in our understanding of the types of pathogens to which humans could be susceptible through laboratory investigations. This work can help to focus wildlife disease surveillance efforts. What is not captured in either framework? Novel diseases have long been a focus of the One Health conceptual framework, which has extensively evolved to meet the challenge of disease spillover events, their containment, and prevention. To better address the complex

Global challenges to human health

interrelationships of humans, animals, and the environment, One Health has expanded to include ecosystem health; however, it does not consider individual human variation that may make individuals more or less susceptible to novel diseases. Conversely, the Exposome concept only considers disease transfer as an aspect of human health that might diminish the resilience of an individual, especially when challenged with other environmental stressors. A gap remains between the macro humananimal-environment focus of One Health and the micro chemical and cellular pathways focus of the Exposome that could be useful when society is confronting a novel disease. That said, Exposome identification of local disease beyond the norm may help identify sources of unknown issues relevant to One Health.

Challenge #3: Anthropogenic pollution Similar to novel diseases, environmental pollutants, including both those in current use and persistent chemicals, such as dichorodiphenytrichloroethane (DDT) and its metabolites, impact wildlife and humans alike both directly and indirectly. Anthropogenic pollutants are generally defined as chemicals produced by human activities, with over 350,000 chemicals and mixtures of chemicals registered for production with some w120,000 claimed as confidential or ambiguously described (Wang et al., 2020). Their uses range from industrial to agricultural to residential while others are inadvertent chemical by-products and pollution from human applications (Fig. 2.18). They can be dispersed into the environment through the air, water, and soil and breathed in, ingested, or absorbed through human skin with deleterious outcomes as shown Fig. 2.19. Many persist in the environment for years and recirculate in various forms. However, it must be noted that there are beneficial effects of chemicals used to control pests, increase the productivity of agricultural plants and animals,

59

reduce disease from parasites and hosts that transmit diseases, and limit human exposure to disease-causing molds and other contaminants in our environment. Their responsible use is critical to minimize potential adverse effects. Several approaches have been developed to standardize the potential risk posed by specific compounds according to their chemical structure and known mechanisms of action. Two of the commonly used standards, referred to as the toxic equivalency factor (TEF) for compounds and toxic equivalency quotient (TEQ) for mixtures, compare the activity and structure of a compound to dioxin, a highly toxic environmentally persistent chemical. In addition, the activation of primary liver detoxifying enzymes via the aryl hydrocarbon receptor (AhR) signaling pathway is a common physiological response to contaminants and is often used as a biometric to assess potential risk to humans as well as to wildlife (Ottinger and Dean, 2022). Numerous studies have revealed that some compounds have the damaging effect of mimicking hormones, specifically endocrine disrupting chemicals (EDCs), but these are not captured in TEF or TEQ estimates. Determining the precise effects of pollutants on people is made more difficult by the great variation in our vulnerabilities to both toxins and to EDCs due to age, sex, and other factors. Most compounds have specific purposes for which many of them were designed and as such are valuable for agriculture, industry, and humanity. For example, DDT is an effective pesticide that has saved many people from contracting malaria. Similarly, atrazine is a herbicide that is useful for no till agricultural practices. Polychlorinated biphenyls are extremely stable compounds that withstand extreme heat and therefore provide excellent insulating properties. In all these cases, there are varied effects on living organisms due to their chemical structure, which in some instances mimic vertebrate hormones (Ottinger and Dean, 2022). Tables 2.5 and 2.6 provide an overview of key groups of

60 FIGURE 2.18

Air, land, and water pollution cycles. CO2 is emitted from burning fossil fuels, tilling soil for farming, and logging and is absorbed by plants and marine microbes. NOx is released through fertilizer applications and automobile exhaust and later deposited on surfaces where it can wash into streams causing alga blooms in lakes and oceans. SO2 is produced from coal-fired power plants and combines with water vapor to later fall as acid rain. CFCs from refrigerants react with the ozone layer and deplete its ultraviolet radiation protection. Plastic pollution washes into streams and out to ocean where it is consumed by aquatic animals. Toxic waste can seep into groundwater supplies. Based on Encyclopedia Britannica. https://www.britannica.com/explore/ savingearth/pollution-overview.

