The New Jersey Department of Environmental Protection is planning to test a new round of private water wells in several Gloucester County towns for an unregulated, toxic material.

The DEP is reviewing a list of 160 private wells to determine which are used for drinking water. The wells will be tested for perfluorononanoic acid (PFNA), a type of perfluorinated compound (PFC). The chemical was used by a West Deptford plastics company that is believed responsible for the spread, Solvay Specialty Polymers.

Solvay, for its part, has already tested about 90 wells in West Deptford and East Greenwich (16 of which showed elevated levels of PFNA, according to the DEP).

Now, the DEP is planning to expand the testing to private wells in West Deptford, Deptford, East Greenwich, Greenwich, and Logan. DEP spokesman Larry Hajna in an email Wednesday said the department has been "asking Solvay to expand the private wells testing" but that no agreement has been reached.

"So DEP is planning to test additional private wells," Hajna said. Tests are expected to begin by the end of the year.

Hajna said the state will pay for the testing and seek compensation from Solvay. That's also what the DEP is doing to provide filtration systems to 14 private wells in West Deptford found with PFNA.

A spokesman for Solvay, David Klucsik, in an e-mail Wednesday said that Solvay has agreed to reimburse the DEP for "most" of those filtration systems, also saying that "Solvay remains willing to discuss with NJDEP the results of Solvay's investigation to date and possible next steps."

Klucsik also said that Solvay's testing of public wells in several municipalities and of the 90 private wells was done "without any admission of liability and despite the lack of sound science that any health risk exists from the trace levels of PFNA that have been detected, or that Solvay's operations are the source of the PFNA detected."

Though PFNA studies are few, the material is considered more toxic than a related chemical, perfluoroctonoic acid (PFOA). A scientific panel that studied PFOA found it to have "probable links" to illnesses including kidney cancer and thyroid disease.

The contamination has triggered much action this year:

• Five municipalities (Paulsboro, West Deptford, Woodbury, East Greenwich, and Greenwich) shut down municipal wells.

• Solvay, up until earlier this month, provided Paulsboro residents with free bottled water. The borough had relied on a contaminated well with PFNA levels described in a DEP report as being "higher than reported elsewhere in the world" in drinking water studies.

• The federal Agency for Toxic Substances and Disease Registry agreed to examine the spread, in partnership with the state Department of Health.

• The state Drinking Water Quality Institute immediately was tasked with examining a possible drinking water standard for PFNA after the advisory board ended a years-long hiatus in May. The DEP is also considering a separate groundwater regulation for the contaminant.