Authors: S Darby; D Hill; A Auvinen; J M Barros-Dios; H Baysson; F Bochicchio; H Deo; R Falk; F Forastiere; M Hakama; I Heid; L Kreienbrock; M Kreuzer; F Lagarde; I Mäkeläinen; C Muirhead; W Oberaigner; G Pershagen; A Ruano-Ravina; E Ruosteenoja; A Schaffrath Rosario; M Tirmarche; L Tomásek; E Whitley; H-E Wichmann; R Doll Journal: BMJ Date: 2004-12-21