Federal health officials had evidence as early as 1965 that excessive leukemia deaths were occurrng among Utah residenst exposed to radioactive fallour from U.S. atomic bomb tests, according to documents obtained by The Washington Post.

But the U.S. Pulic Health Service apparently ignored the findings of one of its won investigators and withheld his study, which cited the leukemia victims' "extended residence" in the fallout area.

The long-forgotten and unpublished study, dated Sept. 14, 1965, was requested and obtained under the Freedom of Information Act.

Officials of the Department of Health, Education and Welfare -- now involved in a major controversy over wherter A-bomb tests caused leukemia and cancer -- were described as "horrified" to learn from the Post request that such an unpublished study existed.

As a result, HEW Secretary Joseph A. Califano has ordered a search of federal health files for any other studies on adverse health in Utah, and their disclosure to the public.

Indeed, another federal study, uncompleted, exists. It shows, according to the man who conducted it, a continual increase in thyroid cancer among Utah residents during the period 1948 through 1969 -- about the time that federal officials are said to have "lost interest" in continuing fallout-related studies, includin this thyroid cancer one.

Both thyroid cancer and certain forms of leukemia can be caused by radiation but may take years to occur after exposure to radioactive material.

More than 80 aboveground nuclear weapons tests were conducted at the Nevada Proving Grounds from 1951 until the atomic testing went underground in 1962. Some 20 to 26 of the tests sent radioactive fallout into areas of Utah populated by thousands of residents. They were repeatedly assured that the fallout posed no health hazard, and even through the 1960s leukemia and cancer victims were rebuffed in claims that fallout caused their diseases.

Nuclear testing officials maintained that the claimants could not have received enough fallout to trigger their illnesses. Nuclear officials have always maintained that the atmospheric tests were conducted safely, and that there wasn't enough fallout outside the testing grounds to cause health problems.

But the 1965 Public Health Service study said "few sophisticated or detailed" fallout measurements were made in populated areas until 1955 -- well after some of the "dirtiest" nuclear test blasts.

The study, conducted by Edward S. Weiss, found that from 1950 to 1964 there were 28 leukemia deaths in the southwest Utah counties of Washington and Iron. Weiss, who at the time was deputy chief of the Population Studies Program for the PHS Division of Radiological Health, calculated that among the 20,000 residents only 19 cases of leukemia should have occurred.

More singnificantly, he found that in 1959 and 1960 seven people in the two counties were diagnosed as having acute leukemia -- five of them children and teen-agers, who are most vulnerable to some radioactive elements.

Weiss said there was no evidence to link these seven cases to fallout exposure "beyond the fact of extended residence in the area." But he also raised the possibilities of "other environmental contaminants or familial disabilities." He urged additional and continuing study of leukemia in Utah and Nevada.

Weiss, who is now retired, acknowledged last week that his study was inconclusive although it raised, apparently for the first time, the question of excessive leukemia deaths in the fallout zone. He said the possibility of a link to radioactive fallout should have been pursued then.

Apparently it was not. Atomic Energy Commission officials criticized the paper internally, citing the relatively few cases.

The only subsequent leukemia studies in the fallout zone were done by other agencies in two Iron County towns, Parowan and Paragonah. Those studies made no connection to radiation because health investigators were not looking at the possibility of radiation having caused an outbreak of leukemia there, according to Dr. Clark W. Heath Jr., a Center for Disease Control official who studied the leukemia clusters.

Health, himself, had reviewed Weiss' paper in 1966 and also called attention to the childhood leukemia of 1959-60 cited by Weiss. "To my way of thinking," he said in 1966, "the burden of proof lies with the person who chooses to ignore them as merely chance events."

Meanwhile, Weiss became involved in two thyroid studies in the fallout areas.

One found an increase in thyroid cancer through 1962. It was inconclusive; nevertheless, it was published in 1967.

The other found no increases in thyroid abnormalities amont a selected group of school children who lived in the fallout area. Despite that study's severe limitations, which were acknowledged at the time, it was also published and has repeatedly been relied on by nuclear testing officials as evidence of the safety of the A-bomb tests.

With the conclusion of the thyroid studies in 1971, the Environmental Protection Agency, which had assumed reponsbility for radiation monitoring, "lost interest" and health studies topped, according to Dan Hoffman, who had gathered additional thyroid cancer data for EPA to update Weiss' earlier thyroid study. Hoffman left EPA and returned to the Bureau of Radiological Health, which is now a part of the Food and Drug Administration.

Besides Weiss' leukemia study, other documents obtained under the Freedom of Information Act reveal that Utah officials detected unusual occurrences of birth defects in the fallout areas. Birth defects in Iron and Washington counties reached what was described as a "marked peak" in 1958.

What was described as an "extraordinary peak" for birth defects occurred in 1962 in three counties to the north -- Juah, Millard and Beaver.

Through other records, The Washington Post traced an extraordinarey pattern of disease among two sisters in Nevada and their cousin in Utah in places where fallout regularly dusted the meadows and cattle feed.

Kenneth Lamoreaux, 15, who drank raw milk from his family's cow in Paragonah, was diagnosed as having acute leukemia on Aug. 14, 1960. One of the childhood cases cited by Weiss, Kenneth was deas within 10 days.

On July 18, 1963, his cousin Therold Stewart, who had grown up in Tempiute, Nev., died of leukemia at age 25. Tempiute is 45 miles northeast of the testing grounds, and her doctor attributed her fatal disease to being burned by radioactive fallout while walking to school in the early 1950s.

Her sister, LaRue Cook, now 43 and living in north Las Vegas, remembers how the family would stand in the door of their Tempiute mountainside home and witness blasts that turned dawn into bright daylight and shook the ground with crashing thunder. Last summer her malignant thyroid gland was removed.