The Environmental Protection Agency last week confirmed that test results in six southern states found high levels of dioxin in fish caught downstream from paper mills and other factories.

Dioxin is one of the most toxic substances known, with the smallest traces of it enough to cause cancer and other serious diseases.The facilities tested include pulp and paper mills that use chlorine to bleach paper. Although scientists have not yet determined exactly how dioxin is formed, chlorine is major ingredient, according to EPA regional scientist Marshall Hyatt.

The tests were conducted as part of the ongoing EPA National Bioaccumalation Study, which is assessing the effect of water pollution of water pollution on fish.

The study was started in 1987 and, when completed, will have tested approximately 400 sites, 100 of which are near pulp and paper mills.

Results from this latest test varied, and no dioxin was detected in many cases. The highest levels detected included 22.8 parts per trillion detected in two striped bass found in the Big Sandy River in Catlettsburg, Ky.; 17.08 parts per trillion found in five carp caught in Nonconnah Creek, Tenn.; and 3.87 parts per trillion found in two striped mullet caught in North River near Augusta, Ga.

The Kentucky site was near a number of industrial facilities, and North River in Georgia is downstream from a pulp and paper mill owned by the Gilman Paper Co. of New York, according to Mr. Hyatt.

Paper industry officials have long argued that current science and research is still insufficient to justify regulation of dioxin found in mill waste water. Regulation could be extremely costly to mill operators, who would have to install pollution-control equipment or find a substitute for chlorine as a bleaching agent.

In February 1987, Congress passed the Clean Water Act, which among other things, mandated that state governments adopt water quality standards for over 60 toxic chemicals and substances.

Since then, nearly 20 states have adopted water quality standards for dioxin. These standards must first be approved by the EPA. Most of those states have chosen to adopt EPA's suggested standards, which are based on a 1 in 1 million chance of contracting cancer.

The standard for dioxin found in water where fish will be caught and eaten is 0.014 parts per quadrillion. The level for drinking water is 0.013 parts per quadrillion.

The EPA also suggests a standard of 0.07 parts per trillion for fish contaminated with dioxin. This is based on a 154 pound male consuming 5 pounds of contaminated fish a year for 70 years. Thus, eating that much fish contaminated with 7 parts per trillion of dioxin would translate into a 1 in 10,000 chance of contracting cancer, according to the EPA.

Of the states named in this latest study, none of the states in the study - Florida, Georgia, Kentucky, Mississippi, South Carolina and Tennessee - have adopted standards.

Georgia, on the other hand, is currently using an emergency standard of 7.2 parts per quadrillion. That standard will expire by the end of March and Georgia's Department of Natural Resources will then have to propose to EPA a permanent standard.