Preface. List of Contributors. Phylogenetic Distribution of Cholinesterases and Related Esterases (C.H. Walker, H.M. Thompson). Biochemical Characteristics of Cholinesterases in Aquatic Organism (C. Habig, R.T. Di Giulio). Methods Used in Determination of Cholinesterase Activity (A. Fairbrother, B.T. Marden, J.K. Bennett, M.J. Hooper). The Mechanism of Organophosphate Inhibition of Cholinesterase - Proposal for a New Approach to Measuring Inhibition (S.W. Kennedy). Biological Variability and the Influence of Stress on Cholinesterase Activity (B.A. Rattner, A. Fairbrother). Serum "B" Esterases as Indicators of Exposure to Pesticides (H.M. Thompson). Use of Cholinesterase Measurements in Surveillance of Wildlife Poisoning in Farmland (P.W. Greig-Smith). Biological Consequences of Depressed Brain Cholinesterase Activity in Wildlife (C.E. Grue, A.D.M. Hart, P. Mineau). Factors Influencing Variability in Brain Acetylcholinesterase Activity in Songbirds Exposed to Aerial Fenitrothion Spraying (D.G. Busby, L.M. White). The Effects of Cholinesterase Inhibiting Insecticides on Fish (J.G. Zinkl, W.L. Lockhart, S.A. Kenny, F.J. Ward). The Use of Cholinesterase Measurements in Assessing the Impacts of Pesticides on Terrestrial and Aquatic Invertrebates (C.A. Edwards, S.W. Fisher). Difficulties in the Regulatory Assessment of Cholinesterase-Inhibiting Insecticides (P. Mineau). Bibliography. List of species or genera mentioned in the text. An index of organophosphate and carbamate insecticides and other cholinesterase-inhibiting chemicals mentioned in the text.