The Risk of Radiation-Induced Cerebrovascular Disease in Chernobyl Emergency Workers

Abstract

The paper deals with estimating radiation risks of non-cancer diseases of the circulatory system among the Chernobyl emergency workers based on data from the Russian National Medical and Dosimetric Registry. The results for the cohort of 61,017 people observed between 1986 and 2000 are discussed. These are essentially updated results for the similar cohort that was studied by authors earlier in 1986-1996. Newly discovered is the statistically significant dose risk of ischemic heart disease [ERR Gy = 0.41, 95% CI = (0.05; 0.78)]. Confirmation is provided for the existence of significant dose risks for essential hypertension [ERR Gy = 0.36, 95% CI = (0.005; 0.71)] and cerebrovascular diseases [ERR Gy = 0.45, 95% CI = (0.11; 0.80)]. In 1996-2000, the assessed ERR Gy for cerebrovascular diseases was 0.22 with 95% CI = (-0.15; 0.58). Special consideration is given to cerebrovascular diseases in the cohort of 29,003 emergency workers who arrived in the Chernobyl zone during the first year after the accident. The statistically significant heterogeneity of the dose risk of cerebrovascular diseases is shown as a function of the duration of stay in the Chernobyl zone: ERR Gy = 0.89 for durations of less than 6 wk, and ERR Gy = 0.39 on average. The at-risk group with respect to cerebrovascular diseases are those who received external radiation doses greater than 150 mGy in less than 6 wk [RR = 1.18, 95% CI = (1.00; 1.40)]. For doses above 150 mGy, the statistically significant risk of cerebrovascular diseases as a function of averaged dose rate (mean daily dose) was observed: ERR per 100 mGy d = 2.17 with 95% CI = (0.64; 3.69). The duration of stay within the Chernobyl zone itself, regardless of the dose factor, had little influence on cerebrovascular disease morbidity: ERR wk = -0.002, with 95% CI = (-0.004; -0.001). The radiation risks in this large-scale cohort study were not adjusted for recognized risk factors such as excessive weight, hypercholesterolemia, smoking, alcohol consumption, and others.

Mortality from circulatory system diseases and low-level radon exposure in the French cohort study of uranium miners, 1946–1999

“…Of 26 identified studies, only one -concerning US radio logy technologists -provided appreciable evidence of an association between cumulative radiation exposure and CSD (8). Other evidence that low doses of external ionizing radiation are associated with an increased risk of CSD has come from a cohort of international nuclear workers (9) and a recent study of Chernobyl clean-up workers (10). These results have not, however, shown a consistent pattern of increased mortality from CSD.…”

“…In this analysis, we used subgroups of CSD similar to those of other studies [ie, IHD and CeVD (8,10,30,32,33)]. It has been recently suggested that IHD might be a particularly sensitive endpoint for radiation exposure to the heart arteries (37).…”

“…In the French cohort, the IHD subgroup represented almost 40% of the CSD deaths (ie, 125 dead miners). Several studies have shown an increased risk of CeVD associated with external ionizing radiation (6,10). In the French cohort, this subgroup accounted for 80 dead miners.…”

Mortality from Circulatory System Diseases among French Uranium Miners: A Nested Case-Control Study

“…Associations between circulatory disease and external radiation exposure have also been found in other cohorts, most notably among Chernobyl clean-up workers (38) and residents living near the Techa River (39) who were exposed to radioactive discharges from the Mayak plant. In the Chernobyl clean-up worker cohort (mean dose 0.109 Sv), significant associations of a similar magnitude to those observed in this study were noted for circulatory disease outcomes, including IHD and cerebrovascular diseases, although dose estimates in that study are very uncertain.…”

Persistent infections and their relationship with selected oncologic and non-tumor pathologies

“…Multiple studies of the effects of the 1986 Chernobyl nuclear power plant (NPP) accident paid close attention to the potential problem of increases in oncological diseases, i.e., thyroid tumors first of all, and of non-tumor pathologies of the cardiovascular, bronchopulmonary, digestive, and urogenital systems in exposed cleanup workers and non-NPP individuals living in the vicinity of the plant (Ivanov et al, 2000(Ivanov et al, , 2006Balonov, 2007;Sumner, 2007;Romanenko et al, 2008). As a dose-effect ratio was not strictly evident in many of the documented cases, our own investigations focused on the potential for non-radiation-based components, i.e., a presence of persisting infections, to contribute to the onset/progression of any observed changes in incidence of the various pathologies (Chumak et al, 2000(Chumak et al, , 2003(Chumak et al, , 2005.…”