1. Department of Public Health, Aarhus University, Aarhus,Denmark
2. Research Centre for Youth and Employment, Regional Hospital West Jutland, University Research Clinic, Herning, Denmark
3. Centre for Social Medicine, Frederiksberg and Bispebjerg Hospital, Copenhagen, Denmark
4. Department of Public Health, University of Copenhagen, Copenhagen, Denmark
5. Department of Occupational Medicine, Danish Ramazzini Centre, University Research Clinic, Regional Hospital West Jutland, Herning, Denmark
6. NORCE, Norwegian Research Centre, Bergen, Norway