2.  The word pollute, comes from the Latin word Pollutus meaning “made foul, unclean, or dirty.” Pollutus was historically used to describe sewage or wastes that contaminate air water or land.

3.  There are many types of pollutants that end up in water these are classed as point source that comes from industrial plants, or municipal discharges; and non-point source that comes from runoff this can be from storm water that erodes soil and picks up land pollutants to be carried to creeks, rivers, lakes where it settles to the bottom and smothers the organisms that feed and breed there. Ground water can be contaminated by leaky underground chemical-storage tanks.

5.  Humans have created and released toxic and hazardous chemicals into the environment for long time.  Hazardous chemicals are dangerous because they are flammable, explosive, strong irritants, sensitizers, or acids and bases.  Toxic chemicals disrupt specific cellular processes in living organisms.

6.  Many metals like mercury, cadmium, chromium, and nickel are highly toxic and persist in the environment.  Lead is another serious pollutant, lead based products are no longer made in the US but lead is found on older houses or in the soil around city streets and freeways. As little as ten parts of lead per billion in the blood can have adverse effects on mental development of young children, once the damage is done it is usually irreversible. (Cunningham William P).

7.  Radiation enters the environment from a wide variety of sources, the most well-known are from the detonation of nuclear weapons and the controlled release of energy by nuclear reactors.  Other sources of radiation include the mining of uranium minerals, by-products of mining and processing operations, spent-fuel reprocessing plants, and experimental research laboratories.  The USA has about 181 million metric tons of nuclear waste left over from weapons production and nuclear power plant operations.(Cunningham William P)

8.  Mining  Nuclear  Power Plant

9.  Pollution control is the management of waste materials in order to minimize the effects of pollutants on people and the environment.  The United States has done a lot to control noticeable pollution of the air, water, and land. However the remaining toxic pollutants like trace pesticides, dioxins, and heavy metals; still remain a problem and large-scale problems like acid rain, depletion of the ozone layer and industrial pollution in other developing countries remains a problem.

11.  Cunningham, William P. "Pollution, Environmental." Grolier Multimedia Encyclopedia. Grolier Online, 2012. Web. 1 May. 2012. Lansford, Henry. "Environmental Pollution." The New Book of Popular Science. Grolier Online, 2012. Web. 1 May. 2012. Randolph, John. "Pollution Control." Grolier Multimedia Encyclopedia. Grolier Online, 2012. Web. 1 May. 2012. Randolph, John. "Pollution, Water." Grolier Multimedia Encyclopedia. Grolier Online, 2012. Web. 1 May. 2012. Schmitz, Richard J. "Water Pollution." Encyclopedia Americana. Grolier Online, 2012. Web. 30 Apr. 2012. Zipper, Carl E. "Pollution, Air." Grolier Multimedia Encyclopedia. Grolier Online, 2012. Web. 1 May. 2012.