[1] Univ Helsinki, Folkhalsan Res Ctr, Biomed 1,POB 63,Haartmansgatan 8, FIN-00014 Helsinki, Finland
[2] Univ Helsinki, Fac Med, Helsinki, Finland
[3] Univ Helsinki, Dept Food & Environm Sci, Helsinki, Finland
[4] Canc Registry Norway, Dept Res, Oslo, Norway
[5] Univ Tromso Artic Univ Norway, Dept Community Med, Tromso, Norway
[6] Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden