Dispatch: Perchlorate in the Water

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Reuters Health reports, “Everyday exposure to perchlorate, an industrial chemical found in drinking water and a range of foods, may not impair thyroid function in pregnant women, a new study suggests.” The CDC study found perchlorate in the urine of all 2,820 subjects tested.

“Perchlorate is found in all groundwater, as it is residue of various industrial processes,” explains ACSH’s Dr. Gilbert Ross. “Doctors use perchlorate in the treatment of overactive thyroid, since it does interfere with thyroid hormone production at sufficiently high doses. You could say it’s an actual endocrine disruptor, in that case. However, the amount found in drinking water is five orders of magnitude less than the amount needed to affect thyroid function, and it has no effect whatsoever on human health at these environmental levels.

“As this study demonstrated, you can find perchlorate in the tissues or urine of anyone you analyze for it. So the lesson from this story is three-fold: First, environmental perchlorate does not affect thyroid function in pregnant women; second, the dose makes the poison; third, as we’ve always known about biomonitoring, being able to find trace amounts of a substance in someone’s body does not help you predict health outcomes.”

“We have to give credit to Reuters Health for publishing this report about the study,” says ACSH’s Jeff Stier. “All too often, the media reports when a study finds a supposed health hazard, and almost never when a study finds something to be safe. The public is left with a skewed point of view, thinking that every chemical causes every ailment, so it’s nice to see Reuters Health acknowledge that there is such a thing as a non-finding in scientific studies.”