Investigations on the radon concentrations in uranium mining and feasible ways for the reduction of lung cancer risk for uranium miners

During the completation of a test chamber the potential alpha-energy concentrations of the short lived 222Rn-daughters and the concentrations of 222Rn were measured in an uranium test mine in the Black Forest nearby Baden-Baden. Without any measures for reduction of the potential alpha-energy concentrations the mean annual potential alpha-energy exposure amounts to about 10 WLM, assuming 170 working hours per month. Epidemiological studies among uranium miners yield a lung cancer risk factor in the range of 1-5.10-4 per WLM (UNSCEAR-REPORT 1977). Therefore in this case an annual lung cancer risk of about 1-5.10-3 for the miners must be expected. Ventilation rates in the test chamber of about 30 m3.min-1 are sufficient to reduce the lung cancer risk about two orders of magnitude. Preliminary laboratory tests showed that by sealing the walls of the mine, a reduction of the risk of one order of magnitude may be achieved. Sprinkling of the rubble with fresh water leads to no reduction of the 222Rn-concentrations. Further measures, e.g. varying the kind of blasting, pressure test, special ventilated helmets for the miners and their effects for the risk factor are in discussion. In the Federal Republic of Germany the mean annual lung cancer risk for members of the public due to inhalation of ''environmental'' radon and daughter products amounts to about 1.10-5. Without any measure for reduction of the potential alpha-energy concentration, the lung cancer risk for the uranium miners is enhanced by a factor of 1-5.10-2. With adequate ventilation, the additional risk for the miners will be comparable with the corresponding value for the population