Fenitrothion residues

The aerial application of insecticides for budworm control results in the deposition of insecticide on the foliage and on the forest litter the proportions of the spray being deposited can be related to tree species (fir collecting more than spruce) and the fate of the insecticide. DDT became a problem of concern partially because of its long residual life, since its withdrawal from use the presently used insecticides, fenitrothion and aminocarb are characterized by their rapid initial disappearance. Although aminocarb cannot be found chemically relatively shortly after the spray application, fenitrothion residues at very low levels can be found for a long time (up to one year) after spray application. Gardona, acephate and chlopyrifos-methyl are also characterized by a rapid initial loss. 

A similar behavior pattern is found in the insecticide residues in the litter-soil complex partly as a result of needle fall fenitrothion residues persist for an extended period (up to one year). Phosphamidon and aminocarb disappear very quickly. 

A Grumman Avenger TBM flying approximately 20 m above the forest canopy applied the dyed spray with an emitted volume median diameter (vmd) close to 100 p. The spray mix, an aqueous fenitrothion emulsion, was applied at a rate equivalent to 1.5 1/ha and had a residual volume of 20% after evaporation of the water. Consequently, the evaporated vmd was approximately 58 p. 

Table III shows the levels of aminocarb present in mayfly nymphs sampled from Portage Brook following the 1st application. Aminocarb concentrations found in insects were not high and no breakdown products of the insecticides were found. The peak concentration detected is only 20 ppb (1 h post-application) exposed to a maximum of 2.26 ppb aminocarb in water, representing a concentration factor of oa 9. Residues declined to below detection limits ( < 20 ppb) rapidly afterwards coinciding with the disappearance of residues in stream water indicating that the uptake and bioconcentration potential by the insects for aminocarb were not high. Further work is necessary to confirm this observation since Penny (16) reported that the other insecticide, fenitrothion, is readily bioaccumulated by aquatic insects yielding a concentration factor of about 60.

The effect of shading an outdoor pond for the first 17 days after addition of fenitrothion was to increase the half-life of the insecticide by about 50%. Despite a 30-fold reduction in light intensity, however, the decline in insecticide residues in water was rapid dropping from 70 jtg/L to about 0.01 jxg/L by 17 days. Shaded conditions decreased the quantities of other products and MNP (but not AF) that were formed however no major products unique to shaded or unshaded conditions were identified. 

Bioaccumulatlon of some pesticides (fenitrothion, aminocarb, permethrin) with real or potential application in forestry in Canada has been examined in laboratory experiments using larval rainbow trout and common duckweed. Bioaccumulation of an aromatic hydrocarbon, fluorene, has also been examined since some commercial formulations employ hydrocarbon solvents. Laboratory exposures of fish or plants were carried out by placing the organisms in dilute aqueous solutions of C labelled pesticide or hydrocarbon, and by measuring transfer of radioactivity from water to fish or plants. After transfer of fish or plants to untreated water, loss of radioactivity was measured similarly. These measures allowed calculation of uptake and depuration rate constants which were used to predict residue accumulations under various exposure conditions. Predicted residue accumulations agreed substantially with other predictive equations in the literature and with reported field observations. 

Residues of fenitrothion in fathead minnows were reported by Malls and Muir (19) following treatment of small ponds. Bioconcentration factors were 42 and 54 at 24 hours post treatment, as compared with predicted steady state bioconcentration factors of 146 (Table I). Following actual forest spraying Lockhart et al. (20) reported 13.7 pg fenitrothion per gram in fish taken from a stagnant pond in the spray zone. The peak water concentration observed was 75.5 pg/L, and so the bioconcentration factor was at least 180. Similarly, Lockhart et al. (21) found maximum fish residues of 4.28 pg/g from the same area sprayed two years later, and in this case the peak water concentration was 22.8 pg/L, with a calculated bioconcentration factor of 190. 

