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From Bioethics Briefings

Environment, Ethics, and Human Health

  • The relationship between human health and the environment is complex, dynamic, and multifaceted.
  • Although the environment supports human health, substances or conditions in the environment can also increase the risk of disease, disability, and death.
  • Activities that promote human health, such as agriculture, control of dangerous pests (such as mosquitoes), energy production, and economic development can also have adverse impacts on the environment that may result in competing detriments to human health.
  • The interactions between the environment and human health raise complex ethical and political questions related to environmental and public health policy.
  • One of these complex ethical and political issues is that those who benefit from specific activities that promote human health may be different from those who suffer the detriments to their health from these activities.
  • Ethical questions about the relationship between human health and the environment are bound to intensify with the emergence of new and evolving technologies that can impact the environment, such as nanotechnology, genetically modified organisms, and biofuels, and the increasing impacts of climate change.

Framing the Issue

Many of the most challenging ethical questions of our time address interactions between human health and the environment:

How can we balance protection for the environment with other important human values, such as promoting human health and well-being? What steps should we take to mitigate or adapt to climate change? (See “Climate Change.”) How should we regulate substances that can have adverse public health and environmental impacts, such as pesticides, industrial chemicals, and pollutants? How should we ensure the safety of our food supply?  Should we use genetically modified organisms (GMOs) to enhance agricultural productivity or control diseases transmitted to human by animals? How should we balance occupational safety protections with economics and the right to work? How should we balance safety and affordability in setting housing standards? How should we regulate energy production and use to protect the environment and human health? How should we make decisions concerning the placement of waste sites, factories, highways, and other structures that impose increased health risks on local residents?  How should we balance progress in environmental health with the need to address the interests of communities that were historically underserved and/or excluded from environmental decisions that affected their health? What steps should we take to facilitate public participation in environmental health decision-making?

The issues that arise in environmental health ethics are complex, multifaceted, dynamic, and global in scope. Finding satisfactory solutions to environmental health problems will become increasingly important as the environmental impacts of human activities continue to mount and we learn more about the relationship between human health and the environment.

Environmental Health, Hazards, and Risks

The environment provides energy, materials, and habitats that are essential for sustaining human life and health. The environment includes the physical environment (e.g., air, water, soil, weather, climate), the biological environment (e.g., food, plants, animals, fungi, microorganisms, ecosystems), the social environment (e.g., familial and personal relationships, communities) and the built environment (e.g., highways, houses, cities, factories, and other structures).

For most of human history, increases in longevity were mostly due to improved access to and improvements in water quality, hygiene, and food rather than innovations in biomedical technology.

Lack of basic necessities is still a significant cause of human mortality.  Every year in the world:

  • About 6 million people die in from hunger or malnutrition.
  • 400,000 people die from food-borne illnesses.
  • 800,000 people, mostly children, die from gastrointestinal diseases caused by unsafe drinking water or poor sanitation or hygiene.
  • Tens of thousands of people die to risks associated with homelessness.

Although the environment sustains human life, it also includes hazardous man-made or natural substances or conditions that can increase the risk of disease, disability, or death.  For example:

