MINDEN, W.Va. — Federal environmental regulators say they have again found signs of potentially troubling levels of toxic contamination at a former mining equipment operation in West Virginia.

The U.S. Environmental Protection Agency found high levels of polychlorinated biphenyls, or PCBs, at the former Shaffer Equipment Company site in the Fayette County community of Minden, media outlets reported.

Regulators say more extensive testing is needed before government investigators can pinpoint the source and devise a response plan.

The community has been the subject of repeated and controversial EPA cleanups that many residents worry haven’t removed the potential dangers from their town.

PCBs have been found to cause a variety of adverse health effects, including cancer and problems related to the immune, reproductive and nervous systems.

More tests will be done at the Shaffer site, EPA officials said Thursday. They’re also gathering more information and awaiting sample analysis from a nearby landfill that residents have pointed to as another potential source of harmful pollution in the area.

No firm timetable was provided for EPA’s continued work.

We’re going to be there for a while, honestly,” EPA acting regional administrator Cecil Rodrigues told the Charleston Gazette-Mail in an interview.

The EPA said Thursday that its testing earlier this year near the Shaffer site had found levels of PCBs in the soils at two residences of 1.2 parts per million and 1.3 parts per million.

Those concentrations were slightly above the 1.0-parts-per-million level that EPA coordinator Melissa Linden described as kicking in the need for further agency investigation.

Agency officials said their next step is to conduct additional sampling “to determine the extent of the contamination” and also to “determine if there is another contributor because the highest result is approximately one-half mile from the Shaffer Equipment site.”

The EPA said related testing done in the Fayetteville area, where residents were concerned a chemical tanker truck had been buried, found “metal anomalies” that could have been such a tanker, but that follow-up sampling of soil found only 0.150 parts per million of PCBs, and that those PCBs were of a different type than those at Shaffer Equipment.

“(The) EPA will have no further action at this location,” the agency said.

Also, the EPA tested around an unnamed tributary of Arbuckle Creek, near a former city landfill. It said it found “low concentrations” of PCBs, pesticides and the toxic chemical dioxin.

Additional information on that dump site is being collected, and the EPA is awaiting the results of additional tests “before making any determinations,” the agency said.

The EPA said it will hold two open house meetings on Oct. 27 and Oct. 28 in Glen Jean to discuss the issue.

From 1970 to 1984, the Shaffer Equipment Co. built electrical substations for the local coal mining industry, the EPA said.

Over the years since 1994, the EPA conducted multiple cleanups at the Shaffer site.