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Fouling our nest. (Archive in ecology.)

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Fouling our nest. (Archive in ecology.)

Posted by Walt Stoll on February 04, 2003 at 10:26:06:


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

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

The study, the Second National Report on Human Exposure to
Environmental Chemicals, was posted at
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

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

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