1. Institute and Policlinic for Occupational and Social Medicine, School of Medicine and Dentistry, University of Cologne, Kerpener Strasse 62, D-50937 Cologne, Lindenthal, Germany
2. School of Engineering and Science, Jacobs University Bremen, D-28759 Bremen, Germany
3. Institute of Clinical Chemistry and Laboratory Medicine, Westphalian Wilhelms-University of Münster, Münster, Germany