Carbamates propoxur

Like other carbamates, propoxur can inhibit the action of cholinesterase and disrupt nervous system function. Depending on the severity of exposure, this effect may be short-term and reversible. 

Carbamate Propoxur Carbaril Fleas, ticks Collars aerosol spray Solution... 

A mystery illness that affected 17 casino workers following fumigation of the premises with a pesticide mixture that contained the carbamate propoxur (1.52), the organophosphate coumaphos (4.13), 1,1,1-trichloro-ethane (2.49), methylene chloride (1.25), xylene (3.15), and acetone... 

Determination. HPLC comparative tables with recoveries for the different solvents and matrixes are given. MAE was applied to study the thermal degradation of five carbamates some nonpolar and polar pollutants spiked in soil, such as PAHs, PCBs, triazines (atrazine, simazine), and carbamates (propoxur, methiocarb, chlorpropham) subjected to MAE were also studied the recoveries ranged between 70 and 99% with excellent reproducibility, except for carbamates Determination. LC—MS-MS recoveries... 

Kobayashi, H Yuyama, A., Ohkawa, T, ami Kajita, X (1988), Effect of single chronic injection with a carbamate, propoxur, on the brain cholinergic sy.stcm and behavior of mice, Jpn. J. Pharmacol. 47, 21-27. 

Cross-tolerance between disulfoton and another organophosphate, chlorpyrifos, was observed in mice (Costa and Murphy 1983b). Because of this cross-tolerance, a benefit is derived as a result of this interaction. In the same study, propoxur-tolerant mice were tolerant to disulfoton but not vice versa. Propoxur (a carbamate) is metabolized by carboxylesterases, and these enzymes are inhibited in disulfoton-tolerant animals disulfoton-tolerant animals are more susceptible to propoxur and/or carbamate insecticides than are nonpretreated animals. In another study, disulfoton-tolerant rats were tolerant to the cholinergic effects of octamethyl pyrophosphoramide (OMPA) but not parathion (McPhillips 1969a, 1969b). The authors were unable to explain why the insecticides OMPA and parathion caused different effects. 

Costa LG, Murphy SD. 1983b. Unidirectional cross-tolerance between the carbamate insecticide propoxur and the organophosphate disulfoton in mice. Fundam Appl Toxicol 3 483-486... 

A photometric flow-through sensor for the determination of carbamate pesticides (carbofuran, propoxur and carbaryl) based on similar principles as regards the detector and sensor used (a diode array spectrophotometer and a flow-cell packed with C,g resin, respectively) was employed to monitor the formation of the products resulting from hydrolysis of the analytes and online coupling of the respective phenols with diazotized sulphanilic acid. This... 

RJ Argauer, KY Eller, MA Ibrahim, RT Brown. Determining propoxur and other carbamates in meat using HPLC fluorescence and gas chromatography/ion mass spectrometry after supercritical fluid extraction. J Agric Food Chem 43 2774-2778, 1995. 

Carbaryl, propoxur (isopropyl phenyl N-metbyl carbamate) Crops Reaction with trifluoroacetic anhydride GC with ECD 0.005 ppm [66]... 

Biocides most often found in the indoor environment are chlorinated hydrocarbons like chlordane, DDT, dieldrin, lindane, heptachlor and methoxychlor, pyrethroids like cyfluthrin, cypermethrin, and permethrin, organophosphates like chlorpyrifos, diazinon, dichlorvos, isofenfos, and malathion, carbamates like ben-diocarb, carbaryl and propoxur and chlorophenols like pentachlorophenol (PCP), chlorocresol (4-chloro-3-methylphenol) and o-phenylphenol. Residues formed in house dust may vary in different countries (Butte, 2003), but biocides like chlorpyrifos, DDT, methoxychlor, permethrin, pentchlorophenol and propoxur seem to be the active compounds in biocide formulations even in different continents, as they are found equally in house dust samples form Germany and the USA (Becker et al., 2002 Butte, 2003 Camann, Colt and Zuniga, 2002). Concentrations of biocides in house dust are mostly in the milligram per kilogram range, they seldom exceed a microgram per cubic meter in indoor air. 

Carbamate insecticides Phosphamidon Aldicarb, Maneb, Propoxur, Thiram, Zineb, Ziram... 

WP formulations of carbamates such as propoxur and bendiocarb were previously used extensively for malaria control in Colombia, Costa Rica, El Salvador, Guatemala, Nicaragua and Panama, and sporadically in Mexico and Venezuela. The use of these products has been all but discontinued in the past 10 years except in Costa Rica and Guatemala, where they are still applied in small quantities. 

N-Dealkylation This is a common reaction in the metabolism of xenobiotics, including organophosphorus and carbamate insecticides. The reaction is believed to proceed by an unstable a-hydroxy intermediate that spontaneously releases an aldehyde in the case of the primary alkyl group. For example, the carbamate insecticide propoxur is N-demethylated to 2-isopropoxyphenyl carbamate via 2-iso-propoxyphenyl N-hydroxymethyl carbamate. Microsomal N-dealkylation results in detoxification (Figure 8.5). 

