U.S. industries and pharmaceutical companies have legally released at least 271 million pounds of drugs into waterways that often provide drinking water, contamination the federal government has consistently overlooked, according to an Associated Press investigation.

Hundreds of active pharmaceutical ingredients are used in a variety of manufacturing, including drugmaking: For example, lithium is used to make ceramics and treat bipolar disorder; nitroglycerin is a heart drug and also used in explosives; copper shows up in everything from pipes to contraceptives.

Federal and industry officials say they don’t know the extent to which pharmaceuticals are released by U.S. manufacturers because no one tracks them as drugs. But a close analysis of 20 years of federal records found that, in fact, the government unintentionally keeps data on a few, allowing a glimpse of the pharmaceuticals coming from factories.

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