POISONINGBY META-ISOSYSTOXINSPRAYMEN AND INACCIDENTALLYEXPOSED PATIENTS

Onehundredandtwenty-six patients poisoned bytheorganic phosphorus insecticide Metaisosystox were investigated. Hiccough andextrapyramidal manifestations were noticed insome patients. Serumcholinesterase levels showed aninitial fall andthen arise abovenormal. Thefall ofcholinesterase was markedinpatients whowereexposed forrelatively longperiods butnotin patients accidentally exposed forshort times. Therise inserumcholinesterase isthought tobea compensatory protective mechanism. Correlation between serum cholinesterase levels andsymptomatology was absentinsome patients butpresent inthemajority. Cholinesterase inhibition may notbetheonlymechanism by whichorganic phosphorus compounds causepoisoning. Sinceorganic phosphorus compounds were first usedasinsecticides inagriculture many reports and reviews havebeenpublished on poisoning bythese compounds (e.g., Report oftheCouncil onPharmacy andChemistry, 1950;BarnesandDavies, 1951; NambaandHiraki, 1958; Barnes, 1959; andQuinby, 1964). InEgypt,0,0-dimethyl S-ethylthioethyl phosphorothiolate (Meta-isosystox, Bayer)hasbeen widely sprayed inearly growing cottonfields to control thrips. IntheBeni-Suef region, 673spraymen were notified as poisoned byMeta-isosystox, including threedeaths aboutone weekafter the programme ofspraying hadbegun.Inthepresent study estimations weremadeofserumcholinesterase (ChE)insome workers whiletheywere showing toxic manifestations, andinan attempt tocorrelate thelevel ofserum ChEwiththedegree ofintoxicationthese patients were followed up until theyhad recovered. Theonly casesreported arethose whose serum ChE was examined. Theothers hadeither recovered or were notavailable atthetimeofthis test.Control individuals living inthesame villages butnotexposed tothespraywerealsoexamined.