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The development of monoclonal antibody-based enzyme-linked immunosorbent assays for azinphos-methyl is described. A panel of haptens was synthesized for immunoconjugate preparation, and a series of haptens for heterologous, coating or tracer, conjugates was also prepared. Hapten synthesis was based on a strategy in which only a fragment of the whole target molecule was present (fragmentary haptens). From immunized mice, a set of monoclonal antibodies was obtained and ELISA sensitivities were assayed in different formats. Affinities estimated as I(50) values in the low nanomolar range for azinphos-methyl and phosmet were observed for several monoclonal antibodies in the conjugate-coated format and in the antibody-coated format under nonoptimized assay conditions.
Two enzyme-linked immunosorbent assays (ELISA) for the insecticide azinphos-methyl have been optimized and characterized. Both ELISAs are based on monoclonal antibodies produced from an immunogen with a hapten containing a phthalimido moiety and on protein conjugates of heterologous ligands containing a 1,2,3-benzotriazine group. Assay I was performed in the conjugate-coated ELISA format and assay II in the antibody-coated format. Several physicochemical factors (ionic strength, pH, incubation times, and Tween 20 and BSA concentrations) that influence assay performance were studied and optimized. Regarding specificity, both monoclonal immunoassays highly cross-reacted with azinphos-ethyl and phosmet. Finally, both assays were applied to the analysis of azinphos-methyl in spiked real water samples. For assay I the sensitivity, estimated as the I(50) value, was 0.40 nM, with a practical working range between 0.10 and 1.75 ng/mL and a limit of detection of 0.05 ng/mL. For assay II the sensitivity was 1.01 nM, with a practical working range between 0.32 and 2.54 ng/mL and a limit of detection of 0.08 ng/mL.
McIntosh, Red Delicious, and Golden Delicious from two years of experimental spray programs using azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl were processed into frozen apple slices, applesauce, single-strength juice, and juice concentrate. Residue levels were expressed as micrograms per 150 g of apple or the equivalent amount of apple product to calculate the percentage change in these pesticides brought about by processing. Producing single-strength apple juice reduced azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues by 97.6, 100, 97.8, and 78.1%, respectively. Production of applesauce reduced all four compounds by >/=95%. Azinphos-methyl, chlorpyrifos, esfenvalerate, and methomyl residues were reduced in apple slices by 94.1, 85.7, 98.6, and 94.7%, respectively. Processing is shown to be very effective in reducing the levels of these pesticides.
The purpose of this study was to characterize worker exposure to azinphos-methyl (Guthion) over an entire 4-6 week apple-thinning season. Twenty workers from three work sites in the Chelan-Douglas County region of Washington state were recruited for the study. Exposure potential was estimated by dislodgeable foliar residue measurements, and individual exposures were estimated by biological monitoring through urinary metabolites. Measureable azinphos-methyl residues were found on apple foliage at all sites throughout the six-week sampling period, indicating continuous exposure potential (median residue level of 0.5 microgram/cm2). Measurable levels of the urinary dialkylphosphate metabolite, DMTP, were found in virtually all urine samples (limit of detection = 0.04 microgram/mL). Mean DMTP concentrations differed significantly across sites (0.53, 0.29, and 0.90 microgram/mL for Sites 1-3, respectively; analysis of variance, p < .002), and intraindividual variability was much greater than interindividual differences. Group mean DMTP concentrations at each site fluctuated according to foliar residue levels. Measurable DMTP concentrations were found in 9% of reference workers, ranging from 0.04-0.18 microgram/mL. Cholinesterase activity levels monitored with a field test kit were not considered reliable due to temperature changes of the instrument.
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The degradation of azinphos methyl in orange and peach juice was studied. The insecticide was aseptically added to packed orange and peach juices and stored at 40, 20 and 0 degrees C. Samples were removed at regular intervals and were analysed for residues of azinphos methyl. Residues were determined with a simple gas-chromatographic method using a 30 m glass capillary column and an NP detector. The recoveries of azinphos methyl were 87-110% for orange juice and 92-108% for peach juice, and the limit of determination was 0.004 mg/kg for both juices. From the experimental data, rate constants, half-lives, and times needed to reach legal limits for the decomposition of azinphos methyl in orange and peach juices were evaluated. Half lives for orange and peach juices were 6.5 and 7.8 days at 40 degrees C, 86.6, and 92.4 days at 20 degrees C, and 407.7 and 495.1 days at 0 degrees C, respectively.
