American Bodies Harbor Some Suspicious Chemicals
March 21, 2001 -- Thanks to advances in technology, scientists
are now able to get a much more accurate picture of how many substances in the
environment accumulate in the human body -- and at what levels. The findings
are mixed: Levels of lead and tobacco-related chemicals have dropped
substantially in recent years, but a chemical used in soap and cosmetics is
The complete findings were released today by the CDC. The CDC
obtained the information in 1999 by measuring blood and urine levels of 27
chemicals in people from 12 U.S. locations.
Of these substances, 24 were measured for the first time, and
three -- lead, cadmium, and cotinine -- have been measured previously. The new
data will serve as a yardstick for comparing future tests.
Researchers tracked four categories of exposures: metals (such
as lead, mercury, and cadmium), tobacco smoke, organophosphate pesticides, and
phthalates (compounds used in soap, shampoo, hairspray, nail polish, and
flexible plastics). In the future, they plan to add more environmental
chemicals to the list, with the goal of reaching 100 in four years. Ultimately,
they will break the findings down by age, sex, race, ethnicity, income level,
and urban/rural residence status of the participants.
Among the positive findings: Efforts to ban public smoking seem
to have resulted in a measurable reduction in harmful tobacco smoke exposure.
Levels of cotinine, the chemical left over after the body breaks down tobacco,
decreased fourfold in 1999, the report says, when compared with data from prior
years. Also, lead levels in children continued to decline in 1999, the data
These success stories are important to note, says Eric Sampson,
PhD, of the CDC's Environmental Laboratory.
"Blood lead levels for children aged 5 and younger keep
going down, [showing that we are] successful in limiting children's exposure to
lead," he says. Nevertheless, he warns, lead poisoning among children is
still a major concern, especially for those who live in homes built before 1950
and those exposed to lead-contaminated dust.
In a bit of a surprise, blood levels of two of the seven
phthalates measured -- diethyl phthalate (DEP) and dibutyl phthalate (DBP) --
were found to be higher than levels of other phthalates that are produced in
greater quantity. Further research is needed to explain this finding,
Mercury, a metal known to be harmful to young children and
pregnant women, was measured for the first time. Although no previous data
exist for comparison, the levels were higher than had been predicted, which is
a cause for some concern, according to information presented at the Washington,
D.C., press conference where the report was introduced.
At this conference, Philip Landrigan, MD, professor of
pediatrics at Mount Sinai School of Medicine in New York City, called the
report a "wake-up call."
"Americans are being exposed to an array of toxic
chemicals, many of which can and should be avoided," says Landrigan, an
expert on children and pesticides.
But Jeff Steir, associate director of the American Council of
Science and Health in New York City, urges caution in interpreting and
analyzing the new report.
"It is important not to overplay the significance of tests
whose purpose it is to find extremely low, or 'trace,' levels of chemicals in
the blood," he tells WebMD. "The mere presence of chemicals, be they
natural or manmade, do not indicate any negative health consequences. In
toxicology, it is the dose that makes the poison," he says.
"The real danger takes place when workers are exposed to
certain chemicals at high levels over long periods of time," Steir