1. SEAC, Unilever Colworth, Sharnbrook, Bedford, MK44 1LQ, England, European Chemicals Bureau TP582, Institute for Health and Consumer Protection, Joint Research Centre, European Commission, Via Fermi, 21020 Ispra (VA), Italy, and School of Pharmacy and Chemistry, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, England