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US EPA proposes limit on perchlorate in drinking water

Maximum level would be 56 ppb, but agency also offers other options

by Cheryl Hogue
May 24, 2019


Photo shows a large rocket launching.
Credit: United Launch Alliance
Perchlorate is a component of solid rocket fuel.

The Trump administration is proposing several options for limiting perchlorate in drinking water, including leaving the chemical unregulated.

Perchlorate interferes with thyroid metabolism, which can damage the nervous system of infants and young children. More than 16 million US residents have perchlorate in their drinking water. The substance is used in solid rocket propellant, fireworks, vehicle-airbag inflators, and flares.

The US Environmental Protection Agency proposed on May 23 to set a maximum contaminant level of 56 parts per billion of perchlorate in drinking water. In contrast, California set its maximum contaminant level for perchlorate at 6 ppb in 2007.

In its proposal, the EPA is seeking feedback from the public on a limit of 56 ppb plus 3 other regulatory options: a limit of 18 ppb, a limit of 90 ppb, or simply not regulating perchlorate in drinking water.

Eric Olsen of the Natural Resources Defense Counsel, an environmental group that sued the EPA to set a standard for perchlorate in drinking water, says the agency’s plan puts Americans at risk, stating that the limit should be at least 10 times lower to protect health. He calls the proposal a “Trump administration gift to polluters and water utilities that have lobbied to be off the hook for cleaning up the problem.”

If the EPA finalizes a maximum allowable level for perchlorate in drinking water, the Defense and Energy departments and NASA would face a cleanup liability. Their operations have tainted groundwater used for drinking. The extent of their financial liability depends on the strictness of the standard the EPA ultimately sets for perchlorate—the tighter the standard, the more expensive the cleanup will be.

The agency’s move comes eight years after the Obama administration determined that the EPA would limit perchlorate in drinking water. That move reversed a 2008 decision by President George W. Bush’s administration not to regulate it.


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