Tracking Environmental Chemicals
The Centers for Disease Control and Prevention has just released its first-ever "National Report on Human Exposure to Environmental Chemicals." The groundbreaking study assessed the exposure of the U.S. population to 27 environmental chemicals, many of which are known carcinogens.
The chemicals being monitored were grouped into four categories: Metals (including lead, mercury and cadmium); Cotinine (an indicator of second-hand smoke); Pesticides; and Phthalates (used in soaps, shampoos and certain plastic products).
CDC researchers measured levels of these chemicals in blood and urine samples collected from approximately 5,000 participants in their ongoing National Health and Nutrition Examination Survey. The data was collected in 1999 from 12 locations across the U.S.
The report is important because it marks the very first time that national exposure levels were measured for 24 of the 27 chemicals that were included in the study. (Previously the CDC had tracked levels for lead, cadmium and cotinine.)
Dr. Richard Jackson, Director of the CDC's National Center for Environmental Health, called the report a "revolutionary" step forward in assessing the exposure of the U.S. population to environmental chemicals.
The CDC researchers were enthused that cotinine levels were found to be lower than in previous studies. 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.
"One significant finding was the more than 75 percent decrease in serum cotinine levels for nonsmokers in the United States," said the Dr. Jim Pirkle, a co-author of the report. "This decrease documents a dramatic reduction in exposure of the U.S. population to environmental tobacco smoke since 1991."
Nonetheless, environmental tobacco smoke remains a major public health concern, he cautioned, "since more than half of American youth continue to be exposed to this known human carcinogen."
The CDC has been measuring population-wide lead levels since 1976, with the current study providing the most recent measurable data. "The good news is that blood lead levels continue to decline among children overall," said Eric Sampson, Ph.D., another 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."
Conversely, not all of the news was positive for phthalates, which are widely used in industry and found in soap, shampoo, hairspray, and nail polish, among other products. "Seven major phthalates were measured and we found that two of the metabolites-diethyl phthalate (DEP) and dibutyl phthalate (DBP)-are at higher levels in the population than metabolites of other phthalates that are actually produced in higher quantities," warned Sampson. "We are conducting additional studies to explain these findings."
During the coming years, data from many more locations will be reported, said the CDC's Jackson. In addition, exposure to more than 100 chemicals will eventually be monitored, and data will be made available for specific population groups (e.g., children, minority populations, or women of childbearing age).
For more information on the CDC report, or to request a full copy, you can call 1-866-670-6052. You can also access a copy of the report online at: www.cdc.gov.
SOURCE:
"National Report on Human Exposure to Environmental Chemicals," March 21, 2001, Centers for Disease Control and Prevention, Atlanta, GA
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