Genetics of somatic mammalian cells XII: Mutagenesis by carcinogenic nitroso compounds

Four known carcinogenic compounds, all of which contain the nitroso group, have been found to be effective in producing cell killing, chromatid breaks, mutagenesis and chromatid rearrangements in Chinese hamster ovary cells. Single cell survival curves revealed these agents to exhibit a 50,000‐fold difference in their mean lethal dose (D o ) values. However, all agents yielded constant values for their efficiencies of production of chromatid breaks and single gene mutagenesis, but not chromatid rearrangements, when these were expressed in terms of the D o value of each agent. Three of the carcinogens produced single‐hit and one produced a multiple‐hit survival curve. The system offers distinct advantages in study of the interrelationships between mutagenic and carcinogenic actions in mammalian cells.