1. Occupational Health and Safety Agency for Health Care in British Columbia, Vancouver, British Columbia, Canada.
2. Department of Health Care and Epidemiology, University of British Columbia, Vancouver, British Columbia, Canada.
3. British Columbia Nurses Union, Burnaby, British Columbia, Canada.
4. Vancouver General Hospital, and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
5. Occupational Health and Safety Agency for Health Care in British Columbia, and Department of Health Care and Epidemiology, University of British Columbia, Vancouver, British Columbia, Canada.