illness incurred because of the conditions or environment of employment. Unlike with accidents, some time usually elapses between exposure to the cause and development of symptoms. In some instances, symptoms may not become evident for 20 years or more.
Among the environmental causes of occupational disease are subjection to extremes of temperature (leading to heatstroke or frostbite), unusual dampness (causing diseases of the respiratory tract, skin, or muscles and joints) or changes in atmospheric pressure (causing decompression sickness, or the bends), excessive noise (see noise pollution), and exposure to infrared or ultraviolet radiation or to radioactive substances. The widespread use of X rays, radium, and materials essential to the production of nuclear power has led to an especial awareness of the dangers of radiation sickness; careful checking of equipment and the proper protection of all personnel are now mandatory.
In addition there are hundreds of industries in which metal dusts, chemical substances, and unusual exposure to infective substances constitute occupational hazards. The most common of the dust- and fiber-inspired disorders are the lung diseases caused by silica, beryllium, bauxite, and iron ore to which miners, granite workers, and many others are exposed (see pneumoconiosis) and those caused by asbestos.
Fumes, smoke, and toxic liquids from a great number of chemicals are other occupational dangers. Carbon monoxide, carbon tetrachloride, chlorine, creosote, cyanides, dinitrobenzene, mercury, lead, phosphorus, and nitrous chloride are but a few of the substances that on entering through the skin, respiratory tract, or digestive tract cause serious and often fatal illness.
Occupational hazards also are presented by infective sources. Persons who come into contact with infected animals in a living or deceased state are in danger of acquiring such diseases as anthrax and tularemia. Doctors, nurses, and other hospital personnel are prime targets for the tuberculosis bacillus and for many other infectious organisms.
Recognition of the effects of working under deleterious conditions and with harmful substances has resulted in efforts to protect workers from exposure to them. Legislation to prevent or limit the occurrence of occupational disease dates from the Factory Act in England in 1802. Prevention of unhealthy or unsafe working conditions and oversight of healthy and safe workplaces are the responsibility in the United States of the federal Occupational Safety and Health Administration (OSHA) and Environmental Protection Agency, as well as many state agencies. Many occupational abuses have been redressed by litigation and legislation in the United States, and workers' compensation takes care, by a system of insurance, of those who suffer from occupational diseases.