1. From the University of Edinburgh, Department of Medicine, Western General Hospital (B.R.W., J.P.N., M.P., R.A., J.R.S., D.J.W.), and Ladywell Medical Centre (H.V.E., D.W.H.), Edinburgh; the MRC Environmental Epidemiology Unit, Southampton General Hospital, Southampton (D.I.W.P.); and the University of Glasgow, Department of General Practice, Woodside Health Centre, Glasgow (G.C.M.W.), UK.