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Lead, tobacco exposure down in U.S., survey finds

July 21, 2005

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) – Levels of lead have dropped
dramatically, exposure to second-hand smoke is down and most
women are not burdened by unsafe levels of mercury, according
to the latest U.S. government survey on chemical exposures.

The third National Report on Human Exposure to
Environmental Chemicals, released on Thursday by the Centers
for Disease Control and Prevention, has details on 148
different chemicals found in the blood and urine of 2,400
volunteers.

But it says virtually nothing about whether the chemicals
pose any danger to people, CDC director Dr. Julie Gerberding
said.

“More important, what are the human health consequences of
those exposures?” Gerberding asked during a news conference.

This is where research is needed, and finding those answers
will take years as scientists look at disease in the population
and correlate it with the findings of the regular CDC surveys,
first started in 1999.

The latest report finds that 1.6 percent of U.S. children
have elevated blood lead levels, compared to 4.4 percent in
1991-94 and 88.2 percent in 1976 to 1988.

“We don’t know what is a safe level, so we continue to
strive to ensure that all children are free of lead exposure,”
Gerberding said, noting that the removal of lead from gasoline
was the main reason for the decline.

The report, found on the Internet at
http://www.cdc.gov/exposurereport/, also looked at exposure to
second-hand tobacco smoke, using a measure of a chemical called
cotinine, a breakdown product of nicotine.

It found that cotinine levels in blood have fallen 68
percent in children aged 4 to 11 from a previous 1988-to-1991
test period, by 69 percent in 12- to 19-year-olds and by 75
percent in adults aged 20 to 74.

But blacks and children still have higher levels than white
adults, the survey found.

SAFE LEVELS OF MERCURY

The report also looked at mercury, specifically
methylmercury, which makes its way into people most frequently
when they eat contaminated fish.

Levels in blood of above 58 micrograms per liter can cause
nerve damage in developing fetuses.

“None of the women in the survey has mercury levels that
approached this level,” Gerberding said.

But 5.7 percent of the women had levels that were one-tenth
of this, and the CDC said it would seek studies to find out if
these levels might affect a fetus.

The report also contains details on pesticides, weed
killers, pollutants known as polycyclic aromatic hydrocarbons,
dioxins, furans, polychlorinated biphenyls or PCBs and
phytoestrogens.

Some are known carcinogens, such as dioxins and PCBs.

Gerberding said some people may have a genetic
predisposition to be sensitive to some chemicals.

“So it is not just a matter of are you exposed to a
chemical or not but how does your body or your unique
composition respond to that chemical,” she said.

“As the CDC cautions, the mere detection of a chemical does
not necessarily indicate a risk to health,” the American
Chemistry Council said in a statement.

Toxicologist Tim Kropp of the Environmental Working Group,
which conducts its own studies on chemicals, said he was
interested on the information of a class of chemicals called
phthalates.

His group has lobbied to force the cosmetics and plastics
industries to at least label products that contain the
compounds, which help make scents stick to the skin, make
plastic malleable and perform other functions. They have been
found to affect the reproductive systems of some animals.

“If you look at the phthalate metabolites, the large
majority of phthalate material comes from fragrances and
cosmetics,” Kropp said in a telephone interview.




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