Drinking water at more than half a dozen Maine schools, from Greater Portland to the Midcoast, recently exceeded the state’s limit for the toxic chemical compounds linked to cancers, developmental disabilities, liver damage, weakened immune systems and more.

When it comes to per- and polyfluoroalkyl substances, as the schools finding emphasizes (one of those affected an island school), “pervasive” doesn’t cut it. PFAS have been used in all manner of packaging, cosmetics, cookware and waterproof coatings for more than 70 years. They’re now in our wells, our deer, our milk, our eggs and our fish. They rain down in parts of the world that have never otherwise encountered them. Roughly 97 percent of Americans have some level of PFAS in our bloodstreams.

Federal officials are working on establishing a limit for PFAS in drinking water, we reported Wednesday, which might supersede the Maine state limit. In June, the Environmental Protection Agency sharply lowered its guideline levels, bringing them well below the Maine standard. The EPA’s PFAS “roadmap,” however, is as toothless as it sounds. Until it makes enforcement a priority, the reins are firmly in states’ hands.

Under no circumstances should the eventual EPA standard be more ambitious than the standard we set for ourselves. One way in which we can ensure that is by lowering our limit to zero.

After decades of spreading sludge from paper mills and wastewater plants on fields, testing for PFAS has rightly been stepped up in Maine. Even on a stepped-up schedule, the latest test was the first for PFAS in Portland’s water district since 2019. The district came back clear, meaning any contamination was fewer than 2 parts per trillion.

Maine’s current “interim” safety standard for PFAS in water is 20 parts per trillion. Other states have implemented the same; New Jersey went as low as 13 ppt. Safety thresholds keep dropping: We now know that a fraction of a part per trillion of one type of PFAS – so low it cannot be measured by lab detection methods – is enough to jeopardize health.

For a variety of reasons, zero is the right place for the limit to be.

Speaking at an EPA advisory meeting last month, Steve Risotto, senior director at the American Chemistry Council, said that an effective goal of zero for one type of PFAS would “alleviate the communications nightmare” while being “no less effective.” The goal of zero is generally understood to be aspirational, Risotto added.

Aspirational or not, zero can and should be the marker for Maine, which has been hailed for leading the way on PFAS prevention and management. Last year, we became the first state in the nation to enact a ban on products that contain PFAS (all but those deemed “unavoidable,” as in certain medical applications where there aren’t ready alternatives). Starting next year, manufacturers of products sold in Maine must report any use of PFAS to the state’s Department of Environmental Protection.

In March, a legislative panel backed the establishment of a $100 million relief fund for farmers whose livelihoods have been ruined by PFAS. In April, Maine passed legislation banning the use of sludge as fertilizer and approved a ban on pesticides containing PFAS by 2030.

“A lot of the work we do in this chamber isn’t particularly historic and probably won’t be remembered 30 years from now, but the work that we do this session on PFAS is the exception,” state Sen. Heather Sanborn said after the bill was approved in the House. “Once we know better, we have to do better.”

We know better.