CDC to Detail Blood Contaminants

The medical and environmental communities are eagerly awaiting a report, to be issued today by the Centers for Disease Control and Prevention, that for the first time measures the public’s exposure to more than two dozen chemicals by testing the blood of a national representative sample of 5,000 Americans.

The report looks at 27 substances to assess the danger to Americans of contamination by everything from heavy metals--such as lead, mercury and cadmium--to phthalates, which are chemicals used in plastics, solvents, detergents and cosmetics and which in animal studies have been shown to cause cancer.

The findings are expected to show generally that most of these chemicals are present in low levels in Americans’ blood, not posing an immediate health risk.

Nevertheless, the information has stirred great interest among experts who are worried about the possible effects over time of chronic exposure to children and fetuses.

“Many substances that are totally nontoxic to adults can be devastating to developing children,” said Dr. John Harris, director of the California Birth Defects Monitoring Program. “We just don’t know one way or the other.”

Until now, estimates of exposure to chemicals were based on their detection in air, water or soil. Sophisticated technology now allows scientists to measure chemicals more precisely in the bloodstream.

“One of the things that has always been less than ideal is that we had to make a lot of assumptions, based on . . . what was in the food, water, air and soil, and we were very often criticized by companies for piling on the assumptions,” said Dr. Lynn Goldman, head of the Environmental Protection Agency’s pesticide office during the Clinton administration. “One of the things this report will be able to do is nail down what the actual exposure levels are.”

The results will serve as a baseline to track trends and are regarded as a critical blueprint for public health officials to identify and target areas where greater efforts are needed to reduce exposure to potentially dangerous substances.

“It’s a very powerful study,” said Dr. Philip J. Landrigan, chairman of the department of community and preventive medicine at Mt. Sinai School of Medicine in New York. “It presents a very valid picture of the distribution of chemicals in the United States.”

And the report is likely to contain a few surprises. For example, higher-than-expected levels of organophosphate pesticides were found, unanticipated because these substances--which include such products as diazinon, malathion and parathion--are short-lived in the body, lasting only a few weeks to a few months at most.

These differ from such pesticides as DDT--now banned in this country--which are cumulative.

“If we are seeing it in many people, it means that most people, on a daily basis, have some exposure,” Goldman said.

The data are also expected to show low levels of cotinine, a byproduct of environmental tobacco smoke, which may be an indication that aggressive approaches aimed at curbing indoor cigarette smoke are having an effect.

The CDC next plans to expand its monitoring to 100 substances and add categories such as dioxins, PCBs and nitrosamines, among others.

Although the report is viewed as an important first step, public health advocates said that more resources will be needed to break down the findings.

“This is the first national snapshot” of exposure levels, but it’s like the doctor only examining the ankle when the patient needs a full physical,” said Jim O’Hara, executive director of Health-Track, an environmental health public education project.

Industry officials stressed that the information should not be interpreted in isolation.

“Biomonitoring is the measurement of substances in the body at the moment the testing is conducted,” said Sandra Tirey, assistant vice president of the American Chemistry Council and co-leader of its public health team. “At the same time, it does not provide information about the source of exposure, when the exposure occurred or, most importantly, what effect, if any, that substance may have on the body.”

The health significance of the data “is virtually impossible to interpret” without research that can help determine potential health hazards, she said, calling upon CDC “to provide context” for understanding the effects of these chemicals on the body.