1. University of Eastern Finland; Kuopio Finland
2. Finnish Institute of Occupational Health; Kuopio Finland
3. University of Eastern Finland; Department of Nursing Science; P.O.Box 1627 Kuopio Finland 70211
4. University of Eastern Finland; Institute of Public Health and Clinical Nutrition, Occupational Health Unit; PO Box 1627 Kuopio Finland 70211
5. Vrije Universiteit Brussel; Interface Demography, Department of Sociology; Pleinlaan 2 Brussels Belgium 1050
6. Erasmus Medical Center; Department of Public Health; PO Box 2040 Rotterdam Netherlands 3000 CA