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Submitted on: 18 February 2009.
Revised on: 22 April 2009.
Accepted on: 11 June 2009.
___________________Journal of Occupational Medicine and Toxicology
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Submitted on: 03 November 2004.
Revised on: 25 November 2004.
Accepted on: 24 January 2005.
___________________Journal of Occupational Medicine and Toxicology