1. University of Montreal Hospital Research Centre, Montreal, Quebec, Canada
2. Institut national de santé publique du Québec, Montreal, Quebec, Canada
3. University of Sherbrooke Hospital Research Centre, Sherbrooke, Quebec, Canada
4. Departments of Pediatrics and Community Health Sciences, Cummings School of Medicine, University of Calgary, Calgary, Alberta, Canada
5. National Collaborating Centre for Environmental Health, British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada