The experience of living in a chemically contaminated world is presented. The statistical picture of cancer incidence is traced over 28 years from 1950 to 1978, and the rates of specific cancers in different countries are described. The changes in the statistical rates of specific types of cancers in different geographic populations at different time periods are presented. Lung cancer produced by occupational exposure to such chemicals as nickel (7440020), acrylnitrile (107131), arsenic (7440382), asbestos (1332214), talc (14807966), radium (7440144), and hematite mining, and bladder cancer produced by mining, and exposure to benzidine (92875), naphthylamine (134327), and aniline (62533) dye are described. The procedures used to establish these associations are reviewed. The importance of the latency period between exposure and appearance of cancers is illustrated by results from studies on large populations of smokers, and on asbestos and vinyl-chloride (75014) workers and their families. The problems associated with extrapolating from higher to lower dose and from animals to humans are presented and the disagreement on scientific interpretation, the significance of benign tumors, the importance of mutagenicity in in-vitro studies, and the significance of initiation, promotion, and enzyme induction during carcinogenesis are discussed.