During the period since 1985, his research focused mainly on the aquatic environmental effects of endocrine disrupting chemicals (EDCs) such as tributyltin, and his team at Cefas was the first to discover that UK fish were becoming feminised by oestrogens in sewage. As well as conducting research (until recently on EDCs which interfere with the corticosteroid system), he advises the UK government on setting Environmental Quality Standards, is a member of the UK Hazardous Substances Advisory Committee, and co-chairs the OECD Validation Management Group for Ecotoxicity Tests which is developing new methods for evaluating endocrine disrupters. He co-authored OECD Guidance Document no. 150 which helps users interpret the results obtained with these methods. Peter will essentially provide internal peer review of various project outputs, with particular attention to the development of endpoints and biomarkers, and the validation of new ecotoxicity tests.