Marilyne Menassa1, Esther Mc Vriend2, Oscar H Franco3. 1. Institute of Social and Preventive Medicine, University of Bern, 3012 Bern, Switzerland. Electronic address: marilyne.menassa@ispm.unibe.ch. 2. Department of Public Health, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, Netherlands. 3. Institute of Social and Preventive Medicine, University of Bern, 3012 Bern, Switzerland.