1. National Public Health Institute, Department of Environmental Health, POB 95, FIN-70701 Kuopio, Finland, Illinois Institute of Technology, Chemical and Environmental Engineering, 10 West 33rd Street, Perlstein Hall, Chicago, Illinois 60616-3793, USA,
2. National Public Health Institute, Department of Environmental Health, POB 95, FIN-70701 Kuopio, Finland
3. Kuopio University and Kuopio University Hospital, Department of Pediatrics, FIN-70210 Kuopio, Finland
4. Illinois Institute of Technology, Chemical and Environmental Engineering, 10 West 33rd Street, Perlstein Hall, Chicago, Illinois 60616-3793, USA