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CDC Releases Assessment of Exposure to Environmental Chemicals

The second National Report on Human Exposure to Environmental Chemicals released by the Centers for Disease Control and Prevention (CDC) on Jan. 31 finds that Americans have lower lead levels for children and lower levels of cotinine in adults, indications that public health efforts to reduce exposure to lead and environmental tobacco smoke have worked.

The report, the largest and most extensive assessment of the U.S. population's exposure to environmental chemicals, presents exposure information for 116 environmental chemicals measured in blood and urine specimens. The blood and urine specimens came from a sample of people who represent the U.S. population for the years 1999 and 2000.

"This report is by far the most extensive assessment ever of exposure of the U.S. population to environmental chemicals," said CDC Director Dr. Julie Gerberding, "This kind of exposure information is essential, it helps us to lay the critical groundwork for future research in ensuring that exposures to chemicals in our environment are not at levels that affect our health."

In addition to new data on declines in blood lead levels in children and decreases in adults' exposure to environmental tobacco smoke, the report contains extensive data on many other chemicals that will help public health physicians and scientists identify and prevent health problems from exposure.

Blood and urine samples were collected from some 2,500 participants for each chemical tested in CDC's National Health and Nutrition Examination Survey (NHANES) an ongoing national health survey of the U.S. population. CDC's Environmental Health Laboratory developed special analytical methods and measured the chemicals and their metabolites (breakdown products) in these blood and urine samples.

For 1999-2000, 2.2 percent of children 1 to 5 years old had elevated blood lead levels (levels greater than or equal to 10 micrograms per deciliter). This percentage is a decrease from 4.4 percent for the years 1991-1994.

"The continued decline of elevated blood lead levels in America's children is a public health success story. However, exposure of children to lead in homes containing lead-based paint and lead-contaminated dust remains a serious public health concern," said Dr. Richard Jackson, Director, National Center for Environmental Health.

In some good news for anti-smoking advocates, cotinine levels have decreased 58 percent for children, 55 percent for adolescents, and 75 percent for adults compared with levels measured during the years1991-1994 for nonsmokers.

"These declines support the effectiveness of public health efforts to reduce environmental tobacco smoke (ETS) exposure during the 1990s, which have mostly targeted adults," Jackson said. "However, continued efforts to reduce exposure to environmental tobacco smoke are warranted, especially for children, adolescents and non-Hispanic blacks."

The second report presents extensive data for many other chemicals that include mercury, uranium, cadmium, thallium and other metals; phthalates; organochlorine pesticides, herbicides and polycyclic aromatic hydrocarbons; carbamate insecticides; and organophosphate pesticides and phytoestrogens.

The report and an executive summary are available online at The report will continue to be released every two years, expanding the number of chemicals covered, providing physicians with reference levels of exposure so that they can recognize unusually high levels of exposure in patients and assessing the effectiveness of efforts to reduce chemical exposure.

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