 Graves became dismissive of the radiation risks from nuclear testing while serving as test director for the Nevada Test Site shots during the 1950s . He announced that the risks from fallout were " concocted in the minds of weak malingerers . " As a spokesman for the Nevada Test Site , he spoke in local areas around Nevada assuring the population of no danger from the activities there . As the head of the Los Alamos Laboratory 's J ( Test ) Division , he was the scientific director or deputy director of most of the nuclear tests from 1948 through the 1950s , including the Desert Rock exercises which exposed military personnel to radiation , and the Castle Bravo test that irradiated many native islanders and test personnel . Asked to testify before the Joint Committee on Atomic Energy on the danger of radiation causing cancer , Graves replied : 
