9 moreTitle: Persistence and retention of active ingredients in four granular cholinesterase-inhibiting insecticides in agricultural soils of the lower Fraser River valley, British Columbia, Canada, with implications for wildlife poisoning Wilson LK, Elliott JE, Vernon RS, Smith BD, Szeto SY Ref: Environ Toxicol Chem, 21:260, 2002 : PubMed
The persistence and retention of active ingredients in granules of Thimet 15G (phorate 15% by weight), Dyfonate 10G (fonofos 10% by weight), Counter 15G (terbufos 15% by weight), and Furadan 10G (carbofuran 10% by weight) were determined in silt loam and organic muck agricultural soils typical of the lower Fraser River valley (BC, Canada). In June 1995, treatment bags made of polyester cloth (7.5 x 7.5 cm) containing granules of a single insecticide, either alone or with soil, were placed during spring planting in the bottom of the furrow and retrieved periodically until April 1996. The parent component of each insecticide declined monotonically except for carbofuran (logistic decline). In the silt loam (organic muck) soil, the average June-to-October first-order rate constants and half-lives were 0.009 (0.010)/d and 80 (71) d for fonofos, 0.012 (0.009)/d and 58 (82) d for phorate, and 0.032 (0.015)/d and 21 (47) d for terbufos; the half-life of carbofuran was 129 (97) d. By December, the average amounts of fonofos and phorate in silt loam (organic muck) were 26% (range: 17-40%; 14% [range: 3.4-21%]) and 21% (range: 15-30%; 10% [range: 5.0-24%]) of the initial amounts of active ingredients measured at time zero, respectively. By April, the percentages dropped to 16% (range: 7.8-24%; 2.3% [range: 0-7.7%]) and 7.3% (range: 1.9-25%; 0.6% [range: 0-1.9%]). During this period, about 95% of the active ingredients were granule bound, the rest remaining in the bag. Only low levels of terbufos and carbofuran persisted in both soils from December to April of the following year. Results indicate an enhanced probability for poisoning of waterfowl and raptors because of the high levels of active ingredients retained on granules of all four insecticides in both soils in the fall. The risk of acute poisoning by phorate and fonofos continued though the winter.
        
Title: Preparation of some toxic metabolites of disulfoton, phorate, and terbufos, their separation by thin-layer chromatography and confirmation by electron impact mass spectrometry Simonovska B Ref: Journal of AOAC International, 80:688, 1997 : PubMed
Milligram quantities of sulfoxides, sulfones, and oxygen analogue (oxon) sulfones of the insecticides disulfoton, phorate, and terbufos were prepared by selective oxidation. Pure insecticides or acetone extracts of granular formulations served as reactants. Structures of 9 compounds were confirmed by comparing their electron impact mass spectra (EI-MS), obtained by the direct inlet system with published data. Thin-layer chromatography (TLC) on silica gel was used to screen oxidation products and to purify products. Products were detected by spraying plates with PdCl2 reagent and exposing to iodine vapors. An esterase inhibition technique gave low detection limits, which are promising for residue analysis.
        
Title: Observations on the influence of water and soil pH on the persistence of insecticides Chapman RA, Cole CM Ref: J Environ Sci Health [B], 17:487, 1982 : PubMed
The pH-disappearance rate profiles were determined at ca. 25 degrees C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water-ethanol (99:1 v/v). Half-lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (greater than 1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1-2 days for trichlorfon and oxamyl to greater than 1 year for fensulfothion and cypermethrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.
        