  • Chronic (i.e., long-term, persistent) exposure to air pollution is associated with increased risks of lung cancer, heart disease, and chronic obstructive pulmonary disease, and can aggravate asthma; acute (i.e., short-term, toxic) exposure to carbon monoxide can cause headache, dizziness, weakness, upset stomach, vomiting, chest pain, confusion, and death; acute exposure to ozone can trigger asthmatic reactions. The World Health Organization estimates that 3.8 million people die every year from indoor smoke from cooking fuels and an additional 4.2 million die from outdoor air pollution.
  • Chronic exposure to some types of pesticides is associated with increased risk of cancer, birth defects, and neurological diseases; acute exposure can cause rashes, blisters, nausea, blindness, and death.
  • Chronic exposure to some types of chemicals used in industry and in making consumer products can increase the risk of various diseases. For example, exposure to per- and polyfluoroalkyl substances (PFAS) is associated with increased risk of cancer, diabetes, liver damage, and high blood pressure.
  • Chronic exposure to lead from household paint, plumbing, and other sources is associated with increased risk of anemia and kidney and nerve damage, and can interfere with human brain development; acute exposure can cause headaches, abdominal pain, irritability, insomnia, and anemia. There is also convincing  evidence  that lead is a human carcinogen.
  • Chronic exposure to sources of radiation, such as ultraviolet light from the sun or medical imaging devices using x-rays, is associated with increased risk of cancer; acute exposures can cause nausea, vomiting, diarrhea, headache, fever, dizziness, fatigue, hair loss, and internal bleeding.
  • Chronic exposure to arsenic from groundwater is associated with increased risk of cancer, diabetes, and vascular disease.
  • Microorganisms in water, food, or soil, or carried by animal vectors, such as mosquitoes, ticks, or other animals, can cause numerous diseases, such as malaria, encephalitis, West Nile virus, Zika virus, schistosomiasis, diarrhea, cholera, meningitis, gastritis, salmonella, Rabies, plague, and Lyme disease.
  • Dangerous working conditions can increase the risks of occupational illnesses and injuries, such as skin cancer, mesothelioma, dermatitis, rashes, ulcers, arthritis, pain, hearing loss, vision damage, and back, neck, knee, and hand injuries.
  • Poor housing conditions can increase the risk of death or injury as a result of accidents, fires, floods, or earthquakes.
  • Adverse weather can cause death or illness from heat prostration, smoke inhalation, drowning, or hypothermia.
  • Oppressive social conditions, such as racial, ethnic, and gender prejudice and discrimination can reduce access to and utilization of health care, are associated with increased risk of various diseases, and are associated with reduced life expectancy.
  • Environmental degradation can increase crime, terrorism, and warfare that directly cause about 500,000 deaths per year and contribute to post-traumatic stress, trauma, and other psychological problems.
  • Automobile traffic accidents kill about 1.3 million people per year.

Bioethical, Social, and Legal Considerations

Relationships between human health and the environment often involve competing values and interests and therefore raise many ethical, social, and political issues.  Some of these issues are discussed below.

Managing the Risks of Pesticides, Hazardous Chemicals, Pollutants, and other Environmental Hazards

Many of the issues at the intersection of health and the environment have to do with managing complex networks of risks and benefits concerning pesticides, hazardous chemicals, pollutants, and other substances that can threaten human health and the environment.  Some of these substances are called persistent organic pollutants because they take a long time (10 years or more in some cases) to degrade in the environment.  Some of these substances can accumulate in animal tissues, which means that organisms on the top of the food chain (such as predatory fish, birds, and mammals) have higher concentrations of these substances than those at the bottom. There are difficult trade-offs for policymakers because many of the activities that benefit human health and well-being, such as agriculture, economic development, industrialization, transportation, and energy production, can utilize or produce substances that pose risks to human health and the environment.

Pesticides play an important role in increasing crop yields, but they can also pose hazards to human health and the environment. Actions designed to minimize these risks, such as banning or significantly restricting the use of pesticides, can lead to food shortages and increased food prices, which would, in turn, increase starvation, malnutrition, and food insecurity. Regulatory agencies in the U.S. and other countries attempt to balance the benefits and risks of pesticides by establishing acceptable uses and exposure levels. An exposure is the amount of substance that a person comes in contact with by inhaling, ingesting, or touching the substance, or receiving it intravenously or subcutaneously.   A dose is a measurement of an exposure.  The dose that is absorbed by the body is usually much lower than the exposure dose.  For example, the U.S. Environmental Protection Agency sets acceptable levels of pesticide residues on food. Generally, the acceptable level must not exceed 1/1000 of the dose that causes adverse effects in rodents. The U.S. and many other industrialized nations have banned the use of the insecticide dichlorodiphenyltrichloroethane (DDT), but some African nations still use it to kill mosquitoes that carry malaria.

The use of hazardous chemicals in industry and consumer goods poses difficult ethical challenges because these chemicals often have important benefits, and substitutes may be less effective or more dangerous. PFAS chemicals, for example, are used to extinguish fires caused by combustible petroleum products, such as jet fuel. Banning these chemicals could reduce the risk of cancer for people who are exposed to them through drinking water but could also cost the lives of firefighters and the people they are trying to rescue unless suitable substitutes are found.  Bisphenol A (BPA) is a chemical that is used to strengthen plastics in bottles, cups, food packaging, and canned food liners. Chronic exposure to BPA is associated with increased risks of cancer, diabetes, and heart disease, and with impaired thyroid function and brain development in infants and children. Since 2010, several countries have banned the use of BPA in products used by infants and children, and the FDA has established acceptable exposures levels for BPA that leaches into foods. Although the U.S. has not banned BPA, companies have responded to consumer demands for BPA-free products and developed alternatives to BPA.  However, since these substitutes are chemically similar to BPA, it is not known whether they will prove to be safer.

