Evaluation of the radiation exposures of chernobyl "liquidators": Exploratory studies of a sample of immigrants to Israel

Workers who were involved in the clean-up and recovery operation after the Chernobyl disaster ("liquidators") numbered about 800,000. Estimates of their exposures are highly relevant to evaluation of possible effects on their health. While some exposure measurements were made, they were also used for job assignments and terminations. The earliest and probably greatest exposure preceded adequate monitoring. By means of exploratory studies, the authors evaluated an exposure-estimating system proposed by a WHO consultation team in St. Petersburg. An index is derived based on recorded or reported 1) calendar time of initiating work, 2) location near or distant from the reactor, 3) duration of exposure, 4) type of work, 5) post-exposure symptoms, 6) blood count decreases, and 7) use of protective equipment. Data were obtained by interviews of liquidators who presented at a Beer Sheva clinic during evaluation of Cs-137 body burden. Of 75 liquidators, four had no data, one had only one item, six had two, 11 had three, 210 had four, 20 had five, 11 had six, and one had seven items. Only 19 had dose estimates. There was no trend in mean scores/item with increase in the number of items, indicating lack of information bias. Measured values, when available, were consistent with the scores. Clastogenic scores were determined for 26 of these subjects; the correlation with exposure indexes was 0.02, but for those with "positive" clastogenic tests (more than six abnormal divisions per 100), the correlation with the scores was 0.44. No such relationship was found for the persons with elevated Cs-137 tests. Glycophorin A antigen tests discriminated between liquidators and others, but, in this small study, did not correlate with the indexes.