[Risk of senile cataract among nuclear industry workers]. / Risk zabolevaemosti starcheskoĭ kataraktoĭ u rabotnikov predpriiatiia atomnoĭ promyshlennosti.

AIM: to assess the relative risk (RR) of senile cataract in a cohort of workers occupationally exposed to external gamma-rays over a long time period. MATERIAL AND METHODS: The RR of cataract development was studied in a cohort of nuclear workers that were first employed in 1948-1982 and followed up till the end of 2008 (n=22,377; females, 25.4%). The mean age at initial employment was 24.9 years. The mean cumulative gamma-ray dose was 0.54 Sv in males and 0.44 Sv in females. The analysis performed with EPICURE software provided RR estimates for cataract incidence in relation to a number of non-radiation and radiation factors. RESULTS: The RR of senile cataract increased with the attained age of the workers. The RR was significantly higher in males during the 2006-2008 period as compared to the 1996-2005 period. The RR was significantly higher in workers that were diagnosed with glaucoma and high myopia as compared to those that were not. The risk of senile cataract increased with the external gamma-ray dose and was the highest in workers who had formerly been exposed to doses above 2.00 Sv. The RR of senile cataract showed no dependency on sex, age at initial employment, smoking status, alcohol consumption, or diabetes mellitus. CONCLUSION: The incidence of senile cataract in the cohort under study was found to depend on both non-radiation and radiation factors.

Chronic bronchitis incidence in the extended cohort of Mayak workers first employed during 1948-1982.

OBJECTIVES: This paper describes findings from the study of chronic bronchitis (CB) incidence after occupational exposure to ionising radiation among workers employed at Russian Mayak Production Association (PA) during 1948 and 1982 and followed up until 2008 based on 'Mayak Worker Dosimetry System 2008'. METHODS: Analyses were based on 2135 verified cases among 21 417 workers. Rate ratios (RR) were estimated by categorical analysis for non-radiation and radiation factors. Excess rate ratios per Gy (ERR/Gy) of external or internal exposures with adjustments via stratification on other factors were calculated. RESULTS: The interesting finding in relation to non-radiation factors was a sharp increase in the RR for CB incidence before 1960, which could be caused by a number of factors. Analyses restricted to the follow-up after 1960 revealed statistically significant associations of the CB incidence and external γ-ray radiation, ERR/Gy=0.14 (95% CI 0.02 to 0.28) having adjusted for sex, attained age, calendar period, plant, smoking status and lung α-particle dose, and internal α-particle radiation, ERR/Gy=1.14 (95% CI 0.41 to 2.18) having adjusted for sex, attained age, calendar period, plant, smoking status and lung γ-ray dose and ERR/Gy=1.19 (95% CI 0.32 to 2.53) having additionally adjusted for pre-employment occupational hazards and smoking index instead of smoking status. CONCLUSIONS: Analyses of CB incidence in the study cohort identified positive significant association with occupational exposure to radiation: however, there are no similar studies of CB incidence in relation to radiation in other cohorts to date with which a meaningful comparison of the results could be made.

Cerebrovascular diseases incidence and mortality in an extended Mayak Worker Cohort 1948-1982.

Incidence and mortality from cerebrovascular disease (CVD) [International Classification of Diseases 9th revision (ICD-9) codes: 430-438] was studied in a cohort of 22,377 workers first employed at the Mayak Production Association (Mayak PA) in 1948-1982 and followed up to the end of 2008. The cohort size was increased by 19% and follow-up extended by 3 years over the previous analysis. Radiation doses were estimated using an updated dosimetry system: Mayak Worker Dosimetry System 2008 (MWDS-2008). For the first time, in an analysis of this cohort, quantitative smoking data were used. Workers of the study cohort were exposed occupationally to prolonged external gamma rays and internal alpha particles. The mean (±standard deviation) total dose from external gamma rays was 0.54 ± 0.76 Gy (95% percentile 2.21 Gy) for males and 0.44 ± 0.65 Gy (95% percentile 1.87 Gy) for females. The mean plutonium body burden in the 31% of workers monitored for internal exposure was 1.32 ± 4.87 kBq (95% percentile 4.71 kBq) for males and 2.21 ± 13.24 kBq (95% percentile 4.56 kBq) for females. The mean total absorbed alpha-particles dose to the liver from incorporated plutonium was 0.23 ± 0.77 Gy (95% percentile 0.89 Gy) in males and 0.44 ± 2.11 Gy (95% percentile 1.25 Gy) in females. After adjusting for nonradiation factors (gender, age, calendar period, employment period, facility, smoking, alcohol consumption), there were significantly increasing trends in CVD incidence associated with total absorbed dose from external gamma rays and total absorbed dose to the liver from internal alpha-particle radiation exposure. Excess relative risks per Gy (ERR/Gy) were 0.46 (95% CI 0.37, 0.57) and 0.28 (95% CI 0.16, 0.42), respectively, based on a linear dose-response model. Adjustments for additional factors (hypertension, body mass index, duration of employment, smoking index and total absorbed dose to the liver from internal exposure during the analysis of external exposure and vice versa) had little effect on the results. The categorical analyses showed that CVD incidence was significantly higher among workers with total absorbed external gamma-ray doses greater than 0.1 Gy compared to those exposed to lower doses and that CVD incidence was also significantly higher among workers with total absorbed internal alpha-particle doses to the liver from incorporated plutonium greater than 0.01 Gy compared to those exposed to lower doses. The results of the categorical analyses of CVD incidence were in good agreement with a linear dose response for external gamma-ray doses but for internal alpha-particle doses the picture was less clear. For the first time an excess risk of CVD mortality was seen in workers whose livers were exposed to internal alpha-particle doses greater than 0.1 Gy compared to those workers who were exposed to doses of less than 0.01 Gy. A significant increasing trend for CVD mortality with internal alpha-particle dose was revealed in the subcohort of workers exposed at doses <1.0 Gy after having adjusted for nonradiation factors, ERR/Gy = 0.84 (95% CI, 0.09, 1.92). These updated results provide good evidence for a linear trend in risk of CVD incidence with external gamma-ray dose. The trend for CVD incidence with internal alpha-particle dose is less clear due to the impact of issues concerning the use of dose estimates based on below the limit of detection bioassay measurements.

