The bodies of American children contain higher levels of about a dozen industrial chemicals and pesticides than their adult counterparts, the report shows.
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Even though the effects of most of the chemicals are largely unknown,
health experts say the new findings are troubling because young children,
infants and fetuses are especially susceptible to the dangers posed by
environmental chemicals.
Thousands of adults and children were tested for 116 chemicals in 1999 and
2000 as part of a broad national survey of American health.
For the vast majority of the chemicals, such testing had never been
conducted in the U.S., and it is the first time that exposure by age, race
and sex has been analyzed on a national scale. For each chemical, the
blood and urine of about 2,500 people were tested.
"This report is by far the most extensive assessment ever made of the
exposure in the U.S. population to environmental chemicals," said Dr.
David Fleming, deputy director of the CDC.
The chemicals were measured in trace amounts, parts per billion or
smaller, the equivalent of less than a drop in a human body.
Researchers suspect exposure to tiny amounts of some environmental
chemicals in the womb or early childhood may permanently alter a child's
intelligence, motor skills, memory, behavior, fertility and immune
response.
"Kids are being exposed. We don't have all the details yet about health
effects, but it can't be good for kids," said Dr. Howard Frumkin, chair of
environmental and occupational health at Emory University in Atlanta and
director of its pediatric environmental health center. "This report is a
wake-up call that we should be looking seriously at alternatives for pest
control."
The analysis reveals "a mixed picture," said James Pirkle, assistant
director for science at the CDC's National Center for Environmental
Health. There were "some encouraging findings and some of concern," he
said.
Compared with adults, children's bodies contain more organophosphate
pesticides, which have been linked to effects on developing brains in some
tests. Levels of the pesticide chlorpyrifos (known as Dursban) were twice
as high in children than in adults. The chemical, used in bug bombs and
lawn and garden sprays, was the most widely used insecticide in the United
States until its household use was banned by the Environmental Protection
Agency a year ago, largely because of the risk to children. Other
organophosphate pest-killers remain in widespread use.
Also, a phthalate compound used in vinyl and other soft plastic was higher
in children and adolescents than in adults. One theory is that young
children often chew on toys and other plastics. Another phthalate
compound, found in soaps, shampoos, perfumes and other consumer products,
is higher in adults.
Children also carry more substances called polycyclic aromatic
hydrocarbons, found in vehicle exhaust and other sources of combustion, as
well as six heavy metals, including lead, cobalt and barium, the CDC said.
Exposure to secondhand smoke is also more than twice as high in children
as adults.
Young people wind up with a bigger dose of contaminants in their bodies
partly because of their slower metabolism. And, pound-per-pound of weight,
they consume larger proportions of food, air and water. They also tend to
play on floors, dig in dirt and put things in their mouths.
"Children literally eat, drink and breathe three times an adult does on a
weight basis," said Dr. Richard Jackson, director of the CDC's
environmental health center. "They absorb more from the environment than
an adult."
The developing bodies of fetuses, infants and toddlers are particularly
vulnerable to the effects of environmental contaminants. Industrial
chemicals and pesticides can build up in a pregnant woman, then pass to
the fetus just as its brain, reproductive organs and immune system are
growing. For most of the chemicals, however, no one knows what level in
the human body may trigger effects.
Some medical experts suspect that environmental contaminants could be
behind some neurological disorders, such as attention deficit disorder and
Parkinson's disease and hormone-related disorders, such as endometriosis,
breast cancer, testicular cancer and infertility.
Environmental groups and health advocates Friday urged government agencies
to strengthen regulation of the compounds, many of which are in common use
by industries and pesticide companies.
"It's time for our government to do more to crack down on these toxic
pollutants in our air, water and food," said Robert Musil, executive
director of Physicians for Social Responsibility.
But industries that use and manufacture the chemicals say that they
already face tough federal standards and tests and that health effects are
mostly unproven. Jay Vroom, president of CropLife America, a group
representing the pesticide industry, said the insecticide with the highest
exposure for children, Dursban, is already gone from households, and that
companies are now required to look deeper for possible health effects.
"We have agreed as an industry ... to accept a whole new battery of
testing for pesticides, looking at exposures to children in particular,"
Vroom said.
Most of the chemicals included in the report disrupt hormones in animal
tests, some by mimicking estrogen or blocking testosterone, others by
attacking brain development, the immune system or the thyroid.
But such effects can be subtle and difficult to detect in people.
Scientists are convinced that wild animals are suffering from suppressed
immune systems and feminization from chemicals acting like hormones. For
humans, there is compelling evidence that mercury, lead, tobacco smoke and
compounds called PCBs are causing harm. But little is known about most
others in the report, such as phthalates, organophosphate pesticides and
atrazine, the country's most widely used herbicide.
The study found that people still are carrying traces of dangerous and
persistent chemicals banned in the United States 25 to 30 years ago. The
major byproduct of the pesticide DDT was found in 98% of the people
sampled, and even Americans who are younger than 19 -- born years after
the manufacture and use of DDT ended in 1972 -- have "clearly measurable"
levels of the pesticide in their bodies.
Mexican Americans are carrying three times more DDT residue than
non-Latino whites or blacks, the study found. The higher exposure may
reflect recent use of the pesticide in Mexico, or it may be that farm
workers in the United States, mostly Mexican Americans, are being exposed
to decades-old DDT that remains in soil. DDT is believed to cause cancer.
The results were more encouraging for PCBs, polychlorinated biphenyls,
which have been shown to suppress immune systems and alter brain
development. Most PCBs and dioxins were not detectable in the majority.
Use of PCBs was banned 25 years ago in the United States, but they remain
in the environment.
The findings about lead exposure were also welcomed as good news. The
percentage of children suffering from elevated lead levels dropped by half
since the early 1990s to 2.2%, according to the report. The main reason is
removal of lead-based paint.
Americans also are breathing considerably less cigarette smoke than they
were a decade ago. Nevertheless, more than half of American children, 58%,
are still exposed to secondhand smoke, the report says. Children and
adolescents have more than twice the levels of a nicotine byproduct,
cotinine, than adults, and blacks have more than twice as much as
non-Latino whites or Mexican Americans.
