San Francisco Chronicle
1 February 2003

Kids bearing brunt of chemical contamination, big study finds
But levels of PCBs, secondhand smoke, DDT in Americans' bodies are lower than 10 years ago

By Jane Kay

American children carry traces of some common pesticides, industrial chemicals and other contaminants at levels twice as high as in adults, according to the largest study ever of human exposure to environmental chemicals.

For the most part, the study by the federal Centers for Disease Control and Prevention found that exposures to the most harmful chemicals -- including lead, DDT, PCBs and secondhand smoke -- had declined among both adults and children from a decade ago.

CDC officials attributed the decline to public health programs and stricter regulations on chemical pollution. But they warned that millions of children still faced hazardous levels of many contaminants.

Half of children in the study had been exposed to tobacco smoke and had levels twice those of adults. Children also had twice the level of industrial chemicals known as phthalates and higher levels of a recently banned insecticide used around households, chlorpyrifos, also known as Dursban.

"Children eat, breathe and drink two to three times as much as adults do" based on weight, said Dr. Richard Jackson, director of the CDC's National Center for Environmental Health. "It's not surprising that children's exposures will be higher from dietary and respiratory sources."

CDC researchers took blood and urine from 2,500 people in 1999 and 2000 and tested for 116 chemicals as part of the National Health and Nutrition Examination Survey, which collects data on 5,000 randomly selected people. An initial study released in 2001 looked at only 27 chemicals.

BIGGEST REPORT EVER

"This report is by far the most extensive assessment ever made of the exposure of the U.S. population to environmental chemicals," said Dr. David Fleming, CDC's deputy director of science. The study was posted Friday at www. cdc.gov/exposurereport. More than 50 separate studies are in progress to determine the health effects of a wide array of chemicals. These data will be used by others to determine a reference point for comparison and to indicate where to regulate.

The Environmental Protection Agency estimates that there are between 80,000 and 100,000 chemicals in commerce today.

"Clearly, a fair number of chemicals have been put into common commerce that weren't adequately tested, particularly as pesticides were grandfathered in in the early '70s and '80s," said the CDC's Jackson. It is "important to begin to have the toxicology data when large numbers of people are being exposed."

He cautioned, however, that the presence of an environmental chemical in a person's body doesn't by itself mean that it causes diseases.

The American Chemistry Council, a manufacturers group, issued a statement saying the CDC study would help researchers look at whether the presence of minute levels of chemicals in the body had any health impact. But it cautioned consumers about reading too much into the study.

"Some people may jump to the conclusion that simply finding a natural or manmade chemical in the body is cause for concern," it said. "Scientists at the CDC warn against scaring people in this way."

DDT, PCBS, DIOXINS

The study found a drop in three cancer-causing pollutants that persist in the environment over long periods -- the banned pesticide DDT; PCBs, which were once used as insulation in electrical transformers; and dioxins, a byproduct of combustion and furnaces.

In a disturbing finding, the study found that up to 10 percent of women of child-bearing age carried toxic mercury at levels estimated by the U.S. EPA to affect the developing fetus. Mercury, a contaminant found in some types of fish, can damage the brain and nervous system.

The study also found that Mexican Americans had levels of DDT three times higher than non-Hispanic whites and African Americans, and that African Americans had twice the exposure to secondhand smoke than whites and Mexican Americans.

Among children, the decline in lead was notable. In the early 1990s, 4.4 percent of children ages 1 to 5 had unsafe levels, but that dropped to 2.2 percent in 1999-2000, the study found. Lead is a major concern because of its effects on brain development.

Even secondhand smoke, which was found in children at twice the levels in adults, declined by 58 percent in children. It dropped more among adults -- 75 percent. The CDC measured exposure to secondhand smoke by testing for cotinine,

a byproduct of nicotine after it enters the body.

CDC officials believe children's exposure to secondhand smoke may be high because public health efforts primarily focused on reducing secondhand smoke in adult areas, such as in the workplace. In addition, children may absorb more from their environment than adults.

Phthalates, plastics softeners that are suspected of causing cancer and developmental harm, were found in children at twice the levels of adults. Exposure probably comes from plastic toys, said Jim Pirkle, deputy director for science at CDC's environmental health lab.

Phthalates are also found in soaps, shampoos, hair sprays and nail polish and are used widely in plastic food packaging, plastic clothing, detergents, garden hoses and some pharmaceuticals.

E-mail Jane Kay at jkay@sfchronicle.com.