Industrial accident experience of one company on 8- and 12-hour shift systems

J Occup Med. 1991 Aug;33(8):903-6. doi: 10.1097/00043764-199108000-00018.


The accident reports of a company were analyzed for 10 years before and after change from 8- to 12-hour shifts. Age-sex standardized ratios were calculated for each year for on- and off-the-job accidents by severity. Times of occurrence of on-the-job accidents were also examined. Overall accident rates were reduced on the 12-hour shift schedule, but statistical significance was reached only for lower accident categories. Off-the-job injuries increased on the 12-hour shift. There were significant gender differences in accident rates on 8-hour but not 12-hour shifts. A distinct circadian pattern of accident frequency was observed. We concluded that the introduction of a 12-hour shift system did not result in increased accidents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accidents, Occupational / statistics & numerical data*
  • Circadian Rhythm
  • Cohort Studies
  • Female
  • Humans
  • Male
  • Ontario
  • Sex Factors
  • Work Schedule Tolerance*