[1] Queen Mary Univ London, Ctr Primary Care & Publ Hlth, Blizard Inst, London, England
[2] Univ London Imperial Coll Sci Technol & Med, Sch Publ Hlth, London, England
[3] Natl Inst Publ Hlth & Environm, Ctr Hlth Protect, NL-3720 BA Bilthoven, Netherlands
[4] Natl Inst Publ Hlth & Environm, Ctr Nutr & Hlth, NL-3720 BA Bilthoven, Netherlands