The Occupational Safety and Health Act of 1970 (Public Law 91-595) is outlined and explained. Its provisions for standards, research, education and training are detailed. One of the functions of the Act is to monitor all hazardous substances and physical agencies responsible for and resulting in occupational hazards. The Health Hazard Evaluation (HHE) Program of the National Institute for Occupational Safety and Health (NIOSH) responds to inquiries from both employees and employers. NIOSH also conducts industrial hygiene surveys and epidemiological studies of specific worker groups in specific industries. It is estimated that about 1% of the current American labor force is exposed to carcinogens monitored by the Department of Labor (DOL), while about 25% of the workers may be exposed to hazardous materials regulated by DOL. Major programs in research on the effects of this exposure in mining, construction, and agriculture as well as for more traditional industry, have been developed.