GREEN BAY, Wis. (AP) - Paper companies and government regulators should respond immediately to environmental dangers created by incomplete dredging at a PCB site on the Fox River, according to a group of scientists and engineers.

"Extremely high" PCB exposure left by unfinished dredging at the Green Bay site represents a substantial risk to the environment and to human health, said the Science & Technical Advisory Committee of the Lower Fox River and Green Bay Remedial Action Plan.

"We find it completely unacceptable for the demonstration project to remain unfinished," the committee wrote in a letter this week.

The PCB hot spot is near the Fort James west mill.

A $9 million cleanup funded by the seven paper mills responsible for creating the problems began last year.  But dredging at the site was halted in December when freezing temperatures forced an equipment shutdown.

The project had been planned to remove 80,000 cubic yards of the most highly contaminated sediments in the river, but it was stopped after removal of 30,000 cubic yards.

The committee, which includes university scientists and experts from government and industry, was formed in the 1980s as part of the Great Lakes Water Quality Agreement between the United States and Canada.

The committee periodically issues reports and statements on plans regarding cleanup of 39 miles of the Fox River.

David Lee of the P.H. Glatfelter Co., one of the paper mills involved in the cleanup, said the failure of dredging at the Green Bay site is the government's responsibility.

"It has to be clear that the (state Department of Natural Resources) selected the location, approved the design and managed the project," he said. "  The companies think they have held up their end of the agreement."

The paper mills oppose dredging as the best way to clean up the river.  They have proposed capping the sediments in place with a layer of sand and gravel.

EPA spokesman Jim Hahnenberg said if the mills fail to voluntarily clean up the site and the risk of exposure is serious enough, the agency could force a cleanup and require the companies to pay for it.

DNR Secretary George Meyer said state and federal officials have been meeting to explore enforcement options, and he was still hopeful the paper mills would voluntarily finish the dredging project.

PCBs, or polychlorinated biphenyls, were widely used in making carbonless paper and other products at paper mills along the Fox River until the government banned the chemicals in 1977.  Studies have linked PCBs to cancer, reproductive problems and poor mental development in children.