COLUMBIA, S.C. (SCRN/WVOC) - State health officials have announced new restrictions after a sixth wastewater treatment plant detected a hazardous material in its system.

The South Carolina Radio Network reports that Department of Health and Environmental Control officials suspect someone, or multiple people, are dumping PCBs into sewer systems.

The chemicals are an industrial coolant banned by Congress over 30 years ago because of its link to cancer.

The material was first found in five wastewater plants around Spartanburg last month.

But now, it's also been discovered in a restaurant grease trap in the Columbia area.

While health officials say the treated water is safe to drink, they're worried about the material left behind in what's known as "sludge."  That sludge is often used as fertilizer by farmers.

The new regulations would not allow any sludge with PCBs to be used for that purpose or stored in landfills.