2. Human Health

61

Global challenges to human health

HEALTH EFFECTS OF POLLUTION

Nerve Damage Dementia

AIR POLLUTION

WATER POLLUTION

Bacteria

Lung Disease Asthma

Cardiovascular Disease

Nerve damage

Parasites Chemicals

Lead CO

Gastro Disorders

Particulate matter

SOIL CONTAMINATION

Ozone SO NO Volatile organic compounds

Cancer

Pesticides

Skin

FIGURE 2.19 Human health effects from air, water, and soil pollution showing their effects on various organs and parts of the body (based H€ aggström, 2014).

environmental chemicals recognized for their adverse effects in humans. Further, Table 2.5 focuses on airborne pollutants, and Table 2.6 overviews terrestrial and water borne pollutants, with the goal of providing the reader a general sense of the groupings of chemicals found in the environment, general targets, and potential adverse outcomes and toxicity. Each of these chemical groupings shares some unique characteristics, often with overlapping physiological consequences from exposure. Groupings are generally based on chemical structure as well as documented effects of exposures and characteristics in the environment (persistence and half-life). Metadata pertaining to areas of high application use (weed killers, pesticides, agricultural chemicals), detection of specific use

chemicals (rodenticides and pharmaceuticals), and highly contaminated areas from spills and other environmental catastrophes (National Resource Damage Assessment) are essential in identifying potential risks to human health. Deleterious health outcomes from exposures to anthropogenic pollutants range from mild skin irritation to asthma onward to cancer and even death. To better understand the risks to human health of individual pollutants, it is important to consider their life cycles and points at which humans may come into contact with the parent or secondary forms. The life cycle of a compound begins with raw materials that are used in a process or incorporated into a product. These “parent compounds” are then used for various purposes and when expended, they are generally disposed

62

2. Human Health

TABLE 2.5

Anthropogenic air pollutants, sources, potential direct and indirect human health effects, and relative toxicity.

Pollutants

Sources

Direct & indirect health effects

Ozone

Secondary photochemical atmospheric product

Respiratory system irritation Chronic lung disease Asthma and compromised immune resistance to respiratory disease

Nitrogen oxides (NO, NO2) Cars, electricity production Carbon monoxide (CO) Sulfur dioxide (SO2)

Cars, fires, industry

Displaces oxygen in red blood cells resulting in respiratory distress and lethal poisoning

Electricity prod., industry, fossil- Respiratory irritation and particulate exposures fuels, volcanoes Asthma

Particulate matter (PM 10 & Industry, fires, smoke, exhaust, 2.5) aerosols indoor and outdoor environments

Lead

Respiratory system irritation Asthma

Paints, gas, ceramics, personal use products, natural deposits

Volatile organic compounds Industry, fires, landfills, from natural disasters and volcanoes, fossil fuels, exhaust industry

Lung and heart impacts Asthma Chronic exposure can result in cancer and other long-term diseases

Toxicity

1

2

3

4

5

Cognitive impairment, toxic to physiological processes, oxidative stress, cancer, cardiovascular and urinary diseases.

6

Lung and respiratory impacts Chronic exposure can result in cancer and longterm respiratory and other system diseases.

7

fast acting lethal effects especially at high relative exposure (emoji Unicode 2620; author Mariella Steeb) impaired immune response and disease susceptibility; chronic exposure associate with cancer and other diseases (emoji Unicode 1F922; CC BU SA 4.0; author Emily Jager) effects poorly understood; needs more characterization and information (emoji Unicode1F9DO; author Emily Jager) 1

https://www.epa.gov/ground-level-ozone-pollution/health-effects-ozone-pollution; https://www.lung.org/clean-air/outdoors/what-makes-air-unhealthy/ ozone; Frontiers Research Topic: Ozone as a Driver of Lung Inflammation and Innate Immunity, and as a Model for Lung Disease: Ryffel et al., 2021. 2 Latza et al., 2009; other papers in resources section 3 https://www.mayoclinic.org/diseases-conditions/carbon-monoxide/symptoms-causes/syc-20370642 4 https://www.epa.gov/so2-pollution/sulfur-dioxide-basics 5 https://www.epa.gov/pm-pollution/particulate-matter-pm-basics; Manisalidis et al., 2020. 6 Boskabady et al., 2018. 7 Manisalidis et al., 2020.

often making their way into the environment. Subsequent metabolism of the parent compound can also occur in the environment, leading to the production of secondary compounds, which also may pose a health risk though few have been studied. The environmental processes affecting

the half-life of compounds, their persistence, and movement in the environment are detailed in Chapter 5, while these dynamic environmental cycles are shown above in Fig. 2.18. One approach to decreasing chemical releases into the environment and later human exposures is

63

Global challenges to human health

TABLE 2.6

Anthropogenic water and terrestrial pollutants, sources, potential direct and indirect human health effects, and relative toxicity.

