Manufacturing Chemical May Hurt Thyroid, U.S. Study Says
WASHINGTON Exposure to perchlorate, a widely used industrial chemical found in U.S. drinking water, may prevent some women's thyroid glands from functioning properly, a government study has found.
Women with higher concentrations of perchlorate in their urine had lower levels of thyroid hormones, which help control energy, temperature, weight and mood, said the report by the U.S. Centers for Disease Control and Prevention released late Wednesday.
A component of rocket fuel and pyrotechnics, perchlorate has been detected in milk, vegetables, fruit and grains, in addition to drinking water across the United States.
The CDC used data from a health survey it conducted during 2001 and 2002, examining statistics on 2,299 male and female participants over the age of 12. Researchers then focused on the women who had low iodine levels in their urine.
In the United States, 36 percent of women have low iodine levels, they said.
The thyroid gland, which sits at the front of the neck, uses iodine to produce hormones.
The CDC said in a statement that the study indicates "that even small increases in perchlorate exposure may inhibit the thyroid's ability to absorb iodine from the bloodstream."
In July Massachusetts became the first state to set a mandatory limit on how much perchlorate can be found in local water. In Southern California, some cities are trying to require manufacturers, especially aerospace companies that use rocket fuel, and county governments to clean up the chemical.
Lewis Braverman, a doctor in the division of endocrinology at the Boston University School of Medicine, said it was surprising that the study only found the trend in women. It did not record any effects of perchlorate on men's thyroid hormones.
He faulted the CDC for not identifying which subjects had autoimmune thyroid disease. That disorder leads to lower levels of the hormone and is more common in women than in men, he said.
Braverman said he was skeptical about the effects of perchlorate in drinking water on human health.
"Perchlorate is almost ubiquitous in the environment, so that areas in the country that do not have perchlorate production or rocket fuel have perchlorate," he said.