Occupational chemical carcinogenesis: new facts, priorities and perspectives.

There is need for a new active approach to the problem of occupational carcinogenesis. It is no longer acceptable to adopt a "wait and see" attitude since: 1. evidence suggests that cancer is an "ecological" disease; 2. The carcinogenic risk has been increasing as industrialisation increased; 3. Factory workers are the most exposed population and hazards spread from the work-place to the general population as consumer goods and pollution. It is necessary and possible, to identify potential carcinogens before workers and the general population are exposed. That predictive experiments could be done, is exemplified by the history of stilboestrol, bis (chloromethyl) ether, vinyl chloride and chromium pigments, all of which were reported carcinogenic in animal tests before any epidemiological results were available. Unforturnately, these results were received with scepticism because the test methods were thought to be inadequate. It is necessary to develop the future policy of prevention by: 1. establishing a priority for testing compounds already produced and widespread in occurence and those about to be produced on a large scale; 2. establishing experimental models for determining carcinogenic risk, especially rapid screening tests; 3. study of the more important compounds by long-term bioassays. Full details are given of the testing of vinyl chloride monamer and preliminary results are tabulated for tests on styrene, acrylonitrile and vinylidene chloride.