The dioxin discharges from two Virginia paper mills rank them among the nation's top five in the estimated risk of cancer and liver damage from eating fish caught nearby, the Environmental Protection Agency said yesterday.

The EPA concluded that 20 of the nation's 104 dioxin-discharging mills pose lifetime cancer risks higher than one in 10,000 for people who eat two meals a month of fish caught near the discharges from the plants. For people who eat such fish daily, 90 percent of the mills pose a risk above one in 10,000, the EPA said.

Virginia officials urged fishermen yesterday to limit or stop their eating of bottom-feeding fish caught near the Union Camp Corp., a mile north of the North Carolina border in Franklin, on the Blackwater River. Union Camp ranked second on the EPA list, with a lifetime cancer risk of two in 1,000 for sport fishermen. North Carolina issued a similar advisory last week.

A Union Camp spokesman said yesterday that he did not think there was justification for the advisory in Virginia because fish caught nearby show no signs of dioxin contamination; fish caught in North Carolina did show dioxin contamination, the spokesman said.

Virginia issued a health warning in December for the Westvaco paper mill in Covington, on the Jackson River. It ranked fifth on the EPA's list, with an estimated lifetime cancer risk for sport fishermen of one in 1,000.

The EPA said dioxin discharges from both Virginia plants were "predicted to cause liver damage" in people who ate fish caught nearby.

The EPA report prompted new calls from environmentalists for tougher standards on discharges of dioxin, a byproduct of paper bleaching. Individual states set the standards, but the EPA must approve them. Environmentalists criticized the EPA for approving a dioxin discharge standard for Maryland that is 100 times weaker than the agency's recommended level. Virginia officials approved a similar standard in May.

"In effect, EPA is giving away to the paper industry citizens' rights to fish and to eat their catch," said Bob Adler, senior attorney for the Natural Resources Defense Council.

Carl Armstrong, acting director of health hazards control in the Virginia Health Department, said yesterday that state officials believe EPA's risk estimates are too high and should be taken "with a grain of salt."

Among other mills in the region, the Chesapeake Corp. plant in West Point, Va., ranked 29th, with a predicted lifetime cancer risk of six in 100,000. The Westvaco mill in Luke, Md., was 36th, with an estimated cancer risk of three in 100,000.

The rivers near the three Virginia and one Maryland plant are not major centers for sport fishing, according to state officials, but the York River near West Point is a commercial fishery for shellfish, eel and finfish.