The carcinogenic activity of some new derivatives of aromatic hydrocarbons; compounds related to 1,2-benzanthracene.

In 1939 a program of investigation was undertaken in collaboration with Professor Louis F. Fieser and his associates at Harvard University, directed toward a further study of the chemistry of artificial carcinogenesis. The main task was a biological testing for carcinogenicity of a number of new hydrocarbon derivatives synthesized by Dr. Fieser's group. Although the chief purpose of this paper is to present data on the carcinogenic tests of compounds related to 1,2-benzanthracene, some discussion of the problem as a whole is necessary in order to relate this report to those that will be published subsequently. In spite of the enormous amount of work that has been done on synthetic carcinogenic agents, and the testing of well over 700 compounds, it is still impossible to formulate any generalization that defines the features of chemical structure necessary for carcinogenic action. It does appear that substituents in the 9-, 10-, 5-, and 6positions of 1,2-benzanthracene are more likely to render the molecule active than if placed elsewhere in the molecule, and that hydrogenation of the aromatic rings or the substitution of large radicals reduces activity; however, none of these generalizations is definitive. Neither physical characteristics such as atomic weight, melting point, solubility, and surface tension effect nor the known chemical reactivity of the various compounds (15) has yet been successfully correlated with carcinogenic activity. Nevertheless, the striking changes in activity that follow the slightest alteration of structure imply a high degree of chemical specificity in the process of chemical carcinogenesis. This makes it appear