Environmental toxin definition of Environmental toxin in the Free Online Encyclopedia.

pollution, contamination of the environment as a result of human activities. The term pollution refers primarily to the fouling of air, water, and land by wastes (see air pollution air pollution, contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health.
..... Click the link for more information. ; water pollution water pollution, contamination of water resources by harmful wastes; see also sewerage , water supply , pollution , and environmentalism .

Industrial Pollution

..... Click the link for more information. ; solid waste solid waste, discarded materials other than fluids. In the United States in 1996, nearly 210 million tons—about 4.3 lb. (2 kg) per person daily (up from 2.7 lb./1.2 kg in 1960)—were collected and disposed of by municipalities.
..... Click the link for more information. ). In recent years it has come to signify a wider range of disruptions to environmental quality. Thus litter, billboards, and auto junkyards are said to constitute visual pollution; noise excessive enough to cause psychological or physical damage is considered noise pollution noise pollution, human-created noise harmful to health or welfare. Transportation vehicles are the worst offenders, with aircraft, railroad stock, trucks, buses, automobiles, and motorcycles all producing excessive noise. Construction equipment, e.g.
..... Click the link for more information. ; and waste heat that alters local climate or affects fish populations in rivers is designated thermal pollution.

The 20th cent. has seen pollution approach crisis proportions throughout the world. At issue is the capacity of the biosphere biosphere, irregularly shaped envelope of the earth's air, water, and land encompassing the heights and depths at which living things exist. The biosphere is a closed and self-regulating system (see ecology ), sustained by grand-scale cycles of energy and of
..... Click the link for more information. to disperse, degrade, and assimilate human wastes (see ecology ecology, study of the relationships of organisms to their physical environment and to one another. The study of an individual organism or a single species is termed autecology; the study of groups of organisms is called synecology.
..... Click the link for more information. ). The biosphere is a closed ecological system with finite resources and is maintained in equilibrium by grand-scale recycling. Under natural conditions organic and certain inorganic materials in the biosphere are continually recycled by processes including photosynthesis photosynthesis (fō'tōsĭn`thəsĭs)
..... Click the link for more information. and respiration respiration, process by which an organism exchanges gases with its environment. The term now refers to the overall process by which oxygen is abstracted from air and is transported to the cells for the oxidation of organic molecules while carbon dioxide (CO
..... Click the link for more information. , nitrogen fixation and denitrification (see nitrogen cycle nitrogen cycle, the continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and denitrification.
..... Click the link for more information. ), evaporation and precipitation, and diffusion by wind and water action. But the introduction of massive quantities of waste matter at any point in the biosystem may "overload" it, disrupting the natural recycling mechanisms.

Public Recognition of Pollution as a Problem

Public awareness that the environment could not absorb limitless amounts of waste came with the Industrial Revolution. By the latter part of the 19th cent. many industrial areas were experiencing severe air pollution caused by the burning of coal to run mills and machinery. The quantities of fly ash, smoke, carbon and sulfur gases, and other wastes had become too great for local environments—like those of London and Pittsburgh—to disperse rapidly. Similarly, industrial effluents and sewage were polluting river systems. Not until after World War II, however, was pollution generally viewed as more than a nuisance that blackened buildings and sullied streams, i.e., as a pervasive threat to human health.

By the 1960s the threat had become great enough, many believed, to challenge the integrity of the ecosystem and the survival of numerous organisms including humans. Population explosion, industrial expansion, and burgeoning truck and automobile use were producing wastes in such gigantic quantities that natural dispersing and recycling processes could not keep pace. Exacerbating the problem was the appearance of new substances that degraded with extreme slowness or not at all: plastics, synthetic fibers, detergents, synthetic fertilizers, synthetic organic pesticides such as DDT, synthetic industrial chemicals such as the polychlorinated biphenyls (PCBs), and the wastes from their manufacture.

Thus waterways and dumps festered with disease-breeding garbage. Industrial wastes created corrosive smogs and, with municipal wastes, polluted inland and marine waters, including drinking supplies. Automobile emissions choked urban and suburban communities. Pesticides and PCBs poisoned fish and birds. These conditions, persisting into the 1970s as year by year waste output increased, evoked demand in many nations, and on the part of the United Nations, for worldwide pollution abatement.

