1. Danish Ramazzini Centre; Department of Occupational Medicine, Aarhus Hospital; Aarhus University Hospital; Aarhus Denmark
2. Department of Neurophysiology, Aarhus Hospital; Aarhus University Hospital; Aarhus Denmark
3. Danish Ramazzini Centre; University Department of Occupational Medicine; Herning Regional Hospital, Gl. Landevej 61, DK-7400 Herning Denmark