Staff Memorandum: the Hazards of Radon in Uranium Mines

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FROM: Advisory Committee Staff Members of the Advisory Committee on Human Radiation Experiments The Hazards of Radon in Uranium Mines In response to requests from Duncan Thomas and Henry Royal, attached are documents relating to what was known about the hazard posed by radon in uranium mines and the effectivencss of ventilation in reducing that hazard. We have also included documents on standard setting and control of radon and other radioactive hazards in other industries and the data\information used to set standards. The documents appear to indicate that by 1952 when the PHS put out its Interim Report on the Uranium Miner and Miller Study and before the cohort and protocol for the long term study was fmnalized: (1) there were many studies on the European miners' experience indicating that radon in the mines caused lung cancer; (2) a review of this literature had been publisnsd ir. English; ( 3 ) that studies in US mkes inGicateci $iar technically and ecoilornicslly feasible ventilation would reduce radon exposure by several orders of magnitude to levels considered "acceptable"; (4) that tolerances had been set for radon for workers in all other industries and were being enforced by the AEC and others; and ( 5 ) that data no better than that available on radon in the mines had been used to set exposure standards for radium and for radon The staff welcomes your reactions to these documents. Please direct your comments to

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Attachment 1 : Hueper, \\'ilhelrn, Section of the chapter, "Occupational Cancers of the Respiratory S>.stem,"dealing with uranium miners and radon hazards from Occiipatiorral Tumors arid Allied Diseases, 19.12. Huepe: discusses radioactive substances and the lung cancer experience of the Schnseberg and Joachimsthal miners and Lvorkers in radium laboratories. This is a critical review of the literature that covers studies going back to 15; 1. but focuses on those studies done after 1879 when the miners' lung ailment was identified as lung cancer. In discussing the literature on the mines. Hueper discusses all the possible causative factors that might be related to lung cancer, and sj-stematically eliminates all but radon. First he eliminates all the non-occupational factors because they are common to all the people in Schneeberg and Joachimsthal none of whom have excess lung cancer except the miners. Second, he eliminates the occupational factors that have not caused lung cancer in other occupational settings. He cites some evidence of a dose response relationship between radon concentration and lung cancer and also refers to animal experiments in which mice put in the mines developed lung cancer. (Mice fed mud, mold, and arsenic-containing compounds from the mines did not.) More than 3 iozen studies of lung cancer ir, t h z miners are cited. Hueper also points out that, "In view of the fact that therapeutic procedures are entirely ineffective in combating the disease once it has become established, the only means of controlling this fatal occupational disorder consists in the introduction of measures that will prevent occupational contact with the causative agent." (p 450) He also points out @. 456) that the evidence that the causal agent in the European mines is radon is "highly suggestive but not entirely conclusive," but is supported by the fact that workers in other settings exposed to radioactive materials have also experienced excess incidence of lung cancer. He then presents the evidence on those workers. He then discusses the inability to reproduce lung cancer in animals using x-rays or radium. (Since it was the radon gas and the radon daughters attached to dust that caused the problem in the mines. this failure is not surprising in retrospect.) He concludes that "the evidence of the statistical and clinical observations on hand does not l e a ~ ~ eany doubt that these agents [radioacti\.e ores] represent the chief cause of the pulmonary malignancies obsemed in workers (miners, artisans. technicians. chemists, etc.) exposed to radioactive matter for occupational reasons." (p 459). He cites a level. 100 s 10"' curies of radon or thoron per liter. that may cause lung cancer in m a and cites a recommended tolerance level of IO-''curies per liter to "remain \vel1 Xvithin a

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.A tt 3ch m en t 2 : Gndatcd Confidential memorandum written in 1951 or 1952: Radiation Exposure in the United States--Uranium &lining Industn This AEC memorandum details Lvhat is know about hazards in the mines and mills. It stales that samples for the mines taken in 1950 and 195 1 showed a median level of 5 100 picocuries per liter of radon. 3 10 times the level set by the Amencan Conference of GoLrernmenr Indusrrial Hygienists for an 8 hour exposure and double the level in German mines where the attack rare was "about 1'3b per year of lung carcinoma and 50-70% of the deaths of the workers in these mines were due to a primary cancer of the upper respiratory system." Attachment 3 : Progress Report (July 1950-December 1951) on the Health Study in the Uranium Mines and Mills This report was clearly the basis for the memorandum discussed above and presents the same information in much greater detail. It also discusses the effectiveness of ventilation measures implemented and studied to date, the importance of radon daughters and dust in A study of persons who worked in the uranium mines and mills pnor to 1950 is proposed. Appendix C includes Bale's explanation of the hazard represented by radon decay products inhaled on dust which "is iikely to far exceed the dosage due to radon and its disinregration products which are formed while radon is in the bronch." 11. RADON DAUGHTERS AND DUST AND THE EFFECTIVENESS OF Attachment 1: July 17,1951 memorandum from William Bale of the University of Rochester and the AEC Health and Safety Branch, to The Files re: Measurements of Air-borne radioactivity in a Colorado Plateau This memorandum explains that radon degradation products (radon daughters) m3y be a greater hazard than radon itself and comments on the very high levels of radon seen in the PHS Bale points out that Colorado Plateau Miners have the geatest and longest lung exposure to radiation 3nd could. therefore. be used for determining permissible exposure limits in the same \vay that the radium dial painters were used 10 set permissibie body burdens for bone. As he explains. the miners "represent the only substantial group of human individuals with long

