New CDC Chemical Exposure Report begins to fill critical information gaps in environmental health for the U.S. population
The Centers for Disease Control and Prevention (CDC) today released the first National Report on Human Exposure to Environmental Chemicals, an important new research tool that will provide better information on levels of exposure to environmental chemicals, and over time what these levels mean for public health
Advances in a technology known as biomonitoring allow CDC to measure chemicals directly in blood and urine samples rather than estimating population exposures by measuring air, water, or soil samples. Based on this scientific advancement, the new report provides data on actual levels of chemicals in humans. As data are collected over the years, researchers will be better able to determine possible health effects and design appropriate public health strategies.
"This new resource is a significant development in the field of environmental health," said Health and Human Services Secretary Tommy G. Thompson. "It will help us to better track the exposures of Americans to chemicals in the environment and to measure the effectiveness of our public health efforts."
This first report initially measures the exposure of the U.S. population to 27 environmental chemicals. The report includes metals (e.g., lead and mercury), pesticide metabolites, phthalate metabolites and cotinine (which tracks exposure to tobacco smoke). Levels of environmental chemicals were measured in blood and urine samples collected from participants in CDC's National Health and Nutrition Examination Survey (NHANES) - an ongoing national health survey of the U.S. population. The Report provides results from the 1999 survey; data from future years will help confirm these findings.
"The Report is a major step toward assessing in the U.S. population which environmental chemicals are present in blood and urine samples, who is exposed, trends in exposure over time, and whether interventions to reduce exposure are working," said Richard J. Jackson, MD, MPH, Director of CDC's National Center for Environmental Health (NCEH).
Although the report does not include new information on health risks of exposures or on potential routes of exposures, this is the first time that national exposure levels of the U.S. population are known for 24 of these 27 chemicals. CDC previously assessed the population's exposure to three substances -- lead, cadmium, and cotinine, and the report provides new data for the 1999 calendar year. Previously, only limited data were available on which environmental chemicals were in the U.S. population and at what levels.
The presence of a chemical in blood or urine does not necessarily indicate that the chemical will cause disease. Additional research is required to determine whether the levels reported are a cause for health concern.
The first Report provides information on the exposure of the U.S. population to these 27 substances. The chemicals, grouped into four categories, are as follows:
Metals: lead, mercury, cadmium, cobalt, antimony, barium, beryllium, cesium, molybdenum, platinum, thallium, tungsten, and uranium.
Tobacco smoke: cotinine - a metabolite of nicotine that tracks tobacco smoke exposure.
Organophosphate pesticides (Six metabolite measurements representing exposure to 28 pesticides): dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, and diethyldithiophosphate. These metabolites are generally formed by the breakdown of 28 pesticides, including chlorpyrifos, diazinon, fenthion, malathion, parathion, disulfoton, phosmet, phorate, temephos, and methyl parathion.
Phthalate metabolites: mono-ethyl phthalate, mono-butyl phthalate, mono-2-ethylhexyl phthalate, mono-cyclohexyl phthalate, mono-n-octyl phthalate, mono-isononyl phthalate, and mono-benzyl phthalate.
Highlights of the Report
Cotinine is a breakdown product of nicotine after it enters the body. Levels of cotinine in the body track the amount of exposure a person has to tobacco smoke. For a nonsmoker, cotinine tracks exposure to environmental tobacco smoke. CDC measured cotinine in nonsmokers in the U.S. population as part of a previous survey, and the Report presents new cotinine data for 1999.
"One significant finding was the more than 75% decrease in serum cotinine levels for nonsmokers in the United States," said Jim Pirkle MD, PhD, of CDC's Environmental Laboratory and co-author of the report. "This decrease documents a dramatic reduction in exposure of the U.S. population to environmental tobacco smoke since 1991. However, environmental tobacco smoke remains a major public health concern since more than half of American youth continue to be exposed to this known human carcinogen."
CDC has been measuring the population's exposure to lead since 1976 through the NHANES surveys. CDC's Childhood Lead Poisoning Prevention Program (www.cdc.gov/nceh/lead/lead.htm)
works to reduce exposure of children in the United States to lead. The Report presents blood lead level measurements for U.S. children in 1999.
"The good news is that blood lead levels continue to decline among children overall," said Eric Sampson, PhD, of CDC's Environmental Laboratory and also a co-author of the report. "However, other data show that children living in environments placing them at high risk for lead exposure remain a major public health concern."
Environmental health is one of the Leading Health Indicators in Healthy People 2010. Information on environmental chemical exposures will assist clinicians and public health officials to better understand the relationship between toxic exposures and health consequences and guide public health prevention efforts. CDC will add other substances to future reports based on data obtained from samples collected in subsequent NHANES surveys. CDC will continue to measure the 27 original substances as well. The goal over the next few years is to expand the Report to provide information about 100 chemicals. CDC will monitor trends over time that may help scientists better understand the impact of the environmental chemicals on our health. In the future, CDC will be able to report exposure levels for more specific population groups (e.g., children, minority populations, or women of childbearing age).
In addition, CDC will expand the Report to include exposure data from studies of people exposed from localized or point-source exposures (e.g., data on levels of mercury in people who eat mercury-contaminated fish from a polluted river). For more information on the Report data, log onto www.cdc.gov/nceh/dls/report or call 1-866-670-6052.
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