The Maine Department of Environmental Protection has begun hunting for so-called forever chemicals at hundreds of licensed sludge dispersal sites across the state, but it will take years to work through the ever-changing list of more than 700 properties.

A team of chemists, geologists, engineers and techs must investigate each location, starting off with the drinking well nearest the fields where the sludge, septic tank sewage, or industrial waste was applied as fertilizer. If unsafe levels of forever chemicals are found, the testing area expands.

“We’ve got a long road ahead of us,” said Victoria Eleftheriou, DEP’s deputy director for the Bureau of Remediation and Waste Management. “Not all of the licenses were put to use. Some of the records go back to the 1970s. Some places received sludge from multiple sources. … It’s going to take time.”

The agency has prioritized the list based on the type and amount of sludge spread at the site and its proximity to housing, Eleftheriou said. About 50 sites in 34 towns fall into its highest risk category, she said. To date, DEP has begun investigating about half of these high-risk cases.

Some people who don’t want to wait are hiring private labs from as far away as California, Washington state and Florida to test their soil and well water for unsafe levels of PFAS, a group of long-lasting and manmade chemicals used in common household products and industrial settings.

If the results come back over Maine’s PFAS limit, DEP will reimburse homeowners, so long as they live near one of the 700 sludge dispersal sites included on this map. Residential PFAS testing can run from $250 to $500, depending on the kind of PFAS testing done.

There are no labs in Maine with the equipment, certification and trained staff required to test for PFAS. The nearest one on DEP’s list of 14 certified labs is Absolute Resources Associates in Portsmouth, N.H. The state itself has had to send some of its trickier samples to Canada for testing.

Absolute has been in business for almost 30 years, but it didn’t open its PFAS testing division until two years ago — partly because of increased demand associated with growing public awareness of the chemicals, but also because PFAS testing has uniquely high start-up costs, according to partner Cliff Chase.

Forever chemicals are found in most industrial settings, Chase said, even within the hoses, casings and linings of most traditional water testing equipment. To avoid cross-contamination, these parts must be replaced with PFAS-free components, and the equipment used only for PFAS testing.

Customers must also take steps to avoid cross-contamination by coming into contact with other sources of PFAS, like waterproof jackets or fast-food wrappers, when collecting the tap water sample they either ship, or often drive, to the Portsmouth lab for testing, Chase said.

Residential PFAS testing with Absolute costs $250 and usually has a one- or two-week turnaround time.

DEP was to brief the Maine Legislature’s environment committee on the latest PFAS developments Monday, Jan. 31.