Congress needs to get “actively involved” in addressing a contamination crisis that may affect the drinking water of 19 million Americans, the chair of a House subcommittee said Wednesday at the first legislative hearing on PFAS.

More than a dozen bills have been proposed aiming to force the Environmental Protection Agency to regulate PFAS, the harmful chemicals that have tainted drinking water in Bucks and Montgomery Counties and other communities across the country.

Proposals include requiring the EPA to set a safe drinking-water standard in the near future, forcing the Department of Defense to clean up contamination caused by its sites, and providing funds, testing and other aid for communities dealing with the issue.

>>> Read more: PFAS water-contamination bills will get a hearing in Congress. Read up on what’s proposed.

“These chemicals are remarkably persistent in the environment and increasingly toxic and dangerous to human health even in very small concentrations,” said Rep. Paul Tonko (D., N.Y.), chairman of the environment and climate change subcommittee, which will consider 13 PFAS bills. “Congress needs to be actively involved to ensure the protection of Americans’ health.”

Members of Congress from Pennsylvania and other states have vowed to compel the federal government to act, increasing calls for a swift response since the EPA released a plan in February that indicated it would take several years to set a safe drinking-water standard for PFAS.

The hearing was a first step toward passing any PFAS-related bills, something Democratic lawmakers appearing in Montgomery County last week said they believed was possible and had the support of House Speaker Nancy Pelosi (D., Calif.).

“EPA has given us little reason for confidence that they will act with the urgency that impacted communities now know is needed,” Tonko said. “Even on the most aggressive timeline, regulatory action will take years."

On Wednesday, subcommittee Republicans said they were open to discussing the bills and understood the desire for action. Some, however, questioned the idea of passing laws to circumvent the EPA’s regulatory process and theorized that could cause lawsuits, slow down cleanup, and distract the EPA from other issues.

“I am not a fan of rushing to install broad-based major changes to federal law at a time when high levels of anxiety exceed what we know,” said Rep. John Shimkus (R., Ill.). “I believe we should not make shortcuts in the law while EPA is taking steps based upon solid scientific data to make regulatory decisions.”

Studies have linked PFAS to thyroid disease, asthma, decreased antibody response to vaccines, decreased fertility, decreased birth weight, preeclampsia and hypertension during pregnancy, and kidney and testicular cancer, said Jamie DeWitt, a scientist and researcher at East Carolina University who has studied the health effects of PFAS since 2005.

Scientists suspect PFAS take even longer to break down in the environment than the banned insecticide DDT, DeWitt said. But when PFAS have been removed from the environment, researchers have seen a decrease in chemical levels in humans living in the area.

With nearly 5,000 types of per- and polyfluoroalkyl substances, scientists and advocates have recommended regulating PFAS as a class rather than treating each chemical individually.

Some objected to that idea, arguing that not enough is known about PFAS and that it may not be necessary to regulate all of them. That question could become a key topic in debating the bills.

“With so many chemicals under the PFAS umbrella … is there concern the EPA could unintentionally focus its time and effort on low-risk chemicals?” asked Rep. Bill Johnson (R., Ohio).

Yes, Jane Luxton, a Washington lawyer who specializes in environmental regulation, told the subcommittee. “To just sort of impose blanket bans is highly risky. It risks over-correcting … and changing, diluting, the priorities that need to be focused on the highest risks,” she said.

Those who focus on health effects disagreed.

“How could we possibly regulate these one by one? If you’ve got 4,700 chemicals and it takes EPA years to regulate a single chemical, how many millennia is it going to take to regulate thousands of chemicals?" said Erik Olson, head of the health team at the Natural Resources Defense Council.

“We know that they share common properties, and we know that they are causing adverse effects in too many cases.”

Said Emily Marpe, a mother of three whose private well in New York state was highly contaminated with PFAS: “It shouldn’t be cost over human health. Nobody should go through what we went through.”