Pollutants

Sources

Direct & indirect health effects

Pesticides Herbicides Lawn treatments, urban use pesticides; PCBs

Runoff from agricultural fields, residential use, recreational fields, golf courses

Developmental impairments, endocrine/immune/toxic effects, potential chronic illness, lethal at high doses

Metals/minerals (lead, copper, mercury, cadmium chorine, arsenic, nitrate, manganese, fluoride)

Plumbing, fertilizers, paints, gas additive, ceramics, personal use products, water treatment, natural deposits

Developmental impacts cancer, diabetes, heart disease, developmental impacts, lethal at high exposures

Industrial chemicals; creosote; superfund sites

Spillages, chemical residues, waste disposal

Illness, risk of cancer, respiratory disease, diabetes, heart disease, developmental impacts, lethal at high exposures

Nano plastics Oil Radioactive materials

Flame retardants Plasticizers

Plastic products, disposed oil spill, seepage Mining, naturally occurring (radon), fuels, fireworks, hospitals, power plants, munitions

Toxicity

1

2

3

Contaminated seafood; respiratory impacts; cancer, dose related lethal impacts 4

Residue on materials (clothes, furniture), Developmental impacts; respiratory, landfills immune impacts 5

PFAS (per- and poly-fluoroalkyl Water contamination; industrial substances; PFCs; PFOA; PFOS processes; fire extinguisher. Teflon

Developmental effects; immune, metabolic, cardiac impacts, asthma

Bacteria, waterborne pathogens, Pollution from sewage, agriculture, Anthrax residential sources; dumping areas

Diseasedserious infections and chronic or episodic exposures

6

7

fast acting lethal effects especially at high relative exposure (emoji Unicode 2620; author Mariella Steeb) impaired immune response and disease susceptibility; chronic exposure associate with cancer and other diseases (emoji Unicode 1F922; CC BU SA 4.0; author Emily Jager) effects poorly understood; needs more characterization and information (emoji Unicode1F9DO; author Emily Jager) 1

van den Berg et al., 2013; Robertson, 2020; Te et al., 2020. 2 Alengebawy et al., 2021; Landrigan et al., 2020; Boskabady et al., 2018. 3 Croisant et al., 2017, 2019; Markowitz, 2018. 4 Landrigan et al., 2020; EFSA Scientific Committee, 2021; Rahman et al., 2021; Trinh and Kim, 2021. 5 Patisaul et al., 2021; Alsen et al., 2021. 6 Calafat et al., 2019; Abdullah et al., 2021; Langenbach and Wilson, 2021; Mokra, 2021. 7 Sokolow et al., 2019.

64

2. Human Health

recycling chemicals/compounds in the manufacturing process. Using the chemicals and compounds recovered in this way enables efficiencies in manufacturing because these recycled materials may have already undergone partial processing. Using recycled chemicals and compounds also reduces the quantity of raw materials needed for future manufacturing. Emerging contaminants are chemicals that are not currently regulated and present significant potential risk to human health. Some examples are the per- and polyfluoroalkyl congeners (PFOS; PFAS) found in drinking water that have built up over time from the extensive use of these compounds in flame retardants. Other examples of emerging risks are the airborne contaminants that outgas from products containing flame retardants, formaldehyde, and other chemicals found in flooring and other components of building materials. Further, as our buildings become more airtight, environmental contaminants can quickly build up inside after outgassing. Aside from their direct effects on human health as toxicants, endocrine disruptors, or carcinogens, the presence of anthropogenic pollutants can also indirectly affect individuals’ abilities to access the following ingredients necessary for human health: clean water, clean air, nutrition, appropriate shelter, and nature as shown in Table 2.7. Recent attention has focused on both individual and community level risks associated with proximity to industrial and other sources of environmental contaminants as well as those encountered in the workplace. More economically disadvantaged communities may experience greater risk of exposure from contaminated sites, which may be poorly managed and lack clean-up. Coincident lack of social services and economic advantages reduces resilience to these chemical stressors. Specific discussion of each of the essential ingredients for human

