The introduction into any environment of substances that are not normally present therein and that are potentially toxic or otherwise objectionable. The most serious atmospheric contaminants have been (1) sulfur dioxide evolved from the fuels used in electric power production and industrial processing, and (2) automobile exhaust gases rich in carbon monoxide and tetraethyllead residues. The former is being alleviated by mandatory use of low-sulfur fuels and the latter by elimination of tetraethyllead from most gasoline and by use of catalytic converters.Water pollution due to discharge of toxic chemical wastes is closely regulated by both the EPA and FDA. Such substances are defined in the 1972 amendment of the Federal Water Pollution Control Act as those “which will cause death, disease, cancer, or genetic malfunctions in any organisms with which they come into contact.” Substances added to water for purification purposes (chlorine, aluminum sulfate, etc.) are excluded from the category of pollutants.See Environmental Protection Agency; Air Pollution; Water Pollution.
