UNSTABLE AND STABLE CHROMOSOMAL-ABERRATIONS IN LYMPHOCYTES OF PEOPLE EXPOSED TO CHERNOBYL FALLOUT IN BRYANSK, RUSSIA

Analyses of unstable and stable chromosomal aberrations in peripheral blood lymphocytes were used in the assessment of radiation exposure of residents of a village situated in the Chernobyl fallout-contaminatio n zone of Bryansk, Russia. Blood samples were taken from subjects resi ding in villages with high (>1100 kBq/m(2) Cs-137; Mirnyi) and very lo w (<37 kBq/m(2) Cs-137; Krasnyi Rog) contamination, 7 years after the Chernobyl accident. The groups were matched by age, sex, smoking habit s and previous medical radiological exposures. A total of 200 people ( 100 exposed, 100 controls) were analysed for the presence of unstable aberrations from Giemsa-stained slides. To study stable aberrations, c hromosome painting analyses were performed on 100 subjects (50 exposed , 50 controls), using painting probes for chromosomes 1, 2 and 4 and a pancentromeric probe. People living in the contaminated area showed s ignificantly higher rates of unstable chromosome-type aberrations but not chromatid-type aberrations in their lymphocytes, indicating radiat ion exposure as a causative factor for the observed difference. No sig nificant differences were found in the aberration rates between the tw o areas by the chromosome painting method. The levels of chromosome ex changes were low in both populations, but consistently higher in Mirny i compared with the control area. The magnitude of radiation exposure resulting from Chernobyl fallout was estimated on the basis of excess stable chromosomal aberrations in the lymphocytes of the Mirnyi popula tion compared with the controls.