CYTOGENETIC EFFECTS OF TRITIUM INCORPORATED INTO DNA OF HUMAN-LYMPHOCYTES

The number of chromosomal and chromatid breaks, deletions, as well as fragments, have been followed in correlation to the physical dose as a ssessed by the specific radioactivity of DNA. Human lymphocytes from a dult donors were incubated for 44 hours in media supplemented with tri tiated thymidine. An uneven distribution of labelling in the cell popu lation has been found and about 50% of the population of cells remaine d unlabelled. The dose-response curve was flat reflecting loss of dama ged cells and/or repair of damage, The dose-response curve showed that at the experimental conditions used the dose of 100 mGy absorbed from incorporated tritium caused about 0.1 deletions per cell. Doubling th e number of deletions to about 0.2 per cell required approximately a f ive times higher absorbed dose.