Pesticides
These pesticides once applied, work for in killing the pest already their, and they continue working while new pests are presented to the environment. Many modern pesticides do not persist for long in the environment.
They act quickly and are then degraded to non-toxic substances. This helps prevent their build-up in crops or other organisms. How quickly a pesticide breaks down depends on its chemical properties, how much is applied and how it is distributed, as well as environmental factors such as temperature, moisture, soil pH and the availability of microorganisms.
Some of the dangers of pesticides lie in the toxicity of the pesticide. Many of the pesticides are not only harmful for insects and crops, but as well as humans which cause problems for their use. They can also travel through many different types of transportation. It can travel through water, air, and food, or insects. This causes problems because these transportations can cause other species to be infected with these poisons.

Sources
Ý Hunt, Andrew. Dictionary of Chemistry. Fitzroy Dearborn Publishers: London. 1999.
Ý McGraw-Hill. Encyclopedia of Science and Technology; Volume 13. McGraw-Hill: New York.
Ý Plimmer, Jack. Chemistry of Pesticides. Academic Press. 2002.
Ý Saari, Peqqi. Scientists: The Lives and Works of 150 Scientists. Gale.1996
Ý Author Unknown. Illustrated Science and Invention Encyclopedia. H.S. Stuttman inc: Westport, Connecticut.
Ý Author Unknown. J.S. Environmental Protection Agency. “Types of Pesticides.” Wednesday April 23, 2003.
Ý Author Unknown. How Pesticides Work. http://www.epa.nsw.gov.au/envirom/pesthwwrk.htm.
Ý Harrison, Karl. DDT a Banned Insecticide. http://www.chem.ox.ac.uk/mom/ddt/ddt.htm. Monday, May 19, 2003.

A scientist called Paul Muller created the first developed pesticides around 1939. It was called dichlorodiphenyltrichloroethane (DDT) was used in World War II to protect soldiers against malaria spread by mosquitoes. DDT became a widely used pesticide and then until it was discovered that DDT was highly toxic to humans, and became a threat to the population. DDT was banned in 1973, due to the killing of many fish in Lake Michigan and the developing resistance from the insects.

Pictures
Farmer Picture: http:// www.ufw.org/LegAct.htm


Airplane: http://www.nrdc.org/health/pesticides/default.asp

 

 

 

 

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