Abstract
The geographic distribution of different cancer types and epidemiologic studies of migrants suggest that the environment markedly influences the incidence of cancer.1 In most cases specific causal agents are unknown. The agents may be related to aspects of life-style, diet or exposure to naturally occurring or man-made environmental carcinogens, such as pesticides, food contaminants or pollutants. Since we are exposed to numerous chemicals of proved carcinogenicity to animals, it is reasonable to assume that some human cancer results from this exposure. A more direct causal relation between chemicals and human cancer has been established for certain occupationally related cancers and . . .