A survey of the pesticide content of 25 commercially available infant formulae and 30 weaning foods available in New Zealand was undertaken in 1996. It included a representative mixture of imported and New Zealand manufactured infant foods. Three different pesticide screening techniques were used: a high-sensitivity organochlorine screen was carried out on all infant formulae, while a multiresidue screen (organochlorine and organophosphorus pesticides, synthetic pyrethroids, carbamate pesticides, fungicides and herbicides), and a specific screen for dithiocarbamate fungicides were both carried out on all weaning foods and on soy-based infant formulae. All results are expressed on a ready-to-feed basis. Extremely low levels of residues of three organochlorine compounds (p,p'-DDE, p,p'-DDT and dieldrin) were detected in infant formulae samples. Residues of p,p'-DDE were found in seven of 20 milk-based infant formulae at concentrations ranging from 0.03 to 0.5 microgram kg(-1). Residues of p,p'-DDT were found in one imported milk-based infant formula at 0.7 microgram kg(-1), and dieldrin residues were detected in four of five soy-based infant formulae at concentrations ranging from 0.05 to 0.08 microgram kg(-1). The multiresidue pesticide screen detected low levels of residues of two organophosphorus pesticides; azinphos-methyl in one soy-based infant formula at a level of 22 microgram kg(-1) and pirimiphos-methyl in two cereal-based weaning foods at concentrations of 5 and 14 microgram kg(-1). None of the other approximately 140 pesticides (including fungicides and herbicides) included in the multiresidue screen were detected in any weaning foods or soy-based infant formulae, at a detection limit of 10 microgram kg(-1). No residues of dithiocarbamate fungicides were detected in any product analysed, at a detection limit of 100 microgram kg(-1).
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Groundwater samples were collected from monitoring wells along an area of intensive fruit production. Different types of correlations were investigated between soil physicochemical characteristics, depths and agricultural practices with pesticide detection frequency. In the three analyzed periods azinphos methyl, S-(3,4-diydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethyl)-O,O-dimethyl phosphorodithioate, showed a definite seasonal behavior related to the application pattern, increasing its concentration in the aquifer from October to November-December and then decreasing towards March. Samples obtained during the non-spraying season showed that azinphos methyl residues were lower than detection limit (LOD). An inverse correlation was observed between azinphos methyl concentration and the time elapsed since the last pesticide application. Seasonal events such as rain and irrigation influence the chemical concentration in the well, while no correlation was obtained between soil characteristics and azinphos methyl concentration. The soil attenuation capacity was not enough to prevent the presence of azinphos methyl in the aquifer during the application season.
A technique for comparing pesticide penetration through fabric was devised. It involved passing fabric swatches through a controlled spray system and measuring the pesticide residue transferring on and through the tested fabric. Six variations in fabric were selected for testing: 100% cotton woven chambray, Scotch-guard treated chambray, Tyvek, Crowntex, and two variations of Gore Tex. Guthion (azinphos-methyl) was chosen as the insecticide for controlled use in this experiment because of its widespread use and relatively high toxicity. Gas chromatographic analysis of the amount of Guthion transferred through the outer fabric was made by the use of analysis of variance (ANOVA) and Duncan's multiple range test. The ANOVA for experiment replication showed no significant difference among the replications of each fabric. The treatment ANOVA was highly significant at the 0.01 level. Duncan's multiple range test further analyzed the differences in the treatment, and three groups were found to be significantly different from each other. The two types of Gore Tex, Tyvek and Crowntex comprised the group permitting the least penetration Scotch-guard treated chambray followed, and untreated chambray allowed the greatest penetration.
Vase-shaped standard apple trees cv. McIntosh were sprayed with azinphos-methyl at pink, pink and 1st cover and 1st cover only. Residue analyses by gas chromatography revealed detectable residues on foliage until mid summer. At harvest, negligible residue levels were found on the peel and the whole apple. On four trees, fluorescein was sprayed in the same manner as the insecticide and maximum levels of the dye were detected on the outside lower canopy along the row. Minimal concentration of fluorescein was detected on the inner upper canopy away from the direction of the row.
