1. a Occupational and Environmental Medicine , University of Gothenburg , Box 414, SE-405 30, Göteborg, Sweden
2. b Department of Environmental and Occupational Health Sciences , University of Washington , Box 357234, Seattle, WA, 98195, USA
3. c Institute of Stress Medicine in Gothenburg , Gruvgatan 8, SE-421 30, Västra Frölunda, Sweden