Study Says No Health Problems From Perchlorate

Gilroy Dispatch, Matt King
Published February 20, 2006

Gilroy - A new perchlorate study has found that high doses of the contaminant seemingly have no effect on the health of pregnant women or fetuses. The study was performed in Chile, where there are large amounts of naturally-occurring perchlorate. Subjects were taken from three cities: Taltal, where perchlorate is in the drinking water at levels above 100 parts per billion; Cha'aral, with levels of 6 ppb; and Antofagasta, with less than 1 ppb. Researchers tracked the pregnancies of 60 women and found no difference in the women's thyroid function or neonatal birth weight, length or head circumference. "This implies that the perchlorate dose is not large enough to affect the thyroid," said Dr. John Gibbs, the study's lead author. Perchlorate is a salt that has been shown in some studies to inhibit the body's ability to process iodine. Pregnant women and infants are believed to be at the greatest risk because women with low iodine levels are more likely to deliver babies with neurological defects. Perchlorate was discovered in South County in 2000, but most of the region's drinking water is contaminated at levels far below 100 ppb. In recent testing, only 34 of 850 wells had levels higher than 6 ppb, the state's public health goal for perchlorate. The U.S. Environmental Protection Agency has issued a federal a cleanup level of 24.5 ppb that does not apply to California. The Olin Corp., which operated a Morgan Hill road-flare factory that polluted South County's groundwater, has proposed a cleanup goal of 11 ppb, though that goal is not likely to be approved. Robert Dowd, a chief toxicologist with the California Office of Environmental Health Hazard Assessment, which set the state's health goal, said the study is sound, but was too limited to have an effect on the health goal. "I think this is an excellent study but it doesn't answer some important questions," Dowd said. "It doesn't address the question of whether there are developmental effects on infants of mothers who are exposed to relatively high levels of perchlorate during pregnancy and infants later exposed to relatively high levels as they're growing up." Dowd said the study is not easily applied to the U.S. because Chileans consume significantly more iodine, which counteracts the thyroids effects of perchlorate. The U.S. is one of the few countries in the world that doesn't mandate iodination of salt. The study has been criticized by some environmental groups because it was funded by the Kerr-McGee Corp., an energy company responsible for contamination in the U.S. Renee Sharp, senior analyst with the Environmental Working Group, said studies currently underway by the Centers for Disease Control and Prevention will be much more useful. "Knowing that the CDC is doing a very large-scale study and has no direct financial interest in the outcome of the study, I think the results of that study are going to be much more influential than a study funded by a polluter group done in a different country." The CDC and the U.S. Department of Defense participated in the Chilean study. "Science is science," Gibbs said. "We had many different researchers along the line. The data is open to everybody."