Benz(a)anthracene, 7,12-dimethylbenz(a)anthracene, dibenz(a)anthracene and benzo(a)pyrene and their related "K region" epoxides were tested for carcinogenic activities using a system in which mouse lung tissue was incubated in the presence of the test compound for 30 min and then implanted into isologous mice. Only 7,12-dimethylbenz(a)anthracene showed any marked carcinogenic activity under the conditions used, but all the compounds tested produced extensive proliferative outgrowths in the implanted tissues that may represent specific responses to the carcinogens
