1. University of Nottingham; School of Community Health Sciences; Nottingham UK
2. National Institute of Occupational Safety and Health; Division of Safety Research; 1095 Willowdale Road Morgantown West Virginia USA 26505
3. VU University; Department of Health Sciences, Faculty of Earth and Life Sciences; De Boelelaan 1085 Amsterdam Netherlands 1081HV
4. Institute for Work and Health; 481 University Avenue, Suite 800 Toronto Ontario Canada M5G 2E9
5. University of Cambridge; The Primary Care Unit; Institute of Public Health Forvie Site, Robinson Way Cambridge Cambridgeshire UK CB2 0SR