The U.S. Environmental Protection Agency will propose a drinking-water limit for perchlorate, a chemical used in rockets and other explosives that can affect thyroid function and pose particular risks for infants, the agency said Monday. EPA said it is moving forward only because a federal court ordered the regulation, adding that it does not expect significant overall public-health benefits to justify the rule’s expected costs.
EPA said it will seek public input on how strict the limit should be and will require water utilities to test for perchlorate. The agency’s filing said that because perchlorate is an “infrequent” chemical of health concern, the vast majority of the roughly 66,000 water systems that would fall under the rule are likely to face substantial administrative and monitoring costs with limited or no corresponding public-health benefits “as a whole.”
Perchlorate is used to make rockets, fireworks and other explosives, though it can also occur naturally. EPA has said perchlorate can seep into groundwater near defense, aerospace and manufacturing sites, creating contamination risks in parts of the Southwest and along sections of the East Coast, and the chemical can interfere with thyroid function that is important for children’s development.
The EPA’s plan is the latest step in a more than decade-long regulatory dispute over whether the Safe Drinking Water Act requires national limits. The AP reported that in 2011 the agency determined perchlorate was a sufficient threat to public health to regulate and that those findings triggered strict deadlines requiring EPA to propose and then finalize rules.
The deadlines were missed, and the AP reported the agency said it took time to update the science used to estimate perchlorate’s risks. By 2016, the nonprofit Natural Resources Defense Council sued to force action, according to the AP. During the first Trump administration, EPA proposed a standard that NRDC said was less restrictive than any state limit and would lead to IQ point loss in children. EPA later reversed itself in 2020, saying no standard was necessary after new analysis found perchlorate was less dangerous and appeared less often in drinking water than previously thought.
EPA has maintained that position, and on Monday it said its data show perchlorate is not widespread in drinking water. The agency estimated that fewer than one-tenth of 1% of regulated water systems would likely find perchlorate above the proposed limits, according to the AP, and said that while a limit could help the small number of places with contamination, it would burden the much larger group with costs the agency says are not needed.
EPA said it will also allow sampling to occur less frequently if a utility’s initial testing does not raise concern. It also said it has committed to working with states and communities to reduce contamination.
Nevada had said in 2020 it would not be affected by EPA’s reversal, the AP reported, pointing to cleanup efforts that it said dramatically reduced perchlorates in Lake Mead after decades of accumulation in the Las Vegas Valley. A federal appeals court, however, ruled that EPA must propose a regulation, arguing that perchlorate remains a significant and widespread public health threat.
As part of the new proposal, EPA will solicit public comment on specific numeric options for the limit—20, 40 and 80 parts per billion—along with other elements of the rule, the AP reported.
NRDC welcomed EPA’s move. Sarah Fort, a senior attorney with the nonprofit, said: “Members of the public deserve to know whether there’s rocket fuel in their tap water. We’re pleased to see that, however reluctantly, EPA is moving one step closer to providing the public with that information,” according to the AP. NRDC also said that even a 20 parts per billion standard would be weak, warning that it would put at risk the health of “millions of people across the country, especially fetuses and young infants who are particularly vulnerable to this toxic chemical.”
The AP reported that while EPA Administrator Lee Zeldin has sought major rollbacks of environmental rules and promoted oil and gas development, the agency’s drinking-water actions have included keeping Biden-era strict limits on two common types of PFAS, while giving utilities more time to comply, and scrapping limits on other PFAS.