Ian Shaw is Professor of Toxicology and head of the Centre for Toxicology at the University of Central Lancashire, UK and visiting consultant toxicologist to the Royal Preston Hospital. He has broad research interests ranging from the cellular toxicity of free radicals through to plutonium biochemistry and is Chairman of the UK Government's working party on pesticide residues. John Chadwick is Head of the Environmental Sciences Section of HSE's Health Divisions Chemical Appraisals Unit and is a member of a number of government expert environmental groups including the Advisory Committee on Pesticides Environmental Panel. He is responsible for environmental risk assessments associated with the revision of existing, and registration of new, agricultural pesticides.