Air pollution regulations also pose difficult challenges for managing risks and benefits.  Combustion of fossil fuels produces chemicals and substances, including sulfur dioxide, carbon monoxide, particulate matter, and ozone, that can increase the risk of respiratory illnesses, cardiovascular illnesses, and cancer when inhaled. Since perfectly clean air is not possible in our modern, industrialized society, the EPA sets air quality standards for these pollutants based on a scientific assessment of risks and benefits. The standards the EPA adopts are acceptable exposure levels, given the conditions and practicalities of modern life. These standards have become more protective over time in response to scientific research on the risks of pollution and the development of technologies that can cut down on pollution, such as clean coal technologies and emission controls on automobiles.

Genetically Modified Organisms

Genetically modified crops and foods have been controversial since they were  introduced in the 1990s. Despite strong opposition from some environmental and consumer organizations, cultivation of GM crops has continued to increase steadily since then. In the U.S., for example, over 90% of corn, soybean, cotton, canola, and sugar beet crops are GM. GM crops have been developed to enhance yields, and to improve pest resistance, herbicide tolerance, drought tolerance, shelf-life, and nutritional value.

GM animals have been used extensively in scientific research as models of human disease. For example, scientists have developed mouse models of cancer, diabetes, Parkinson’s disease, obesity, and other illnesses. GM animals have also been developed to produce human hormones in their milk. So far, GM animals have not been commercialized as meat products, although the U.S. and Canada have approved the marketing of GM salmon.

Opponents of GM crops, foods, and animals are concerned that they pose unacceptable risks to human health and the environment. Some people oppose all GMOs for religious or philosophical reasons because they view genetic engineering as “playing God.”

Although hundreds of scientific studies have shown that GM foods are just as safe to eat as non-GM foods, almost all of these studies are short-term (90 day) feeding experiments using laboratory animals. The risks of consuming GM foods for many years are therefore not known. Moreover, many consumers would rather not eat GM foods, regardless of scientific evidence concerning risks.  To allow consumers to make informed decisions about what they eat, many countries, including the U.S., require that GM foods be clearly labelled. However, it can be difficult to label foods accurately because of the intermixing of GM and non-GM foods in food processing and agriculture.  For example, a company that makes breakfast cereal may use corn syrup made from GM and non-GM corn, and a company that makes frozen pizzas may use cheese that comes from cows that have eaten GM corn or soy products.

The environmental risks of GM foods, crops, and animals are probably of greater concern than the public health risks. First, GM crops can hybridize with non-GM crops. Second, some GM crops secrete biopesticides to kill pests, which may also harm non-target organisms, such as butterflies, bees, or ground worms. Third, GM plants and animals can become invasive species if they escape from the areas where they are being used. For example, creeping bent grass, which is used on golf courses, has become an invasive species in Oregon. Invasive species can destabilize and disrupt ecosystems, as has happened with rodents in Australia and New Zealand.  Fourth, viruses might transfer genes for evolutionarily advantageous traits, such as herbicide resistance or drought tolerance, to native plants, which could lead to proliferation of vigorous strains that interfere with agriculture and disrupt ecosystems.  Finally, genetic modification of plants that allow for herbicide resistance can lead to widespread use of certain herbicides that can alter the soil microbiome and, through spray drift, damage surrounding non-GMO crops.

Some nations have addressed the dilemmas posed by GM crops by banning them. Over 20 nations, mostly in Europe, currently prohibit the cultivation of GM crops. The U.S. does not ban any GM crops but regulates them under existing environmental and public health laws. The Food and Drug Administration allows a GM crop to be cultivated if it determines that the food produced from the crop is substantially equivalent to non-GM food. The FDA has the authority to restrict production of the crop if evidence emerges that it poses an unreasonable risk to human health. If a GM crop produces a biopesticide, the EPA will make regulatory decisions based on an analysis of the environmental and public health risks of the crop.

