Shiftwork and Industrial Injuries at a Chemical Plant in South-East Texas

Abstract

A historical retrospective study of 242 shiftworker (SW) and 224 non-shiftworker (NSW) injuries at a chemical manufacturing plant in southeast Texas was performed. The shiftworker schedule comprised an 8-hour, 7-day backward rotation program, while the NSW schedule consisted of a normal 40-hour work week. Injury records were matched against payroll/attendance records to enhance the probability of isolating possible effects of the shiftwork rotation schedule on the rates, distribution and severity of injuries. For SW injuries, analysis by chi-square comparing day worked into shift with shift rota indicated that the occurrence of an injury, the day worked into each shift and the rota were associated. For the period studied, SW's had more confirmed injuries during the first 4 days of day and night shift than during the evening shift. Female SWs had a significantly higher reported injury incidence rate than did male SWs while maintaining a similar distribution of injury severity ratings. Among NSWs, injury incidence rates were not significantly different between males and females. The number of injuries were not found to vary significantly by clock hour during each shift but did decrease on the average as the shift worked occurred later in the day. It was believed that the rotation direction and reduced number of hours off during evening-day and day-night shift changes may have contributed to the differences in the distribution of injuries for shiftworkers.