Vinyl chloride and bischloromethyl ether are examples of associations between single agents and rare histologic types of cancer. It is more difficult to conduct epidemiologic studies to identify cancer risks associated with complex mixtures. Studies of diesel exhaust and lung cancer and metal machining oils are cited as having employed advanced industrial hygiene and epidemiologic methods for studies of complex mixtures. Elevated cancer risks have also been identified in broad occupational groups, including painters and dry cleaners. Epidemiologic case-control studies are often used to detect such associations but are limited in their abilities to detect the causal agents.
Major gaps exist in knowledge of occupational cancer risks among women workers and workers of color.
Because epidemiologic research measures illness and mortality that have already occurred, a positive study can be interpreted to represent a failure in prevention. This article was presented at the President's Cancer Panel Conference on Avoidable Causes of Cancer held 7-8 April 1994 in Bethesda, Maryland.