Pesticide residues organophosphates

Each sample was analyzed for a specific set of compounds, corresponding to pesticide residues that might occur in the Suit or vegetable from use of one or more organophosphate insecticides on the growing crop. Insecticides of interest are listed in Table 1. 

Chemical degradation has been investigated by Shlh and Dal Porto Q) and by Lande ( ) under EPA auspices as an alternative approach (to landfill disposal) for the removal of pesticide residues. Among candidate reactions for the safe detoxification of pesticides, only alkaline hydrolysis was recommended. Several organophosphates and carbamates were identified as amenable to a degradation procedure using strong base/aqueous alcohol. The... 

An automated supercritical fluid extraction and in-line clean-up system has been developed for organochlorine and organophosphate pesticide residues contained in fats (Hopper, 1999). 

Hopper ML. 1988. Improved method for partition of organophosphate pesticide residues on a solid phase partition column. J Asso Off Anal Chem 71(4) 731-734. 

Over 25 years ago Carman and coworkers recognized the adverse potential of fieldworker exposure to pesticide residues ( ). Subsequent fieldworker acute organophosphate intoxications and resulting political pressure led to regulations by the Occupational Health and Safety Administration and the Environmental Protection Agency. These regulations and the worker reentry situation have been the subject of reviews (, 3). 

Kahn, E. Outline guide for performance of field studies to establish safe reentry intervals for organophosphate pesticides, Residue Reviews, 1979, 0, 27. 

Simcox, N.J., R.A. Fenske, S. Wolz, I. Lee and D. Kalman (1995). Organophosphate Pesticide Residues in Residential Housedust and Soil in the Tree Fruit Region of Washington State, Environ. Health Perspect., 103, 1126-1134. 

Techniques. In 1962, McKinley and Read (42) developed an esterase-inhibition technique for the detection of organophosphate pesticide residues on paper chromatograms. The procedure involved conversion of the thiophosphates with bromine to yield active esterase inhibitors, the inhibition by the pesticide of the esterases from a beef liver homogenate sprayed onto the chromatogram, the hydrolysis of the substrate (a-naph-thyl acetate) which was sprayed onto the paper after the liver homogenate had dried, and the development of a background color between Fast Blue RR and the hydrolysis product, a-naphthol. 

Pesticide residues Acetochlor Alachlor Atrazine Carbendazin/Benomyl Cyclodienes, 2,4-D DDE Diuron Glyphosate Metolachlor Organophosphate/Carbamate Pyrethroids Spynosyn Surfactants Alkyl ethoxylate (AE) Alkylphenol ethoxylate (APE) Linear alkylbenzene sulfonate (LAS) Estrogens 17-B-Estradiol (E2) ... 

Mills PK, Zahm SH. Organophosphate pesticide residues in urine of farmworkers and their children in Fresno County, California. Am J Ind Med 2001 40 571-7. 

An Environmental Working Group study utilised detailed government data on food consumption patterns and pesticide residues to conduct the first comprehensive analysis of the toxic dose that infants and children receive when the entire organophosphate family of insect killers is assessed in combinations, and at levels, that actually occur in the food supply. Based on the most recent government data available on children s eating patterns, pesticides in food, and the toxicity of organophosphate insecticides, the EWG estimated that ... 

Since biodegradation is one of the most important techniques for the removal of pesticide residues, the following sections present studies on the biodegradation of organophosphate pesticides mainly by fungi and bacteria. 

Mice that were exposed dermally to residues of methyl parathion in emulsifiable concentrate on foliage, and were muzzled to prevent oral intake, developed inhibition of plasma cholinesterase and erythrocyte cholinesterase after two 10-hour exposures (Skinner and Kilgore 1982b). For the organophosphate pesticides tested in this study, cholinergic signs generally were seen in mice with cholinesterase inhibition >50% results for this end point were not broken down by pesticide. 

Maddy KT, Fong HR, Lowe JA, et al. 1982. A study of well water in selected California communities for residues of 1,3-dichloropropene, chloroallyl alcohol and 49 organophosphate or chlorinated hydrocarbon pesticides. Bull Environ Contam Toxicol 29 354-359. 

The OPMBS was sponsored by a task force, consisting of major registrants of organophosphate pesticides, and utilized three contract organizations to carry out study management, design and conduct of sample collection, and quality assurance (QA). Four analytical laboratories performed the necessary residue analyses. 

In the OPMBS, all compounds were determined that occurred in the tolerance expression for organophosphate pesticides being supported by the registrants in each of the 13 commodities. Thus, compounds to be determined were those that might occur as residues of organophosphate pesticides whose continued use was supported by members of the OPMBS Task Force. 

Organophosphate and carbamate pesticides are potent inhibitors of the enzyme cholinesterase. The inhibition of cholinesterase activity by the pesticide leads to the formation of stable covalent intermediates such as phosphoryl-enzyme complexes, which makes the hydrolysis of the substrate very slow. Both organophosphorus and carbamate pesticides can react with AChE in the same manner because the acetylation of the serine residue at the catalytic center is analogous to phosphorylation and carbamylation. Carbamated enzyme can restore its catalytic activity more rapidly than phosphorylated enzyme [17,42], Kok and Hasirci [43] reported that the total anti-cholinesterase activity of binary pesticide mixtures was lower than the sum of the individual inhibition values. 

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