- Scientists on Tuesday reported that perchlorate, a toxic
component of rocket fuel, was contaminating virtually all samples of women's
breast milk and its levels were found to be, on average, five times greater
than in cow's milk.
-
- The contaminant, which originates mostly at defense industry
plants, previously had been detected in various food and water supplies
around the country. But the study by Texas Tech University's Institute
of Environmental and Human Health was the first to investigate breast milk.
-
- The findings concern health experts because infants and
fetuses are the most vulnerable to the thyroid-impairing effects of the
chemical.
-
- Breast milk from 36 women in 18 states, including California,
was sampled, and all contained traces of perchlorate.
-
- Perchlorate blocks the nutrient iodide and inhibits thyroid
hormones, which are necessary for brain development and cellular growth
of a fetus or infant. A baby with impaired thyroid development may have
neurological defects that result in lower IQ or learning disabilities.
-
- The researchers recommended that pregnant and nursing
women block the effects of perchlorate by taking iodine supplements as
a precaution.
-
- At the levels they found in breast milk, the scientists
reported that 1-month-old infants would take in enough perchlorate to exceed
a safe level, called a reference dose, that was established last month
by a panel of the National Academy of Sciences.
-
- "It is obvious that the NAS safe dose will be exceeded
for the majority of infants," the report published in the journal
Environmental Science and Technology says. Some infants would ingest so
much that they would exceed levels that altered the brain structure of
animals in laboratory tests.
-
- The findings come as the U.S. Environmental Protection
Agency is developing an enforceable limit on the amount of perchlorate
in drinking water based on the recommendations of the National Academy
of Sciences panel. Currently there is no national standard.
-
- "This is not just another study," said Renee
Sharp, a senior analyst at the Environmental Working Group, which advocated
a strict national standard. "It ends the questions about whether women
are passing along perchlorate to their kids through breast milk, and the
sky-high levels the scientists found put more than half the kids over the
safe levels the NAS now recommends."
-
- Environmentalists have urged the EPA to set its standard
based on the body weight and perchlorate intake of an infant rather than
an adult. Toxicologists said that would probably mean a standard of a few
parts per billion. Pentagon officials have said that would shut down many
water systems across the country and cost the military and its contractors
billions of dollars in cleanup costs. They have instead lobbied for a standard
of about 200 parts per billion based on thyroid studies of adults.
-
- The new findings "will practically force EPA officials
to write a drinking water standard that protects infants ó not just
healthy adults," Sharp said.
-
- California has set its own public health goal of 6 parts
per billion but it is not an enforceable limit.
-
- The Texas Tech researchers, led by Andrea Kirk, reported
that the perchlorate in breast milk was not linked to the water the mothers
drank. Instead, the main source was probably food, which apparently was
tainted by irrigation water.
-
- The finding that perchlorate is pervasive in breast milk
and reaches high levels is somewhat of a surprise to toxicologists, because,
unlike many other industrial chemicals, it does not build up in tissues
over time.
-
- Instead, it appears that the amount passed on to the
infant in breast milk is determined by what the mother has just eaten.
-
- Perchlorate levels are particularly high in the lower
Colorado River, which supplies irrigation water to almost 2 million acres
of cropland. The river, government officials believe, has been tainted
by leaks from a Kerr-McGee plant near Lake Mead.
-
- The highest perchlorate levels, one reaching 92 parts
per billion, were found in the breast milk of two women from New Jersey.
The average was 10.5 parts per billion, compared to 2 parts per billion
in cow's milk. Forty-six of 47 samples of dairy milk purchased in 11 states,
including California, contained perchlorate.
-
- Sujatha Jahagirdar, clean-water advocate at Environment
California, an advocacy group, said it was "absolutely appalling"
that a component of rocket fuel was found in mother's milk.
|
