1. Institute of Environmental and Occupational Toxicology, Casella Postale
108, CH-6780 Airolo, Switzerland
2. Alpine Institute of Chemistry and Toxicology, CH-6718 Olivone, Switzerland
3. Walther-Straub-Institut für Pharmakologie und
Toxikologie, Ludwig-Maximilians-Universität, D-80336 München, Germany