Monday, February 28, 2005

Perchlorates as Medicine?

Back in the 1950's, perchlorate was approved by the FDA as a treatment for hyperthyroidism. It appears that the dose is sometimes more than a gram a day. There does seem to be some worry about causing goiter in unborn children, whose thyroid glands are more susceptible to perchorate.

As I mentioned in the post for methylmercury, the dose makes the poison. It appears (from the review by Wolff linked above) that perchlorate passes quickly through the body, unchanged. This suggests that low levels in water would not be a problem for adults, because the dose is low, and the perchlorate isn't retained (except, perhaps, in breast milk as noted below). The toxicity reported in Wolff's review for adults comes only at high, prolonged doses and the harm caused to children in utero (caused by perchlorate crossing the placenta, after the mother ingested a gram of the stuff) is based on pretty high doses, certainly more than from drinking water containing perchlorate in the 50-100 parts per billion range. So I think it is likely that adults are not directly threatened by perchlorates in the environment (nor did the reports in the news suggest that there is any threat to adults. I'm just walking myself throught this, confirming that I come to the same conclusions). The original article that I linked about perchlorates suggests that breastfed infants would get too much, based on the levels in human breast milk. If the ion doesn't concentrate in the body, then the perchlorates in the water couldn't be the only source in breast milk. (I reach a conclusion from the article. I'm both fact-checking the article, and making sure I understand the issues involved.) So, where's the rest coming from? Irrigation water? Natural sources? Is it possible that perchlorate does get stored in some people? More to find out...


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