Insecticides degradation

Getzin, L.W. and I. Rosenfield. 1968. Qrganophosphorus insecticide degradation by heat-labile substances in soil. Jour. Agric. Food Chem. 16 598-601. 

Getzin, L.W. Factors inflnencing the persistence and effectiveness of chlorpyrifos in soil, J. Econ. Entomol, 78 412-418,1985. Getzin, L.W. and Rosefield, I. Organophosphoms insecticide degradation by heat-labile snbstances in soil, J. Agric. Food Chem., 16(4) 598-601, 1968. 

Consider the following purely hypothetical example assessment for the exposure of an insectivorous bird to a new agricultural insecticide. This insecticide degrades very quickly after application, so that its toxicity dissipates after 24 hours. It does not bioaccumulate, and nonlethal doses are metabolized with no long-term consequences for the bird. These features imply a fairly simple assessment, involving the following expression for computing exposure of a bird to the insecticide within 1 day of its field application... 

Laboratory Studies on Insecticide Degradation. Degradation in natural waters Stream water (pH 6.0) and sediment (organic content 36%) were taken from a small shallow stream (depth ca 20 cm, width oa 1.5 m) in the Goulais River watershed, a mixed conifer-deciduous forest area, ca 50 km northeast of Sault Ste. Marie, Ont., Canada. Two degradation studies in duplicate (one for aminocarb and another for fenitrothion) were set up according to Sundaram and Szeto ( 1 ). Aminocarb and fenitrothion (100 pg/L in acetone) were added separately to 1000 mL aliquots of sterilized (Ameco Sterilizer 1 h) and unsterilized stream water in either open or closed 1500 mL Erlenmeyer flasks. The latter were sealed with polyethylene snap caps which were removed once a day for about 1 min. to allow air exchange. The flasks were incubated at 15 0.2°C in an environmental chamber. Unfortified water... 

Syvanen, M., Zou, Z., Wharton, J., Goldsbury, C., and Clark, A., Heterogeneity of the glutathione transferase genes encoding enzymes responsible for insecticide degradation in the house fly, /. Med. Evoi, 43, 236,1996. 

The first part of the laboratory methodology for study of enhanced degradation Involved use of a rapid degradation assay by which an Idea of the rate of insecticide degradation could be obtained for a large number of soils. The soils for this assay were collected during the fall from Iowa cornfields with known histories of Insecticide use. In some cases the soils collected were specifically from fields in which an insecticide had been used for several years and no longer provided suitable control of soil insect pests. In these cases a separate soil was also collected from an adjacent field or from the field fencerow. 

FELSOT TOLLEFSON Coping with Soil Insecticide Degradation... 

Malathion provides an elegant example of the way in which the different enzymes present in mammals and insects lead to detoxification in one case and activation in the other. Oxidation and hydrolysis, two of the commonest processes occurring in insecticide degradation, are involved. Rapid oxidation occurs in insects, converting the mildly active malathion into strongly active mala-oxon, while in mammals there is rapid hydrolysis to an inactive compound. The schane can be represented approximately as in Figure 12.21. 

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