health is summarized below, with explanation of potential sources and outcomes. It is worth noting that healthy ecosystems may buffer humans from the negative impacts of some pollutants. One Health and Exposome views on anthropogenic pollutants and human health Though it is not a dominant theme, anthropogenic pollution is considered within the One Health framework as one of the risks to ecosystem health that in turn may affect human health. Since these chemicals are ubiquitous throughout the environment and occur even at the poles, they pose a risk for human and animal populations virtually everywhere on the globe. For example, catastrophic pollution events, such as the Deepwater Horizon Oil Spill, may cause significant environmental perturbations that disrupt ecosystem processes damaging wildlife, human health, and human economies in the process. The One Health framework is well equipped to tackle situations where the interrelationships of humans, animals, and the environment are affected using its stepwise program to monitor, respond, and/or intervene as understanding of the drivers is uncovered. The Exposome framework is perfectly positioned to tackle the proximate factors associated with human exposures to anthropogenic inputs because of its biomedical underpinnings. Specifically, the framework focuses on understanding the actions of single compounds or mixtures of environmental pollutants at a point in time or as accumulated over time/lifespan on an individual. These exposures may come through a variety of sources, including diet, air, water, contact with contaminated materials and soils, containing both parent and secondary metabolites. This approach allows for the development of diagnostics, based on mechanisms of action of chemicals and possibly toxic or nontoxic

Global challenges to human health

TABLE 2.7

65

Anthropogenic pollution affects our ability to obtain the ingredients necessary for Human Health (

¼ combination of positive and negative effects;

¼ negative effects only; N/A ¼ not applicable).

Anthropogenic pollutants Cumulative effects on:

N/A

Ingredients for human health

Explanation

Access to clean water

• Pollution from industrial, agricultural, and urban centers may contaminate surface or ground water sources thus decreasing access to clean water • Some chemicals put in water to decrease microbes can be beneficial but also can be pollutants with increased quantity

Access to nutrition

• Water, air, and terrestrial pollution affects access to nutrition by contaminating crops • Pesticides, herbicides, and fertilizer have increased productivity to feed more people, but can also pollute the environment

Access to clean air

• Pollution from industrial, agricultural, and urban centers decreases air quality

Access to appropriate shelter

• Nearby ambient pollution affects the safety of shelters • Indoor pollution from off gassing of materials compromises the safety of shelters

Access to medical care

• There are indirect effects of pollution primarily through distribution of medical facilities related to disparities, often being less available in areas of greater pollution

Access to nature/ recreation

• Pollution decreases environmental quality resulting in fewer opportunities to access nature, such as poor water quality limiting fishing

Access to human community

• Pollution can limit human community by poor air and water quality causing people not to congregate

Limit toxic substances

• Pollution by its very nature increases exposure to toxic substances

Limit infectious diseases

• Pollution affects our ability to limit infectious diseases by being an additional stressor and reducing immunocompetence

Limit trauma Promote healthy behaviors

• Pollution, especially of the air and water, may limit people’s ability to exercise or find healthy foods

effects of exposures. This is a critical aspect for biomedicine, given the vast array of potential pollutants and exposures to individuals. Increasing attention is also being focused on community-level dynamics to better understand the long-term impacts of exposure. Catastrophic pollution events, such as 1984 Union Carbide pesticide plant explosion in India, occur around

the globe and cause health risks to communities living in proximity to industrial plants. Gaining an understanding of the human health effects of acute and chronic exposures will require gathering data that include outcomes of disaster relief as well as consolidation of databases to link individual health effects with chemical exposures.

66

2. Human Health

What is not captured in either framework? Although the combination of these two conceptual frameworks covers a vast array of human health impacts from pollutants and anthropogenic change, gaps in our understanding remain, particularly in understanding subtle nonlethal chronic impacts. A great deal about developmental impacts of exposures to environmental chemicals has been uncovered through extensive research, such as respiratory diseases (asthma, cancer, etc.) associated with tobacco smoke or volatile organic compounds in the air. Less is known about age-related health impacts, and there are large gaps in our understanding of how earlier exposure translates into later disease. The tipping point for each individual may differ, meaning that personalized medicine will play an important role in understanding adverse effects of exposures at an individual level. The Exposome captures this important concept and, as more data are collected, will provide valuable insights into lifelong responses to exposures. Finally, the regulatory process for bringing new chemicals to market across various applications should provide another effective mechanism for decreasing exposures to new environmental chemicals and serve to review those existing in the market to determine safety. Both One Health and the Exposome could benefit from including regulating entities in their processes to prevent exposures before they occur. They could also broaden their scope to account for the indirect effects of chemical pollutants on a person’s ability to access the ingredients necessary for human health.

