WASHINGTON (NEXSTAR) — Congress is inching closer to passing reforms in the new national defense bill to protect Americans from PFAS, a likely carcinogen that has been found in drinking water in 43 states, particularly around military bases.

Lawmakers on both sides of the aisle are fighting to toughen provisions, but the House of Representatives and Senate are disagreeing on scope.

Environmentalists want Congress to take bold action.

“The urgency is now. We have people who are losing their lives each and every day,” Mustafa Ali of the National Wildlife Federation said. “We’ve got military folks being exposed, we’ve got low-income communities being exposed, we’ve got fireman being exposed.”

PFAS has been used in a number of products, but one of its most common sources is a type of flame retardant used to fight aircraft fires.

“We need to be more protective,” Ali said.

The House’s plan is more aggressive than the one in the Senate. Some in the House want to label PFAS a hazardous chemical, which would make clean-up projects eligible for cash from the U.S. Environmental Protection Agency Superfund program.

“The problem is overbreadth,” environmental attorney Jane Luxton. “To sweep 5,000 substances into the hazardous designation risks a number of things.”

Rep. Dan Kildee, D-Mich., disagrees and said there’s no time to waste.

“Let’s be clear: There’s plenty of science that points to the dangers of PFAS,” he said. “We know enough. It’s just an excuse to not do something that they don’t want to do.”

He said the House plan will hold the Department of Defense and corporations responsible for the multibillion-dollar mess.

He and 162 members of Congress have sent a letter to the lawmakers deciding the bill’s fate, urging them to keep the House’s aggressive approach intact.

This summer, President Donald Trump vowed to veto provisions in the House bill.

The version he’ll ultimately see on his desk could be finalized by the end of the month.