1. Department of Biological Sciences, Brunel University, Uxbridge, UB8 3PH, U.K., School of Biological Sciences, Hatherly Laboratories, University of Exeter, The Prince of Wales Road, Exeter, EX4 4PS, U.K., Brixham Environmental Laboratory, AstraZeneca, Freshwater Quarry, Devon, TQ5 8BA, U.K., Shell Chemicals Ltd., London, SE1 7NA, U.K., and The Society of the Plastics Industry Inc., 1801K Street NW, Suite 600K, Washington, D.C.