1. Institute for Preventive Medicine of the Rostock University Medical Center , St.-Georg-Str. 108, 18055 Rostock , Germany
2. Government Safety Organisation Foods and Restaurants, German Social Accident Insurance Institution for the Foodstuffs and Catering Industry , Office of Coordination Potsdam, Germany, Eleonore-Prochaska-Str. 11, 14480 Potsdam , Germany