rs unpleasant to look at, to smell, and to swim in. Fish and shellfish harvested from polluted waters may be unsafe to eat. People who ingest polluted water can become ill and if they're exposed for a long time, may develop cancers, or have children with birth defects. p> There are two types of water pollution; point source and nonpoint source. Point sources of pollution occur when harmful substances are put directly into a body of water (such as an oil spill). A nonpoint source is when pollutants enter the water indirectly through environmental changes (like when fertilizer is carried into a stream by rain)
The major water pollutants are chemical, biological, and physical materials that lessen the water quality. Pollutants can be separated into eight different classes:
1. Petroleum Products - oil and chemicals from oil are used for fuel, lubrication, plastics manufacturing, and many other purposes. The petroleum products get into water by accidental spills from ships, tanker trucks, and leaky underground storage tanks. Many petroleum products are poisonous if ingested by animals and spilled oil damages the feathers of birds and the fur of animals, often causing death. p> 2. Pesticides and Herbicides - chemicals used to kill unwanted animals and plants may be carried into streams by rainwater. The chemicals in these that are not biodegradable can remain dangerous for a long time. p> When an animal eats a plant that's been treated with certain non-degradable chemicals, the chemicals are absorbed into the tissues or the organs of the animals. When other animals feed on a contaminated animal, the chemicals are passed up to them. As it goes up through the food chain, the chemical becomes more harmful, so animals at the top of the food chains may suffer cancers, reproductive problems, and death. p> More than 14 million Americans drink water contaminated by pesticides, and the EPA estimates that ten percent of wells contain pesticides. Nitrates can cause a lethal form of anemia called blue baby syndrome in infants. p> 3. Heavy Metals - heavy metals, such as copper, lead, mercury, and selenium, get into the water from industries, automovile exhaust, mines, and natural soil. Heavy metals also become more harmful as they follow the food chain. When they reach high levels in the body, they can be immediately poisonous, or can result in long-term health problems. They can sometimes cause diarrhea and, over time, liver and kidney damage. Children exposed to lead in water can suffer mental retardation. p> 4. Hazardous Wastes - chemical wastes that are either toxic, reactive, corrosive, or ignitable. If not treated or stored properly, they can pollute water supplies. They can reach toxic levels when animals eat one another. p> 5. Excess Organic Matter - fertilizers and other nutrients used to promote plant growth on farms and in gardens may fine their way into water. At first the nutrients will help the pla...
