4-N-Pyrrolidinylazobenzene (4N) is a close structural analog of the rodent liver carcinogen 4-dimethylaminoazobenzene (DAB). This structural similarity led us to evaluate it for genotoxic activity in vitro. We observed activity for 4N and DAB in the BHK cell transformation assay and subsequently in the Salmonella mutation assay of Ames. By a curious chance, Scribner, Miller and Miller, probably...

I. T H E N A T U R E AND SCOPE OF E N V I R O N M E N T A L CANCER HAZARDS Almost ~00 years have passed since the first environmental carcinogen, coal soot, was recognized as the cause of cancer of the human skin. The environmental carcinogenic spectrum composed of accepted, suspected, and potentially carcinogenic agents present in the natural and artificial human environment has grown consider...

ln 1969, the International Agency for Research on Cancer (IARC) initiated a programme to evaluate the carcinogenic risk of chemicals to humans and to produce monographs on individual chemicals. The Monographs programme has since been expanded to include consideration of exposures to complex mixtures of chemicals (which occur, for example, in some occupations and as a result of human habits) and...

I would like to consider the problem of chemical carcinogenesis arising from exposure to certain aromatic amines as a basis for my remarks about the predictive value for man of data obtained in other species and biological systems. This example was chosen because it illustrates the complexity of extrapolation very well, and there is new knowledge derived from a variety of disciplines including ...

An alternative in vitro approach to drug screening has been the use of human cell cultures for antiviral agents and microbial cell cultures for the assessment of the carcinogenic potential of selected compounds. A number of protozoan species have been also used as drug screens for anti-protozoal agents. The ciliated protozoan Tetrahymena pyriformis species has been widely utilised as a dru...

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 ...