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Many chronic diseases and disabilities have been linked with exposure to environmental contaminants, including asthma, cardiovascular disease, cancer, birth defects, and learning & developmental disabilities. The Collaborative on Health and the Environment has prepared a series of Peer Reviewed Papers on chronic diseases and their links with environmental quality, as well as Toxicant and Disease Database.
Chronic health problems are now reaching epidemic proportions in the US, affecting more than 100 million women, men and children. The economic cost of these diseases exceeds $325 billion a year in health-care costs and lost productivity. At the same time, more than 85,000 synthetic chemicals have been registered for use and about 2,000 new ones are added each year. These chemicals include pesticides, chemicals used, manufactured and emitted by industries, chemicals in consumer products, and pharmaceuticals. These chemicals are now widespread in our air, water, soil, food, homes, schools and workplaces. Many are also present in our bodies.
Low-income communities and communities of color often bear a disproportionate burden of health risks from environmental contamination.
Thus, there is an urgent need to reduce exposures to toxic chemicals and other environmental hazards to protect our health and the health of our children. This requires effective action from all sectors of society, including government, the private sector, researchers, health affected groups and environmental organizations. But planning and implementing effective action requires a basis in scientific information and knowledge.
Science has already taught us a lot about how the environment affects health but this information must be more widely shared and understood, so that it can lead to actions to reduce exposures. While there is a need for more research, it is also vital that we use what we already know to reduce exposures to environmental risks.
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The Clearinghouse
This "clearinghouse" contains a collection of sources of scientific information on health and environmental quality in Washington State. Its intention is to ensure that information is more widely available and accessible to everyone, and especially nonscientists.
The sources summarized in the clearinghouse are categorized as follows:
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Approach to Developing the Clearinghouse
Diseases and disabilities linked with environmental contaminants were identified using the Collaborative for Health and Environment's Toxicants and Disease Database. This database identifies about 180 diseases or disabilities associated with chemical contaminants in the environment. The database categorizes the ‘strength of the evidence' for the association between specific health effects and environmental contaminants into "strong", "good", or "limited or conflicting". We chose health effects with "strong" or "good" evidence of association with environmental contaminants. Effects with "limited/conflicting evidence" were not included.
In a few cases, we used the scientific literature and our best professional judgment to associate environmental hazards with specific health effects. This includes the links between air particulates and asthma and cardiovascular disease; the health effects of climate change; and land use, sprawl and health.
The following types of scientific information were collected and summarized:
- Environmental monitoring information;
- Health surveillance information;
- Studies of exposure, risk assessments, and epidemiological studies.
All websites referenced were accessed in late October or early November 2006.
To keep the clearinghouse manageable, we have focused on information sources on public exposures and health outcomes. Thus, the clearinghouse does not address occupational exposures and effects in any detail.
We have tried to include only credible and authoritative sources of scientific information in the clearinghouse. Indeed, most the sources of information that are included the database are peer-reviewed or the equivalent. However, CHE–Washington is not responsible for the accuracy or validity of the information sources listed.
If you know of additional sources of scientific information on health and environmental quality in Washington State, please contact: Kate Davies at kdavies@antiochsea.edu. We plan to update the clearinghouse approximately once a year.
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Proving that Environmental Contaminants Cause Effects on Health
It is very difficult to prove that exposure to a specific environmental contaminant causes a specific health effect. This is because the effects of chemical exposures in humans are difficult to study. There are several reasons for this:
- Ethics: It isn't ethical to experiment on human beings by deliberately exposing them to toxic chemicals. There is some human data obtained from accidental exposures, overdoses, or studies of workers exposed occupationally, but not very much.
- Measuring Exposure:Measuring human exposures to toxic chemicals is difficult. A person's exposure may change over time, and exposures occur to multiple chemicals both in the home and work environments. It is difficult for individuals to remember what they have been exposed to and, moreover, most people are unaware of what their exposures were.
- Variability in the Population: The effects of chemical exposures may vary, depending on the age at exposure (in utero, childhood, adult), the route of exposure (ingestion, inhalation, dermal), the severity and duration of exposure, exposures to multiple chemicals simultaneously, and other personal susceptibility factors, including genetic variability.
- Time Delay: Many diseases, such as some forms of cancer, do not manifest until decades after exposure making it difficult for causal associations to be identified. For example, the rare lung disease, mesothelioma, can take decades to become apparent after the onset of exposure to asbestos.
- Toxicology: Most studies on toxic chemicals involve animal studies. Animal studies can provide strong evidence of disease if the chemical's mechanism of action is the same in humans as in the animal species. Many regulatory decisions to limit or ban a chemical's use are based on animal data. However, extrapolation from effects on experimental animals to effects in human populations is not always accurate.
- Epidemiology: There is a growing number of epidemiological studies that have linked exposure to environmental contaminants with specific health effects in human populations. However, these studies do not often provide conclusive evidence because very large populations may be needed to study rare diseases and disabilities, people move a lot over time, and it is difficult to measure exposures precisely.
Nevertheless, it is possible to make "associations" or "correlations" between exposure to many environmental contaminants and health effects.
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The Collaborative on Health and the Environment – Washington
