In the largest
study of chemical exposure ever conducted on
human beings, the U.S. Centers for Disease
Control and Prevention reported Thursday
that most American children and adults were
carrying in their bodies dozens of
pesticides and toxic compounds used in
consumer products, many of them linked to
potential health threats.
The report documented bigger doses in
children than in adults of many chemicals,
including some pyrethroids, which are in
virtually every household pesticide, and
phthalates, which are found in nail polish
and other beauty products as well as in soft
The CDC's director, Dr. Julie L.
Gerberding, called the national exposure
report — the third in an assessment that is
released biennially — a breakthrough that
would help public health officials home in
on the most important compounds to which
Americans are routinely exposed.
The latest installment, which looked for 148
toxic compounds in the urine and blood of
about 2,400 people age 6 and older in 2000
and 2001, is "the largest and most
comprehensive report of its kind ever
released anywhere by anyone," Gerberding
said. Findings were broken down by age group
At Thursday's news conference, CDC officials
emphasized the good news: Steep declines
were found in children's exposure to lead
and secondhand cigarette smoke.
Lead levels in children have dropped
significantly over several years, which
Gerberding called an "astonishing public
health achievement" attributable largely to
its removal from gasoline and paint.
About 1.6% of young children tested from
1999 to 2002 had elevated levels of lead,
which could lower their intelligence and
damage their brains, compared with 88.2% in
the late 1970s and 4.4% in the early 1990s.
But the discovery of more than 100 other
substances in humans, particularly children,
distressed environmental health experts.
"The report in general shows that people —
kids and adults — are exposed to things that
aren't intended to be in their body," said
Dr. Jerome A. Paulson, an associate
professor of pediatrics at the George
Washington University School of Medicine and
Health Sciences who specializes in
children's environmental health. "In and of
itself, that is a concern. Whether it's
harmful or not we can't tell from this
The new data in the 475-page report reveal
how "we have fouled our own nest," Paulson
said. "We contaminated the environment
sufficiently that there are measurable
amounts of potentially toxic substances in
people — kids and adults."
The CDC did not try to gauge the health
threat the chemicals might pose. A
measurable amount of a compound in a
person's body does not mean it causes
disease or other damage, the agency noted.
For many compounds in the report, experts
have little information on what amounts may
be harmful or what they may do in
"We are really at the beginning of a very
complicated journey to understand the
thousands of substances we are exposed to,"
said Thomas Burke, associate professor at
the Johns Hopkins Bloomberg School of Public
The discovery of pyrethroids in most people
is especially important, as no one had
looked for them in the human body before.
Pyrethroids are synthetic versions of
natural compounds found in flowers, and they
have been considered safer than older
pesticides, such as DDT and chlordane, that
build up in the environment and have been
banned in the United States.
But in high doses, pyrethroids are toxic to
the nervous system. They are the second most
common class of pesticides that result in
poisoning. At low doses, they might alter
hormones. The compounds are used in large
volumes in farm and household pesticides and
are sprayed by public agencies to kill
Pyrethroids "were a step forward [from DDT
and other banned pesticides], but now we're
beginning to understand that while they
don't persist in the environment, many of us
are exposed," Burke said. "We don't quite
know what those levels mean."
Eleven of 12 phthalates tested were higher
in children than adults. All of the
phthalates but one are used in fragrances.
In animal tests, and in one recent study of
human babies, some of the compounds have
been shown to alter male reproductive organs
or to feminize hormones.
Representatives of the chemical and
pesticide industries praised the study,
saying that human biomonitoring is the best
available tool to measure exposure. They
echoed the CDC in saying that discovery of
the chemicals in the human body did not
automatically mean they posed a threat.
The report demonstrates "that exposure to
these man-made and natural substances is
extremely low," said American Chemistry
Council spokesman Chris VandenHeuvel.
The CDC's Gerberding said that "for the vast
majority" of the 148 chemicals in the
report, "we have no evidence of health
Many toxicologists and environmental
Studies of animals, and in some cases
people, suggest that most of the compounds
can affect the brain, hormones, reproductive
system or the immune system, or that they
are linked to cancer. "These are some bad
actors," Burke said.
Many of the compounds have not been studied
sufficiently to know what happens with
chronic exposure to low doses. "No evidence
of health effects does not imply that they
are not harmful," Paulson said. "It just
means we don't know one way or another."
Environmental groups have called for U.S.
law to require chemical companies to test
industrial compounds more comprehensively, a
proposal similar to one that the European
Parliament is to debate in the fall.
The evidence that many contaminants amass in
children more than in adults could mean that
they are exposed to larger amounts — perhaps
from crawling, breathing more rapidly or
putting items in their mouths — or that
their bodies are less able to cope with or
In the womb and in the first two years after
birth, children undergo extraordinary cell
growth, from brain neurons to immune cells,
so there are more opportunities for toxic
compounds to disrupt the cells, Paulson
said. Animal tests show that fetuses and
newborns are the most susceptible to harm
from many chemicals.
In the CDC study, one of every 18 women of
childbearing age, or 5.7%, had mercury that
exceeded the level that the U.S.
Environmental Protection Agency deemed safe
to a developing fetus.
Tests on schoolchildren show that mercury
exposure in the womb can lower IQs, with
memory and vocabulary particularly impaired.
The CDC plans to expand the national
chemical report to more than 300 compounds
in two years and about 500 in four years. An
estimated 80,000 chemicals are in commercial
Copyright 2005 Los Angeles Times