Challenge #4: Climate change Unlike “weather,” which refers to atmospheric conditions that occur locally over hours or days, “climate” is defined as the long-term

regional or global average temperature, humidity, and rainfall patterns observed over seasons, years, and decades. “Climate change” then refers to significant changes in global temperature, precipitation, and wind patterns occurring over several decades or longer and is the result of changes in atmospheric composition in combination with interactions between the atmosphere and other geologic, chemical, biological, and geographic factors. Since preindustrial times (after the 1800s), the world has warmed 1.2 C and atmospheric CO2 concentrations have increased by 50% (NASA Goddard Institute for Space Studies, 2021). Scientific studies indicate that the current change in climate is the direct result of greenhouse gas emissions from burning fossil fuels and land conversion accumulating and increasing the atmosphere’s ability to trap heat radiating from the Earth toward space. The resulting rising global temperatures have myriad repercussions from increased frequency of severe storms, wildfires, and droughts to increasing ocean temperatures, melting glaciers, and sea level rise. As shown in Fig. 2.20, these changes interact with each other and can result in positive and negative feedback loops that can exacerbate and/or accelerate climate change and its effects. Similar to novel diseases and environmental pollutants, climate change directly and indirectly impacts human health. Human health is directly affected by climate change induced flooding, heatwaves, water shortages, landslides, and increased exposure to ultraviolet radiation and pollutants (World Health Organization, 2002). There are also “ecosystem-mediated health impacts” that alter infectious disease risk, reduce food yields, and increase stress and mental health issues. Further afield are the indirect, deferred, or displaced health impacts spurred by loss of livelihood, population displacement, and conflict. To illustrate these climate impacts,

Global challenges to human health

67

FIGURE 2.20

Climate change feedback loops showing how rising temperatures accelerate the release of additional greenhouse gases or hamper their uptake by plants. From Climate Emergency Institute; https://files.secure.website/wscfus/8154141/ 25902888/some-large-ve-feedbacks.png.

Fig. 2.21 outlines how rising temperatures, sea level rise, increasing CO2, and more extreme weather events result in increased exposures to air pollution, vector-borne pathogens, increasing allergens, and water and food insecurity, which lead to increased risk for asthma, cardiovascular disease, vector-borne infectious disease such as malaria, malnutrition, heat stroke, injuries, fatalities, and declines in mental health. The Lancet Countdown, an international collaboration independently monitoring the health consequences of a changing climate, released an extensive report in 2021 using 44

indicators to track the health impacts of climate change and the current health consequences of delayed or inconsistent response to the crisis (Romanello et al., 2021). The findings are staggering and reveal inequitable effects of climate change disproportionally affecting the most susceptible individuals within the past few decades (Box 2.4). As elucidated above and shown in Table 2.8, climate change compromises people’s ability to access the ingredients necessary for health. Nearly all the ingredients for health are negatively affected by climate change with floods,

68

2. Human Health

CLIMATE IMPACTS

Extreme Weather

Rising Sea Levels

Increasing CO

Rising Temperatures

Air pollution

Increasing allergens

Water and food supply impacts

Extreme heat

Poor water quality

Environmental degradation

Severe weather

EXPOSURES

Vector-borne diseases

ENVIR. & INSTITUTIONAL CONTEXT

Increasing allergens

Land-use change

SOCIAL & BEHAVIORAL CONTEXT

Water borne pathogens

Clinical Care

HEALTH OUTCOMES

Ecosystem change Infrastructure condition Geography Agricultural production & livestock use

