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HUMANS AND ENVIRONMENTAL HEALTH: WATER CONTAMINATION
Any substance that gets into the soil can potentially get into the water supply. Contaminants from industrial air pollution and acid rain eventually work their way into the soil and then into the groundwater. Pesticides sprayed on crops wash through the soil into the groundwater. Spills of oil and other hazardous wastes flow into local rivers and streams.
Underground storage tanks for gasoline may develop leaks. The list continues.
Pollutants can enter waterways by a number of different routes. Congress has coined two terms, point source and non-point source, to refer to the two general sources of water pollution. Pollutants that enter a waterway at a specific point through a pipe, ditch, culvert, or other such conduit are referred to as point source pollutants. The two major sources of this type of pollution are sewage treatment plants and industrial facilities.
Nonpoint source pollutants - commonly known as runoff and sedimentation - run off or seep into waterways from broad areas of land rather than through a discrete pipe or conduit. It is currently estimated that 99 percent of the sediment in our waterways, 98 percent of the bacterial contaminants, 84 percent of the phosphorus, and 82 percent of the nitrogen come from nonpoint sources. Nonpoint pollution results from a variety of human land use practices. It includes soil erosion and sedimentation, construction wastes, pesticide and fertilizer runoff, urban street runoff, wastes from engineering projects, acid mine drainage, leakage from septic tanks, and sewage sludge.
Septic Systems
Bacteria from human waste can leach into the water supply from improperly installed septic systems. Toxic chemicals that are disposed of by being dumped into septic systems can also get into the groundwater supply.
Landfills
Landfills and dumps generate a liquid called leachate, a mixture of soluble chemicals that come from household garbage, office waste, biological waste, and industrial landfill has not been properly lined, leachate through its layers of garbage and eventually into the water supply as acid and into the atmosphere as methane gas.
Gasoline and Petroleum Products
In the United States, there are more than 2 million underground storage tanks for gasoline and petroleum products, most of which are located at gasoline filling stations. One quarter of these underground tanks are thought to be leaking.
Most of these tanks were installed 25 to 30 years ago. They were made of fabricated steel that was unprotected from corrosion. Over time, pinpoint holes develop in the steel, and the petroleum products stored in the tanks leak into the groundwater. The most common way to detect the presence of petroleum products in the water supply is to test for benzene, a component of oil and gasoline. Benzene is highly toxic and is associated with the development of cancer.
Service station owners throughout the country are being informed that their underground storage tanks may be public health hazards because of leakage. In many cases, repairs or reinstallation expenses would bankrupt the businesses, so concerned owners are requesting government aid to solve the problem.
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GENERAL HEALTH
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