GAMMA-RAY MUTAGENESIS MEASUREMENT IN MAMMALIAN-CELLS

Application of conventional in vitro mutagenesis testing has so far fa iled to result in marked reduction of the total incidence of cancer. A t least part of the reason may lie in the frequent use of a cell targe t too small to yield adequate sensitivity, and in failure to take into account the effects of cell killing in the assessment of mutagenic ac tion. A single theoretical analysis fits the results of experimental d ata on gamma-irradiation applied to single marker gene testing in bact eria and to cytogenetic analysis of irradiated mammalian cells, and pe rmits determination of the mean mutagenic dose, D-M(o), without compli cation due to cell killing. Cytogenetic monitoring of human lymphocyte s which can detect mutagenic effects of gamma-radiation down to doses of < 0.1 Gy (10 rad) will also furnish an estimate of repair effective ness at these low levels and may well be a useful tool in a program fo r prevention of cancer and other genetic disease.