The Honolulu Board of Water Supply has identified the presence of several toxic so-called “forever chemicals” in water samples taken from two Waipio wells last month, the utility said on Friday.

The results revealed several types of PFAS, or perfluoroalkyl and polyfluoroalkyl substances, which have been linked to serious health impacts, including cancer. The samples came from the Waipio Heights Wells Pumping Station, which serves the Waipio Crestview area between Lumikula Street to Lumi Street, BWS said.

PFOA and PFOS, two of the most notorious PFAS varieties, were found at levels exceeding 2 parts per trillion, according to a BWS press release. The levels don’t violate legal standards at this time but are considered dangerous by the U.S. Environmental Protection Agency.

The EPA proposed PFAS regulations on Tuesday that would legally limit PFOA and PFOS to 4 parts per trillion. Testing for amounts much smaller than that isn’t feasible at this time. But if public health alone were the sole consideration, the EPA says the only amount of PFOA and PFOS that is safe to consume is zero.

BWS said the levels detected did not exceed the Hawaii Department of Health’s environmental action levels of 40 parts per trillion for PFOA and PFOS. These thresholds are not legal limits but are used for decision-making.

“Based on existing Hawaii Department of Health environmental action levels and drinking water standards for PFOS proposed by the U.S. Environmental Protection Agency, the levels at Waipio Heights Wells pose no significant health concerns,” BWS said in a press release.

BWS Manager and Chief Engineer Ernest Lau said in a statement that the utility takes seriously its kuleana to provide safe drinking water.

“While the current levels do not pose a health issue, we will continue to regularly test to monitor for any changes,” he said.

PFAS have been widely used for decades in the manufacturing of items that repel water, stains and fire. They are a key ingredient in aqueous film forming foam, or AFFF, a fire suppressant that has contaminated the environment around military bases and airports around the world.

The chemicals are likely to be detected more frequently across Hawaii and throughout the country as regulations that require regular testing go into effect. At-home water filters certified for their ability to remove some PFAS can be found on the website of the National Sanitation Foundation.

Those who buy water treatment systems should be sure to maintain them and replace filters regularly, BWS Deputy Manager Erwin Kawata said in an email.