Two months after the atomic bomb was exploded over Nagasaki in 1945, two U.S. government research teams found low-level radiation in the Japanese city's outskirts that was about twice the level now considered safe for nuclear workers and over 10 times the radiation safety standard for the general population.
Reports of the two groups, scientists from the Manhattan Engineering District which built the bomb and a U.S. Navy medical research team, were completed in 1946 and are filled in the National Archives.
The once-secret reports are bound to increase the controversy that has developed over whether U.S. troops sent to Nagasaki and Hiroshima in 1945 absorbed enough radiation to cause cancers that appeared after 20 years or more.
About 100 veterans of the postwar cleanup damages in the two cities filed claims with the Veterans Administration saying they now have maladies stemming from radiation exposure at Hiroshima and Nagasaki.
The scientists and engineers carried out 900 measurements in Nagasaki from Sept. 20 to Oct. 6, 1945. The bomb was dropped Aug. 9, 1945.
A fallout cloud passed over the Nishyama area, two miles from ground zero, and "fission products from the cloud left droplets of yellow-brown liquid," one report quoted Japanese eyewitnesses saying.
The highest levels measured by the Americans at Nichyama 40 to 70 days after the bomb were one milirem per hour or 8,760 milirem a year. At the time of the measurements, according to there studies, the government-recognized "maximum tolerance dose" was considered to be four milirem per hour.
Today's permissible standards are far lower and different for individuals who work with radiation or live in an area with radiation exposure.
The nuclear-worker level is 3,000 milirem in three months or 5,000 milirem over a year.
The government standard for individuals not working with radioactive matter is 500 milirem a year.
The U.S. researchers estimated in 1945 that residents of the Nichyama area received a cumulative total of about 56 rem within 23 days after the fallout passed over.
By the time the U.S. scientists were taking measurements, around Sept. 25, they concluded the 24-milirem daily level was safe.
The levels at Hiroshima and Nagasaki, the two teams wrote in their reports, were "found to be far below the dose necessary to produce perceptible physiological effects."
To be on the safe side, the cleanup troops were rotated out, usually after a six-week tour, so none apparently approached even today's much lower safety level, according to the 1946 conclusions.
Norman Solomon, chief researcher for the Committee for Veterans of Hiroshima and Nagasaki, said Friday he had never heard of the studies filed in the archives.
Solomon's committee is one of several groups sponsoring a three-day national citizens' hearing for radiation victims that ends here today.
Defense Nuclear Agency officials also apparently are not aware of the 1946 studies.
In a Dec. 18, 1979, letter, White House aide Ellen L. Goldstein wrote that DNA said "the maximum dose which might have been received by any U.S. serviceman in either [Nagasaki or Hiroshima], in an absolutely worst case, is less than one rem."