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 (o55 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.

An increased risk of cardiovascular diseases after exposure to low doses of ionizing radiation has been suggested among the atomic bomb survivors. Few and inconclusive results on this issue are available from miner studies. A positive correlation between coronary heart disease mortality and radon exposure has been reported in the Newfoundland fluorspar miners study, yet low statistical power due to small sample size was of concern. To get further insight into this controversial issue, data from the German uranium miners cohort study were used, which is by far the largest miner study up to date. The cohort includes 59,001 male subjects who were employed for at least six months between 1946 and 1989 at the former Wismut uranium company in Eastern Germany. Exposure to radon, long-lived radionuclides and external gamma radiation was estimated by using a detailed job-exposure matrix. About 16,598 cohort members were deceased until 31 December 1998, including 5,417 deaths from cardiovascular diseases. Linear Poisson regression models were used to estimate the excess relative risk (ERR) per unit of cumulative radiation exposure after adjusting for attained age and calendar period. No trend in risk of circulatory diseases with increasing cumulative exposure to either radon [ERR per 100 working level month: 0.0006; 95% confidence limit (CI): -0.004 to 0.006], external gamma radiation (ERR per Sv: -0.26, 95% CI: -0.6 to 0.05) or long-lived radionuclides (ERR per 100 kBqh/m3: -0.2, 95% CI: -0.5 to 0.06), respectively, was observed. This was also true for the sub-group heart disease and stroke. Our findings do not support an association between cardiovascular disease mortality and exposure to radiation among miners, yet low doses and uncontrolled confounding hamper interpretation.

A new analysis of lung cancer mortality in a cohort of male Mayak workers who started their employment in the plutonium and reprocessing plants between 1948 and 1958 has been carried out in terms of a relative risk model. The follow-up has been extended until 1999, moreover a new dosimetry system (DOSES2000) has been established. Particular emphasis has been given to a discrimination of the effects of external gamma-exposure and internal alpha-exposure due to incorporated plutonium. This study has also utilized and incorporated the information from a cohort of Mayak reactor workers, who were exposed only externally to gamma-rays. The influence of smoking as the main confounding factor for lung cancer has been studied. The baseline lung cancer mortality rate was not taken from national statistics but was derived from the cohort itself. The estimated excess relative risk for the plutonium alpha-rays was 0.23/Sv (95%CI: 0.16-0.31). The resulting risk coefficient for external gamma-ray exposure was very low with a statistically insignificant estimate of 0.058/Sv (95%CI: -0.072-0.20). The inferred relative risk for smokers was 16.5 (95%CI: 12.6-20.5).

Mainly between 1945 and 1955, several thousand German patients with ankylosing spondylitis, tuberculosis, or--in a few cases--other diseases received multiple injections of the short-lived alpha-particle emitter radium-224. In the early 1950s, the follow-up of 899 patients was initiated, and the study has continued since then. It includes most of the high-dose patients and nearly all of those treated as children or juveniles, i.e. under the age of 21. In the study cohort, 56 malignant bone tumors occurred in a temporal wave that peaked 8 years after exposure, whereas less than one case would have been expected during the follow-up. Most of the malignant bone tumors were osteosarcomas and fibrous-histiocytic sarcomas. A new analysis has now been performed, primarily because an improved dosimetry resulted in modified bone surface doses, especially for those treated at younger ages. A significant increase in bone tumor risk with decreasing age at exposure is now demonstrated. The earlier finding of an inverse protraction factor is confirmed. In the new formulation, the dependence on dose rate or duration applies only at higher doses; i.e., the initial slope of the dose dependence is unrelated to dose rate or exposure duration, which is in contrast to earlier analyses but is in agreement with microdosimetric considerations and general radiobiological experience.

An analysis of lung cancer mortality in a cohort of 1,669 Mayak workers who started their employment in the plutonium and reprocessing plants between 1948 and 1958 has been carried out in terms of a relative risk model. Particular emphasis has been given to a discrimination of the effects of external gamma-ray exposure and internal alpha-particle exposure due to incorporated plutonium. This study has also used the information from a cohort of 2,172 Mayak reactor workers who were exposed only to external gamma rays. The baseline lung cancer mortality rate has not been taken from national statistics but has been derived from the cohort itself. For both alpha particles and gamma rays, the results of the analysis are consistent with linear dose dependences. The estimated excess relative risk per unit organ dose equivalent in the lung due to the plutonium alpha particles at age 60 equals, according to the present study, 0.6/Sv, with a radiation weighting factor of 20 for alpha particles. The 95% confidence range is 0.39/Sv to 1.0/Sv. For the gamma-ray component, the present analysis suggests an excess relative risk for lung cancer mortality at age 60 of 0.20/Sv, with, however, a large 95% confidence range of-0.04/Sv to 0.69/Sv.