Regulation of GMOs faces some technical challenges. One of them is classifying GMOs under existing laws and regulations. Depending on its function and purpose, a GMO could be classified as a food, a biologic drug, or a pesticide, or it might not even fit into existing categories. For example, GloFish™ are GM goldfish that glow, but they are not regulated under federal laws because they don’t fit into any regulatory categories.  The FDA initially claimed regulatory authority over a GM mosquito produced by Oxitec to suppress Aedes aegypti populations because the agency classified it as a biologic used to prevent human diseases, but the EPA later claimed regulatory authority over the mosquito because it classified them as a biological pesticide. Another technical challenge with regulation is that methods for producing GMOs are constantly changing with advances in biotechnology. Some regulations apply to GMOs that are created by transferring genes between species but not to GMOs created by editing genes already present in the species. To deal with technical issues such as these, some scientists and policy analysts have argued that countries should adopt comprehensive GMO regulations.

The Precautionary Principle

Most environmental and public health agencies in the U.S. make risk management decisions based on information from scientific research, such as chemical analyses, cell studies, animal experiments, clinical trials, and epidemiological studies. U.S. agencies usually refrain from making regulatory decisions until they have conclusive scientific evidence concerning risks and benefits. If evidence is inconclusive, agencies may issue guidance but not take regulatory action. However, waiting for scientific evidence concerning an issue to become conclusive may prevent agencies from taking effective action to avert serious harms to public health or the environment. For example, during the 1990s some politicians and scientists argued that we should not do anything to address global warming until we have more evidence concerning its extent and causes and effects, but we now see that this attitude toward the problem was unwise because it wasted valuable time that could have been used to make progress in addressing the problem.

Because waiting for scientific evidence to accumulate can prevent policymakers from taking effective action to address serious threats, many commentators and organizations have endorsed a modification to traditional risk/benefit decision-making known as the precautionary principle. The basic idea behind this principle is that societies should take reasonable measures to avoid, minimize, or mitigate irreversible and serious harms, even when scientific evidence is inconclusive. Although the precautionary principle has gained many adherents, especially in Europe and California, it remains controversial, especially in the U.S.  One of the criticisms of the principle is that it is risk-averse and therefore endorses policies that impair technology development, industry, and the economy. Another criticism is that the principle is vague and could therefore be manipulated to achieve various political goals. Proponents of the principle have tried to address these criticisms by formulating versions of the principle that are clearly defined and not risk-averse although, by definition, the precautionary principle will ultimately rely on a perception of the magnitude and reversibility of any perceived threat.

Environmental Justice

Virtually every environmental health issue has implications for social and economic justice. The environmental justice movement began in 1982, when residents of Shocco Township, a low-income community of color located in Warren County, N.C., held a peaceful protest opposing the state’s plan to locate a polychlorinated biphenyl (PCB) disposal site in their neighborhood. Since then, hundreds of studies have documented socioeconomic inequalities related to proximity to environmental hazards (such as waste sites, landfills, and sewage treatment plants) and inequalities related to environmental risks arising from exposures to environmental hazards such as pollution, lead, pesticides, and industrial chemicals. Although the environmental justice movement focused initially on inequalities related to race, ethnicity, and income, environmental scientists and environmental justice advocates have come to see the importance of dealing with inequalities related to age, infirmity, poor access to health care, and other vulnerabilities. Today, environmental justice is widely recognized as a key concern in environmental laws, regulations, and international agreements.

In thinking about environmental justice, it is important to distinguish between environmental justice as a fair distribution of environmental benefits and burdens and environmental justice as a fair process for making decisions that impact the distribution of environmental benefits and burdens. An environmental burden could be unfair in the first sense but not the second or vice versa. In many cases of environmental justice, however, neither the outcome nor the process is fair. The Shocco incident, for example, involved unfairness in the distribution of environmental benefits and burdens because residents were exposed to the health risk associated with living near the PCB site and unfairness in the process that impacted this distribution because the residents had little input into the state’s decision-making concerning placement of the waste site.

