Perchlorate is a highly toxic chemical found in rocket fuel, fireworks, and explosives. Not exactly something we’d want coming out of the tap, right? And yet the U.S. Environmental Protection Agency just proposed allowing levels of perchlorate in drinking water that are 10 to 50 times higher than what its own agency scientists have recommended. The EPA’s latest proposal—56 parts per billion—is also dozens of times higher than some existing state-level protections. Massachusetts, for example, allows only 2 ppb in its drinking water, and California just 6 ppb. Those states have the right idea: Exposure to perchlorate can impair hormone production critical to brain function—particularly for fetuses and infants. And the chemical has already been detected in drinking water systems that serve up to 16.6 million Americans.