DISCLAIMER The following is a staff memorandum or other working document prepared for the members of the Advisory Committee on Human Radiation Experiments. It should not be construed as representing the final conclusions of fact or interpretation of the issues. All staff memoranda are subject to revision based on further information and analysis. For conclusions and recommendations of the Advisory Committee, readers are advised to consult the Final Report to be published in 1995. TAB D-6 þþþDRAFT þ FOR DISCUSSION PURPOSES ONLYþþþ MEMORANDUM TO: Members of the Advisory Committee on Human Radiation Experiments FROM: Advisory Committee Staff DATE: May 1, 1995 RE: Documentary Update on Proposed Human Experimentation Related to Radon in the Uranium Mines In prior briefing books we have presented information on what was known about radon in uranium mines and on the actual levels of radon in mines on the Colorado Plateau. Attached are two documents that are critical to this story. Attachment 1: August 1944, Egon Lorenz "Radioactivity and Lung Cancer: A Critical Review of Lung Cancer in the Miners of Schneeberg and Joachimsthal." This is the Lorenz review cited in BEIR IV. Interestingly, Holaday said in his court testimony that Lorenz's conclusion that "radon is the sole cause of the lung cancer in the mines" is not supported by his own presentation of the literature. Attachment 2: Charts from the report of the Federal Radiation Council, Guidance for the Control of Radiation Hazards in Uranium Mining, September 1967. These charts summarize to rise and fall of the uranium rush from 1954 to 1966, the control of radon in the mines from 1956 to 1966, and the cancer mortality of uranium miners between July 1955 and June 1965. Table 1 shows the number of uranium mines operating by year. The peak year in terms of the number of underground mines was 1959; by 1967, the year Secretary of Labor Wirtz issued radon exposure standards for mines contracting with the federal government, the number of operating mines was down by a third, falling from 801 to 533 operating underground mines. Similarly, Table 2 shows that the peak year for the number of underground miners was 1960. By 1 1967, the number of underground miners had fallen by almost 1/2 from 4908 to 2545. The fact that there were fewer miners per mines in 1966 than in 1960 suggests that it was smaller mines that were closing. Table 4 indicates that radon levels in the mines were not falling between 1956 and 1959. Comparing data in Table 4 to data in Table 5, we can observe a significant improvement in radon levels from 1959 to 1965 and a slight improvement from 1965 to 1966. Nevertheless, even in 1966 fewer than half the mines had achieved levels below 1 Working Level, the level recommended by PHS in 1952. Table 6 and Figure 1 show that for exposed miners with more than 10 years between the beginning of underground uranium mining and death from lung cancer, the observed lung cancer deaths were 2.7 times the number expected in the lowest exposure group, 33.3 time the number expected in the highest exposure group, and 8.9 times the number expected for all the exposure groups taken together. The report notes that 49 lung cancer deaths actually occurred in the exposed study group, rather than the 34 that appear in Table 6. These 49 cases are "more indicative of the real incidence of lung cancer in the study group" but 15 deaths were not included because they did not meet the requirements for group comparisons (the underlying cause of death on the death certificate was not lung cancer or the date of death was after June, 1965) and therefore no expected number of deaths could be calculated that would be comparable to these 49 cases. Both Table 6 and Figure 1 indicate a dose response relationship between exposure to radon and its daughters defined as cumulative Working Level Months and lung cancer mortality. 2