1. Division of Toxicology, Swedish National Food Administration, Box 622, S-751 26 Uppsala, Sweden, Division of Occupational and Environmental Medicine, Lund University, S-221 85 Lund, Sweden, Institute of Environmental Medicine, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden, and Hospital Dr Nicolás Cayetano Pagano, 4411 San Antonio de los Cobres, Departamento Los Andes, Provincia de Salta, Argentina