Estimation of Non-Cancer Stochastic Effects of Prolonged Occupational Exposure in Low Dose Range

摘要

This study is aimed at estimation of acute myocardial infarction (AMI) incidence and riskamong persons exposed to prolonged low dose rate ionizing radiation. Prevalence and socialand medical relevance, and available data on the increased cardio-vascular diseases mortalityamong nuclear workers determined the chosen clinical model (Howe G.R.,et. Al., 2004).A study was carried out into AMI incidence in closed population of Seversk in 1998-2004,the study was supported by the Federal Agency for Science and Innovations (grant MK-4931.2007.7). Siberian Group of Chemical Enterprises (SGCE) is a town-forming enterprise.Because of this the whole population was divided into residents and SGCE workers, of whomgreat majority was exposed to long term ionizing radiation in low doses (total cumulativeexternal dose was up to 1 Sv).In the study period, increased incidence was found in both groups (from 5.12 up to 7.11 per1 000 workers, and from 1.86 up to 2.44 per 1 000 residents). Cross-group analysis (SGCEworkers – residents) revealed that general AMI incidence in SGCE employees wassignificantly greater (χ2 = 64.44-89.05-86.22-65.17-39.78-114.89-96.14; р < 0.001) than thatin residents (1.86-1.90-1.96-2.28-2.52-2.15-2.44 per 1 000 persons in 1998-2004 respectively)during the whole study period.SGCE workers are subdivided into groups of main production, exposed to ionizingradiation sources, and auxiliary production, who do not receive any exposure.In the main production group, AMI incidence at the study period was significantly greaterthan that in the auxiliary production and was 6.39-7.51-7.55-7.74-6.05-9.88-10.40 and 3.96-4.45-4.52-4.23-4.72-4.73-4.20 (χ2 = 3.54-3.97-3.27-4.59-0.59-18.19-17.58; р = 0.0601-0.0462-0.0706-0.0322-0.4443-0.0000-0.0000 in 1998-2004 respectively).Analysis of standardized relative risk coefficients of developing AMI demonstrated theirsignificant increase in the main group production (auxiliary production incidence was taken asthe standard): 1.5 in 1999 (CI 95% 1.15-2.79), 1.8 in 2000 (CI 95% 1.07-2.47), 2.0 in 2001(CI 95% 1.31-2.99), 2.1 in 2003 (CI 95% 1.42-3.11), 1.9 in 2004 (CI 95% 1.27-2.89).At present, there is data indicating close relationship between AMI development and doseaccumulation rate; however, because of irradiation dose homogeneity of the study groups(great majority of AMI patients had doses up to 200 mSv) and limited number of cases in thesample, it was not possible to establish association between AMI development and irradiationdose.