Respiratory allergies

Respiratory allergies, asthma

Malnutrition, diarrheal disease

Asthma, cardiovascular disease

Cholera, cryptosporidiosis, campylobacter, leptospirosis

Forced migration, civil conflict, mental health impacts

Malaria, dengue encephalitis, hantavirus, Rift Valley fever

Heat-related illness and death, cardiovascular failure

Social & Economic

Injuries, fatalities, mental health impacts

Genetics and Biology

Built Environment

Health Behaviors

Diarrheal disease

Injuries, fatalities, mental health impacts

FIGURE 2.21 Climate change impacts on human health. Extreme weather, rising sea levels, increasing CO2 levels, and rising temperatures increase exposures to negative elements resulting in poor health outcomes. These are all nested within the environmental, institutional, social, and behavioral contexts in which a person lives (modeled after EPA: https://www.epa. gov/sites/default/files/2016-07/8129_intr_pathwaysweb.png).

droughts, and extreme weather events decreasing access to clean water, appropriate shelter, and medical care while increasing potential exposures to toxic substances, infectious diseases, and trauma. The two ingredients that could be both positively or negatively affected by climate change are access to nutrition and promoting healthy behaviors because people in very cold climates may be able to grow more food locally as well as exercise outdoors during longer periods of time as their local temperatures rise. However, this same warming effect will cause other parts of the world to decline in food output and access to time outdoors because of extreme heat.

One Health and Exposome views on climate change and human health Since climate change affects humans, domestic animals, and wildlife, the One Health framework is well suited to address the many direct and “ecosystem-mediated” effects of climate change on human health. Its focus on the emergence of novel infectious diseases spurred by human activities, including land use change and wildlife trade, has proven the strength of this approach in bringing together different disciplines and stakeholder groups to monitor, assess risk, develop programs to intervene in a stepwise manner as outbreaks arise. Zinsstag and

Global challenges to human health

69

BOX 2.4

Health impacts of climate change from the Lancet Countdown (highlighting details found in Romanello et al., 2021) Evidence for climate change’s increasing impacts on human health: ➢ Since 1990, vulnerability to extreme heat has increased 19%e20%. ➢ In 2020, children younger than one and adults older than 65 were affected by 626 million and 3.1 billion more person-days of heatwave exposure, respectively, compared to the average for the years 1986e2005. ➢ In 2019, heat related deaths in people older than 65 years reached a record high of an estimated 345,000 deaths. ➢ Over the last 40 years, the number of hours in which temperatures were too high for safe outdoor exercise has increased, with people in developing countries having an average loss of 3.7 h of safe exercise per day in 2020. ➢ In 2020, 295 billion hours of potential work were lost due to extreme heat. ➢ In 2017e20, nearly 60% of countries had an increase in the number of days people were exposed to very high or extremely high fire danger compared with 2001e04. ➢ In 2020, up to 19% of the global land surface was affected by extreme drought in any given month.

Colleagues (2018) proposed using the One Health framework to respond to climateinduced problems by combining efforts among veterinarians, public health workers, and others to address food security and safety issues, water quality and sanitation, and infectious disease surveillance, and vaccination programs. Combining efforts lowers costs and results in

➢ The past 30 years have seen statistically significant increases in the number of extreme weather events; however, only developing countries had a statistically significant increase in the number of people affected by these events. ➢ Compared to the 1950s decade, the 2010s decade saw a 39% increase in the number of months suitable for malaria transmission in highland areas of developing countries. ➢ Current crop yields have declined compared to averages between 1981 and 2010 with 6.0% reduction in the crop yield potential for maize, 3.0% for winter wheat, 5.4% for soybean, and 1.8% for rice. ➢ Between 2018 and 2020, nearly 70% of countries showed increases in average sea surface temperature in their territorial waters compared with 2003e05 that could threaten their marine food productivity and security. ➢ In 2020, 569.6 million people resided on land lower than 5 m above sea level and are at risk of direct and indirect hazards posed by sea level rise.

better outcomes. Many One Health practitioners have moved beyond responding to crises and are now focused on combatting the threats at their source, such as the movement to eliminate wet markets where disease spillover events are more likely. However, the One Health approach to climate change has not focused on the root causes of increasing greenhouse gas emissions,

70 TABLE 2.8

2. Human Health

Climate Change affects our ability to obtain the ingredients necessary for Human Health. ( positive and negative effects;

¼ combination of

¼ negative effects only). Climate change

Cumulative effects on:

Ingredients for human health

Explanation

Access to clean water • Climate change increases severe weather events, such as droughts and flooding, which compromises communities access to clean water • Rising sea levels compromise water quality as saltwater infiltrates fresh water sources Access to nutrition

