Mortality Among the Chernobyl Emergency Workers: Estimation of Radiation Risks (Preliminary Analysis)

Abstract

This paper presents results of the analysis of mortality among Chernobyl accident emergency workers who are resident in Russia. The analysis is based on information for the cohort of emergency workers (males) from six regions of Russia including 65,905 persons with documented external doses in the range 0.005-03 Sv. These data were gathered during the period 1991 to 1998 and cover a total of 426,304 follow-up person-y. In this period, 4,995 deaths occurred in the cohort under study. The mortality analysis was performed for four groups of causes of death (ICD-9 codes): (1) malignant neoplasms (140-239); (2) cardiovascular diseases (390-459); (3) injuries, poisoning and violent deaths, (800-999); and (4) the remainder (other than the above). The standardized mortality rate for groups 1, 3, and 4 is less than unity and varies from 0.6 to 0.9. For group 2 (death from cardiovascular diseases) the standardized mortality rate conforms with the control within 95% confidence intervals. The control was the mortality rate (males) for the corresponding ages in Russia in general and the internal control, the spontaneous mortality among emergency workers, derived from the equation of the observed and expected number of cases in the followed up cohort. Dose response of mortality was studied. Statistically significant radiation risks were obtained for mortality from malignant neoplasms (515 cases) and cardiovascular diseases (1,728 cases). The values of the excess relative risk per unit dose (ERR Sv(-1)) for malignant neoplasms and cardiovascular diseases are estimated as 2.11 (1.31, 2.92 95% CI) and 0.54 (0.18,0.91 95% CI) (for external control), 2.04 (0.45, 4.31 95% CI) and 0.79 (0.07, 1.64 95% CI) (for internal control), respectively. The risk of death from all noncancer causes is close to zero and not statistically significant.

Do Low Doses of Ionizing Radiation Affect the Human Brain?

“…Among Russian liquidators, statistically significant radiation risks were obtained for mortality from malignant neoplasms and cardiovascular diseases, while the risk of death from all non-cancer causes is close to zero and not statistically significant (Ivanov, Gorski, Maksioutov, Tsyb, & Souchkevitch, 2001 at-risk group with respect to cerebrovascular diseases are those who received external radiation doses greater than 150 mGy in less than 6 weeks (RR -1.18 (1.00; 1.40)). However, radiation risks were not adjusted for recognized risk factors such as excessive weight, hypercholesterolemia, smoking, alcohol consumption, and others (Ivanov, Maksioutov, Chekin, Petrov, Biryukov, Kruglova, et al, 2006).…”

The cancer epidemiology of radiation

“…An increasingly important source of information on occupational exposure is workers in the former USSR. Many of the approximately half a million workers involved in recovery operations after the Chernobyl accident in 1986 received doses of 100-200 mSv and studies of these workers may be capable of detecting increased risks if the numbers included are sufficiently large (Ivanov et al, 2001;Kesminiene et al, 2002). However, length of follow-up is currently limited, so interest should be focused on leukaemia with its shorter minimum latency.…”

Biological Effectiveness of Ionizing Radiation: Acute vs. Protracted Exposures

“…In the author's opinion, the dose-effect relationships with non-neoplastic diseases [30][31][32][33][34] call in question such relationships with cancer, reported e.g. in the studies [23,24,[35][36][37][38][39][40][41][42][43] including those cited in [2,25] in support of the DDREF lowering. Although there may be some risk of cardiovascular disease at high dose and dose-rate exposures [16], existing data are insufficient to confirm a cause-effect relationship between radiation and cardiovascular diseases at doses below 1-2 Gy, while plausible biological mechanisms are unknown [44].…”