1 February 2003
Finds Lower Level of Old Toxins but New Trends Are Worrying
By Andrew C. Revkin
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
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.
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.
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.
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.
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."
study, the Second National Report on Human Exposure to Environmental
Chemicals, was posted at www.cdc.gov/exposurereport yesterday.
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.
surveys will be published every two years.
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.
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.
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.
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.
federal officials said, the smaller 2001 survey has borne fruit.
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.
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.
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.
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.
and chemical industry groups had different reactions to the report
campaigners highlighted the need for more work to reduce chemical
releases into the environment and more research on risks.
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.