Three major studies to be released within a year may be inconclusive on whether atmospheric nuclear blasts in the 1950s and 1960s in Nevada caused health problems like cancer, scientists say.

The first results from two studies sponsored by the U.S. Energy Department and the National Cancer Institute focusing on radiation problems in Western states are due by the end of this year, and results from a nationwide study by the National Cancer Institute should be released within a year.Officials of each study met last week to discuss their efforts with scientists conducting a fourth study on radiation releases during the past four decades from the Hanford Nuclear Reservation in Washington state.

"I think the overall result of the study is going to be that while there has been some harm done by these tests, finding that harm is going to be extremely difficult to do," said Lynn Anspaugh, director of environmental sciences at Livermore National Laboratory.

Anspaugh is scientific director for the Offsite Radiation Review Project, which the Energy Department started in 1979 in hopes of determining the radiation doses people received in Western states from the Nevada atmospheric weapons tests that were conducted mainly in the 1950s and finally ended in 1963.

Anspaugh said the study has confirmed previous reports that people in St. George, Utah, received doses of radiation much higher than what normally occurs in the environment - particularly children who drank milk contaminated because cows ate radioactive feed.

"Within the other locations throughout the area we think the doses were quite a bit smaller than that, although at some isolated locations like ranches and so forth the doses might have been somewhat larger," he said.

Walter Stevens, dean of the University of Utah Medical School, is principal investigator for a National Cancer Institute study on whether residents of southern Utah, western Nevada and northern Arizona suffered higher rates of leukemia and thyroid disease because of the tests.

U.S. District Judge Bruce Jenkins in Salt Lake City ruled in 1984 in favor of nine test-case plaintiffs in a suit filed by 1,200 residents of the three states claiming fallout from the test caused cancer.

The ruling and $2.6 million in damages he awarded were overturned in April 1987 by the 10th Circuit Court of Appeals in Denver, and the appeals court was upheld in January 1988 by the U.S. Supreme Court.

The appeals court said the government is immune from suits challenging discretionary conduct like the weapons tests.

But Stevens said the ruling "indicates there's not the certainty that one would expect or hope to see in the results that have been done in the past.

"And I'm not convinced in our own studies that we will have any certainties that could be used unequivocally in a court of law," he said.

Asked whether the study has found a direct link between the tests and cancer, he said, "We're dealing with a small number of people so it may be difficult to give an absolute answer of yes, no or maybe."

"There's nothing that is alarming," he added of the results so far.

Andre Bouville, lead scientist for the National Cancer Institute study trying to determine radiation doses nationwide from the Nevada fallout, also said there is considerable uncertainty.

That study focuses on contamination of milk nationwide because cows ate radioactive iodine 131. It has found great differences in how much milk individuals drank at the time.

"You find evidence - at least indirect evidence - of contamination all throughout the United States. Generally speaking the people living in the eastern United States were more exposed than people living in the West because of prevailing winds from the West to the East."

John Till, head of the Hanford study, said a chief benefit of the studies is that scientists are now in a position to better measure doses of future dangerous releases of both radioactive and non-radioactive materials.

"There's no question that if we had to make the same decisions today about atmospheric weapons testing, then we wouldn't have taken the same course that we took in the 1950s," he said. "On the other hand I think in the 1950s we probably used the best judgment and the best evidence at the time.

"We've learned a lot. Let's hope we take what we've learned and apply it as we make decisions today," he said.