Exposure to Chemicals Is Declining, CDC Finds

Published October 1, 2005

In its Third National Report on Human Exposure to Environmental Chemicals, released July 21, the U.S. Centers for Disease Control (CDC) has documented significant declines in the population’s exposure to environmental chemicals.

The study used biomonitoring to assess exposure levels. The report is based on measurements of chemicals and metabolites in blood and urine from a random sample of participants in the National Health and Nutrition Information Survey.

The report presents exposure data for 148 chemicals during 2001-2002. The CDC’s Second Report had examined exposure data for 116 chemicals during 1999-2000. Some elements of the Third Report combine data from 1999-2000 with data from 2001-2002.

Lead Lower, Mercury Gone

Dr. Judy Louise Gerberding, director of the CDC, discussed the study’s results in a July 21 telebriefing.

The report concludes that during 1999-2002 only 1.6 percent of U.S. children ages 1 to 5 had elevated blood levels of lead (10 micrograms per deciliter). By comparison, 4.4 percent of children in that age group had elevated levels about a decade earlier.

“This is an astonishing public health achievement,” Gerberding said, “and I think really speaks to the removal of lead from gasoline, which was one of the major correlates of this reduction, but also the lead abatement programs and other steps, being able to screen, treat and protect children from lead exposure.”

Data from the Third Report show no women of childbearing age from 1999-2002 had levels of mercury above 58 milligrams per liter, an amount believed to create a higher risk of neurological problems in developing fetuses.

Environmental Tobacco Smoke Down

The report also indicated traces of environmental tobacco smoke, sometimes known as second-hand smoke, had fallen by nearly 70 percent between the 1988-1991 and 1999-2002 study period.

“Efforts to reduce ETS exposure in the population show significant progress,” the report states.

In addition, the now-banned but once widely used pesticides Aldrin, Endrin, and Dieldrin were barely detectable in people studied in the current report.

Exposure Alone Not Harmful

In addition to documenting the reductions in exposure, the report notes that having an environmental chemical present does not mean there necessarily will be some disease. “Small amounts [of chemicals] may be of no health consequence,” the report states.

“For most of the environmental chemicals for which information is presented, more research is needed to determine whether exposure at levels reported here is a cause for health concerns,” the report states.

The report also does not indicate the source of the environmental chemicals; they could come from either natural or manmade sources.

Low Levels Not Harmful

Cliff Curtis of the World Wildlife Fund (WWF) criticized the report, claiming it “falls short in recognizing the scale of chemical exposure to people and wildlife.

“The number and levels of chemicals reported by both the CDC report and WWF’s biomonitoring show that voluntary measures by industry are not working,” argued Curtis.

But experts disagreed.

“Using government biomonitoring data to terrify Americans about trace environmental exposure to chemicals will do absolutely nothing to promote public health,” said Dr. Elizabeth Whelan, president of the American Council on Science and Health.

Whelan was particularly critical that the CDC collected data on 38 chemicals for which there is “no evidence that these very low levels pose any harm.”

Her advice: “Take the CDC report with a hefty grain of sodium chloride.”

Michael Coulter ([email protected]) teaches political science at Grove City College.

For more information …

The CDC’s 475-page Third National Report on Human Exposure to Environmental Chemicals is available online at http://www.cdc.gov/exposurereport/3rd.