Parathion paraoxon

Chemicals. Insecticides, at least 95% pure, were prepared as acetone solutions p-p DDT, lindane, parathion, paraoxon, malathion, malaoxon, propoxur, carbaryl, LandrinR, aminocarb, mexacarbate, allethrin (90%), piperonyl butoxide (PBO) and sesamex. Aldrin was 98.5% and dieldrin was 99+% pure. 

Walter Reed-Wistar and Charles River male adult rats were exposed to oral doses of turpentine or to turpentine vapors, which consisted of a- and p-pinene. These exposures were followed by oral administration of heptachlor epoxide or of one of three pesticides, paraoxon, heptachlor, or parathion, or by an intraperitoneal injection of hexobarbital. The studies revealed that pretreatment with turpentine reduced hexobarbital sleeping time, reduced the parathion LDso, and increased the heptachlor LDso. The paraoxon and heptachlor epoxide LOo values were unchanged. a-Pinene and P-pinene vaporized from turpentine had no effect on either hexobarbital sleeping time or parathion, paraoxon, or heptachlor epoxide mortality but did increase the heptachlor LDso (Sperling et al. 1972). The authors speculated that increases in hepatic microsomal enzyme activity are responsible for these differences. 

Methyl Malathion Malaoxon Parathion Paraoxon Ethion ... 

Water and beef muscle Chlorpyriphos, fenphur, fenthion, fenthoxon, 3-methyl-4-(methylthio) phenol, parathion, paraoxon, p-nitrofenol, ronnel, ronnel oxon, 3,4,5-trichlorophenol stirophos ... 

The procedure involves converting oxon to thion toxicity equivalents by multiplying the oxon value by its relative toxicity (ED of thion r ED,.q of oxon) in Table I. The ED. value is the aermal dose in ug/cnr of total body surface which produces 50% inhibition of red cell ChE activity 72 hours after application. The total thion and oxon level is then divided by the thion toxicity equivalents and the factor is multiplied by the safe level established for thion in Table I. This procedure was conducted for the dislodgeable residues of parathion-paraoxon, methidathion-methidathion oxon, and azinphosmethyl-azinphosmethyl oxon. The safe levels for the total disloggeable residues were determined to be 0.06, 0.2 and 1.6 ug/cm, respectively, for... 

The safe levels established for parathion + paraoxon, azinphosmethyl + azinphosmethyl oxon and methidathion + methi-dation oxon on foliage have absorbance values determined by the rapid field method (4 ) equal to those given in Table III. Absorbance values greater than those listed in Table III signal an unsafe working condition. Field testing can also be conducted by standard gas chromatographic analysis of the leaf disk samples by state-approved laboratories. 

Parathion, paraoxon Flame -ionisation 0.2ppg (parathion) 2ppb (paraoxon) [387]... 

Breakdown products of parathion (paraoxon and jp-nitrophenol), trifluralin (ethylbenzimidazole), and chlorpyrifos (chlorpyrifos oxon) were surprisingly significant residues. 

The OPPs with an aromatic ring (e.g., azinphos-methyl, azinphos-ethyl, coumaphos, diazinon, fenitrothion, fenthion, parathion, paraoxon, tetrachlorvinphos, trichloronate) can be determined with UV/DAD because they contain good chromophores. Problems are encountered with pesticides such as, dimethoate, disulfoton, malathion, or trichlorfon, which have no chromophores. The wavelength data for analyzing OPPs using LC-UV/DAD are given in Table 23.13. 

Results. Redox Reaction Models of Parathion, Paraoxon, and p-NiTROPHENOL OXIDATIONS BY KMn04. Before proceeding to the kinetic studies, computations and experiments were conducted to determine the fate of the reactants under acidic and alkaline conditions. Assumptions were made concerning the oxidation states of the various elements ... 

The experimental values of the ratio are given in Table VI. From the same experiment the number of moles of KMn04 required to oxidize completely I mole of compound (parathion, paraoxon, or p-nitrophenol) was calculated (Table VI). The observed experimental data agree well with the hypothetical reactions proposed to oxidize completely parathion, paraoxon, and p-nitrophenol (Equations 6, 7, 8, 9, 10, II). 

Table VI. Potassium Permanganate Consumed by the Oxidation of Parathion, Paraoxon, and -NitrophenoP (25)...

KMn04 OxmATiON of Parathion, Paraoxon, and p-Nitrophenol. The rates of oxidation of parathion, paraoxon, or p-nitrophenol by potassium permanganate depended upon pH. The oxidation rate is proportional to the product of the residual concentrations of both reactants. Determining the reaction order was done by fitting the data into the difierent kinetic equations. Regardless of the complex stoichiometry. 

KMn04 oxidizes parathion, paraoxon, and p-nitrophenol and follows a second-order kinetic equation ... 

Paraoxon is not the final oxidation product of parathion oxidized by KMn04 as reported by Robeck et ah (21) and Schiavone and Torrado (38). By comparing overall rates of paraoxon and p-nitrophenol oxidation with the rate determined for parathion, it is possible to explain the differences in their accumulation rates during the parathion oxidation under acidic, neutral, and alkaline conditions. Table X summarizes the rate constants of oxidations of the three compounds, parathion, paraoxon. 

Parathion, paraoxon and EPN are subject to reduction of the aromatic nitro group to an amino group [159] by mammalian, avian and piscine tissues [160], Paraoxon is the most readily reduced of the three compounds, EPN the least. Paraoxon metabolism to aminoparaoxon is the route of inactivation by rat, chicken and guinea-pig livers in vitro [160]. However, enzymatic hydrolysis of the phosphorus-nitrophenyl linkage of the oxo-analogues appears to he a major pathway of detoxication in manunals [142, 161, 162] but bovine rumen fluid is capable of reducing parathion and EPN to their... 

Azomethine group (>C=N-) containing compounds cyolane, cytrolane, chlordimerform, drazoxolon s-Triazines atrazine Chlorinated compounds 2,4-D (2,4-dichlorphenoxyacetic acid), propachlor (2-chloro-A/-2-propylacetanilide), pentachlorophenol, picloram (4-amino-3,5,6-trichloropicolinic acid), hexachlorocyclohexane Nitro-group-containing compounds metaphos (o,o-dimethyl-o-(4-nitrophenyl) thiophosphate, parathion, paraoxon... 

Organophosphorus hydrolase (OPH, EC 3.1.8.1) is a homodimer with a binuclear metal center. OPH has broad substrate specificity and can hydrolyze organophosphate pesticides such as methyl paradiion, ediyl parathion, paraoxon, chlorpyrifos, coumaphos, cyanophos and diazinoa Table I 9,12-14). The enzymatic hydrolysis rates are 40 - 2450 times faster than chemical hydrolysis at pH 7.0 and the enzyme is reported to be stable at ten ratures of up to 4S-S0°C (3). However, hydrolysis rates varied from very fast for phosphotriesters and phosphothiolester pesticides (P-0 bond) such as paraoxon (ken > 3800s ) and coumaphos (kcat = 800s ) to limited hydrolysis for Diazinon (kcat == 176 s ) and fensulfothion (l a, = 67 s ) (14). 

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