Study finds lower level of old toxins, but new trends are worrying.

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Study Finds Lower Level of Old Toxins but New Trends Are Worrying

 

By ANDREW C. REVKIN

The broadest study yet of toxic chemicals that Americans absorb in

their bodies showed a continuing decline in the clearest threats,

like lead, pesticides and tobacco residues, but turned up numerous

other findings that federal scientists and other experts called

troublesome yesterday.

 

The study tested blood and urine collected in 1999 and 2000 from

more than 2,000 volunteers chosen as a representative slice of the

American population. It determined that almost 8 percent of the

roughly 50 million American women ages 16 to 49 had blood levels of

mercury exceeding 5.8 parts per billion, the precautionary standard

set by the Environmental Protection Agency.

 

Federal health officials said the danger level for mercury was 10

times that high, a level not found in any of the women in the study.

But they said the finding justified a greater effort to find ways to

cut women's exposure to mercury, which at high levels can cause

birth defects and other problems.

 

Much of the mercury exposure is likely to accumulate through eating

fish. It is the second such study by the federal Centers for Disease

Control and Prevention, but in examining 116 chemicals it greatly

expands on the first report, published in 2001, which looked for

only 27. Health researchers, environmental campaigners and industry

representatives hailed the report as a vital tool in trying to

discern, or rule out, health effects from chemicals in the

environment. " This allows us to begin connecting the dots, " said Dr.

Patricia Butterfield, a researcher and professor of nursing at

Montana State University. " We can begin in the next generation of

citizens to understand these issues and make science-based

decisions. "

 

The study, the Second National Report on Human Exposure to

Environmental Chemicals, was posted at www.cdc.gov/exposurereport

yesterday. Because the study measured exposures by age, sex and

ethnic background, it could help public health officials focus their

priorities, officials and experts said. For example, it found that

all other population groups, including children, had blood levels of

mercury well below the government safety limit.

 

Future surveys will be published every two years. Among other

findings, the new study disclosed that children had higher

levels of residues from secondhand smoke, some pesticides and

plastics than adults, and that Mexican-Americans have three times

the levels of a DDT residue of other Americans.

 

The children's higher levels of residues could be a result of

several factors, federal scientists said. For one, children eat,

drink and breathe three times as much as adults pound for pound.

More work should be done to understand the DDT levels in Mexican

Americans, scientists from the disease control agency said. The

pesticide has long been banned in the United States and since 1997

has been phased out in Mexico. The study did not differentiate

between native-born Americans of Mexican descent and Mexican

immigrants.

 

The study used new methods able to detect the slightest traces of

chemicals in the blood and urine. Tests were run to check for dozens

of constituents or breakdown products of pesticides and plastics as

well as long-lived compounds that are now largely banned but persist

in the environment. Already, federal officials said, the smaller

2001 survey has borne fruit. They cited a recent investigation of a

cluster of childhood leukemia cases in Fallon, Nev. Investigators

sifted for clues to any link to 132 chemicals, said Dr. James L.

Pirkle, the deputy director for science at the federal laboratories

that conducts the studies.

 

A significant finding was that levels of tungsten, a toxic metal,

were higher locally than in the 2001 general overview of the

population. Now the researchers can try to determine whether

tungsten levels can be linked to the leukemia, he said. The new

study echoed the 2001 study's findings on DDT; tobacco residue,

called cotinine; lead; and other toxic compounds that have been

measured for many years. All concentrations have continued to drop

in all age and ethnic groups, according to the new study.

 

Cotinine is a compound left behind after the body breaks down

cigarette smoke and is used as an indicator of exposure to a host of

other cigarette ingredients that can cause cancer and other

diseases. The new study found that children had more than double the

level of cotinine found in nonsmoking adults. The researchers said

this was probably because most efforts to curtail smoke exposure had

occurred in workplaces and public spaces, not the home.

Environmental and chemical industry groups had different reactions

to the report yesterday. Environmental campaigners highlighted the

need for more work to reduce chemical releases into the environment

and more research on risks. Industry groups said the data showed the

robustness of humans, whose longevity and health have been steadily

improving even with trace exposures like those measured in the new

research.