WASHINGTON — A government report released Wednesday shows that a family of industrial chemicals turning up in public water supplies around the country is even more toxic than previously thought, threatening human health at concentrations seven to 10 times lower than previously realized.

The chemicals are called perfluoroalkyl and polyfluoroalkyl. They were used in goods such as fire-suppressing foam, nonstick pans and fast-food wrappers.

A draft of the report had set off alarms within the Trump administration earlier this year. A January email from a White House official, released under the Freedom of Information Act, refers to it as a “potential public relations nightmare.”

The Environmental Protection Agency has since launched national hearings on the contaminant.

Environmental groups say the report should lead water agencies to boost filtering.