1. Food and Environment Research Agency, Sand Hutton, York YO41 1LZ North Yorkshire, United Kingdom, Somagenics, Inc., 2161 Delaware Avenue, Santa Cruz, California 95060, Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305, Veterinary Medicines Directorate, Woodham Lane, New Haw, Addlestone, Surrey KT15 3LS, United Kingdom, and Department of Chemistry, University of York, Heslington Lane, York YO10 5DD, United Kingdom