9 lessTitle: Comparative toxicities of organophosphate and pyrethroid insecticides to aquatic macroarthropods Halstead NT, Civitello DJ, Rohr JR Ref: Chemosphere, 135:265, 2015 : PubMed
As agricultural expansion and intensification increase to meet the growing global food demand, so too will insecticide use and thus the risk of non-target effects. Insecticide pollution poses a particular threat to aquatic macroarthropods, which play important functional roles in freshwater ecosystems. Thus, understanding the relative toxicities of insecticides to non-target functional groups is critical for predicting effects on ecosystem functions. We exposed two common macroarthropod predators, the crayfish Procambarus alleni and the water bug Belostoma flumineum, to three insecticides in each of two insecticide classes (three organophosphates: chlorpyrifos, malathion, and terbufos; and three pyrethroids: esfenvalerate, lambda-cyhalothrin, and permethrin) to assess their toxicities. We generated 150 simulated environmental exposures using the US EPA Surface Water Contamination Calculator to determine the proportion of estimated peak environmental concentrations (EECs) that exceeded the US EPA level of concern (0.5xLC50) for non-endangered aquatic invertebrates. Organophosphate insecticides generated consistently low-risk exposure scenarios (EECs<0.5xLC50) for both P. alleni and B. flumineum. Pyrethroid exposure scenarios presented consistently high risk (EECs>0.5xLC50) to P. alleni, but not to B. flumineum, where only lambda-cyhalothrin produced consistently high-risk exposures. Survival analyses demonstrated that insecticide class accounted for 55.7% and 91.1% of explained variance in P. alleni and B. flumineum survival, respectively. Thus, risk to non-target organisms is well predicted by pesticide class. Identifying insecticides that pose low risk to aquatic macroarthropods might help meet increased demands for food while mitigating against potential negative effects on ecosystem functions.
        
Title: Prophylactic administration of non-organophosphate cholinesterase inhibitors before acute exposure to organophosphates: assessment using terbufos sulfone Lorke DE, Nurulain SM, Hasan MY, Kuca K, Petroianu GA Ref: J Appl Toxicol, 34:1096, 2014 : PubMed
Poisoning with organophosphorus compounds (OPCs) poses a serious threat worldwide. OPC-induced mortality can be significantly reduced by prophylactic administration of reversible acetylcholinesterase (AChE) inhibitors. The only American Food and Drug Administration (FDA)-approved substance for such pre-treatment (to soman exposure) is presently pyridostigmine, although its efficacy is controversial. In search for more efficacious and broad-spectrum alternatives, we have assessed in vivo the mortality-reducing efficacy of a group of five compounds with known AChE inhibitory activity (pyridostigmine, physostigmine, ranitidine, tacrine and K-27), when given in equitoxic dosage (25% of LD01 ) 30 min before exposure to the OPC terbufos sulfone. Protection was quantified in rats by determining the relative risk of death (RR) using Cox analysis, with RR = 1 for animals given only terbufos sulfone, but no pre-treatment. All tested AChE inhibitors reduced terbufos sulfone-induced mortality significantly (p </= 0.05) as compared with the non-treatment group (RR = 1: terbufos sulfone only). Best in vivo protection from terbufos sulfone-induced mortality was achieved, when K-27 was given before terbufos sulfone exposure (RR = 0.06), which was significantly (P </= 0.05) superior to the pre-treatment with all other tested compounds, for example tacrine (RR = 0.21), pyridostigmine (RR = 0.28), physostigmine (RR = 0.29) and ranitidine (RR = 0.33). The differences in efficacy between tacrine, pyridostigmine, physostigmine and ranitidine were not statistically significant. Prophylactic administration of an oxime (such as K-27) in case of imminent OPC exposure may be a viable option. Copyright (c) 2013 John Wiley & Sons, Ltd.
Neuroinflammation (NI) contributes to the pathogenesis of several neurodegenerative disorders. Epidemiological and a few animal studies have shown that chronic exposure of organophosphorus compounds (OPC) may cause neuronal injury and predispose to neuro- as well as psychotic disorders in conjunction with NI. However, in vivo studies are meager and do not represent the entire toxicologically diversified OPC. The present study aimed to investigate the result of non-observable adverse effect level dose of a highly toxic OPC, terbufos sulfone (TBS), on sub-chronic exposure on the status of proinflammatory cytokines; interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha in rats brain. In addition, lactate dehydrogenase, nitric oxide and reduced glutathione were also determined in brain. Red blood cell acetylcholinesterase was measured weekly. Total of four groups' saline control, diabetes control, non-diabetes TBS and diabetes treated with TBS were employed in the study. Control groups received saline and the experimental groups were injected with TBS intraperitonealy for fifteen days daily. Twenty four hours after the last injection, the animals were euthanized for collection of brain and serum samples. The study showed significant elevation of interleukin-6, tumor necrosis factor-alpha and lactate dehydrogenase in brain of TBS treated groups, while the presence of interleukin-1beta was significantly greater in the non-diabetes TBS treated group when compared with saline control. The increase was observed to be independent of acetylcholinesterase level and diabetes condition. The change in reduced glutathione was modest as compared with control. Based on the findings, the study concludes that the non-observable adverse effect level dose of TBS has potential to cause NI and subsequent neurodegeneration, a remarkable sign of many chronic neuronal and psychotic disorders. Further studies with prolonged exposure and other neurodegenerative parameters are warranted.
        
