Putting Perchlorate in Perspective

Low Levels of Perchlorate in the Body No Different Than A Serving of Brussels Sprouts

A number of other substances found in everyday foods have the same effect on the thyroid as perchlorate, and these foods are safe and recommended as part of a healthy diet.

Much attention has focused recently on perchlorate's ability at high levels (200 parts per billion) to prevent the thyroid gland from absorbing iodide from the bloodstream (iodide uptake). Iodide is necessary for the production of thyroid hormones that the body uses for metabolism and for normal growth and development. But, there are several important facts to keep in mind:

  1. A number of other substances found in everyday foods have the same effect on the thyroid as perchlorate, and these foods are safe and recommended as part of a healthy diet.
  2. Most Americans eat a diet that provides more than twice the recommended daily allowance of iodide.
  3. The body has a natural ability to deal with changes in iodide levels with no adverse health effects. For example, the thyroid gland has an enormous iodide reserve to compensate for times when it is not taking in a high level of iodide.

Where Other Iodide-Inhibiting Substances are Found

Nitrates and thiocyanates, substances that are common in the human diet, have the same effect on the thyroid as perchlorate.

Nitrates – salt-like substances composed of nitrogen and oxygen – occur at some level in most drinking water, as well as in processed meats and garden vegetables like carrots and celery. Thiocyanate, another salt-like substance, is found in foods such as milk, cabbage, broccoli, cauliflower and Brussels sprouts.

Nitrates and thiocyanates are both considered safe at levels typically found in food.

  1. U.S. Environmental Protection Agency (U.S. EPA) standard for nitrates in drinking water is equivalent to 90 parts per billion (ppb) of perchlorate. The U.S. EPA says nitrate is safe in drinking water at very high levels (10,000 ppb). Nitrates have essentially the same effect on the thyroid as perchlorate and the amount of nitrate allowed in drinking water is equivalent to 90 ppb of perchlorate. By comparison, the nitrates in a single serving of broccoli have the same harmless effect on the thyroid as 100 ppb of perchlorate.

  2. A single serving of cauliflower or Brussels sprouts is equivalent to 8,000 ppb of perchlorate. Research shows that single servings of common foods have tens, hundreds or even thousands of times more effect on the thyroid's ability to absorb iodide than exposure to perchlorate at levels found in any drinking water.

The following table shows these equivalencies:

This food or beverage

Has the same iodide-inhibiting effect as two quarts of drinking water containing perchlorate equal to:

8 ounces of milk (which contains thiocyanate)

16-80 ppb

Recommended daily water intake (about two quarts) that meets the U.S. EPA's standard for nitrates

90 ppb

A 3.5 oz. serving of cauliflower or Brussels sprouts (which contain thiocyanate)

8,000 ppb