Perchlorate, a component of rocket fuel and contaminant of some fertilizer, is also a contaminant in drinking water and in many common foods including milk, tomatoes, lettuce, carrots, and fruit juice. It has also been found in breast milk and human urine, demonstrating widespread human exposure. Last month government scientists reported elevated perchlorate levels in infant formula.
Perchlorate acts on the thyroid gland to inhibit its ability to make the thyroid hormones that are necessary for normal infant and childhood growth and brain development.
Unfortunately, the U.S. Environmental Protection Agency (EPA) has not reversed its Bush-era preliminary regulatory decision not to set a health-protective standard perchlorate in drinking water. Instead, EPA had said that a national primary drinking water regulation for perchlorate would not present "a meaningful opportunity for health risk reduction for persons served by public water systems."
In addition to its failure to take action on perchlorate in drinking water, EPA has proposed a Health Advisory Level (HRL) of 15 micrograms per liter (µg/L, equal to parts per billion, ppb) of perchlorate in drinking water, which EPA says would be used as a cleanup level in contaminated sites. However, EPA's own scientific experts calculated that if drinking water were contaminated at that level approximately 400,000 children under one year old would be drinking unsafe levels of perchlorate daily (i.e. they would exceed EPA's calculated daily allowable level (reference dose, RfD) of 0.7 microgram per kilogram body weight per day (µg/kg bw/d).
The report from government scientists last month found that levels of perchlorate in some milk-based infant formula and formula reconstituted with contaminated drinking water were so high that infants drinking these contaminated food sources would exceed the RfD for perchlorate.
It seems clear to us that regulating perchlorate does represent "a meaningful opportunity for health risk reduction for persons served by public water systems" that are contaminated with the toxic chemical.
You've done the math, EPA. Now act on it!
(maps of perchlorate contaminated sites can be seen here from the American Water Works Association)