Jeff Stier

Why would the Environmental Protection Agency (EPA) overturn its own scientists and decide to regulate trace levels of perchlorate in drinking water after it recently decided it didn't need to be regulated?

Earlier this month, the EPA announced it will develop a standard for how much perchlorate would be allowed in tap water.

When the EPA reviewed the chemical's safety profile in 2008, it found that the low level of perchlorate in water supplies did not present a health concern that could be reduced by regulation. And there haven't been groundbreaking studies to change that. Nor does it cite any major change in our exposure to the chemical.

What has changed is an increasing adherence to the unscientific precautionary principle, which requires that unless we can prove something absolutely safe, we should assume it is not.

In this case, because the chemical presents risks to animals at high doses, advocates argue it must be regulated, reduced, or perhaps banned, without consideration of cost or whether the regulatory action shows any health benefit. As EPA Administrator Lisa Jackson awkwardly put it at a recent Senate hearing on water regulation, "I don't know how you price the ability to forestall a child who may not get autism if they are not exposed to contaminated water." In other words, we don't know, but we have to protect children from industrial chemicals regardless of the cost or our lack of knowledge. (Her example about autism and water is completely out of left-field.)

Perchlorate, which occurs naturally in the environment and is also man made, has even been used as a medication. At appropriate doses, the chemical blocks iodine uptake in the thyroid, which is useful in an overactive thyroid. So activists have been claiming that it has the same effect at very low level environmental levels. But the environmental exposure is many thousands of times smaller than the pharmaceutical dose of 400 milligrams daily and has not been shown to affect the thyroid.

In fact, human studies of workers exposed to perchlorate showed no increased thyroid function.

But you won't hear that from the advocates seeking to regulate perchlorate. Because one major source of exposure to the chemical is from rocket fuel, activists repeatedly argue that citizens shouldn't be forced to have rocket fuel in their drinking water. This rhetoric disregards the fact that there are traces of almost everything everywhere. When you are arguing against rocket fuel in tap water, you don't need the science. Unfortunately, celebrity medical correspondents such as CNN's Dr. Sanjay Gupta repeat the scary claims without even questioning their validity.

Jeff Stier

Jeff Stier is a Senior Fellow at the National Center for Public Policy Research and directs its Risk Analysis Division. You can follow him on Twitter at @JeffAStier.