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s x n d i n g lung exposure to substmtial doses of radi31ion. As such. their potential \\.oflh ir! sexing permissible \ d u e s of lung exposure IO radiarion m 3 ~ 'be comparable to rhat of the intenrionai or unintentional human recipients of radium [radium dial painters] in setting permissible limits for the radioactiviry burden of bone." He applauds the PHS researchers for conducting "their work so far without unduly alarming miners as to hidden hazards that may exist. or in any way impeding mining operations." A tt a c h rn en t 5 : 1950 letter from Duncan Holaday to official of Vanadium Corporation of America This letter describing how ventilation reduced radon exposures by a factor of 500 from 26, 900 micromicrocuries (micromicro=pico) to about 500 micromicrocuries. in the draft 1952 Interim Report about the causal relationship between radon and lung cancer in miners: This memorandum, while disputing the ciiusal relationship between lung cancer and radon (a dispute referred to in BEIR I\?, suggests that ventilation and wet drilling (to keep domn the dust) "represent the initial preventive measures which should be instituted," even suggesting that until more is known. mines that cannot institute these practices should be shut down. The memorandum goes on to challenge the czrcinogenicity of radon and present other possible causes of lung cancer in miners, to question the possibility of accurately measuring radon daughters, to propose an extensive study of the mines and miners and a small informal conference between NCI, PHS and AEC staff. Attachment 7: John Harley (AEC Health and Safety Division), Sampling and Measurement of Airborne Daughter Products of Radon. Nucleonics, This article presents a method for interpreting levels of radon daughters in air samples and explains (in the box on Hazard of Esposure to Radon and Radon Daughters) "the hazard from inhalation of daughter products is much more serious than that from radon itself. This paper and the thesis from Lvhich it is abstracted speaks directly to the probiems raised by Lorenz related to measurement and interpretation of radon daughter activity. The article is based on Hxley's dissertation submitted the previous year.

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.A tt zc h men t 8: February 25,1952 memorandum from Duncan Holnday to Chairman, Technical Advisory Committee re: Proposed Working Level for RaX This memorandum jusrifies the proposed 1 WL standard in light of the limited scientific information, relying on estimates of the dose to the lung thought to be carcinogenic “in a fairly short period of time.” While regretting the need to set a standard on “meager” information, Holaday states the necessie of setting one so that controls can be implemented. Attach men t 9: April 14, 1952 memorandum from Chief, Division of Occupational Health, to Director, National Cancer Institute re: Proposed Cooperative Project between the Division of Occupational Health and the National Cancer Institute--Establishment of a Safe Concentration of Radon, RaA and RaC’ for Use In hlines and Other Industrial This April 1952 memorandum from the Chief, Division of Occupational Health (PHS) to Director NCI, acknowledges controversy over worker esposure to radon and its daughters and points out that both the US Committee on X-ray and Radium Protection and the American Conference of Governmental Industrial Hygienists have adopted a 10 pic0 curie per liter exposure limit (for an 8 hour day) based on the experience of the European miners. It also points out that levels in US mines are very high and cannot feasibly be reduced to the 10 pCi limit and suggests and justifies a 100 pCi limit. Finally, the memorandum proposes a cooperative study to arrive at a safe level of radon and its daughters for use in uranium mines. The nest two documents discuss setting occupational standards for radiation outside the A tta ch men t 10: Summary of the J C A E hearings regarding uranium mine standards prepared by the State Program Services Section (of the PHS) for the Compliance and Control Branch of the National Center for At the JCXE hearings, Willard Wirtz. Secretary of Labor announced and defended his proposed 0.3 WL standard for uranium mines. s This document refers to testimony by Dr Taylor. representing the ICRP and the NCRP,

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esphining that the standard recommended by these organizations, 0.3 lt'orking Level. was meant for "enclosed environments," not mines. Since canaries were routinely sent into mines to see if there was an adequate supply of oxygen, it Lvould seem rhey are also enclosed environments. Attachment 11: "Inception of Standards for Internal Emitters, Radon and Radium", a 1981 Health P/zysics articIe written by Robley Evans (11:137-118) This document describes how the radium standard was set and the level of scientific information used to set it. Evans reports that the Navy came to him at the beginning of World War I1 and told him if he did not recommend a standard, he would be inducted into the Navy and ordered to produce one. He responded by setting up a committee which came up with a standard based on data on 27 human beings who had been exposed to radium, 20 of whom had been injured. Evans went around the room and asked each of the men for a standard that they would have felt comfortable having their wives or daughter work with. The committee agreed on a 1.1 pCi for a maximum body burden of radium.