Elevated frequencies of hypoxanthine phosphoribosyltransferase lymphocyte mutants are detected in Russian liquidators 6 to 10 years after exposure toradiation from the Chernobyl nuclear power plant accident

This study was conducted to determine whether the frequency of hypoxanthine phosphoribosyltransferase (HPRT) deficient lymphocyte mutants would detect an effect of radiation exposure in a population of Russians who were expos ed to low levels of radiation while working in 1986 and 1987 as liquidators cleaning up after the Chemobyl nuclear power reactor accident. The HPRT ly mphocyte cloning assay was performed on peripheral blood lymphocytes collec ted between 1992 and 1996 from 142 liquidators and 66 Russian controls, and between 1989 and 1993 from 231 American controls. Russian and American con trols were not significantly different for either cloning efficiency or mut ant frequency (MF); inclusion of both sets of controls in the analysis incr eased the ability to detect a Chernobyl exposure effect in the liquidators. After adjusting for age and smoking, the results revealed no significant d ifference in cloning efficiency of Chernobyl liquidators relative to Russia n controls but a significant, 24% increase in liquidator HPRT mutant freque ncy over Russian controls (90% confidence interval was 7% to 45% increase). The analytical method also accounted for differences in precision of the i ndividual estimates of log CE and log MF and accommodated for outliers. The increase in HPRT mutant frequency of liquidators is an attribute of the ex posed population as a whole rather than of individuals. These results demon strate that, under appropriate circumstances, the HPRT specific locus mutat ion assay of peripheral blood lymphocytes can be used to detect a semi-acut e, low dose radiation exposure of a population, even 6 to 10 years after th e exposure. (C) 1999 Elsevier Science B.V. All rights reserved.