Myths vs. Facts

Get the facts behind common misconceptions about perchlorate.

Myth:
Perchlorate causes cancer.
Fact:

Perchlorate does not cause cancer. The National Academy of Sciences’ (NAS) January 2005 report on the health implications of perchlorate ingestion confirmed "it is unlikely that perchlorate poses a risk of cancer in humans." The NAS committee reviewed numerous credible studies which found no evidence that perchlorate causes cancer in humans, even when consumed at levels far higher than any found in drinking water.

Learn more about why perchlorate does not pose a cancer risk

Myth:
Perchlorate can damage the thyroid gland.
Fact:

Perchlorate does not damage the thyroid gland. Levels of perchlorate above 245 parts per billion (ppb) can temporarily affect the thyroid's ability to absorb iodide from the bloodstream, a process called Iodide Uptake Inhibition, or “IUI” but this in itself is not an adverse effect. IUI happens naturally as a result of diet and other factors, and the human body is able to compensate before adverse effects of Perchlorate can occur. An adverse health effect would likely require daily consumption of more than 14,000 ppb in drinking water. Perchlorate is not stored in any human tissues, including the thyroid gland and does not mimic thyroid hormones.

Myth:
Perchlorate in drinking water is dangerous in any amount.
Fact:

Perchlorate has actually been used as a medicine since the 1950s. Credible, published scientific reports have shown that levels as high as 14,000 ppb must be consumed regularly, for a period of months or years, before there would even be a risk of adverse effects. The U.S. EPA has tested more than 34,000 water samples from U.S. water systems and in more than 99 percent of those samples, the amount of perchlorate detected was less than 7 ppb. It is important to underscore that when perchlorate is used as a medicine to treat overactive thyroid glands, levels tens of thousands of times higher than what has been found in drinking water are needed to have the desired effect.

Learn more about perchlorate and drinking water

Myth:
Low levels of perchlorate can cause birth defects and are harmful to young children.
Fact:

Scientific research provides reason to believe that low levels of perchlorate have no measurable effect on pregnant women, fetuses or young children. This was confirmed by the National Academy of Sciences’ (NAS) 2005 report, which included a total uncertainty factor of 10 when recommending a reference dose of perchlorate at 0.0007 milligrams per kilogram per day (about 24.5 ppb). According to the NAS, this number protects the most sensitive population — the fetuses of pregnant women who might have hypothyroidism or iodide deficiency. Learn more about the science of perchlorate.

Myth:
Perchlorate must be removed from water to the point where it cannot be detected, no matter what the cost.
Fact:

In February 2005, the U.S. Environmental Protection Agency (EPA) established its official reference dose of perchlorate at 0.0007 milligrams per kilogram per day, and translated that number to a Drinking Water Equivalent Level (DWEL) of 24.5 ppb. This level is consistent with the recommended reference dose included in the National Academy of Sciences (NAS) report. Both the NAS and the EPA state that these numbers are appropriate and protective for all populations, including the most sensitive population — the fetuses of pregnant women who might have hypothyroidism or iodide deficiency.

Further, because levels of perchlorate below 245 ppb have no measurable effect on human health, and no study has shown that perchlorate causes adverse effects on human health, total removal of perchlorate serves no public health purpose. In fact, doing so could cost millions of taxpayer dollars for treatment facilities and/or replacement water supplies, taking resources away from addressing other, real health issues, while potentially causing severe water shortages — all without providing any public health benefit.

Myth:
Perchlorate is rocket fuel.
Fact:

Perchlorate is often found as a salt, which exists naturally in some fertilizers and can be manufactured. The large amounts of oxygen in perchlorate make it an optimal oxidizer to help solid rocket propellant (not "rocket fuel") burn.

Myth:
Perchlorate is unstable and can explode.
Fact:

Perchlorate-based chemicals are typically extremely stable when dissolved in water. It is impossible for the perchlorate found in water to explode.