Myths & Facts

Myths & Facts

Get the facts behind common misconceptions about perchlorate.

Myths:

• Perchlorate causes cancer.
• Perchlorate can damage the thyroid gland.
• Perchlorate in drinking water is dangerous in any amount.
• Low levels of perchlorate can cause birth defects and are harmful to young children.
• Perchlorate must be removed from water to the point where it cannot be detected, no matter what the cost.
• Perchlorate is rocket fuel.
• Perchlorate is unstable and can explode.

Myth: Perchlorate causes cancer

Fact: 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. High 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 but the human body is able to compensate before adverse effects 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: 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. US EPA has tested more than 34,000 water samples from U.S. Water systems and in 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: A review of the research shows that the low levels of perchlorate found in drinking water do not harm newborns or young children. Studies include:

• Long Term Environmental Exposure to Perchlorate Through Drinking Water and Thyroid Function During Pregnancy and the Neonatal Period Tellez et al. 2005
  This study found no impacts from perchlorate on pregnant women during the critical period between the late first and early second trimesters, and no effect on fetal development or thyroid levels in newborns. The study examined pregnant women and babies from three cities in Chile, where perchlorate levels range from non-detectable to 110 ppb, and daily intake of dietary iodide is similar to the U.S.
  View Abstract »

• Primary congenital hypothyroidism, newborn thyroid function, and environmental perchlorate exposure among residents of a Southern California community. Kelsh et al. 2003
  This study evaluated whether newborns had higher rates of primary congenital hypothyroidism (PCH) or elevated concentrations of thyroid-stimulating hormone in a community where perchlorate was detected in groundwater wells. The findings, according to the Journal of Occupational and Environmental Medicine, suggest that residence in a community with potential perchlorate exposure has not impacted PCH rates or newborn thyroid function.
  View Abstract »

• Neonatal Thyroid Stimulating Hormone Level and Perchlorate in Drinking Water Li et al. 2000
  A comparison of standard test results of newborns in two cities in Nevada, one with perchlorate in its drinking water and one without. Authors concluded that they detected no effect from environmental exposures to perchlorate.
  View abstract »

The findings of the studies above provide reason to believe that low levels of perchlorate have no measurable effect on pregnant women, fetuses or young children. This was confirmed by the NAS report, which included a total uncertainty factor of 10 when recommending a reference dose of perchlorate at 0.0007 milligrams per kilogram per day. According to the NAS, this number protects the most sensitive population - the fetuses of pregnant women who might have hypothyroidism or iodide deficiency.

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 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 low levels of perchlorate (below 245 ppb) have no measurable effect on human health, (and levels below 14,000 ppb have no documented adverse effects) 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 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 a salt, which exists naturally in some fertilizers and can be man-made. The large amounts of oxygen in perchlorate make it an optimal oxidizer to help solid rocket fuel burn.

Myth: Perchlorate is unstable and can explode.

Fact: Perchlorate is extremely stable when dissolved in water. It is impossible for the perchlorate found in water to explode.