Section for Biostatistics and Epidemiology, Norwegian University of Life Sciences (NMBU), Oslo, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås and Norwegian Institute of Public Health, Division of Epidemiology, 0403 Oslo, Norway.|Section for Biostatistics and Epidemiology, Norwegian University of Life Sciences (NMBU), Oslo, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås and Norwegian Institute of Public Health, Division of Epidemiology, 0403 Oslo, Norway.|Section for Biostatistics and Epidemiology, Norwegian University of Life Sciences (NMBU), Oslo, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås and Norwegian Institute of Public Health, Division of Epidemiology, 0403 Oslo, Norway.