NEUROLOGICAL SYNDROMES OF ORGANOPHOSPHORUS COMPOUNDS

In addition to the acute cholinergic poisoning, organophosphorus (OF) compounds are capable of producing several subacute, delayed and chron ic neurological, neurobehavioural and psychiatric syndromes. These inc lude the intermediate syndrome, the organophosphate induced delayed ne uropathy (OPIDN) and a number of chronic neurological and psychiatric manifestations lumped in this review under the term chronic organophos phate induced neuropsychiatric disorder (COPIND). A critical review of the concept of the neuropathy target esterase (NTE) inhibition and ag eing as a marker of OPIDN and the related hen test is presented. It is concluded that the use of the hen test as an exclusive screening test for neurotoxicity of organophosphorus compounds is flawed. A number o f recent studies are presented to demonstrate the unreliability of the test and flaws of scientific concepts underlying the hen test which i s used to identify OPs as safe and ''non-neurotoxic''. The components of this new COPIND syndrome are described and the evidence for its exi stence is reviewed. Studies are in progress to further determine the p rofile of this syndrome and to define the overlap between its various components. The review also attempts to determine the clinical feature s so far described of these components and the investigations or marke rs used to identify and characterize COPIND and the behaviour of these markers. Evidence for chronic neurological/psychiatric effects of OP compounds have come from case studies, clusters of neurological diseas es or from epidemiological investigations. New concepts in neurotoxico logy are being produced from recent studies which may necessitate a ne w radical approach to the assessment of neurotoxicity of pesticides be fore releasing them for widespread use.