Frequency of sister chromatid exchanges in human lymphocytes cultivated with a human hepatoma cell line as an indicator of the carcinogenic potency of two cyclopenta[a]phenanthrenes.

We demonstrate here that the carcinogen 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one can cause sister chromatid exchange in human lymphocytes as well as it can cause mutation in bacterial cells and in V79 hamster cells. The non-methylated parent compound which has no tumorigenic action and yet significantly mutates both Salmonella typhimurium TA 100 and hamster V79 cells, has no effect on the frequency of sister chromatid exchange. These results support the idea that sister chromatid exchanges are a valuable additional indicator of tumorigenic potential.