PITTSBURGH, FEB. 21 -- One or more industries apparently took advantage of a major fuel spill last month to dump cancer-causing industrial solvents into the Ohio River, water quality experts said.

"They dumped dirty solvents because getting rid of them is expensive," said Edgar Berkey, executive vice president of the University of Pittsburgh's Center for Hazardous Materials Research.

"What these misdirected and misguided industrial people dumped are chemicals and materials far more harmful, far more biologically active, than the diesel fuel," Berkey said.

An estimated 730,000 gallons of diesel oil poured from a ruptured Ashland Oil Inc. tank into the Monongahela River south of Pittsburgh on Jan. 2, then flowed into the Ohio River. The fuel threatened drinking supplies for residents in Pennsylvania, Ohio, West Virginia, Kentucky, Illinois and Indiana.

Samples taken along a 15-mile stretch of the Ohio River between Wheeling and Moundsville, W.Va., the week of Jan. 10 contained high concentrations of chloroform, methylene chloride, and 1,1,1-trichloroethane, according to Peter Tennant, water quality program manager for the Ohio River Valley Sanitation Commission in Cincinnati.

Chloroform and methylene chloride are cancer-causing substances and can accumulate in the bodies of fish and other marine life. The third substance, 1,1,1-trichloroethane, also is toxic.

"It's not unusual to see those chemicals in that part of the river occasionally, but never at that high a concentration," Tennant told The Pittsburgh Press in an article published Sunday. "Offhand, I'd estimate those concentrations at about 10 times more than what we normally might see."

"At the time of the spill, we were getting calls from lots of industries up and down the river about where it was located," he said. "We thought they were worried about their {water} intakes."

At the levels found, chloroform and methylene chloride significantly exceed the federal cancer risk level criteria for rivers and streams, according to Tennant.

Tennant said his commission has several aerial photographs taken during the fuel spill that seem to show discharges from the Ohio side of the river below Wheeling. The agency in the past has investigated reports of pollutant discharges at that site.

Tennant said the photographed discharges have not been identified and do not seem to be coming from any building or industrial facility. He declined to speculate about their origin, except to say they could be intermittently flowing from a drainage ditch or sewer.

Tennant said it's "very doubtful" that those responsible for discharging the chemicals will be identified.