[Cerebrovascular disease incidence in workers occupationally exposed to radiation over prolonged time periods].

OBJECTIVE: To estimate incidence rates for cerebrovascular diseases (CVD) in a cohort of workers occupationally exposed to radiation over prolonged time periods. MATERIAL AND METHODS: CVD incidence was estimated in a cohort of 22.377 workers of the nuclear facility "Mayak" Production Association over the follow-up period 1948-2008. Non standardized and standardized incidence rates were estimated. An indirect method of standardization was used for the estimates. RESULTS: As of 31/12/2008, 8.717 CVD cases (5.802 men and 2.915 women) were registered in the study cohort of workers. CVD incidence in the cohort was significantly associated with sex, age, smoking, alcohol consumption (in men) and arterial hypertension. CVD incidence was increased in workers exposed to external gamma-rays at total dose above 0.5 Gy and/or to internal alpha-radiation due to incorporated plutonium at total absorbed liver dose above 0.025 Gy. CONCLUSION: CVD incidence in the cohort of workers occupationally exposed to radiation over prolonged time periods was associated both with non-radiation and radiation factors.

[Prevalence of aortal atherosclerosis in workers underwent occupational irradiation].

The authors evaluated prevalence of aortal atherosclerosis in dependence on radiation and non-radiation factors in workers underwent occupational prolonged irradiation.The study included 22,377 workers of nuclear industry enterprise "Mayak", with verified diagnosis of aortal atherosclerosis. Up to 31th December 2008, a total of 1,840 aortal atherosclerosis cases were registered in the examinees group. Aortal atherosclerosis prevalence appeared to depend reliably on sex, age, smoking habit (in males), alcohol consumption (in males) and arterial hypertension. Findings are that aortal atherosclerosis prevalence was higher in males and females underwent external gamma-irradiation of total dose over 0.5 Gy, in males and females underwent internal alpha-irradiation from incorporated plutonium of total absorbed radiation dose in liver over 0.025 Gy. Thus, aortal atherosclerosis prevalence in workers underwent occupational irradiation de- pended both on radiational and non-radiational factors.

Chronic bronchitis in the cohort of Mayak workers first employed 1948-1958.

Incidence of chronic bronchitis has been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948-1958 and followed up to 31 December 2005. Information on external gamma doses is available for virtually all of these workers; in contrast, plutonium body burden was measured only for 30% of workers. During the follow-up period in the study cohort 1,175 incident cases of chronic bronchitis were verified. The analyses of nonradiation factors revealed that the underlying risk of chronic bronchitis incidence increased with increasing attained age and was higher among smokers compared with never-smokers as would be expected. The most interesting finding in relationship to nonradiation factors was a sharp increase in the baseline chronic bronchitis risk before 1960. The cause of this is not clear but a number of factors may play a role. Based on the follow-up data after 1960, the analysis showed a statistically significant linear dose response relationship with cumulative external gamma-ray dose (ERR/Gy = 0.14, 95% CI 0.01, 0.32). Based on the same subset but with an additional restriction to members with cumulative internal lung dose below 1 Gy, a statistically significant linear dose response relationship with internal alpha-radiation lung dose from incorporated plutonium was found (ERR/Gy = 2.70, 95% CI 1.20, 4.87). In both cases, adjustment was made for nonradiation factors, including smoking and either internal or external dose as appropriate. At present there are no similar incidence studies with which to compare results. However, the most recent data from the atomic bomb survivor cohort (the Life Span Study) showed statistically significant excess mortality risk for respiratory diseases of 22% per Gy and this value is within the confidence bounds of the point estimate of the risk from this study in relation to external dose.