Several qualitative and quantitative immunochemical methods and their application to the analysis of environmental samples have been described for OP insecticides, a family that includes widely used pesticides such as azinphos-ethyl/methyl, dichlorvos, fenitrothion or fenthion, malathion, mevinphos, and parathion. Mercader and Montoya202 produced monoclonal antibodies against azinphos-methyl and developed an ELISA that was used for the analysis of water samples from different sources, reaching detectability levels near 0.05 pg I. Watanabe et al.203 reported the production of polyclonal antibodies and ELISA procedures to analyze fenitrothion in river, tap, and mineral water (LOD = 0.3 pg L ). Banks et al.204 produced polyclonal antibodies against dichlorvos, an organophosphate insecticide used for stored grain, which also cross-reacts with fenitrothion. Nishi et al.205 reported the first immunoassay for malathion. Residues of this insecticide have... 

Watanabe, E., K. Baba, H. Eun, et al. 2006. Evaluation of performance of a commercial monoclonal antibody-based fenitrothion immunoassay and application to residual analysis in fruit samples. J. Food Prot. 69 191-198. 

Organophosphorus compounds such as malathion and fenitrothion were introduced in 1975 and remained in use in 1997 in seven countries. WP formulations are the most common for indoor residual applications. However, in some countries, notably Brazil and Mexico, malathion and fenitrothion ultra-low-volume (UL) sprays and fogging have also been used as space sprays. In Brazil, malaria has been restricted to the Amazonian region, where precarious housing... 

In 1975 the first estimation of the impact of an insecticide applied on a large scale was published [22]. The author compared the diversity and abundance of native pollinators of Canadian lowbush blueberries in a control area and in areas contaminated with fenitrothion sprayed on forests of New Brunswick. Pollinators were mainly Bombus spp., Andrenidae, and Halictidae. Data of the population census were interpreted through statistical analyses which evidenced that the lowest diversity and abundance index was in areas close to treated forests. Moreover, carcasses found in these areas showed the highest residue rates. Both results corroborated the crop failures reported by blueberry growers of the province. 

Finally, even if most of the pesticides worldwide are used in fruit and vegetable crops, data on pesticide residues in animal products are also essential, taking into account that livestock can be easily exposed to pesticides directly or through residues in their feed. For instance, the 2009 European Union Report revealed the presence of 34 different pesticides in animal products [115]. Garcfa de Llasera et al. [128] revealed the presence of chlofenvinphos and chlorpyrifos in liver samples, whereas a-endosnlfan, endosulfan sulfate, and dichloran have been reported in pork and lamb samples (<10 pg/kg) [129]. Bolafios et al. [130] studied the occurrence of organochlorine pesticides and polychlorinated biphenyls in chicken eggs. Benzene hexachloride and 28 polychlorinated biphenyl were detected in only one of the 30 samples at concentrations of 15 and 10 ng/g, respectively. However, five samples also contained traces of OC and PCB residues, even if at concentration levels below the limit of quantification. Einally, a-endosulfan and P-endosulfan were found in commercial milk-based infant formulas at concentration levels from 1.18 to 5.03 pg/kg [35]. The same study also showed the presence of fenitrothion, chlorpyrifos ethyl, and bifenthrin at maximum concentrations of 0.23,1.30, and 0.68 pg/kg, respectively. 

The residues of four pesticides (diazinon, caibaryl, malathion, fenitrothion) were recovered from sesame seeds and baseline resolved on a Cjg column (2 = 225 nm) using a 50/50 acetonitrile/water (0.1% acetic acid) mobile phase [969]. Excellent separation and elution were achieved in 21 min. Linearity was obtained over the range 2-4500 ng/mL with detection limits of 5-50 ng/mL (analyte dependent). 

Analogous to the on-column derivatization used in gas chromatography, an oxidative chemical transformation was carried out on a TLC plate by m-chloroperbenzoic acid. The oxygen analogs of fenthion, disulfoton, and phorate that were produced were separated after this derivatization (57) (Table 3). Another example of on-plate derivatization involves a reduction reaction carried out in order to determine the residues of methylparathion, parathion, and fenitrothion. Parent compounds and corresponding amino derivatives were also separated (58) (Table 3). 

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