Title: Secondary poisoning of eagles following intentional poisoning of coyotes with anticholinesterase pesticides in western Canada Wobeser G, Bollinger T, Leighton FA, Blakley B, Mineau P Ref: J Wildl Dis, 40:163, 2004 : PubMed
Records of eagles, coyotes (Canis latrans), and red foxes (Vulpes vulpes) necropsied at the Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada, between 1967 and 2002 were reviewed for cases suggestive of anticholinesterase poisoning. From 1993 to 2002, 54 putative poisoning incidents involving 70 bald eagles (Haliaeetus leucocephalus) and 10 golden eagles (Aquila chrysaetus) were identified. Of these, 50 incidents occurred in Saskatchewan, two were in Manitoba, and one occurred in each of Alberta and the Northwest Territories. The diagnosis was confirmed in eight instances by demonstration of pesticide in ingesta from eagles or known use of pesticide at the site together with brain cholinesterase (AChE) reduction of >50% in at least one animal. A presnmptive diagnosis of poisoning was made in 33 incidents based on brain AChE reduction of >50% in at least one animal; 13 incidents were considered suspicious because of circumstantial evidence of the death of eagles in association with other species and limited AChE reduction. Other wild species were found dead in 85% of the incidents involving eagles. Coyotes, foxes, black-billed magpies (Pica pica), and striped skunks (Mephitis mephitis) were associated with 34, six, six, and three incidents, respectively. There were eight additional incidents that did not involve eagles in which poisoning was diagnosed in coyotes. Carbofuran was identified in nine incidents. Carbamate poisoning was indicated on the basis of reactivation of brain AChE activity in two additional incidents. Brain AChE activity was not reduced from normal in eagles in four of seven incidents in which carbofuran was identified. The organophosplorous insecticide terbufos was found together with carbofuran in one incident. Brain AChE activity was measured in wild canids and in eagles in 15 incidents; in all of these incidents, brain AChE was redulced by >50% in at least one mammal, whereas this level of reduction occrred in eagles in only four incidents. Use of anticholinesterase pesticides to poison coyotes is illegal, but the practice continues and secondary poisoning of eagles is a problem of unknown proportions in western North America.
The biotransformation by Flavobacterium sp. of the following organophosphate pesticides was experimentally and theoretically studied: phorate, tetrachlorvinphos, methyl-parathion, terbufos, trichloronate, ethoprophos, phosphamidon, fenitrothion, dimethoate and DEF. The Flavobacterium sp. ATCC 27551 strain bearing the organophosphate-degradation gene was used. Bacteria were incubated in the presence of each pesticide for a duration of 7 days. Parent pesticides were identified and quantified by means of a gas-chromatography mass spectrum system. Activity was considered as the amount (micromol) of each pesticide degraded by Flavobacterium sp. Also, structural parameters obtained by means of the CAChe program package for biomolecules, the reactivity index of phosphorus, of oxygen at the P = O function and of sulfur at the P = S function, and lipophilicity (log Poct) (ALOGPS v. 2.0) were obtained for each pesticide. Pesticides were hydrolyzed at the bond between phosphorous and the heteroatom, producing phosphoric acid and three metabolites. Enzymatic activity was significantly explained by the following multiple linear relationship: Enzymatic activity = 162.2 - 9.5(dihedral angle energy) - 25.0(Total energy) - 0.51(Molecular weight). Finally, a mechanism of Flavobacterium sp. to hydrolyze pesticides was proposed.
        
Title: Persistence and retention of active ingredients in four granular cholinesterase-inhibiting insecticides in agricultural soils of the lower Fraser River valley, British Columbia, Canada, with implications for wildlife poisoning Wilson LK, Elliott JE, Vernon RS, Smith BD, Szeto SY Ref: Environ Toxicol Chem, 21:260, 2002 : PubMed
The persistence and retention of active ingredients in granules of Thimet 15G (phorate 15% by weight), Dyfonate 10G (fonofos 10% by weight), Counter 15G (terbufos 15% by weight), and Furadan 10G (carbofuran 10% by weight) were determined in silt loam and organic muck agricultural soils typical of the lower Fraser River valley (BC, Canada). In June 1995, treatment bags made of polyester cloth (7.5 x 7.5 cm) containing granules of a single insecticide, either alone or with soil, were placed during spring planting in the bottom of the furrow and retrieved periodically until April 1996. The parent component of each insecticide declined monotonically except for carbofuran (logistic decline). In the silt loam (organic muck) soil, the average June-to-October first-order rate constants and half-lives were 0.009 (0.010)/d and 80 (71) d for fonofos, 0.012 (0.009)/d and 58 (82) d for phorate, and 0.032 (0.015)/d and 21 (47) d for terbufos; the half-life of carbofuran was 129 (97) d. By December, the average amounts of fonofos and phorate in silt loam (organic muck) were 26% (range: 17-40%; 14% [range: 3.4-21%]) and 21% (range: 15-30%; 10% [range: 5.0-24%]) of the initial amounts of active ingredients measured at time zero, respectively. By April, the percentages dropped to 16% (range: 7.8-24%; 2.3% [range: 0-7.7%]) and 7.3% (range: 1.9-25%; 0.6% [range: 0-1.9%]). During this period, about 95% of the active ingredients were granule bound, the rest remaining in the bag. Only low levels of terbufos and carbofuran persisted in both soils from December to April of the following year. Results indicate an enhanced probability for poisoning of waterfowl and raptors because of the high levels of active ingredients retained on granules of all four insecticides in both soils in the fall. The risk of acute poisoning by phorate and fonofos continued though the winter.
        
Title: Organophosphate poisoning in a group of replacement heifers and dry cows Khan O Ref: Can Vet J, 42:561, 2001 : PubMed
Terbufos ingestion caused acute organophosphate poisoning in 67 Holstein heifers and dry cows, 7 months to 5 years old. Overall mortality was 31%, with attack rates of 4% and 48% for the dry cows and heifers, respectively. Less severely affected animals were treated with atropine sulfate for 7 days.
        
Title: Larval susceptibility of an insecticide-resistant western corn rootworm (Coleoptera: Chrysomelidae) population to soil insecticides: laboratory bioassays, assays of detoxification enzymes, and field performance Wright RJ, Scharf ME, Meinke LJ, Zhou X, Siegfried BD, Chandler LD Ref: J Econ Entomol, 93:7, 2000 : PubMed
Soil insecticides were evaluated in laboratory and field studies against larvae of an insecticide resistant population (Phelps County, NE) of western corn rootworm, Diabrotica virgifera virgifera LeConte. Insecticide toxicity was evaluated by topical application of technical insecticides to 3rd instars from Saunders County, NE (susceptible) and Phelps County populations. Resistance ratios (LD50 Phelps County/LD50 Saunders County) for the insecticides methyl parathion, tefluthrin, carbofuran, terbufos, and chlorpyrifos were 28.0, 9.3, 8.7, 2.6 and 1.3, respectively. Biochemical investigation of suspected enzymatic resistance mechanisms in 3rd instars identified significant elevation of esterase activity (alpha and beta naphthyl acetate hydrolysis [3.8- and 3.9-fold]). Examination of 3rd instar esterases by native PAGE identified increased intensity of several isoenzymes in the resistant population. Assays of cytochrome P450 activity (4-CNMA demethylation and aldrin epoxidation) did not identify elevated activity in resistant 3rd instars. Granular soil insecticides were applied at planting to corn, Zea mays L., in replicated field trials in 1997 and 1998 at the same Phelps County site as the source of resistant rootworms for the laboratory studies. In 1997, planting time applications of Counter 20CR, Counter 15 G (terbufos), and Lorsban 15 G (chlorpyrifos) resulted in the lowest root injury ratings (1-6 Iowa scale); 2.50, 2.55, 2.65, respectively (untreated check root rating of 4.55). In 1998, all insecticides performed similarly against a lower rootworm density (untreated check root rating of 3.72). These studies suggest that resistance previously documented in adults also is present in 3rd instars, esterases are possibly involved as resistance mechanisms, and resistance to methyl parathion in adults is also evident in larvae, but does not confer cross-resistance in larvae to all organophosphate insecticides.
        
