This testimony considered research efforts designed to determine whether illness and injury are job related. Since 1970 when the Occupational Safety and Health Act was passed, awareness has increased that chemical and physical agents play a role in the etiology of disease. A survey conducted in 1972 to 1974 indicated that one in four American workers was potentially exposed either full or part time to hazardous substances regulated by OSHA. Often illnesses were improperly diagnosed, resulting in difficulties of accurately determining the magnitude of the problem. Most of the past research has centered on the effect of exposure to one agent at a time, but most occupational exposures were to multiple agents, simultaneously. A suggested approach to developing occupational disease standards involved the determination of whether the worker have symptoms which were compatible with the effects of occupational exposure and whether the workers had received sufficient exposure to cause the disease. Specific efforts which have been directed toward the specific substances and advancements which have thus been made were detailed for asbestos (1332214), cotton dust exposure, toluene- diisocyanate (584849), and dibromochloropropane (96128). Brief mention was made of a respiratory disease report, criteria for diagnosing occupational disease, and strategies for prevention.