Poisons organophosphates

In 1916, calcium arsenate [7778-44-1] dusted by airplane was used to control the boU weevil however, throughout many developments in effective insecticides, such as organophosphates, the boU weevils became resistant to poisons that were formerly effective (see Insectcontroltechnology). 

Cholinesterases (ChEs), polymorphic carboxyles-terases of broad substrate specificity, terminate neurotransmission at cholinergic synapses and neuromuscular junctions (NMJs). Being sensitive to inhibition by organophosphate (OP) poisons, ChEs belong to the serine hydrolases (B type). ChEs share 65% amino acid sequence homology and have similar molecular forms and active centre structures [1]. Substrate and inhibitor specificities classify ChEs into two subtypes ... 

Diagnosis of organophosphate poisoning (including methyl parathion) can be confirmed by evaluation of serum (plasma) cholinesterase and erythrocyte cholinesterase. However, cholinesterase inhibition is not specific for organophosphates. For example, carbamate insecticides also result in cholinesterase inhibition, which is usually transitory. Erythrocyte cholinesterase measurement is a specific test for... 

A classification of organophosphate poisoning has been proposed by Tafuri and Roberts (1987) modified from Namba et al. (1971). Clinical signs and symptoms of intoxication may occur when serum cholinesterase levels drop to below 50% of the normal value. Mild poisoning, with the patient still ambulatory, may occur when serum cholinesterase levels are 20-50% of normal moderate poisoning with inability to walk with levels 10-20% of normal and severe poisoning with respiratory distress and unconsciousness with serum cholinesterase levels <10% of normal. 

Dean A, Pugh J, Embrey K, et al. 1984. Organophosphate insecticide poisoning among siblings—Mississippi. MMWR 33 592-594. 

De Bleecker JL. 1992. Transient opsoclonus in organophosphate poisoning. Acta Neurol Scand 86 529-531. 

Lotti M, Becker CE. 1982. Treatment of acute organophosphate poisoning Evidence of a direct effect on central nervous system by 2-PAM (pyridine-2-aldoxime methyl chloride). J Toxicol Clin Toxicol 19 121-127. 

Midtling JE, Barnett PG, Coye MJ, et al. 1985. Clinical management of field worker organophosphate poisoning. West Med 142 514-518. 

Namba T, Nolte CT, Jackrel J, et al. 1971. Poisoning due to organophosphate insecticides—Acute and chronic manifestations. Am J Med 50 475-492. 

Vandekar M, Reiner E, Svetlicic, et al. 1965. Value of ED50 testing in assessing hazards of acute poisoning by carbamates and organophosphates. Br J Ind Med 22 317-320. 

Use of the muscle relaxant succinylcholine, which is metabolized by plasma cholinesterase, is contraindicated in cases of organophosphate poisoning (Giurini et al. 1986). 

Organophosphate Ester Hydraulic Fluids. Human studies of exposure to organophosphates are primarily those of acute, accidental poisonings with tricresyl phosphate (Goldstein et al. 1988 Senayanake and Jeyaratnam 1981 Srivastava et al. 1990). 

MintonNA, Murray VSG. 1988. A review of organophosphate poisoning. Med Toxicol 3 350-375. 

Suggested Alternatives for Differential Diagnosis Anthrax, tetanus, rabies, meningitis, encephalitis, cerebral trypanosomiasis, piroplasmosis, theileriosis, listeriosis, parasitism poisoning by strychnine, lead, organophosphates, arsenic, and various plants that affect the central nervous system. 

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