WASHINGTON (AP) _ People who regularly eat fish taken from streams near pulp and paper mills that discharge dioxin run a increased risk of developing cancer, the Environmental Protection Agency said Monday.

The EPA made public the results of a study showing that dioxin concentrations in fish downstream from 19 such mills ''may be high enough to pose an increased cancer risk greater than one in 10,000'' to average consumers of fish caught there.

''The estimated cancer risk is potentially higher for avid sports fishermen and subsistence level fishermen because their consumption of fish is generally higher than that of average consumers,'' the EPA said.

The EPA said its risk estimates are based on the consumption of fish - such as catfish, bass, suckers and squaw fish - that spend their entire lives near a paper mill and accumulate greater concentrations of dioxin in their tissues.

The risk estimates do not apply to migratory fish, such as salmon, that spend only a short portion of their lives in the contaminated waters.

The one-in-10,000 estimate is an upper bound. Any risk, if present, could be lower. The agency generally tries to act against risks this large, and treats smaller risks with less concern.

The average risk in the United States of dying of cancer from any source is about one in five.

The cancer risk for fish taken from waters below the International Paper Co. mill at Georgetown, S.C., could be as high as one in 50, the EPA said.

There are 104 paper mills operated by 38 companies that produce paper bleached with chlorine compounds and that discharge dioxin.

Dioxin, a byproduct of the bleaching process, is a powerful cause of cancer and birth defects in laboratory animals. The EPA lists it as a probable cause of cancer in humans, but there has been no proof it actually causes human cancers.

The EPA said it is issuing waste water discharge permits, over the next two years, to 66 mills to limit dioxin discharges. Many of the permits will require mills to reduce the use of chlorine, and the 66 mills will have to comply no later than June 1993.

The environmental agency said it is also developing national guidelines and standards to limit dioxin contamination from the manufacture of bleached paper products, and will seek cooperation from industry and the states for further pollution reduction initiatives.

It said that the new standards will likely focus on changes in the bleaching process to prevent the formation of dioxin in sludge and pulp as well as waste water.

Many of the 104 mills have already reduced dioxin discharges, some of them significantly, the EPA said.

Here are the mills posing a maximum likely risk of greater than one in 10,000. After each mill is the risk estimate and whether an advisory against eating fish from the stream has been issued.

Boise Cascade, Rumford, Maine, one in 10,000, yes.

International Paper, Jay, Maine; one in 10,000, yes.

Westvaco Corp., Covington, Va.; one in 1,000, yes.

Union Camp, Franklin, Va.; two in 1,000, no.

Georgia-Pacific, Palatka, Fla.; six in 10,000, no.

St. Joe Paper, Port St. Joe, Fla.; one in 10,000, no.

International Paper, Moss Point, Miss.; three in 10,000, yes.

Champion International, Canton, N.C.; two in 10,000, yes.

Wyerhaeuser, Plymouth, N.C., two in 1,000, yes.

International Paper, Georgetown, S.C., two in 100, yes.

Buckeye Cellulose, Perry, Fla., two in 1,000, no.

Georgia-Pacific, Crosset, Ark.; two in 10,000, no.

Boise Cascade, Deridder, La., one in 10,000, no.

International Paper, Texarkana, Texas; two in 10,000, no.

Temple-Eastex, Evadale, Texas, three in 10,000, no.

Simpson Paper, Anderson, Calif., one in 10,000, yes.

Simpson Paper, Fairhaven, Calif. one in 10,000, no.

Wyerhaeuser, Everett, Wash. one in 10,000, no

Wyerhaeuser, Cosmopolis, Wash., one in 10,000

The agency's announcement identified a mill operated by the Leaf River Forest Co. at New Augusta, Miss. as posing a cancer risk from fish of greater than one in 10,000, but an accompanying table appeared to state a lower risk. Sean McElheny, the agency spokesman on the issue, said the table was correct and the mill should not have been listed in the statement.