Environmental Pollution




Environmental pollution is the release of chemical waste that causes detrimental effects on the environment. Environmental pollution is often divided into pollution of water supplies, the atmosphere, and the soil. In his book Environmental Chemistry, Stanley Manahan lists several different types of pollutants, including toxic inorganic and organic compounds, high concentrations of normally innocuous compounds, and heat and noise. While much pollution is produced by the chemical industry, domestic sources include human waste and automobile exhaust.

While physical sources, such as noise and light, of pollution are important, people most often notice the damage of chemical pollution on animals and plant life. These chemicals can react with tissues in the body and change the structure and function of the organ, cause abnormal growth and development of the individual, or bind with the genetic material of cells and cause cancer. The study of the effects of poisons on the body is called toxicology . One of the central tenets of toxicology states that the dose of a chemical determines its overall effects and that most chemicals can be dangerous at high exposures.

Individuals and chemical and petroleum companies contribute to the pollution of the atmosphere by releasing inorganic and organic gases and particulates into the air. The atmosphere is a paper-thin layer of gas (representing 1 percent of the mass of Earth) that protects the planet from damaging cosmic and ultraviolet radiation , contains life-giving oxygen, and allows the efficient cooling of the planet.

Atmospheric Pollution

Some examples of atmospheric pollutants include nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), and chlorofluorocarbons (CFCs) . The first two pollutants combine with water to form acids, which not only irritate the lungs but also contribute to the long-term destruction of the environment due to the generation of acid rain . Carbon monoxide, generated by the incomplete combustion of hydrocarbons, displaces and prevents oxygen from binding to hemoglobin and causes asphyxiation. Also, it binds with metallic pollutants and causes them to be more mobile in air and water. CFCs and other halogenated hydrocarbons react with light to form highly reactive species, called radicals, which destroy ozone in the upper atmosphere. These reactions greatly reduce the protective effects of ozone against ultraviolet radiation.

Water Pollution

Fresh, clean, and drinkable water is a necessary but limited resource on the planet. Industrial, agricultural, and domestic wastes can contribute to the pollution of this valuable resource, and water pollutants can damage human and animal health. Three important classes of water pollutants are heavy metals , inorganic pollutants, and organic pollutants. Heavy metals include transition metals such as cadmium, mercury, and lead, all of which can contribute to brain damage. Inorganic pollutants like hydrochloric acid, sodium chloride, and sodium carbonate change the acidity, salinity, or alkalinity of the water, making it undrinkable or unsuitable for the support of animal and plant life. These effects can result in dire consequences for higher mammals such as humans. A list of organic pollutants includes pesticides such as chlorpyrifos and paraquat, and their byproducts, such as dioxin. All of these substances are highly lethal to animals, and many can be readily absorbed through the skin.

Pesticides

The use of pesticides in agriculture contributes to environmental pollution. Pesticides are used to control the growth of insects, weeds, and fungi, which compete with humans in the consumption of crops. This use not only increases crop yields and decreases grocery prices, but also controls diseases such as malaria and encephalitis. However, the spraying of crops and the water runoff from irrigation transports these harmful chemicals to the habitats of nontarget animals. Chemicals can build up in the tissues of these animals, and when humans consume the animals the increased potency of the pesticides is manifested as health problems and in some cases death. Chemists have recently developed naturally occurring pesticides that are toxic only to their particular targets and are benign to birds and mammals. The most significant pesticide of the twentieth century was DDT, which was highly effective as an insecticide but did not break down in the environment and led to the death of birds, fish, and some humans.

Industrial Pollution and Love Canal

The infamous case of the pollution of Love Canal, on Lake Erie in New York, brought environmental pollution to the public attention in the 1970s, and the history of this incident has been thoroughly described at a University of Buffalo web site. From 1942 to 1953, several chemical companies dumped 20,000 metric tons of chemical waste at this site. In 1953 the land was sold to the local board of education, and the 99th Street School was constructed on the land. The school attracted families to the neighborhood, which grew to contain 800 single-family homes and 240 apartment units by 1978. Unfortunately, eighty different chemicals, including dioxins and polychlorinated biphenyls (PCBs), started to leach through the soil, and residents began complaining of odd smells in their houses and experiencing many unexplainable health problems. The school was closed in August 1978, and the federal government contributed $10 million for the relocation of 200 families nearest the site. In 1980 President Carter sent additional funds, for the relocation of 700 more families. Today federal laws stipulate that generators of hazardous waste are responsible for the proper storage and disposal chemicals from the "cradle to the grave."

New Pollutants: Toxic Mold

Recently many people have complained of illnesses associated with the presence of toxic mold in their homes and workplaces. These molds, which thrive in damp surroundings, are members of the fungi kingdom and produce chemicals called mycotoxins that can produce a variety of health problems. Additionally, molds produce strong allergic reactions in some individuals. According to the Centers for Disease Control and Prevention (CDC), little strong evidence exists that can tie all of the health problems seen in damp or flooded areas to molds, but the CDC also recommends that one should repair leaking plumbing and all other causes of damp environments as soon as they occur.

While some of the environmental pollution created in society is avoidable, industrial nations will always produce a low level of pollutants. Pesticides greatly increase overall food production; pharmaceuticals, which require organic chemicals for their manufacture, extend life; and plastics are used in all aspects of medical and domestic life. Society must find a balance between the desire to minimize the cost of manufactured items and the desire to require industries and individuals to reduce pollution.

ERIN BROCKOVICH: THE STORY BEHIND THE MOVIE

In December 1987, Pacific Gas and Electric (PG&E) reported to the Environmental Protection Agency that it had detected levels of chromium (VI) at its natural gas compression station near Hinkley, California, that were ten times higher than those allowed by government standards. These reports devalued land in the community and sparked the curiosity of Erin Brockovich, who was working in a law office as a secretary. Her passionate investigation into the actions of the large public utility led to the discovery of a thirty-year cover-up of the improper disposal of cooling water contaminated with the chromium (VI). Dr. Robert A. Goyer has stated that chromium (VI) irritates the skin of humans and causes cancer in laboratory animals. According to an article by attorney Carole Bos on the LawBuzz web site, Erin Brockovich's work forced PG&E to pay damages of $300 million to the residents of Hinkley.

SEE ALSO Air Pollution ; Water Pollution .

G. Brent Dawson

Bibliography

Freedman, Bill (1989). Environmental Ecology: The Impacts of Pollution and Other Stresses on Ecosystem Structure and Function. San Diego: Academic Press.

Gallo, Michael (2001). "History and Scope of Toxicology." In Casarett and Doull's Toxicology: The Basic Science of Poisons, 6th edition, ed. Curtis D. Klaasen. New York: McGraw-Hill.

Goyer, Robert A., and Clarkson, Thomas W. (1996). "Toxic Effects of Metals." In Caserett and Doull's Toxicology: The Basic Science of Poisons, 5th edition, ed. CurtisD. Klaasen. New York: McGraw-Hill.

Manahan, Stanley (1999). Environmental Chemistry , 6th edition. Boca Raton, FL: Lewis Publishers.

Internet Resources

Bos, Carole D. "Erin Brockovich, Famous Trials." Law Buzz. Available from http://www.lawbuzz.com/famous_trials/erin_brockovich/erin_brockovich_ch1.htm .

Ecumenical Task Force of the Niagara Frontier. "Background on the Love Canal." Available from http://ublib.buffalo.edu/libraries/projects/lovecanal/background_lovecanal.html .



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