The U.S. Centers for Disease Control and Prevention conducts the most extensive biomonitoring program at present. Most recently, the agency released its Third National Report on Human Exposure to Environmental Chemicals, which includes the results of testing for 148 chemicals* in blood and urine samples from 5,000 people selected randomly nationwide. As Graphic 1 indicates, the number of chemicals included in the CDC’s biennial testing, which began in March 2001, has increased dramatically.
The CDC selects chemicals for analysis from among hundreds nominated by scientists and the general public. The factors considered in the selection include:
The potential for human exposure to the chemical.
The seriousness of health effects from exposure.
An adequate number of people whose blood and urine samples could be tested for the target chemical.
The availability of testing methods with adequate performance and acceptable costs.
The CDC analyses demonstrate how biomonitoring data can inform environmental and public health policy. The data reveal a significant decline in the blood concentrations of many chemicals, indicating the benefits of new technologies that reduce or eliminate emissions and discharges of chemicals, and the success of other pollution prevention efforts. Among the declines noted in the CDC’s latest exposure report:
Only 1.6 percent of children ages 1-5 had “elevated” blood levels of lead, down from 88.2 percent between 1976 and 1980.
From 1988 to 2002, the median levels of cotinine, a marker of “second-hand smoke,” decreased 68 percent for children, 69 percent for adolescents and 75 percent for adults.
There are now undetectable or very low levels of the pesticides Aldrin, Endrin and Dieldrin — all of which have been discontinued in the United States.
All women of childbearing age had mercury levels below the concentration associated with neurological effects in a fetus.
Other federal agencies involved in biomonitoring include the National Institutes of Health, the U.S. Environmental Protection Agency, the Agency for Toxic Substances and Disease Registry, and the National Institute of Environmental Health Sciences.
Biomonitoring capabilities are not widely available in most commercial laboratories, nor does the CDC perform laboratory tests at the request of individuals. A physician may be able to test blood or urine for lead, mercury and a few other chemicals that have known health consequences. If necessary, doctors can refer patients for further evaluation to a toxicologist or a physician who specializes in occupational and environmental medicine.
California established the nation’s first state biomonitoring program when Gov. Arnold Schwarzenegger signed Senate Bill 1379 on Sept. 29, 2006. The California Environmental Contaminant Biomonitoring Program will screen 2,000 volunteers every two years for a variety of compounds and in the future conduct smaller, community-based studies.
In 2001, the CDC began distributing $10 million in grants to 25 states and regional groups for planning biomonitoring programs. The Michigan Department of Community Health was among the recipients. In 2003, Gov. Jennifer Granholm requested the state’s Environmental Science Board to evaluate the scientific validity of the compounds targeted for testing in the state’s draft biomonitoring plan. Among its findings, the board concluded: “As currently written, the Draft Report does not provide a credible source of rationales for including or excluding many of the identified toxic substances for biomonitoring. In addition, most of the discussions presented are lacking in rigor, clarity, and coherence.” In response to the evaluation, the Department of Community Health declined to pursue the establishment of a biomonitoring program.
* The 148 chemicals are grouped into the following categories: metals; cotinine; polycyclic aromatic hydrocarbons; dioxins; furans; polychlorinated biphenyls; phthalates; phytoestrogens; organochlorine pesticides; organophosphate pesticides; herbicides; pyrethroid insecticides; other pesticides; and carbamate insecticides.