ATTACHMENT 10 Bureau of Disease Prevention and Environmental Center Chief, Compliance and Control Branch National Center for Radiological Health June 12, 1967 Chief, State Program Services Section, In reply refer to: Compliance and Control Branch, "illegible" "illegible" Joint Committee on Atomic Energy hearings regarding uranium mine standards. Hearings June 6, 1967: In general, the tone of these hearings indicated that the Committee and the vast majority of the witnesses believed that Department of Labor's Secretary Wirtz has established an excessively restrictive radon standard for uranium mines. It would appear that the consensus of both the Committee and the witnesses is that a working level of around 1 would be a much more practical radon level without appreciable hazard to the mines as opposed to the 0.3 working level established by the Department of Labor. It appeared that the general belief is that Dr. Archer's projection of lung cancer as related to radon daughter exposure of uranium miners is somewhat in error. Thus, the recommended level of 0.3 would have no basis in fact. The first witness was the Director of the U.S. Bureau of Mines who presented the following highlights: The Bureau of Mines has closed mines at the 10 working level and issued orders to mine owners to reduce radon levels a the 5 to 10 working level. The order issued for reduction of radon levels is by ventilation only. Bureau of Mines is only concerned with mines on Indian reservations (approximately 11 underground mines). They have performed 35 inspections over the past five years and the Geological Survey has performed an additional 175 inspections on these mines over the same period of time. The Bureau of Mines has not been overly restrictive on compliance by the mine operators but has merely recommended that the radon be reduced to "illegible" working levels or less. The second witness, Dr. Robley Evans. Dr. Evans' testimony provided the key testimony of the hearings (a copy of the testimony is attached). Subsequent testimony revolved around, and questioning by the Committee was shaded toward, Dr. Evans' testimony. The following highlights were presented: He believes that somatic damage from radiation has a threshold and is nonlinear. He pointed out that Labor Secretary Wirtz made a mistake in the definitions as they appear in the regulations concerning radon levels in the mines affected by the Walsh-Healy Act. By the definition used in the regulations it would appear that the actual working level imposed by Secretary Wirtz 1 The next witness was Dr. Taylor representing "illegible" and "illegible". Dr. Taylor briefly described the history of the organizations and went into further detail in the history of the recommended maximum permissible concentrations advocated by both organizations. In response to a question: to what extent the "illegible, NCRP recommended levels of 0.3 "illegible" associated with uranium mines, he responded that this level had been originally promulgated for use in medical, laboratory, and other closed environments and that up until 1960 the organizations did not concern themselves with uranium mines. Neither Committees perform their own studies but rely upon other groups such as Duncan Holaday's studies to provide answers to any questions they may have. They feel that most of these groups are doing an adequate job. He stated that the ICRP has looked the studies performed with uranium mines and is preparing to recommend levels some time in the future. He stated that he felt the levels they would be establishing would generally be around 1 working level. He also said that the organizations would not establish standards per se unless they felt that the "illegible" did not do an adequate job. Dr. Taylor had no specific comments to the FRC report Number 8 because he had not studied it closely enough but generally feels that the models used in this report are more applicable to mines than those models used by RCRP for confined areas. He stated that there was no 1:1 relationship between the NCRP maximum permissible levels and the working level but rather that the relationship depends upon many parameters. The question was asked whether he felt it would be permissible to set a working level based on the NCRP, "illegible" maximum permissible levels if used in terms of the FRC report Number 8. He responded that, basically, no, it would not be permissible; that that model may be different since the maximum permissible levels of the NCRP, ICRP is based on enclosed environment. Duncan Holaday was then called to the stand and asked whether Dr. Evans' working level equation presented in Page 10 of his testimony would be associated with the NCRP and FRC working level. Dr. Holaday stated that the NCRP standards were set for a condition in which radon is in equilibrium with its daughters and explained the rationale for this standard. He further stated that from their studies in mines it would appear that that radon- daughter product equilibrium fluctuates widely. Dr. Taylor then testified that the maximum permissible levels, particularly those associated with the NCRP, ICRP, are designed for use as a physical aid in determining environment conditions with the absence of observable injury as the criteria. He then quoted paragraphs 30 and 31 from the 2