Americans' Exposure to Environmental Chemicals

The Centers for Disease Control and Prevention (CDC) has released the second National Report on Human Exposure to Environmental Chemicals, the largest and most extensive assessment of the US population’s exposure to environmental chemicals. The report presents exposure information for 116 environmental chemicals measured in blood and urine specimens, which came from a sample of people who represent the US population for the years 1999 and 2000.

“This report is by far the most extensive assessment ever of exposure of the US 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.”

The report contains new data on declines in blood lead levels in children; decreases in adults’ exposure to environmental tobacco smoke, and for the first time, 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. CDC’s Environmental Health Laboratory developed special analytical methods and measured the chemicals and their metabolites (breakdown products) in these blood and urine samples.

Some Progress, But Concerns Remain
Lead: New data on blood lead levels in children aged 1 to 5 years allow the CDC to estimate the number of children with elevated levels. For 1999-2000, 2.2% of children in this age group had elevated blood lead levels. This percentage has decreased from 4.4% for the period of 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 of the National Center for Environmental Health.

Exposure to Environmental Tobacco Smoke: Cotinine is a metabolite of nicotine. Compared with levels measured during the period 1991-1994 for nonsmokers, cotinine levels have decreased 58% for children, 55% for adolescents and 75% for adults. “These declines support the effectiveness of public health efforts to reduce environmental tobacco smoke (ETS) exposure during the 1990s, which have mostly targeted adults,” Dr. Jackson said. “However, continued efforts to reduce exposure to environmental tobacco smoke are warranted, especially for children, adolescents, and non-Hispanic blacks.”

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

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

The complete Second National Report on Human Exposure to Environmental Chemicals is available online fro the CDC.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.