Press-Enterprise (CA), David Danelski
Published October 4, 2006
More than a third of U.S. women are more vulnerable to the harmful effects of a rocket-fuel chemical found in hundreds of water supplies and various foods nationwide, federal researchers found in a study released on Wednesday.
The researchers discovered that women with low levels of iodine in their bodies had reduced thyroid function from consuming perchlorate, most probably in their water and food.
The scientists said they were surprised because the thyroid changes were detected even when perchlorate exposure was very low.
An estimated 36 percent of the nation's female population have low levels of iodine, the researchers said.
Perchlorate contamination is widespread in Inland groundwater supplies, forcing water agencies to shut down some wells. They also treat the water or blend it with cleaner sources before sending it to customers.
The study, published in the federal journal Environmental Health Perspectives, is expected to be a bombshell in a years-long debate over how much perchlorate should be allowed in drinking water and food, observers said.
With more than 2,000 research subjects, the study by scientists at the Centers for Disease Control and Prevention in Atlanta is the most comprehensive to date on the human health effects of perchlorate, an oxidizer used in rockets, munitions, road flares, fireworks, matches and car airbag propellants.
A California health official said the new research could prompt the state to could reconsider a recommended drinking water standard.
The federal scientists measured perchlorate in the urine of 2,299 people 12 and older from 30 locations nationwide; 1,111 of them were female. The thyroid changes were not observed in men.
Among 348 women with low iodine, higher perchlorate levels correlated with reduced thyroid function, researchers found.
It was measured by the amount of thyroid hormones in their blood.
Thyroid hormones control the body's metabolism and, in pregnant women, guide fetal brain and nerve development.
Mild hypothyroidism -- reduced thyroid function -- during pregnancy has been linked to "subtle cognitive deficits in children," the researchers said.
Rene Sharp, an analyst with the Environmental Working Group research and advocacy organization, said the group will demand tough state and federal standards for food and drinking water because of the CDC research.
California and federal officials are moving toward standards that wouldn't protect people's health, she said. "They were wildly off."
Ben Blount, a CDC research chemist, and his colleagues found that low-iodine women with as little as 2.9 parts per billion of the chemical in their urine were affected by perchlorate. Two parts per billion is equivalent to about a teaspoon in an Olympic-size swimming pool.
It's unclear how much perchlorate the women were consuming in their food and water during the study, which took place in 2001-2002
The study did not make clear the relationship between perchlorate in urine and the amount consumed; but the CDC group found that perchlorate levels in 62 colleagues were much higher in their urine than in the city's drinking water.
Water agencies didn't routinely test for perchlorate until the late 1990s, when a technique was developed that could detect tiny amounts. Some Inland wells have been found to contain perchlorate in hundreds of parts per billion, but the water is not served to consumers.
Perchlorate has been found in cow's milk, human breast milk, grain, fruit, lettuce and other foods.
California health officials have proposed a drinking water limit of 6 parts per billion. Most Inland water agencies say they serve water with 0 to 4 parts per billion.
The U.S. Environmental Protection Agency, based on a National Academy of Sciences review, last year declared that 24.5 parts per billion is safe for drinking water.
Both California and National Academy officials relied heavily on an industry-sponsored study, published in 2002, that exposed 37 people to different levels of perchlorate and concluded that 245 parts per billion had no effect on humans.
That study did not look specifically at women with low iodine levels. Some scientists criticized the research because the raw data showed that some of the subjects appeared to affected by the chemical at levels the authors said had no effect.
Richard Pleus, a Seattle toxicologist who co-authored the industry study, could not be reached for comment Wednesday.
