CHROMOSOMAL-ABERRATIONS IN LYMPHOCYTES OF RESIDENTS OF AREAS CONTAMINATED BY RADIOACTIVE DISCHARGES FROM THE CHERNOBYL ACCIDENT

Approximately 5 years after the Chernobyl accident blood samples were collected and analysed for unstable chromosomal aberrations in lymphoc ytes from persons who have lived continuously in contaminated areas of Belarus and Russia. including controls, 1855 persons were studied. Th e majority of subjects comprised 10 cohorts of children including one control group and one group who were initially exposed at a high dose rate prior to their evacuation to a lightly contaminated area. One con trol and two exposed cohorts of adults were also examined. The mean yi elds of chromosomal aberrations in the exposed subjects were generally above those of the controls, although statistical significance was ob served in only the evacuee children and in children and adults permane ntly resident in one community where the average environmental contami nation with Cs-137 was approximately 1000 kBq.m(-2). The average dose in excess of background to subjects in this community, received over 5 years, was tentatively estimated from the chromosomal damage and the radionuclide contamination to be approximately 100 mGy. One cohort of children was especially selected to include a number of subjects who h ave received in utero exposure. There was no significant difference fo und in the level of induced aberrations in these children's lymphocyte s compared with those exposed only post-natally.