Radon and risk of extrapulmonary cancers: results of the German uranium miners' cohort study, 1960–2003

Data from the German miners' cohort study were analysed to investigate whether radon in ambient air causes cancers other than lung cancer. The cohort includes 58 987 men who were employed for at least 6 months from 1946 to 1989 at the former Wismut uranium mining company in Eastern Germany. A total of 20 684 deaths were observed in the follow-up period from 1960 to 2003. The death rates for 24 individual cancer sites were compared with the age and calendar year-specific national death rates. Internal Poisson regression was used to estimate the excess relative risk (ERR) per unit of cumulative exposure to radon in working level months (WLM). The number of deaths observed (O) for extrapulmonary cancers combined was close to that expected (E) from national rates (n=3340, O/E=1.02; 95% confidence interval (CI): 0.98–1.05). Statistically significant increases in mortality were recorded for cancers of the stomach (O/E=1.15; 95% CI: 1.06–1.25) and liver (O/E=1.26; 95% CI: 1.07–1.48), whereas significant decreases were found for cancers of the tongue, mouth, salivary gland and pharynx combined (O/E=0.80; 95% CI: 0.65–0.97) and those of the bladder (O/E=0.82; 95% CI: 0.70–0.95). A statistically significant relationship with cumulative radon exposure was observed for all extrapulmonary cancers (ERR/WLM=0.014%; 95% CI: 0.006–0.023%). Most sites showed positive exposure–response relationships, but these were insignificant or became insignificant after adjustment for potential confounders such as arsenic or dust exposure. The present data provide some evidence of increased risk of extrapulmonary cancers associated with radon, but chance and confounding cannot be ruled out

Lung cancer risk among German male uranium miners: a cohort study, 1946–1998

From 1946 to 1990 extensive uranium mining was conducted in the southern parts of the former German Democratic Republic. The overall workforce included several 100 000 individuals. A cohort of 59 001 former male employees of the Wismut Company was established, forming a large retrospective uranium miners' cohort for the time period 1946–1998. Mean duration of follow-up was 30.5 years with a total of 1 801 630 person-years. Loss to follow-up was low at 5.3%. Of the workers, 16 598 (28.1%) died during the study period. Based on 2388 lung cancer deaths, the radon-related lung cancer risk is evaluated. The excess relative risk (ERR) per working level month (WLM) was estimated as 0.21% (95% CI: 0.18–0.24). It was dependent on time since exposure and on attained age. The highest ERR/WLM was observed 15–24 years after exposure and in the youngest age group (<55 years of age). While a strong inverse exposure-rate effect was detected for high exposures, no significant association was detected at exposures below 100 WLM. Excess relative risk /WLM was not modified by duration of exposure. The results would indicate the need to re-estimate the effects of risk modifying factors in current risk models as duration of exposure did not modify the ERR/WLM and there was only a modest decline of ERR/WLM with increasing time since exposure

Radon and cancers other than lung cancer in uranium miners Results of the German uranium miner cohort study

Background It is well established that lung cancer is caused by radon, while uncertainty exists as to whether cancers other than lung might be related to exposure from radon. To investigate further the risk of extra-pulmonary cancers, mortality data from the German uranium miners cohort study are analysed. Materials and methods The cohort includes 58,747 men who were employed for at least 6 months between 1946 and 1989 at the former Wismut uranium company in Eastern Germany. Exposure to radon and its progeny, long-lived radionuclides, external gamma radiation as well as exposure to arsenic and dust was estimated by using a detailed job-exposure matrix. A total of 20.680 deaths were observed in the follow-up period 1960 to the end of 2003. The different causes of death were compared with the age- and calendar-year specific national death rates of Eastern Germany, formerly GDR. Standardized mortality ratios (SMR) with 95% confidence limits (CI) were calculated. To investigate the exposure-response relationship an internal poisson regression using a linear model was applied and the excess relative risk (ERR) per unit of cumulative exposure to radon in Working Level Month (WLM) was calculated. Results For 19.598 (94.3%) of the deceased cohort members causes of death had been available, among them 2.999 lung cancer deaths and 3.341 deaths from cancers other than lung. After adjusting for missing causes of deaths, for all cancers other than lung combined mortality in the cohort was close to that expected from national rates (SMR=1.02, 95% CI: 0.98-1.05). Among 23 individual cancer categories, statistically significant increases in mortality for cancers of the stomach (SMR=1.15, 95% CI: 1.06-1.25) and liver (SMR=1.26 , 95% CI: 1.07-1.45) and statistically significant decreases for cancers of the tongue, mouth and pharynx combined and bladder were observed. A statistically significant relation with cumulative exposure was observed for all non-lung cancers combined (ERR/WLM=0.014%) and stomach cancer (ERR/WLM=0.021%). Conclusion Our findings suggest a weak evidence for a relationship between exposure to radon and mortality from cancers other than lung cancer. Chance, confounding by unconsidered risk factors and bias due to missing causes of deaths cannot be ruled out. If at all, the risk for extrapulmonary tumors associated with radon is appreciably lower than that for lung cancer

SR measurements of the magnetism of Sr3Fe2O7

We present a preliminary report of zero and transverse field ¿SR measurements in a high quality single crystal of fully oxygenated Sr3Fe2O7[1], the insulating 3d magnetic analogue of the well studied Sr3Ru2O7, in its charge-disproportionated state, through the magnetic transition to the incommensurate phase at TN ¿ 115 K. A very broad distribution of static fields below Tn yields a large (2/3) missing fraction. Rapidly damped zero field oscillations indicate a large internal field at the muon, estimated to be 0.46 T at 0 K. In the paramagnetic state, we find two muon precession frequencies at 0.25 T applied field, reminiscent of the Mössbauer spectra

Lung Cancer Risk from Radon among European Uranium Miners Modifying Effects of Time and Age at Exposure

Epidemiological evidence of lung cancer risk from radon is known since the early 1960s, when first studies on uranium miners were published. The risk was modeled in terms of relative risk in dependence on cumulated exposure. Since then, follow-up of studies has been extended, which allowed the analysis of modifying factors such as time since exposure (TSE), age at exposure (AE), attained age, and exposure rate. The present analysis was conducted in the frame of the Alpha-Risk European research program and aimed at estimating the lung cancer risk associated to radon exposure among miners with low levels of exposure and good quality of exposure assessment. The large numbers of miners included in the joint study allow a simultaneous analysis of modifying effects using exposure windows, which are appropriate in studies with protracted exposures. The analysis is based on three European cohort studies of uranium miners: Czech, French and German, including 9979, 5086 and 35084 miners, respectively. By the end of follow-up, 921, 159, and 458 lung cancer deaths were observed in these cohorts, respectively. The excess relative risks per working level month (ERR/WLM) for the three studies were 0.0116 (95%CI 0.0076-0.0157), 0.0061 (95%CI 0.0018-0.0105), and 0.0043 (95%CI 0.0028-0.0057), respectively. The different estimates are caused mainly by the so-called inverse effect of exposure rate and by quality of exposure, which both are correlated with time since exposure. We evaluated simultaneously the effects of TSE in 3 windows (5-19 years before, 20-34, 35+) and of AE in 3 windows (-29 years, 30-39, 40+). The analysis showed a strong decrease of the ERR/WLM with TSE (28% in period 20-34 years and 11% after 35 years in comparison to window 5-19). The simultaneous effect of AE was also significant: ERR/WLM for AE more than 40 years was 53% of that for AE below 30). These results will permit to improve our knowledge on the long-term risks associated to radon exposure. The present work was supported by the European Commission (Contract FI6R 516483)