Hand exposures of apple thinners to the pesticide azinphos-methyl (Guthion) were measured using three methods (glove, handwash, and wipe). Hand exposure sampling for each method was conducted following apple thinning work for a period of two hours for six to eight workers. Foliar residue samples were collected on each day of hand exposure sampling in the same orchard blocks that were thinned; foliar residues are considered to have been constant during the four-day study, which took place, on average, six days after pesticide application. Hand exposure estimates derived from each of the three methods differed significantly (ANOVA: p < 0.001). Mean measured exposure rates for the glove, handwash, and wipe methods were 6.48, 1.83, and 0.28 mg/hr, respectively. A corrected estimate of hand exposure, 2.7 mg/hr, was calculated from the handwash measurements and the handwash removal efficiency factor from a laboratory study. Comparison with this hand exposure estimate suggests that the glove method produced a 2.4-fold overestimate of exposure, whereas the wipe method produced a 10-fold underestimate. Studies that measure hand exposure to pesticides should include a careful description of sampling methods and should recognize the potential for measurement bias. Furthermore, the standardization and validation of dermal exposure assessment methods are critical to developing more comparable and more accurate pesticide exposure estimates.
Exposure to and absorption of Guthion 50 W.P. (azinphos-methyl) were estimated in orchardists from the Okanagan Valley in British Columbia who were involved in mixing, loading, and application with ultra-low volume air blast equipment. Air monitoring and patch techniques were used to estimate exposure, and alkyl phosphate excretion and cholinesterase inhibition were measured to estimate absorption. All workers were issued with standardized cotton shirts, trousers, and long-sleeved coveralls. All wore half-face respirators, gloves, boots, and hats. Eight wore rubberized protective clothing in addition. The indirect method of measuring urinary metabolites appeared to be the most sensitive. All workers had quantifiable levels of alkyl phosphates following exposure, and 24-h urine samples provided a more reliable estimate than first morning voids. A high correlation was observed between 48-h alkyl phosphate excretion and amount of active ingredient sprayed. A fluorescent tracer was added to the tank along with the Guthion. The finding of Guthion on patches beneath the clothing was confirmed by the presence of the tracer on the skin. With the ultralow-volume application used in this study, the rubberized clothing did not appear to be significantly more protective than the heavy coverall. There was no significant depression of either red blood cell or serum cholinesterase activity in any workers.
The effect of environmental parameters (temperature and relative humidity) on the degradation rate of azinphos methyl and parathion methyl was studied. Proprietary emulsifiable concentrates were diluted and added to each of 90 glass Petri dishes for each pesticide and were left overnight to dry. Petri dishes were placed in 18 air-tight containers (9 for each pesticide) in which were created environments with relative humidity (RH) of 60, 82, and 96%. The containers were stored at 0, 20, and 40 degrees C. From the experimental results best fit curves, kinetic equations, rate constants, and half-lives were calculated. Half-lives of azinphos methyl for the RH studied were, from 124 to 267 days at 0 degrees C, from 89 to 231 days at 20 degrees C, and from 25 to 71 days at 40 degrees C. Corresponding half-lives for parathion methyl were from 48 to 57 days at 0 degrees C, from 9.2 to 10.5 days at 20 degrees C and from 1.3 to 1.5 days at 40 degrees C. The results were correlated with relevant results from the decomposition of the same or similar pesticides on apples both, on the trees and during refrigerated storage. These correlations are suggesting that biological factors strongly affected the decomposition rate of azinphos methyl. On the contrary the decomposition of parathion methyl was mainly affected by environmental rather than biological factors.
Azinphos-ethyl concentrations in the blood, urine, and gastric lavage liquid from medical examiner cases are reported. In all cases, there was ingestion of the organophosphate pesticide. They are presented under three categories of intoxication: less serious, more serious, and fatal intoxications. The results of this study indicate that it was not possible to determine the blood levels that show the correct degree of intoxication and of lethal dose. Fast methods are given for identification and quantification of azinphos-ethyl in human biological fluids.
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