• Climate change affects water supplies, which may make some areas unusable for agriculture while others may receive more rain and thus be useable when previously they were not • Climate change may result in higher average temperatures, making some locations unusable for agriculture/livestock while others will become useable • Effects of climate change are decreasing crop yields

Access to clean air

• Climate change may result in higher average temperatures, increasing ground-level ozone • Climate change results in more severe storms, which cause power outages at some facilities resulting in their releasing excess pollution into the air

Access to appropriate • Climate change results in sea level rise that will decrease current housing stock as many shelter coastal and low-lying areas become flood prone • Climate change increases severe weather events, which damage or destroy housing Access to medical • Climate change increases severe weather events, which may compromise patients’ ability to care seek medical care Access to nature/ • Climate change increases severe weather events, which may compromise people’s ability to recreation recreate • Climate change may result in more or less good weather days for recreation Access to human community

• Climate change increases severe weather events, which may limit community engagement • Climate change may cause higher air temperatures, decreasing people’s ability to gather outdoors in public spaces

Limit toxic substances

• Climate change causes an increase in severe weather events that result in more failures at nuclear power facilities, chemical plants, resulting in more toxic substances being released • Climate change increases flooding events where contaminated runoff comes into contact with people

Limit infectious diseases

• Climate change increases severe weather events, which decrease water quality resulting in an increase in water-borne infectious diseases • Climate change may increase temperatures and standing water, which support growth of mosquitoes and other disease vectors, though drier conditions in other places may limit these

Limit trauma

• Climate change increases severe weather events, increasing the likelihood for injuries and weather-related fatalities • Climate change increases environmental degradation and severe weather events, which increase mental health issues

Promote healthy behaviors

• Climate change results in increased temperatures, which can increase or decrease people’s ability to exercise safely outside depending on location • Climate change results in increased temperatures, which may increase or decrease access to fresh locally grown produce depending on location

Global challenges to human health

but instead on the effects of floods, droughts, and extreme weather events on humans, domestic species, and wildlife. Similarly, the Exposome addresses the proximate causes of poor human health driven by a changing climate, such as increased exposures to pollutants. It has the capacity to build extensive data sets of climate-induced exposures, including those involving extreme heat, allergens, and contaminated flood waters, and the biological responses to them for individuals and populations. The work highlighting the effects of extreme heat on the very young and old is a case in point of how such exposures can disproportionately affect some populations more than others and how the Exposome approach can help to tease these out. While the Exposome is able to track the internal biological pathways and responses following an exposure, it lacks an iterative process to identify and address the root causes of these exposures. For climate change, this would be the drivers of increased greenhouse gas emissions that do not reside in the biomedical world. What is not captured in either framework? Both concepts address proximate and intermediate effects of climate change but do not go beyond these to confront the drivers of climate change. Part of the difficulty in using these frameworks to address the root causes lies in the distance both in terms of time and space from where the emissions occur and where effects are felt. The One Health framework and protocols work well when tackling local or regional challenges, while the Exposome framework addresses direct personal exposures. Given the global action needed to confront the drivers of climate change, the number of stakeholders that must be engaged could be too unwieldy for either framework. However, both are useful when used as part of a larger unified strategy with the Exposome revealing physiological effects of direct exposures while One Health captures the ecological impacts.

71

Challenge #5: Social and economic disparities A person’s health is determined not only by their genetics and biology, but also by their behavior/lifestyle, access to medical care, social and economic circumstances, and the physical environment in which they live and work. As healthcare providers and practitioners look to move health interventions “upstream” to focus on preventing instead of treating disease, they continue to uncover the critical role of the social determinants of health, which account for the majority of differences in health outcomes among populations, also referred to as health disparities. Fig. 2.22 depicts many factors from level of education attainment to access to greenspace that encompass a person’s social determinants of health. In fact, because of its tight coupling with income level and access to resources, a person’s zip code or census tract is a better predictor of their life expectancy than any other single metric in the US (Arias et al., 2018). Essentially, social and economic disparities are the main drivers of health disparities. Health issues and health disparities vary widely worldwide as do their causes. On a macro level, people in lowest income countries live on average 18 fewer years than those in highest income countries (World Health Organization, 2019). This difference is largely driven by differences in income, which directly effects a person’s ability to access the ingredients necessary for health. The most acute example is the 650 million people living in extreme poverty (