Scientific Symposium - The Health Effects of Shift Work - Toronto, April 12, 2010

Shift work and the risk of work injury

Cameron Mustard (presenter), Andrea Chambers, Peter M Smith, Christopher McLeod


Currently, 25% of Canadian full-time workers aged 19-64 work some form of non-traditional work schedule. There is strong evidence that night, evening, rotating and irregular shifts are associated with an elevated risk of occupational injury. These risks are generally understood to arise from the joint influence of worker fatigue (due to sleep disturbance or long work hours) and typically lower levels of supervision and co-worker support during non-daytime work schedules.

This paper is organized in four sections: 1) a narrative review of the epidemiologic evidence for a relationship between exposure to shift work and work injury risk, 2) an assessment of the population attributable risk for work injury arising from exposure to shift work, 3) an overview of the research challenges in this field and 4) an assessment of opportunities to improve the surveillance of the risks of work injury associated with shift work.

Estimates of the population attributable fraction indicate that 6-7% of workplace injuries can be attributed to the higher risk of injury associated with shift work schedules. On the basis of this estimate, an excess of 13,000 compensated injuries (lost-time and no lost-time) to men and 20,000 compensated injuries to women in Ontario can be annually attributed to the higher risk of injury associated with shift work schedules.

Among the challenges in conducting high quality population research on the health effects of shift work are: limited information at the population level on work hours, individual work demands and the availability of supervision over the 24 hour clock, and information on the health status of workers who work regular and non-regular work schedules.

Surveillance information is a foundation for the identification of potential prevention efforts and can inform the design of more sophisticated etiologic research to understand the specific mechanisms of hazards associated with non-regular work hours. The risk of work injury arising from shift work is sufficient to justify developing methods for the routine surveillance of work hours and work injury. This presentation will conclude with a discussion of the strengths and limitations of three potential approaches to monitoring work schedules and work injury risk: 1) the use of time of injury information on workers' compensation claims, 2) the use of emergency department records containing proxy information on the time of injury and the attributable cause of injury and 3) the use of labour market panel surveys that collect information on usual work schedule and the incidence of work injury in the previous 12 month recall period.

Presenter Biography

Cameron Mustard is President and Senior Scientist at the Institute for Work & Health and a Professor in the School of Public Health, Faculty of Medicine, University of Toronto. Dr. Mustard has a background in public health sciences, with an emphasis on epidemiology and health policy. He completed his doctoral training in epidemiology, health policy and behavioral sciences at the Johns Hopkins University School of Hygiene and Public Health.

Dr. Mustard has active research interests in the areas of work environments and health, the organization and delivery of health services and the adequacy and equity of disability income security programs. Dr Mustard is a past member of the Board of Directors of the Canadian Institute for Health Information where he served as Chair of the Canadian Population Health Initiative Council. He was a Fellow of the Population Health Program of the Canadian Institute for Advanced Research (1998-2003) and a past recipient of a CIHR Scientist award (1998-2003).



Mustard C, Chambers A, Smith P, McLeod C



 Occupational Cancer Research CentreInstitute for Work & Health | Research Excellence Advancing Employee Health