Environmental Health

by

Mark F. Miller, Kelly J. Chandler, Linda S. Birnbaum

• LAST REVIEWED: 26 February 2020
• LAST MODIFIED: 26 February 2020
• DOI: 10.1093/obo/9780199363445-0127

Introduction

Each day people are exposed to a wide variety of agents and stressors that have the potential to impact human health and well-being. Environmental health is the study of those environmental factors and how they may contribute to human health and disease. An individual’s environment is one of the most important contributors to one’s overall wellness and quality of life. Environmental factors play a role in at least 85 percent of all human diseases. More importantly, an individual’s environment is the most easily modified aspect of one’s overall health. Understanding the impact of the external environment, how it interacts with biological processes, and what can be done to eliminate or mitigate negative effects provides better protection for human populations from deleterious health outcomes. Traditionally, science has looked at environmental factors by using a risk-based approach. In this model, information on an agent’s potential to cause harm, as depicted by a dose-response relationship for a given adverse effect, is integrated with an individual’s potential to be exposed to that hazard in order to characterize the likelihood and severity of health risk. As we move into a new era of environmental-health research, scientists are thinking about environmental impacts on human health in new ways. It’s no longer as simple as “the dose makes the poison,” where high doses of a chemical are bad and lower doses are not as bad. While there are still many instances of high-concentration exposures to toxic heavy metals, pesticides, or other substances, a new understanding of how low-level exposures contribute to the development of common disorders such as diabetes, developmental delays, and other modern epidemics is changing the traditional paradigm of toxicology. Timing of exposure during fetal and early-childhood development, mixture effects from combined exposures, impacts on genetic and epigenetic gene regulation, and individual human susceptibilities can result in increased disease incidence or severity. Further, these effects are seen not only in exposed individuals, but also in their direct offspring and potentially subsequent generations. The study of environmental health provides opportunities to mitigate or prevent a wide range of human disease and disability from an individual, community, and policy perspective. We can’t change our genes, but we can change our environment, behaviors, and exposures. This article describes the ways we are exposed to stressors in our environment, the primary fields that contribute to our understanding of environmental health, and some emerging issues that require 21st-century approaches to promoting healthy environments and preventing human disease.

Environmental-Health Historical Overview

The scientific community’s view of environmental health has evolved and expanded greatly since the late 1960s. Rachel Carson’s groundbreaking book, Silent Spring, detailed the impact of indiscriminant pesticide use on avian populations. Carson 1962 was one of the first alerts to the general public detailing the devastating negative impacts humans can have on the environment, and how commercial and agricultural chemicals can affect environmental and human health. The increased understanding of our role in environmental health led directly to the creation both of the National Institute of Environmental Health Sciences and the US Environmental Protection Agency as well as alerted a host of other government bodies to environmental concerns within their purview. As the field of environmental health evolved, many specific areas for study were identified, including air, water, and land; also, fields such as indoor environments, susceptible populations, exposure science, and risk assessment applications in regulatory decision-making were created. The federal government, states, and local communities began addressing major environmental issues. The open fires on the Cuyahoga River, rampant DDT use on agricultural crops, ground-level air pollution in the Los Angeles basin, and indoor air-quality issues in our nation’s schools are a few examples of environmental issues that were recognized and addressed. Over the years, a new era of toxicology was evolving that moved away from a primary focus on the lethal dose, where the primary question was “How much of a chemical does it take to kill 50 percent of an exposed testing group?,” and began to focus instead on lower chemical doses with more-subtle effects of greater public health significance. An example of this for carcinogens can be seen in Wartenberg and Gallo 1990. In addition, the science of risk assessment and its applications in policy decisions underwent an evolution, as presented in Paustenbach, et al. 1990. In the 1990s, our view of environmental health expanded beyond our domestic borders and was recognized as a truly global issue. World Health Organization 1992 documents the global challenges to health and the environment, including recommendations for the future. Equally important that year was the World Bank’s World Development Report, which highlights many of the same environmental health issues from an economic-disparity perspective (World Bank 1992). In the late 1990s, the authors of Colborn, et al. 1997 challenged many of the dogmas of environmental health, focusing on the effects of low doses of endocrine-disrupting chemicals.

• Carson, R. 1962. Silent spring. Boston: Houghton Mifflin.

  Silent Spring is a groundbreaking publication that highlighted humans’ potential to impact the environments in which we live, and the consequences of environmental exposures. The book specifically details the negative impacts of pesticide use on avian populations and marked the beginning of a new era of environmentalism.

• Colborn, T., D. Dumanoski, and J. P. Myers. 1997. Our stolen future: Are we threatening our fertility, intelligence, and survival? A scientific detective story. London: Abacus.

  Details the nature of endocrine-disrupting chemicals (EDCs), the biological mechanisms through which they work, what EDCs mean for current and future generations, and how families can protect themselves and their communities. This book had great impact across scientific and lay audiences because it presented the complex concept in clear, simple language. Publication raised public awareness of issues related to endocrine disruption, and prompted numerous studies in the field.

• National Research Council Committee on Indoor Pollutants. 1981. Indoor pollutants. Washington, DC: National Academies Press.

  This report describes the state of the science for indoor environmental exposures. Importantly, it also comments on the data gaps that were identified for future indoor air research and priority setting. It further includes a chapter on the codes and standards that were created to control indoor pollution.

• Paustenbach, D. J., J. D. Jernigan, B. L. Finley, S.R. Ripple, and R.E. Keenan. 1990. The current practice of health risk assessment: Potential impact on standards for toxic air contaminants. Journal of the Air & Waste Management Association 40.12: 1620–1630.

  DOI: 10.1080/10473289.1990.10466808

  This early review of risk assessment methods highlights the need for objective ambient air standards and emission limits based on scientific data. Specifically, it notes the need for physiologically based pharmaco-kinetic models and supports the move to more biologically based models in a tissue-specific context to account for a variety of environmental factors.

• Wartenberg, D., and M. A. Gallo. 1990. The fallacy of ranking possible carcinogen hazards using the TD₅₀. Risk Analysis 10.4: 609–613.

  DOI: 10.1111/j.1539-6924.1990.tb00546.x

  This publication provides a nice example of the changing paradigm away from extrapolations using a toxic dose at which 50 percent of organisms are affected, toward a more refined assessment of impacts at lower doses, nearer to the levels of human exposure.

• World Bank. 1992. World development report 1992: Development and the environment. Oxford: Oxford Univ. Press.

  This report specifically focuses on the links between economic development and the environment. It highlights the need to involve local communities and governments to achieve better decision-making, identifies environmental priorities for development, and discusses the challenges associated with sustainable development globally.

• World Health Organization. 1992. Our planet, our health: Report of WHO Commission on Health and Environment. Geneva, Switzerland: World Health Organization.

  This report reviews the relationships among health, cultural development, and the environment. It highlights global challenges to health and the environment. Four independent expert panels (food and agriculture, energy production, industry, and urbanization) convened to develop this report, which includes chapters dedicated to evaluating these broad areas. Additionally, the report addresses the specific areas of water and international issues. Also provided are government strategies for securing a healthy environment for its communities and recommendations for governments and international organizations.