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Main article: Environmental effects of pesticides

Pesticide use raises a number of environmental concerns. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil.[1] Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides are one of the causes of water pollution, and some pesticides are persistent organic pollutants and contribute to soil contamination.

In addition, pesticide use reduces biodiversity, contributes to pollinator decline,[2] destroys habitat (especially for birds),[3] and threatens endangered species.[1]
Pests can develop a resistance to the pesticide (pesticide resistance), necessitating a new pesticide. Alternatively a greater dose of the pesticide can be used to counteract the resistance, although this will cause a worsening of the ambient pollution problem.

Since chlorinated hydrocarbon pesticides dissolve in fats and are not excreted, organisms tend to retain them almost indefinitely. Biological magnification is the process whereby these chlorinated hydrocarbons (pesticides) are more concentrated at each level of the food chain. Among marine animals, pesticide concentrations are higher in carnivorous fishes, and even more so in the fish-eating birds and mammals at the top of the ecological pyramid.[4] Global distillation is the process whereby pesticides are transported from warmer to colder regions of the Earth, in particular the Poles and mountain tops. Pesticides that evaporate into the atmosphere at relatively high temperature can be carried considerable distances (thousands of kilometers) by the wind to an area of lower temperature, where they condense and are carried back to the ground in rain or snow.[5]

In order to reduce negative impacts, it is desirable that pesticides be degradable or at least quickly deactivated in the environment. Such loss of activity or toxicity of pesticides is due to both innate chemical properties of the compounds and environmental processes or conditions.[6] For example, the presence of halogens within a chemical structure often slows down degradation in an aerobic environment.[7] Adsorption to soil may retard pesticide movement, but also may reduce bioavailability to microbial degraders.[8]

ReferencesEdit

  1. 1.0 1.1 Miller GT (2004), Sustaining the Earth, 6th edition. Thompson Learning, Inc. Pacific Grove, California. Chapter 9, Pages 211-216.
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  3. Palmer, WE, Bromley, PT, and Brandenburg, RL. Wildlife & pesticides - Peanuts. North Carolina Cooperative Extension Service. Retrieved on 2007-10-11.
  4. Castro, Peter, and Michael E.Huber. Marine Biology. 8th. New York: McGraw-Hill Companies Inc., 2010. Print.
  5. L. Quinn, Amie. "The impacts of agriculture and temperature on the physiological stress response in fish." Uleth. University of Lethbridge, n.d. Web. 20 Nov 2012.
  6. Sims, G. K. and A.M. Cupples. 1999. Factors controlling degradation of pesticides in soil. Pesticide Science 55:598-601.
  7. Sims, G. K. and L.E. Sommers. 1986. Biodegradation of pyridine derivatives in soil suspensions. Environmental Toxicology and Chemistry. 5:503-509.
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External linksEdit

Wikimedia Commons has media related to:
Pesticide regulatory authorities
Human health

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