Public Health Service and Pentagon doctors have begun to investigated whether an unusual number of leukemia and other cancer cases have developed in servicemen who were exposed to low-level radiation during U.S. nuclear weapon test 20 or more years ago.

PHS's Center Control is focusing on a nuclear weapons test shot called "Smokey" in Nevada on Aug 31, 1957, where 700 Army infantrymen maneuvered in the vicinity of ground zero less than four hours after a 44-kiloton device was exploded from a 700-foot tower.

The Smokey test device had three times the explosive power of the 1945 Hiroshima bomb. President for the shot were 1,195 troops, 583 scientists and assistants and 457 observers.

After 250 interviews, CDC's Dr. Glyn G. Caldwell, who is running the study, said he had four ex-servicemen with confirmed leukemia cases. He is "certain" two of the men were in Smokey: the other two say they were there but "we still checking" military records.

Caldwell also said he had one other possible cancer case, pilot who flew through the radioactive cloud and now says he has skin cancer.

Caldwell said if he finds a total of "seven to ten" cases of the 2,235 Smokey participants it would be "significant," and would raise questions about previously believe safe low levels of radiation.

Most scientists and medical doctors agree there is now only limited factual data on the long-term effects of less than killing doses of radiation. Human effects are limited to studies of Hiroshima and Nagasaki victims. Marshall Islanders who received fall-out dosages 1954 and indiciduals exposed in accidents.

In the 1950s, knowledge of radiation and fallout was even less.

A Pentagon spokesman, for example, pointed out last week that the film worn by servicemen at 1950s tests did not record radiation from fallout.

Another government official said there was no way then to determine how much irradiated matter an individual inhaled.

"Metal vaporized off the tower" where the nuclear device was detonated, he said, "could be breathed in, not recorded on a film badge, and stored as irradiated matter in an individual's bone or bone marrow." That could cause leukemia or cancer years later, he said.

Government interest in Smokey was sparked intially be the case of Paul R. Cooper, a 43-year-old expara-trooper from the Idaho who [WORD ILLEGIBLE] leukemia.

Cooper was in the Veteran Administration Hospital in Salt Lake City last December when a doctor learned he had been among maneuver troops at Smokey. [WORD ILLEGIBLE] that was sent to CDC headquarter, Atlanta.

At the same time, Cooper [WORD ILLEGIBLE] press the VA for 100 per cent [WORD ILLEGIBLE] connected disability. Publicity of Cooper's case brought word of other cancer cases from servicemen around the country who participated in clear tests.

In February 1977, a second Smokey leukemia case appeared - Donald Coe from Tompkinsville, Ky. At this point, CDC began to get interested.

Locating the participants was CDC most difficult job, since neither the Defense Department nor the Atomi Energy Commission has complete records from those tests.

Pressed by publicity on the Cooper case and requests from Coe's congressman. Rep. Tim Lee Carter (R-Ky.), the Pentagon has now moved to put together its own plan for locating test participants and exploring what medical effects, if any, can be associated with nuclear radiation exposure.

According to a Defense Department spokesman, "Our doctors see no correlation between exposure in the tests and cancer now."

Nevertheless, he said, an inter-service group is proposing that the Defense Department establish a permanent committee "to research this futher, decide what to do about physicals and follow-up."

There were more than 12 test series of varying size involving close to 170,000 servicemen, according to one government official.

One reason for the Pentagon's hesitancy is the prospect of being flooded with claims from ex-servicemen.

The VA, with reluctance granted Cooper his full disability claim but did not directly link his luekemia with the Smokey test.

Cooper's film badge record, unearthed from storage, showed he had received only 1.25 rads (a measure of radiation) at the Smokey test. His VA claim was granted by the appeals board after a finding that he showed some minute symptoms before his discharge from the Army in 1972.

The VA has initially denied Coe's claim for diability, saying his leukemia is not service connected.

Rep. Carter, who is a medical doctor, said he is convinced Coe's disease is a result of radition received at the Smokey test.

The Kentucky Congressman and Cooper met with a presidential aide, Frank Rains, Aug. 2 to enlist White House support for the CDC study.