Organo-phosphorus poisoning

It is indicated as antidote for organo-phosphorus poisoning like malathion, TEPP, parathion etc. 

Cowan, F.M., Shih, T.M., Lenz, D.E., Madsen, J.M., Broomfield, C.A. (1996). H pothesis for synergistic toxicity of organo-phosphorus poisoning-induced cholinergic crisis and anaphylactoid reactions. J. Appl. Toxicol. 16 25-33. 

Bobba, R, Venkataraman, B, V Pais, P. and Joseph, T. (1996). Correlation between the severity of. symptoms in organo-phosphorus poisoning and cholinesterase activity (RBC and plasma) in humans. Indian J. Physiol. Pharmacol 40, 249-252. 

Willems, J.L., de Bisschop, H.C., 1993. Cholinesterase reactivation in organo-phosphorus poisoned patients depends on the plasma concentrations of the oxime pralidoxime methylsulphate and the organophosphate. Arch. Toxicol. 67, 79-84. 

Hopf2 concludes that although insect nerve tissues produce substances that simulate acetylcholine and a cholinesterase which is inhibited by organo-phosphorus insecticides, these substances (in locusts at any rate) are not antagonized by atropine. Furthermore, tubocurarine does not poison insects, although it is active in warm-blooded animals and affects the neuromuscular junctions (see pp. 36, 37). In short, different physiological mechanisms appear to be at work in insects. In particular, it seems that acetylcholine, when injected into a variety of insects, has no marked toxic action. It seems then that, in some... 

As mentioned above, to apply to insects a conclusion drawn directly from tests on mammals may sometimes be misleading.3 For instance, American cockroaches have a remarkably high tolerance for acetylcholine,4 but, on the other hand, a substance showing some of the pharmacological properties of acetylcholine does accumulate in flies and cockroaches poisoned with D.D.T. Similarly, Hopf, working with locusts, was unable to demonstrate any increase in toxicity of eserine or T.E.P.P. resulting from the subsequent injection of acetylcholine. From this, Lord and Potter infer that acetylcholine may not be directly involved in the insecticidal action of organo-phosphorus compounds, either because the enzymes which hydrolyse acetylcholine are not inhibited to any considerable extent in vivo or because the functions performed by acetylcholine in mammals are performed by another substance in insects. 

Organo-phosphorus compounds and fly control. Certain organo-phosphorus compounds have been used as fly-controlling agents, where fly populations have become resistant to chlorinated hydrocarbons such as D.D.T.2 The compounds are applied in the form of sugar baits which attract the flies and so increase the effectiveness of the poisons. 

Further interesting observations along these lines2 are awaited especially in connexion with poisoning by organo-phosphorus compounds. 

If rats, during a brief hexobarbitone anaesthesia, are intravenously injected with barely sublethal doses of organo-phosphorus cholinesterase inhibitors which are able to pass the blood-brain barrier, the animals produce a hypothermia of 4-6° in 2-3 h, followed by spontaneous recovery in 12-20 h. This phenomenon has also been demonstrated in mice but not in guinea pig or rabbit. A few clinical reports of human cases of organo-phosphate poisoning mention a severe drop in the body temperature of the victims. The anticholinesterase hypothermia in the rat can partly be prevented by systemic atropine, but not by atropine methyl nitrate (for details and references, see Meeter, 1971a). 

Another suggestion germane to this article is that the tents the troops were using were sprayed with organo-phosphorus insecticides and were then used while still wet with insecticide on this thesis. Gulf War syndrome is due to organo-phosphorus insecticide poisoning (see above). 

Modeling of Poisoning by Organo Phosphorous Compounds. - Hegedus and Cavendish have proposed a mathematical model for phosphorus poisoned automotive catalysts. Using electron microprobe analysis they observed four different zones in a partially deactivated pellet. The schematic representation of the cross section of this pellet is shown in Figure 18. 

Various organo-phosphorus compounds are used two of the commonest are demeton-S-methyl and chlorpyrifos. Poisoning causes headaches, nausea and blurred vision. Further symptoms include muscle twitching, cramps in the belly muscles, severe sweating and respiratory difficulties. Extreme exposure may lead to death. All these effects are due to interference with a chemical enzyme called cholinesterase which is concerned with the passage of nerve impulses. The level of this enzyme in the worker s blood can be measured and if it falls below a certain value the worker must be removed from contact with the chemical until his blood returns to normal. The appropriate protective clothing must be worn at all times when working with these materials. 

Green, A.L., 1983. A theoretical kinetic analysis of the protective action exerted by eserine and other carbamate anticholinesterase against poisoning by organo-phosphorus compounds. Biochem. Pharmacol. 32, 1717-1722. 

The introduction of the organo-phosphorus insecticides, about 1945, greatly widened the spectrum of available types. Like the chlorinated hydrocarbons, these are also nerve poisons, but they act in a quite different way, namely by inhibiting esterases. Unfortunately the early examples, discovered in Germany by Schrader, were as toxic for those who sprayed... 

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