Roepstorff, Vibe; Sigsgaard, Torben; Roepstorff, Vibe, Department of Occupational and Environmental Health, University of Aarhus, Bldg. 180, 8000 Aarhus C, Denmark; Sigsgaard, Torben, Department of Occupational and Environmental Health, University of Aarhus, Bldg. 180, 8000 Aarhus C, Denmark(Sage Publications, 1997)