Lack of dose-rate effect for mutation induction by gamma-rays in human TK6 cells.

Survival and mutation induction in a human lymphoblastoid cell line ('TK6'), after acute X- and low dose rate continuous gamma-irradiation, were investigated using the hypoxanthine guanine phosphoribosyl transferase (HGPRT)- and the thymidine kinase (TK)-mutation assay. The surviving fraction after acute exposure decreased exponentially (D0 = 0.47 Gy). The HGPRT- and TK-mutation frequencies after acute X- and continuous gamma-irradiation (2.7 and 27 mGy/h) showed linear responses and no dose-rate dependence.