Perchlorate and the Thyroid


Perchlorate is almost impossible to avoid, but you may be able to diminish its impact on the thyroid.

“Perchlorate is pretty much all around us, so everybody has it in their urine,” says Maricel Maffini, a toxicologist formerly with the Natural Resources Defense Council. “But we’d all be better off not being exposed to it.”

Why? Perchlorate can block the thyroid gland from taking up iodine, which it needs to make thyroid hormone.

“The hormone is essential for fetal and infant brain development, as well as for normal metabolism in people of all ages,” explains Maffini.1 “If you’re not making enough thyroid hormone, any amount of perchlorate is a problem.”

Perchlorate can occur naturally in soil. It’s also manufactured for use in rocket fuel and explosives and to reduce static in carpets, electronic equipment, and, since 2005, plastic materials used to transport and store dry food ingredients.

“The Food and Drug Administration apparently didn’t realize at the time how much perchlorate food can pick up as it rubs against the plastic,” says Maffini. According to the FDA, infants are consuming 34 percent more—and toddlers 23 percent more—perchlorate than they did in 2005.2

“Children eat more of the kinds of foods, like rice and oats, that come into contact with perchlorate-​containing plastic,” notes Maffini.

The FDA finds small amounts of perchlorate in virtually every category of food it tests. In 2014, a coalition of nine consumer groups (including the Center for Science in the Public Interest, Nutrition Action‘s publisher) urged the FDA to ban perchlorate in materials that come into contact with food. Last spring, the agency denied the petition, largely on technicalities. The groups have appealed.3

You can’t really avoid perchlorate, but you can counter it by getting enough iodine. That means using iodized salt, eating iodine-rich foods (like milk, yogurt, and seafood), or taking a daily supplement with 150 micrograms of iodine (the amount in many multis).

“Iodine is especially important for women who are pregnant or breastfeeding,” says Maffini. (Talk to your doctor about your iodine intake if you’re taking ACE inhibitors, diuretics, or anti-thyroid medications.)


1Curr. Environ. Health Rep. 3: 107, 2016.
2J. Expo. Sci. Environ. Epidemiol. 2016. doi:10.1038/jes.2016.78.

Check out our downloadable guide for avoiding other endocrine disruptors here.

Photos: ©NASA, ©volff/fotolia.com.

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