Cross-resistance refers to a situation in which a strain that becomes resistant to one insecticide automatically develops resistance to other insecticides to which it has not been exposed. For example, selection of a strain of Spodoptera littoralis with fenvalerate resulted in a 33-fold increase in tolerance to fenvalerate. The resistant strain also showed resistance to other pyrethroids (11- to 36-fold) and DDT (lower than for the pyrethroids). Exposure of Cidex qninquefasciatus to fenitrothion resulted in the development of resistance to the carbamate insecticide propoxur. Similarly, selection of a housefly strain with permethrin resulted in a 600-fold increase in resistance to permethrin. The resistant strain also showed resistance to methomyl, DDT, dichlorvos, and naled (Hassall, 1990). 

Caibamate pesticides are used as insecticide, acaricide, and herbicide. Various subclasses can be distinguished. Aryl V-methyl carbamates (1), such as caibaiyl, carbofuran, propoxur, and oxime V-methyl carbamates(2), such as aldicaib, methomyl, oxamyl, have most widely been studied. LC-MS is the method-of-choice for carbamates, since their thermal lability prohibits GC analysis. 

In APCI mass spectra of carbamates, fragment ions are observed, which are most likely due to thermal decomposition in the heated nebulizer interface and snbseqnent ionization of the thermal decomposition products [11, 14, 20-23]. For example, base peaks were observed at m/z 163 for oxamyl, due to the loss of methyl isocyanate, at m/z 168 for propoxur, dne to the loss of propylene, and at m/z 157 for aldicarb, due to the loss of HjS. The APCI mass spectra of aldicaib and two of its metabolites, aldicarb sulfoxide and aldicarb snlfone, showed significant fragmentation. Major fragments for aldicarb were dne to the loss of carbamic acid (to m/z 116) and due to charge retention at [CH3-S-C(CH3)2]. For aldicarb sulfoxide and aldicarb sulfone, the loss of carbamic acid resnlted in the base peaks of the spectra (at m/z 132 and 148, respectively). 

The most important inhibitors of CarbEs are organo-phosphorus insecticides (malathion, parathion, para-oxon, methyl parathion, EPN, and others), nerve agents (DFP, soman, sarin, tabun, and VX) and carbamate insecticides (carbofuran, carbaryl, aldicarb, propoxur, oxamyl, methomyl, and others). Organo-phosphorus toxicants inhibit CarbEs irreversibly by phosphorylation and carbamates inhibit CarbEs reversibly by carbamylation similar to the basic mechanism (i.e., acylation of the active site) ... 

Toxicity of organophosphates can be potentiated 15-20-fold in rats and mice by pretreatment with a metabolite of tri-O-cresylphosphate, CBDP (2-0-cresyl)-4H-l,3,2-benzodioxa-phosphorin-2-oxide), which is an irreversible inhibitor of CarbEs. In similar studies, tetraisopropylpyrophosphoramide (iso-OMPA), or mipafox, an organophosphate-irreversible inhibitor of CarbEs, potentiates three-to fivefold the toxicity of several OPs (soman, DFP, and methylparathion) and carbamates (carbofuran, aldicarb, propoxur, and carbaryl). Inhibition of CarbEs by CBDP, iso-OMPA, or mipafox pretreatment, particularly in plasma, liver, heart, brain, and skeletal muscles, is a major contributory factor in the potentiation of toxicity of organophosphates and carbamates. Thus, the toxicity of any drug, pesticide, or other type of agent that is normally detoxified by CarbEs, could be potentiated by pre-exposure to an organophosphorus or other carboxylesterase inhibitor. 

The mixture of the carbamate pesticide propoxur with either arsenic or mercury resulted in unanticipated changes in the spleens of laboratory animals orally exposed to the mixtures, when compared to the effects noted after treatment with propoxur, arsenic, or mercury alone.I37l... 

In resistant green rice leafhopper, an acetylcholinesterase with reduced affinity for N-methyl carbamate insecticides had increased sensitivity to inhibition by longer N-alkyl groups however, the inverse relationship was observed against the susceptible enzyme (21). The optimal substitution appeared to be N-(n-propyl) and the use of this chemistry in a resistance breaking strategy was discussed. Unfortunately, N-(n-propyl)propoxur was inhibitory of neither susceptible nor resistant acetylcholinesterase of predatory mites, Amblyseius potentillae so that this type of vulnerability is not common to all resistant acetylcholinesterases (22)-... 

The LC/MS positive-ion mode analysis of grape carbamates reported in Fig. 9.11 (carbaryl, carbofuran, diethofencarb, ethiofencarb, fenobu-carb, fenoxycarb, isoprocarb, methiocarb, metholcarb, oxamyl, pirimi-carb, propoxur, and thiobencarb) was performed by matrix solid-phase dispersion (MSPD) extraction using either atmospheric pressure-chemical ionization (APCI) or electrospray ionization (ESI) (Fernandez et al., 2000). 

Figure 9.11. Carbamates determined by LC-atmospheric pressure chemical ionization (APCI) or electrospray (ES) in positive-ion mode (Fern ndez et al., 2000). (24) car-bofuran, (25) ethiofencarb, (26) methiocarb, (27) fenobucarb, (28) isoprocarb, (29) fenoxycarb, (30) diethofencarb, (31) metholcarb, (32) propoxur, (33) pirimicarb, (34) oxamyl, (35) thiobencarb. Structure of carbaryl is reported in Fig. 9.1.

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