In 1959, the geneticist Edward B. Lewis computed that children exposed to fallout from nuclear tests may have received very high doses of radioactivity from iodine-131 in cow milk. His estimates prompted the Joint Committee on Atomic Energy to request that the AEC produce a report on the risks of short-lived isotopes. In 1960, Harold A. Knapp, a mathematician working within the AEC Division of Biology and Medicines Fallout Studies Branch, authored this report, but since it was finished during an international moratorium on atmospheric nuclear tests, it had no notable impact. Then, in 1962, while the USSR and the USA had resumed nuclear tests and the Limited Test Ban Treaty was being prepared in response to huge international pressure, Knapp took on the task of estimating the radioiodine exposure of Americans before 1958, at a time when milk was not monitored. Knapp conclusions were alarming, and blatantly departed from preceding AECs reassurances that the public had never been exposed to harmful levels of radioactivity. He "showed that, from just one 1953 test, infants who had been living in a radiation hotspot around St. George, Utah, might well have received I-131 doses anywhere from 150 to 750 times existing annual permissible doses."
Beginning in fall 1962, the AEC resorted to diverse pretexts to block the publication of Knapps findings. In spring 1963, Gofman, was solicited to participate in a so-called "Ad Hoc Working Group on Radioiodine and the Environment" assembled by AECs Division of Operational Safetys director, Gordon Dunning. Gofman reported that "In essence, the message to [this] Committee […] was « How can we stop this report - a report which will, in effect, make the AEC reports over the past 10 years look untrue? »". In spite of AECs Headquarters objections, the committee recommended publication of Knapps report, which was finally published by the AEC in June 1963, followed by a summary in Nature.