Scientists say the levels are below public health limits, but are cause for concern and more study on fracking-related emissions.

“It just kind of changed the game for all industries, including this one,” said a spokesman for a company that wants to build an ethane cracker. “And so they have had to put off their announcement of a decision.”

A Trump administration rollback of rules for toxic waste water from coal plants won’t have an immediate effect on coal-fired power plants in Pennsylvania, because the state has already adopted tougher Obama-era EPA standards for treating the waste.