Scientists can't answer the public's questions about dioxin because "25 years of research hasn't been done," one of the country's leading environmental scientists charged yesterday.

The same goes for many other pollutants that now clog the environment, said Dr. Irving Selikoff, director of the Environmental Sciences Laboratory at Mount Sinai Medical School in New York.

The same applies, he said, to chemicals contaminating a third of the nation's drinking water.

There has been a "disconcerting and frustrating" lack of research on the health effects of chemicals, he told a House subcommittee investigating dioxin, the toxic chemical that forced the government to buy out residents of Times Beach, Mo.

"It's now more than 25 years ago that dioxin was identified as a hazardous chemical in chemical manufacturing, and we still don't know" positively what it will do or has done, Selikoff said. He added tha"there are virtually no human data." Federal investigation of seven soft-tissue sarcoma victims, six of them nomplete, though the cases were reported in medical journals and linked to dioxin exposure two years ago.

Furthermore, Selikoffd, "About one-third of the American public is now drinking water that is chemically contaminated, and we don't have the hat the health effects will be . . . . A scientist can't answer Mrs. Smith's question, 'Is it all right for myter to drink the water?' . . . . Or should a pregnant woman be drinking bottled water."

The problem, he saiederal and other funds for research. Selikoff praised federal scientists' work, but called for far more of it. "We should learn ho to translate animal studies to man," he said. "We can't even translate from rat to mouse, let alone from mouse to man," but learning to do so "is by no means beyond us."