Koch, Holger M., Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Bürkle-de-la-Camp-Platz 1, 44789 Bochum, Germany, Tel.: +49 (0)30 13001 4415, Fax: +49 (0)30 13001 864415, E-mail: koch@ipa-dguv.de, Germany