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OAKLAND, California, USA - October 5 - A startling new study by the U.S. Federal
Centers for Disease Control (CDC) says minute traces of a toxic rocket fuel
chemical found in milk, fruit vegetables and drinking water supplies nationwide
lowers essential thyroid hormones in women. An Environmental Working Group (EWG)
analysis finds that 44 million American women who are pregnant, thyroid
deficient or have low iodine levels are at heightened risk from exposure to the
chemical.
Regulators have known for years that perchlorate, the explosive component of
solid rocket fuel, can lower levels of the thyroid hormones essential to proper
development of fetuses and infants and good health in adults. But new scientific
evidence clearly shows that perchlorate is a much greater public health threat
than previously realized. Tests of almost 3,000 human urine and breast milk
samples — along with tests of more than 1,000 fruit, vegetable, cow's milk,
beer, and wine samples — reveal that perchlorate exposure in the population is
pervasive.
The CDC's new study, released today, found that perchlorate exposure is
affecting thyroid hormone levels in American women, particularly those with
lower iodide intake. CDC researchers analyzed urine samples from more than 1,100
women for perchlorate, and then looked to see if perchlorate exposure could
predict thyroid hormone levels. They found a statistically significant
relationship between perchlorate levels as low as 3 parts per billion — about
one teaspoon of water in an Olympic-sized swimming pool — and one type of
thyroid hormone for all women, and an even more marked relationship between
perchlorate levels and two types of thyroid hormones in women with lower iodine
intake. Thirty-six percent of U.S. women have iodine intake that falls into this
category.
"The Pentagon and defense contractors, who are responsible for much of the
perchlorate in drinking water supplies, have lobbied hard against federal
standards, arguing that perchlorate posed no threat to healthy adults," said
Renee Sharp, an EWG analyst who has studied the chemical since 2000. "This new
study shows that even very small levels of perchlorate in water or food can have
a marked effect on thyroid levels in women. We can't ignore this serious public
health issue any longer."
The median level of perchlorate in urine in CDC's study was just 2.9
micrograms per liter (a microgram per liter is equal to 1 ppb). Since average
urine output is about 1.5 liters per day, this means that women in the study
were ingesting somewhere around 5 micrograms of perchlorate per day. Even at
this low level, researchers found effects on thyroid hormone levels. But the
federal "safe dose" level corresponds to almost ten times this dose. This
clearly indicates that the current EPA reference dose and cleanup guidance is
several orders of magnitude too high.
EWG urges the federal government to act promptly to set a drinking water
standard of no more than 0.1 parts per billion of perchlorate — almost 250 times
more stringent than the current federal recommendation for cleanup of
contaminated water, and 20 to 60 times stricter than drinking water standards
set by Massachusetts and pending in California and New Jersey, the only states
to take action so far. With new evidence showing widespread food contamination
and effects on the thyroid at typical exposure levels, perchlorate exposure
through drinking water cannot be tolerated. EWG also urges the Food and Drug
Administration (FDA) to consider making the iodization of salt mandatory,
because insufficient iodide in your diet can compound perchlorate's health
effects, and iodide deficiency has increased sharply since the 1970s.
The vast majority of perchlorate manufactured in the United States is used by
the Department of Defense to make solid rocket and missile fuel, while smaller
amounts of perchlorate are also used to make firework and road flares.
Perchlorate is also a contaminant of certain types of fertilizer that were
widely used in the early part of the 20th century but are in limited use today.
In July, Massachusetts set the nation's first drinking water standard for
perchlorate of 2 parts per billion, while California and New Jersey are
currently considering standards of 6 ppb and 5 ppb, respectively. The EPA has
yet to set a federal drinking water standard, but has issued a controversial
cleanup "guidance" level of 24.5 ppb. In March, a federal advisory committee on
children's health sharply criticized the agency, writing in a letter to EPA
Administrator Stephen Johnson that the guidance was "not supported by the
underlying science and can result in exposures that pose neurodevelopmental
risks in early life."
In 2003, EWG and the Riverside Press Enterprise independently tested
store-bought winter lettuce for perchlorate and found the contaminant in more
than half of the samples tested — in some cases at high levels. A year later EWG
tested California milk for perchlorate, finding the chemical in 31 out of 32
samples. Around the same time, the California Department of Food and Agriculture
secretly conducted their own milk tests and found perchlorate in all 32 samples
collected. These studies were some of the first indications that food might be
an important route for perchlorate exposure in addition to contaminated drinking
water.
More than 1,000 tests by government and independent scientists later, there
can be no debate: The US population is being widely exposed to perchlorate, both
in water and in the food supply. Perchlorate is polluting water supplies for
millions of Americans. According to tests conducted under the EPA's Unregulated
Contaminant Monitoring Rule, 160 public water systems in 22 states are
contaminated with perchlorate.
Perchlorate has also been found in a wide variety of domestic and imported
produce, with some of the highest levels being found in oranges, grapes,
raspberries, apricots, melons, lettuce, tomatoes, basil, kale, spinach and
asparagus. The chemical has also been found in 98 percent of 222 milk samples
collected from 22 US states, and in hundreds of samples of beer and wine. Fruits
and vegetables had the highest concentrations. Overall, 69 percent of the 1,090
food and beverage samples tested had detectable perchlorate.
Tests by the CDC and independent researchers confirmed that many Americans
are carrying levels of perchlorate in their bodies well above the levels found
to lower thyroid levels. CDC sampled the urine of almost 3,000 Americans — a
valid statistical sample of the entire population — and found perchlorate in
everyone at an average of 5.5 parts per billion. An academic study of breast
milk from 36 women in 18 states also found perchlorate in everyone tested, with
an average level of 10.4 ppb. http://www.commondreams.org/news2006/1005-02.htm
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