Addresses: 1 Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden. 2 Section of Occupational and Environmental Medicine, University Hospital of Lund, Sweden. 3 IVL Swedish Environmental Research Institute Ltd. BOX 210 60, SE-100 31 Stockholm Sweden. 4 Division of Laboratory Sciences, National Centre for Environmental Health, Centers for Disease Contro...