1. Department of Occupational and Environmental Medicine, Copenhagen University Hospital Bispebjerg and Frederiksberg , Copenhagen 2400 , Denmark
2. Department of Public Health, University of Copenhagen , Copenhagen 1500 , Denmark
3. School of Public Health and Community Medicine, Sahlgrenska Academy, University of Gothenburg , Gothenburg 405 30 , Sweden
4. Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University , Lund 22363 , Sweden
5. Clinical Pharmacology, Pharmacy and Environmental Medicine, University of Southern Denmark , Odense 5000 , Denmark
6. Division of Public Health, Kristianstad University , Kristianstad 29188 , Sweden