1. BGFA-Research Institute of Occupational Medicine, German Social Accident Insurance, Ruhr-University Bochum, Bürkle-de-la-Camp Platz 1, 44789 Bochum, Germany E-mail: k.sucker@gmx.de
2. North Rhine-Westphalia State Agency for Nature, Environment and Consumer Protection, Leipnizstraße 10, 45659 Recklinghausen, Germany E-mail: ralf.both@lanuv.nrw.de
3. Medical Institute of Environmental Hygiene at Heinrich-Heine-University Düsseldorf, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany E-mail: gerhard.winneke@uni-duesseldorf.de