1. Department of Science and Technology, University of Verona, Strada Le Grazie 15, CV1, I-37134 Verona, Italy; Department of Organic and Industrial Chemistry, University of Parma, Viale G.P. Usberti 17/a, University Campus, I-43100 Parma, Italy; and Department of Medicine and Public Health, Unit of Occupational Medicine, University of Verona, c/o Policlinico G.B. Rossi, I-37134 Verona, Italy