BREAKING: EPA to Pull Regulation for Tap Water Contaminant


Analies Dyjak, M.A.  |  Policy Analyst

Another drinking water contaminant has failed to make its way through the Environmental Protection Agency's grueling regulatory process. On Thursday, May 14, 2020, EPA made the decision to no longer pursue a perchlorate regulation in tap water. This perchlorate regulation would have been EPA's first proposed standard in 24 years. 

What Is Perchlorate?

Perchlorate is a colorless, odorless salt, that is both naturally-occurring and man-made. Perchlorate is used in rocket propellants, munitions, fireworks, and flares. According to the ATSDR, about 90% of man-made perchlorate is manufactured for defense and aerospace industries. Naturally-occurring perchlorate can be found in soils in the Southwestern United States. Perchlorate finds its way into drinking water through runoff and other means of stormwater pollution. Because perchlorate is not regulated very well, rules for disposal and mitigation are relatively weak. Unlike PFAS, perchlorate is not ubiquitous in tap water across the United States. 

How Does Perchlorate Impact Health?

Exposure to perchlorate can impact the thyroid glands ability to take up iodine. EPA’s Integrated Risk Information System (IRIS) has indicated that perchlorate is not carcinogenic to humans, but does state that it’s known to cause negative impacts to the endocrine system. Long term perchlorate exposure is also known to lower thyroid hormone levels, which can impact the cardiovascular system, pulmonary system, liver function, and more. Scientific literature regarding how perchlorate impacts humans is not sufficient. In addition, health and regulatory bodies have stopped prioritizing perchlorate research in recent years, making EPA's decision even more suspicious.

Why Is Perchlorate Still Allowed In Drinking Water? 

In short, perchlorate is extremely expensive to remove. EPA must consider the cost of removal with the benefit to public health when determining a regulation. EPA does this for all drinking water contaminants - the most famous and controversial being the arsenic standard. Most municipalities in the U.S. can not afford the technology necessary to get rid of many harmful contaminants at the distribution level. This includes contaminants like arsenic, PFAS, chromium 6, perchlorate, and more. 

How Does EPA Determine Which Chemicals Get Removed From Drinking Water?

EPA has an exhaustive process for regulating contaminants in tap water. We wrote an in-depth article about the Unregulated Contaminant Monitoring Rule (UCMR) and the Contaminant Candidate List (CCL). In short, a list of 30 contaminants gets whittled down so that EPA can decide whether to regulate or not. The major factor that goes into a “regulatory determination” is the cost. EPA must weigh the cost of removing a contaminant at the municipal level with the benefits to public health. “Unfunded mandates” are difficult to justify and doing so is the equivalent of forcing a community to pay for something they can’t afford.

Regulatory Case Study: Perchlorate

EPA first introduced a regulation for perchlorate in 2001, during EPA’s first Contaminant Candidate List (CCL). A CCL listing indicates that federal agencies have concerns about the health impacts associated with a contaminant found in drinking water. Further, CCL is a refined list that is composed of the top contaminants that likely threaten the nation's drinking water. A CLL listing also indicates the need for further research to determine if a regulation is even financially possible. 

Our Take:

The failure to regulate perchlorate was a surprise to our team of Water Nerds. The decision made by EPA last week was especially confusing because Perchlorate has been listed on three out of the four most recent CCL's since 2001. As recent as 2019, health and regulatory agencies believed that perchlorate posed a big enough threat to warrant a regulation. The only reason that perchlorate wasn’t included in the most recent UCMR list is most likely because so many other new contaminants were added, including various PFAS chemicals.

Unfortunately, perchlorate is another example of the UCMR process and its inability to regulate contaminants found in drinking water. EPA stated that a regulation was not necessary because perchlorate is no longer a problem in drinking water. Whether that’s true or not, testing and monitoring for perchlorate has reduced so significantly in recent years that we find it hard to believe their claims. As previously stated, perchlorate has been included in 3 out of 4 UCRM CCL lists - indicating that regulators and public health officials believe that it’s still a problem. 

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