KITTERY, Maine (AP) Testing wells in a Maine town contains per- and polyfluoroalkyl (PFAS) and the chemicals may have traveled through well systems and drinking water, the state’s department of environmental protection found.

Last month, the DEP said 10 Kittery homes will have to test their wells after routine PFAS testing found the chemicals in three test wells. The DEP recently discovered that one in four homes contained chemicals levels that would be harmful if ingested, The Portsmouth Herald reported.

All the homes that tested positive for the chemicals are within 1,000 feet (305 meters) from the town’s dumping location, Kittery Resource Recovery Facility. The contamination source is reportedly from Kittery’s landfill that closed in 1993. A town report said water from decomposed waste in landfills can contain high levels of chemicals.

The town has provided bottled drinking water for the residents that water contamination affected and will potentially install a water filtration system, Chris Redmond, an employee for the department’s landfill closure and remediation program said.

Town Manager Kendra Amaral said Kittery officials are concerned about the testing results and “we are taking every step we can to address the immediate issues as well as trying to make sure that the neighborhood is aware of what this means and that we’re looking to address it in the long term.”

PFAS are sometimes called “forever chemicals” because they last so long in the environment. These chemicals are found in products like pots and pans, carpets, clothing and personal care products.

Maine’s Center for Disease Control said the chemicals could cause an increase risk of kidney and testicular cancer, high cholesterol levels and changes in liver enzyme levels.