We have measured the sebaceous gland suppression index of 103 compounds. Thirteen of these had an index of 1,000 or more, while 74 had no measurable activity. High levels of sebaceous gland-suppressor activity were clearly associated with the benz[a]anthracene structure. Within this class of compounds the suppression index was roughly parallel to mouse skin carcinogenic potency.
Sebaceous gland suppression was neither necessary nor sufficient as a criterion of skin carcinogenic activity. Thus, the potent carcinogen 7,9-dimethylbenz[c]acridine had very weak suppressor activity, while colchicine was moderately active though not a skin carcinogen.
Subject to these limitations, sebaceous gland tests can be of great value for the study of carcinogenesis. They can be employed to suggest the presence or absence of benz[a]anthracene-type carcinogens and to measure efficiency of their isolation. To a lesser extent, the tests are helpful in identification of partially purified hydrocarbons. Uses of the test to study the mechanism of skin carcinogenesis were also pointed out.
6-Methylbenzo[a]pyrene was demonstrated to be a very active skin carcinogen.
This investigation was supported in part by a research grant from the Tobacco Industry Research Committee.