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New Study Suggests Perchlorate is Thyroid Danger to 44 Million American Women


Updated October 05, 2006

New Study Suggests Perchlorate is Thyroid Danger to 44 Million American Women

What Can You Do?

Unfortunately, at the consumer level, it's very difficult to avoid perchlorate, as it's pervasive in our food and water supply. For example:
  • One EWG study found perchlorate in more than half of all store-bought winter lettuce samples
  • Another EWG study found perchlorate in 31 of 32 samples of milk in California
  • The California Department of Food and Agriculture found perchlorate in 32 out of 32 milk samples
  • According to tests conducted under the EPA's Unregulated Contaminant Monitoring Rule, at least 160 public water systems in 22 states are contaminated with perchlorate
  • Perchlorate can be found in domestic and imported produce, with highest levels frequently seen in oranges, grapes, raspberries, apricots, melons, lettuce, tomatoes, basil, kale, spinach and asparagus.
  • Overall, according to the CDC, 69 percent of the 1,090 food and beverage samples tested had detectable perchlorate.
According to the CDC, this widespread exposure in our water and food supply means that the typical American has a circulating level of perchlorate of 5.5 parts per billion.

To help protect your thyroid, you can make sure that you are not one of the almost four out of ten women with an iodine deficiency. A good daily multivitamin with iodine can ensure that you are getting the iodine you need. (But keep in mind, if you are one of the people who are NOT iodine deficient, excess iodine may aggravate and even worsen hypothyroidism and thyroid conditions. (For more information on the issue of how much iodine is too much, read The Iodine Controversy: Too Much vs. Not Enough, and What It Does To Your Thyroid?)

This is also an issue that calls out for citizen action. For example, at the national level, there is no drinking water standard for perchlorate. The only national oversight is FDA guidance suggesting cleanup be undertaken at a level of 24.5 ppb. A federal advisory committee on children's health has severely criticized that standard, however, warning that it may result in exposures that pose neurodevelopmental risks to infants and young children.

At the state level, the only state that currently has a drinking water standard for perchlorate is Massachusetts, which set their standard at 2 parts per billion in July of 2006. As of October 2006, California and New Jersey are considering standards of 6 ppb and 5 ppb.

Contact your state legislators and urge them to adopt stringent perchlorate standards for your state's water supply. And urge your federal legislators to adopt a national standard. (EWG recommends that the federal government set a drinking water standard of no more than 0.1 parts per billion of perchlorate). Also, urge federal legislators to mandate perchlorate cleanups at contaminated military bases and aerospace plants. Mandatory cleanup of existing contamination sites, and remediation of contaminated water supplies are the only ways to reduce perchlorate exposure.

Renee Sharp, an EWG analyst who has studied the chemical since 2000, summed it up, saying:

The Pentagon and defense contractors, who are responsible for much of the perchlorate in drinking water supplies, have lobbied hard against federal standards, arguing that perchlorate posed no threat to healthy adults. This new study shows that even very small levels of perchlorate in water or food can have a marked effect on thyroid levels in women. We can't ignore this serious public health issue any longer.


Blount, Benjamin C. et. al. "Environmental Health Perspectives: Urinary Perchlorate and Thyroid Hormone Levels in Adolescent and Adult Men and Women Living in the United States," Environmental Health Perspectives Branch (EHPB), National Institute of Environmental Health Sciences, National Institutes of Health, U. S. Department of Health and Human Services, Published October 5, 2006, Online

"44 Million Women at Risk of Thyroid Deficiency From Rocket Fuel Chemical," Environmental Working Group Press Release, Online

Environmental Working Group Analysis, Online

Shomon, Mary. "Perchlorate in Your Drinking Water," About.com, Online

Shomon, Mary. "Perchlorate and the Thyroid," About.com, Online

Shomon, Mary. "Perchlorate & its Danger to the Thyroid," About.com, Online

Shomon, Mary. "The Iodine Controversy: Too Much vs. Not Enough, and What It Does To Your Thyroid?" About.com, Online

Mary Shomon, About.com's Thyroid Guide since 1997, is a nationally-known patient advocate and best-selling author of 10 books on health, including "The Thyroid Hormone Breakthrough: Overcoming Sexual and Hormonal Problems at Every Age," "The Thyroid Diet: Manage Your Metabolism for Lasting Weight Loss," "Living Well With Hypothyroidism: What Your Doctor Doesn't Tell You...That You Need to Know," "Living Well With Graves' Disease and Hyperthyroidism," "Living Well With Autoimmune Disease," and "Living Well With Chronic Fatigue Syndrome and Fibromyalgia." Click here for more information on Mary Shomon.

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