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Fact Sheet Series: Pesticides in Drinking WaterWhat are Pesticides?Widespread use of synthetic pesticides in the United States began after the second world war and their use was credited with increasing crop production. Since the 1950’s, American agriculture relying totally on pesticides has dispersed 30 billion pounds into the environment. Pesticides are chemicals that are used to destroy insects, weeds, and pests around yards and gardens. There are three major families of pesticides: The Chlorinated hydrocarbons or organochlorine, the organic phosphates or organophosphates and the carbamates compounds. The last family of pesticides is considered highly toxic to humans. What is the extent of the problem of pesticides in the environment?Every year in the United States, 1.1 billion pounds of active pesticide ingredients are released into the environment. In addition, the Environmental Protection Agency estimates that in 1991, U.S. manufacturers exported 390 million pounds of pesticides. The uncontrolled use of pesticides over the past 50 years has led to the contamination of many of our hydrologic systems. Pesticide contamination of ground water is an issue of national importance because ground water is used for drinking water by about 50% of the population. How does Pesticide contamination occur?The "pathways" of human exposure to pesticides are numerous. The three main places where pesticide contamination of water occurs:
Pesticides can reach surface and underground waters: through runoff and leaching. What are the evidences of Pesticide contamination?More than 700 synthetic organic compounds have been identified in various U.S. drinking water supplies. This contamination originates from a variety of sources, including household products and leakage or improper disposal of chemical wastes from commercial and industrial establishments. For decades, by-products of industrial manufacturing and cleaning operations have been disposed of in unrecorded dumpsites across the U.S., and some of these chemicals have leached to groundwater. Pesticides constitute another category of synthetic organic compounds that have been found in the water. The EPA has developed guidelines that weigh the evidence about a pesticide's carcinogenicity. Pesticides are classified from Human Carcinogen to non-carcinogenic for humans, based on the type of evidence available and the weight of that evidence. What are the health effects of Pesticides?Now that people are aware of organic contaminants in drinking water; methods have been developed to assess the presence of pesticides. The health effects associated with some pesticides found in the water are different whether the exposure is acute or chronic. Acute exposure causes diarrhea, nausea, vomiting, abdominal pain, profuse salivation and sweating, blurred vision, skin and eye irritation, upper respiratory tract distress, edema of the lungs, acute gastro-intestinal distress, headache, dizziness, drowsiness and seizure. The effects of long-term exposure to low levels are much harder to define. However, growth depressions in laboratory animal, liver and lung cancer in human as well as other types of cancer, genetic mutation and fetal deformities have been associated with the chronic exposure. The detection depends on the duration of exposure to the chemical, and how quickly the compound is metabolized and excreted from the body. What can be done to prevent Pesticides in the drinking water?As awareness has grown of the potential for pesticides to move into the water, attention has focused on ways of preventing such contamination and to determine what levels of pesticides are acceptable in water supplies. Guidelines have been proposed, their aims is to keep pesticides at levels below those that are considered to cause any health effects in humans. They are derived from laboratory data using methods, depending on whether or not the compound causes cancer. In 1970, Congress granted authority for pesticide regulation from to the newly created Environmental Protection Agency (EPA), one of the duties of the EPA was to set drinking water standards for pesticides. However, for most of those present in the water, standards have yet to be set. If your water comes from a well, the potential for pesticide contamination of your well should be evaluated. Finally, pesticide applicators should take measures to help protect groundwater quality. These include assessing the susceptibility of the site before using pesticides, then tailoring pesticide applications to the particular site conditions. What are the alternatives to Pesticides?When pesticides do get into groundwater, the contamination can last many years and spread over a large area before dilution, cleanup usually is impossible. However, federal and most state pesticide laws do not focus on use reduction. A major challenge facing modern agriculture, therefore, is to control pests and protect crop yields without allowing pesticides to contaminate surrounding water sources. The reduction of pesticides use, beside its proper application, seems mandatory to reduce its leakage to the drinking water sources. In several states, there is a real effort to reduce pesticide use in all places where it is used called "alternative agriculture" or "sustainable agriculture". These terms generally refer to a variety of practices, including crop rotation, integrated pest management, reduced chemical inputs and organic farming. Many of these are centuries-old successful farming practices that were abandoned with the advent of chemical pesticides. References:Richard Wiles, "Testimony Before the Subcommittee on Health and the Environment." October 21, 1993, Environmental Working Group, Washington, DC. United States General Accounting Office, Report to the Chairman, Committee on Agriculture, Nutrition, and Forestry, United States Senate. Pesticides: Limited Testing Finds Few Exported Unregistered Pesticide Violations on Imported Food (Washington, DC: GAO, October 1993), 3. Larson, S.J.; Capel, P.D.; Majewski, M.S. Pesticides in Surface Waters: Distribution, Trends, and Governing Factors. Chelsea, Michigan: Ann Arbor Press, 1997, 373 p.
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