One of the most important problems related to environmental justice is ensuring that decision-making processes that affect public health and the environment are fair and effective–that is, democratic, deliberative, open, and inclusive. Fairness can be difficult to achieve because industry and political groups often use their power and money to influence elected representatives and government officials and sway public opinion to achieve outcomes that align with their interests. To counterbalance these dominant groups, it is important to ensure that underrepresented and marginalized groups have the opportunity to express their needs and concerns and that their voices are heard and given due consideration.

Environmental justice requires special attention to the needs of vulnerable subpopulations–groups with an increased susceptibility to the adverse effects of an environmental risk factor, due to their age, genetics, health status, or some other condition. For example, children are more susceptible to the effects of lead, mercury, and some pesticides than adults; elderly people are more susceptible to the effects of extreme heat or cold and air pollution than younger people; and some people have genetic mutations that increase their susceptibility to developing cancer from exposures to carcinogens such as tobacco smoke and certain industrial chemicals.

Environmental regulations should protect not only average members of the population but also vulnerable subpopulations. Regulations in the U.S. do this to some degree. The EPA’s air quality standards, incorporate protections for people with respiratory diseases, such as asthma and pesticide regulations provide additional protections for children.

While protecting vulnerable subpopulations from environmental harms is a worthy public goal, it may be difficult to achieve, due to practicalities and tradeoffs with other valuable social goods. For example, about 0.4% of the U.S. population has a severe allergic reaction to peanuts. Banning the sale of peanuts would be an impractical way of protecting this population because it would prevent

other people from benefiting from eating peanuts. A more reasonable way of protecting people with peanut allergies is the FDA’s requirement that products containing peanuts be clearly labelled so that they can avoid eating them.

Allocation of health care funding also raises environmental justice issues. In the U.S., public and private payors spend hundreds of billions of dollars each year on health care, most of which goes toward medical diagnosis and treatment. One might argue, however, that a higher proportion of that money should be spent on preventive measures, which tend to be more cost-effective than treatment. This has been demonstrated for many diseases with environmental linkages, like asthma. Controlling exposures to environmental triggers of asthma attacks has been demonstrated to be highly cost-effective. Some of these preventative measures could include public and environmental health interventions and programs, such as improved sanitation, water treatment, waste management, health education, disaster preparedness, and mosquito control; enforcement of occupational and public health regulations; and oversight of food and drug safety.

Human Rights

Various public and environmental health strategies and policies pit the rights of individuals against the good of society. For example, during the Covid-19 pandemic, societies implemented many different measures to control the spread of the disease, such isolation and quarantine; mandatory mask-wearing, testing, and vaccination; physical distancing; travel restrictions; business and school closures; curfews; stay-at-home orders; and disease surveillance. The main argument in favor of these public health strategies and policies is that individual human rights can be restricted for compelling societal goals, such as preventing transmission of a highly infectious, deadly disease. However, restrictions on rights should be guided by scientific evidence and sound ethical arguments. (See “Public Health Ethics and Law.”)

Some environmental health protections may also restrict human rights. Many of these have to do with restricting economic and property rights. For example, water pollution regulations restrict the rights of property owners to dispose of waste products on their land that may contaminate fresh water supplies. The owner of a coal-burning power plant must deal with many laws concerning air pollution generated by the plant, disposal of solid waste, and workplace safety. A developer who plans to build 150 new homes may have to deal with laws concerning storm drainage, water and sewage lines, gas lines, lots sizes, sidewalks, protected species, and so on. Restrictions on economic and property rights should be guided by sound ethical arguments and scientific evidence.

Emerging Issues

Future developments in medical science, combined with improvements in science, technology, and industry, such as advances in nanotechnology, artificial intelligence, genetic engineering, energy production, and geoengineering, are likely to raise novel ethical issues concerning the relationship between human health and the environment. To deal with new and longstanding issues fairly and effectively, it is important for scientists, scholars, policymakers, and laypeople to engage in free, open, and inclusive discussions about ethics and environmental health.


This research was supported by the intramural program of the National Institute of Environmental Health Sciences/National Institutes of Health. It does not represent the views of the NIEHS or NIH. We are grateful to Ken Olden, Richard Sharp, and William Schrader for helpful comments.

David B. Resnik, JD, PhD, is a bioethicist and IRB chair at the National Institute of Environmental Health Sciences, National Institutes of Health. Christopher J. Portier, PhD, is a senior collaborating scientist at the Environmental Defense Fund.

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