The National Environmental Policy Act in 1969 and the establishment of the Environmental Protection Agency the following year was a turning point in federal regulatory policy. Since then Congress has also passed the Clean Air Act (1970), the Clean Water Act (1972), the Noise Control Act (1979), and the Comprehensive Environmental Response, Compensation, and Liability Act (1980), more commonly known as the Superfund Act, which created a fund to clean up hazardous waste sites. While the United States and many other industrialized nations have acted to control and reduce pollution, many developing nations, such as China, have experienced increased pollution as they have industrialized.

The potential for environmental disaster has been dramatically underscored by such events as the evacuation of Love Canal Love Canal, section of Niagara Falls, N.Y., that formerly contained a canal that was used as chemical disposal site. In the 1940s and 50s the empty canal was used by a chemical and plastics company to dump nearly 20,000 tons (c.
..... Click the link for more information. (1978), the chemical accident at the Union Carbide plant in Bhopal Bhopal (1991 pop. 1,062,771), the former capital of the principality and now the capital of Madhya Pradesh, was founded in 1728. It is a trade center with manufactures of cotton cloth, jewelry, electrical goods, and chemicals. In Dec.
..... Click the link for more information. , the oil spills from the tankers Exxon Valdez in Alaska (1989), Braer off the Shetland Islands (1993), and Prestige off Galicia, Spain (2002), and the nuclear accidents at Three Mile Island Three Mile Island, site of a nuclear power plant 10 mi (16 km) south of Harrisburg, Pa. On Mar. 28, 1979, failure of the cooling system of the No. 2 nuclear reactor led to overheating and partial melting of its uranium core and production of hydrogen gas, which
..... Click the link for more information. (1979) and at Chernobyl Chernobyl (chĭrnō`byēl), Ukr. Chornobyl, abandoned city, N Ukraine, near the Belarus border, on the Pripyat River.
..... Click the link for more information. in Ukraine (1986).

Control and Abatement

The cost of substantially reducing industrial pollution is high; how to finance it without undue economic burden remains a question. Some experts hold that since population growth automatically increases waste production, pollution can best be combated by population control. Another view is that worldwide proliferation of industry and technology is the chief culprit, posing the threat of global warming global warming, the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution .
..... Click the link for more information. and requiring curtailment if pollution is to be conquered. The early 1990s brought discussion of more effective means to calculate the true costs of pollution in terms of its effects on health, productivity, and quality of life. There is considerable agreement, nonetheless, on the need for revised technology to diminish industrial and automotive emissions, to produce degradable wastes, and to dispose of all wastes in ways less damaging to the environment—for example, by returning sewage to the farm as fertilizer and by recycling glass and metal materials. Finally, improvement is required in techniques for preventing pollution by especially hazardous wastes. The difficulty of finding adequate permanent storage locations has been increased by opposition from residents of potential sites, who are concerned about health hazards. In 1997 more than 1.3 million people in the United States were employed in environmental industries related to pollution control.

See environmentalism environmentalism, movement to protect the quality and continuity of life through conservation of natural resources , prevention of pollution , and control of land use .
..... Click the link for more information. ; land use land use, exploitation of land for agricultural, industrial, residential, recreational, or other purposes. Because the United States historically has a laissez-faire attitude toward land use, the land has been exploited at will for economic gain.
..... Click the link for more information. ; pollution allowance pollution allowance or emission rights, government-issued permit to emit a certain amount of a pollutant. The holder of the permit may use it to pollute legally, may trade permits, or may sell the permit for a profit.
..... Click the link for more information. .

Bibliography

See B. Commoner, Science and Survival (1966) and The Closing Circle (1971); M. H. Brown, The Toxic Cloud (1987); C. S. Silver, One Earth, One Future (1988); J. Marte et al., Toxics A to Z (1991); M. Feshbach and A. Friendly, Jr., Ecocide in the USSR (1992).

pollution [pə′lü·shən]

(ecology)

Destruction or impairment of the purity of the environment.

(physiology)

Emission of semen at times other than during coitus.