1. Faculty of Public Health, Khon Kaen University; Department of Environmental Health Science, Occupational Health and Safety; 123 Moo 16 Mittapap Rd. Khon Kaen Thailand 40002
2. Norwegian Institute of Public Health; Department for Health Services; PO Box 4404, Nydalen Oslo Oslo, Norway Norway N-0403
3. Faculty of Public Health, Hue University of Medicine and Pharmacy; Department of Biostatistics - Demography - Reproductive Health; 06 Ngo Quyen Hue Thua Thien Hue Vietnam 47000
4. University of Toronto; Faculty of Medicine; 1 King's College Circle Toronto ON Canada M5S 1A8
5. University Hospital of Brest; Occupational and Environmental Diseases Center; 5 avenue Foch Brest France 29609
6. Norwegian Institute of Public Health; Division for health services; PO Box 4404 Nydalen Oslo Norway N-0403