Court orders EPA to regulate perchlorate in drinking water

The US Environmental Protection Agency must set a limit for perchlorate in drinking water, a federal appeals court ruled May 9. The ruling restarts the clock for the EPA to propose regulations to control the chemical under the Safe Drinking Water Act (SDWA).

The EPA determined in 2011 that perchlorate in drinking water should be regulated. The chemical, which is used to make rocket fuel, military weapons, and fireworks, inhibits the thyroid from taking up iodine. A lack of iodine during pregnancy is linked to abnormal brain development in the fetus, and iodine deficiency in lactating people is associated with neurodevelopmental problems in their children.

But the EPA never proposed a perchlorate drinking-water regulation. In 2020, under the administration of Donald J. Trump, the agency decided it didn’t need to regulate the chemical.

The EPA has long faced pressure from other federal agencies, including the Department of Defense, the Department of Energy, and NASA, to not regulate perchlorate. Those agencies’ activities have contaminated groundwater across the US with the chemical.

The Natural Resources Defense Council (NRDC), an environmental group, sued the EPA in 2020. The group claimed that the agency lacks authority to withdraw a regulatory determination under the SDWA.

Two out of three judges on a panel of the US Court of Appeals for the DC Circuit agreed with the NRDC, stating that the law does not permit the EPA to withdraw a regulatory determination for drinking water. The third judge agreed to strike down the EPA’s decision for a different reason, saying the action was “arbitrary and capricious.”

“The court ruled that EPA must regulate perchlorate-contaminated drinking water because the agency had found that it poses a health risk to millions of Americans,” Erik Olson, senior strategic director for health at the NRDC, says in a statement. “After more than a decade of delay and litigation, EPA now must issue a drinking water standard for this widespread and dangerous contaminant. It’s about time.”