Fish in the Trinity River in North Texas won't be safe for people to eat until the river's levels of polychlorinated biphenyls come down by more than half, a state study presented Wednesday shows.

FILE 2009/Staff photo

Fish from the Trinity aren't safe to eat because of PCBs.

Just writing a plan for the Trinity's PCB pollution could take two years. And in the end, the only answer may be to wait for nature to break down the stubborn chemicals – a process that might take decades.

"It's been there 25 years," Dania Grundmann, Trinity River water quality project manager for the Texas Commission on Environmental Quality, told local officials and others at a meeting in Arlington. "It might be there another 25."

A formal search for solutions to the lingering amounts of the long-banned industrial compounds is expected to start this summer.

The region's cities, counties and other interests – from industries to environmental groups – will have to decide, with help from the state and regional planners, how to address pollution that continues to wash into the Trinity from spills of a past era.

PCBs are a group of 209 compounds once widely used in electrical equipment, caulk and other products. They cause chloracne, a serious skin disorder, and probably cause cancer, studies show.

Congress banned new manufacturing of PCBs in 1977 but let existing uses continue. Once spilled, PCBs stay in the environment for decades and build up in fish and other animals.

Texas health officials said in 2002 that high levels of PCBs made fish in the Trinity's North Texas segments unsafe for people to eat.

According to the state environmental commission's new study, the amount of PCBs in different parts of the river would have to drop by at least 60 percent – and in some spots by as much 86 percent – before fish would again be safe for human consumption.

The study by Parsons Corp., a consulting firm, showed how difficult achieving those reductions might be. First, planners would have to pinpoint exact sources.

Sewage treatment plant discharges and stormwater runoff, for example, account for 28 percent of the PCBs affecting the river, the study found. How the PCBs get into the treatment plants' discharges and the runoff, however, isn't known.

The study found that nearly two-thirds of the Trinity's continuing loads of PCBs come from the river's sediments. PCBs enter the river and bind to the bottom soil, recontaminating the water when floods stir up the sediment.

Dredging the sediment could be on the table when regional representatives assemble to discuss options, but that process can be controversial and expensive. Years of negotiations preceded General Electric's agreement to dredge the PCBs the company dumped in the upper Hudson River in New York state.

The Environmental Protection Agency estimates that GE will spend $750 million on the Hudson dredging, which started last spring. For the Trinity, there's no single entity such as GE to pay for a cleanup, said Kirk Dean, Parsons' manager for the Trinity study.

Finding a lone source of the contamination would make a Trinity cleanup far easier, Dean said. Unfortunately, he said, "we didn't find many hot spots."

What are they?

A group of compounds with two to 10 chlorine atoms (thus the "polychlorinated") attached to a biphenyl molecule. Biphenyl is a hydrocarbon, or a molecule with only carbon and hydrogen. There are 209 different PCB compounds, or congeners.

PCBs were used in U.S. manufacturing from the 1920s to 1977. They were placed in electrical equipment, paint, caulk, copy paper, lubricants and hundreds of other products. They were used as a heat absorber, insulator and plasticizer.

What happened?

Congress banned new manufacturing or uses of PCBs after 1977. The law allowed existing uses to continue. Use has declined since then, but much equipment with PCBs remains in service

The Environmental Protection Agency required registration of PCB-containing equipment in 1998, but the database is out-of-date. The agency is considering updating it to reflect the reduction in remaining uses.

The EPA also has rules governing the labeling and handling of equipment and response to spills.

Why the concern?

PCBs can cause a severe skin disfigurement called chloracne. The liver is especially a target. PCBs can damage the immune, reproductive, nervous and endocrine systems. Many experts and health agencies say PCBs probably cause cancer in people.

PCBs persist in the environment, sometimes for 70 years or longer, and build up in the fat tissues of fish, wildlife and people. Eating contaminated fish or shellfish is the main way people can be exposed.

SOURCES: Environmental Protection Agency; Dallas Morning News research