1. a Division of Environmental Health , National Public Health Institute , Kuopio , Finland
2. b School of Engineering and Technology , Jyväskylä Polytechnic, Jyväskylä , Finland
3. c Department of Environmental Health Sciences, School of Public Health , University of California , Berkeley , California , USA
4. d Product Registration Unit , National Product Control Agency for Welfare and Health , Tampere , Finland
5. e Department of Environmental Sciences , University of Kuopio , Kuopio , Finland
6. f Division of Environmental Health , National Public Health Institute , Kuopio , Finland