public health [L, publicus, of the people; AS, haelth] , a field of medicine that deals with the physical and mental health of the community, particularly in such areas as water supply, waste disposal, air pollution, and food safety. In the United States there are more than 3000 state, county, or city public health agencies. The U.S. Public Health Service was organized in 1798 to provide hospital care for American merchant seamen. Subsequent legislation has expanded the role of the federal agency to include such services as the Food and Drug Administration; the National Library of Medicine; health care for Native Americans and Alaska Natives; protection against impure and unsafe foods, drugs, cosmetics, and medical devices; control of alcohol and drug abuse; and protection against unsafe radiation-producing projects.