Title: Activity of Soil Insecticides on Eggs of Diabrotica undecimpunctata howardi: Effects on Embryological Development and Influence of Egg Age Michaelides PK, Wright DJ Ref: Pest Sci, 49:1, 1997 : PubMed
The activity of tefluthrin, carbofuran, terbufos and dieldrin in soil against eggs of different ages of the southern corn rootworm, Diabrotica undecimpunctata howardi (Barber) (Coleoptera: Chrysomelidae) was determined. Embryological development following treatment with these insecticides was also investigated to determine the stage of developmental arrest. Generally, younger eggs were found to be more susceptible, dieldrin being the least and tefluthrin the most potent ovicide of combined egg age mortalities. Terbufos and carbofuran were relatively inactive against older eggs compared with tefluthrin. Terbufos stopped embryonic development at the time when acetylcholine esterase activity has been shown to commence. Carbofuran, dieldrin and tefluthrin slowed but did not arrest embryonic development, although the two former compounds prevented eclosion to a greater degree than tefluthrin, suggesting death during absorption of serosal fluids at eclosion. Neonate emergence following treatment of eggs with tefluthrin resulted in death within a few hours. The results are discussed in relation to insecticidal action and permeability changes of egg membrane structure with age.
        
Title: Preparation of some toxic metabolites of disulfoton, phorate, and terbufos, their separation by thin-layer chromatography and confirmation by electron impact mass spectrometry Simonovska B Ref: Journal of AOAC International, 80:688, 1997 : PubMed
Milligram quantities of sulfoxides, sulfones, and oxygen analogue (oxon) sulfones of the insecticides disulfoton, phorate, and terbufos were prepared by selective oxidation. Pure insecticides or acetone extracts of granular formulations served as reactants. Structures of 9 compounds were confirmed by comparing their electron impact mass spectra (EI-MS), obtained by the direct inlet system with published data. Thin-layer chromatography (TLC) on silica gel was used to screen oxidation products and to purify products. Products were detected by spraying plates with PdCl2 reagent and exposing to iodine vapors. An esterase inhibition technique gave low detection limits, which are promising for residue analysis.
        
Title: [Efficacy of alcoholates and clay in percutaneous contamination of rats with highly toxic organophosphorus compounds] Knezevic D, Tadic V Ref: Vojnosanit Pregl, 49:343, 1992 : PubMed
Efficacy of decontamination by alcoholate and clay has been examined in animals percutaneously poisoned by nerve war gases (VX, soman) and organophosphorous insecticides (parathion, dichlorvos, terbufos) at exposure of 2, 5 and 60 minutes. High efficacy was achieved after two minutes using alcoholates which, except for VX, was lower for 50% after 5 minutes. The similar results were also achieved with clay in nerve war gas poisoning, however, the efficacy of this material was somewhat lower. By delayed decontamination (after 60 minutes) in animals poisoned by parathion and terbufos somewhat lower but still satisfying efficacy was achieved (ZI = 3.3, that is, 11.5). The results obtained have shown that efficacy of decontamination, except for the used materials, depends also on duration of the procedure.
        
Title: Observations on the influence of water and soil pH on the persistence of insecticides Chapman RA, Cole CM Ref: J Environ Sci Health [B], 17:487, 1982 : PubMed
The pH-disappearance rate profiles were determined at ca. 25 degrees C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water-ethanol (99:1 v/v). Half-lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (greater than 1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1-2 days for trichlorfon and oxamyl to greater than 1 year for fensulfothion and cypermethrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.