Submitted on: 07 March 1999.
Revised on: 08 May 1999.
Accepted on: 28 May 1999.
___________________JOURNAL OF OCCUPATIONAL HEALTH
Submitted on: 11 July 2006.
Revised on: 03 November 2006.
Accepted on: 19 November 2006.
___________________JOURNAL OF OCCUPATIONAL HEALTH
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