In sufficient amounts, these chemicals can act like the female hormone estrogen. Although the effects of any exposure are unknown, some scientists have suggested that environmental estrogens might be reducing sperm counts in men and causing breast cancer, fibroids and other reproductive diseases in women. At present, scientists know little about which of the environmental estrogens people are exposed to and how much exposure they have. The study underway by NIH and CDC will address these questions.
Richard J. Jackson, M.D., director of CDC's National Center for Environmental Health, said, "This kind of assessment of exposure to environmental estrogens is absolutely critical to the scientifically credible assessment of potential health risk from these compounds. The study builds on CDC's longstanding expertise in measuring toxic substances in people's blood and urine and is a valuable public health collaboration with NIEHS."
Kenneth Olden, Ph.D.,director of both NIEHS and the National Toxicology Program, which is headquartered at NIEHS, said, "The study will help us develop priorities for studying the potential adverse health effects of exposure to environmental estrogens. We hope this kind of collaboration will be expanded in the future to address many other toxic substances that we know or suspect cause cancer, reproductive, and other health effects."
The NIEHS and NTP are providing $2.1 million to CDC to measure approximately 50 environmental estrogens in 200 persons to determine the level of exposure to the population. CDC and NIEHS will jointly agree on the final list of environmental estrogens to be measured in people. Among the more familiar chemicals that will be tested are: insecticides such as arsenic, dieldrin, mirex, lindane, parathion, and DDT and its metabolics; herbicides such as 2,4-D, alachlor and atrazine; nematocides such as aldricarb; fungicides, plant and fungal estrogens, and industrial chemicals such as cadmium, lead, mercury, PCBc, and dioxins. CDC will use existing analytical methods for blood and urine to measure most of the chemicals and develop new analytical methods to measure 10 to 20 of the environmental estrogens.
The coordinator for this research for NIEHS and NTP, George Lucier, Ph.D., said "This project will give us an idea of human exposure to each of the chemicals and help us set priorities for the studies done in the National Toxicology Program. Comparing the levels with other health and toxicity data, we should be able to determine if some of the higher exposures we find are linked to increased incidences of disease."
By measuring chemicals in people's blood and urine, scientists can determine what chemicals Americans are being exposed to, how much exposure is occuring to each chemical, what population groups are at the highest risk of excessive exposure, and whether interventions aimed at reducing exposure to a chemical have actually been effective and reduced the chemical level in people.
For example, blood lead measurements obtained as part of the National Health and Nutrition Examination Surveys conducted by CDC's National Center for Health Statistics have documented a more than 78% reduction in lead in the U.S. population, since 99.8% of lead has been removed from gasoline and lead is no longer used in food and drink cans in the U.S. Similar assessments could be made for other toxic substances to determine whether the U.S. populations' exposure is increasing or decreasing. This exposure information helps prioritize public health efforts in environmental health and direct toxicologic reseach towards exposures of most health concern.