Residues of dicofol on cucumber grown under plastic covers in jordan

Abstract

Residues of dicofol were determined on cucumber leaves and fruits under plastic house (PH) and plastic tunnels (PT). Five sprays, 8 d apart, were applied at 0.15% concentration. initial deposits on leaves were 48 and 58 ppm under PH and PT, respectively. In the last sampling date of leaves, the amounts of 191 and 135 ppm were detected under both cultures, respectively. There was a continuous increase in the initial residue after each spray. The highest amount of dicofol (401) was determined 1 d after the fifth spray under PH. The exposure to high residues may pose a risk to fieldworkers.

On cucumber fruits, residues of 0.95 and 1.60 ppm were determined 1 d after the fourth spray under PH and PT, respectively. These residues decreased after 4 d to 0.40 and 1.49 ppm, respectively. Almost no detectable residues could be determined 8 d after sprays number 4 and 5 under both cultures. All dicofol residues on the fruits were below the tolerance level of 2 ppm.     

Analysis and fate of acephate and its metabolite,methamidophos, in pepper and cucumber

Abstract

Levels of acephate (Orthene^R) and its principle metabolite, methamidophos, in/on greenhouse‐grown pepper and cucumber fruits and leaves in relation to the applied methamidophos were monitored. Dislodgeable and total residues of acephate and methamidophos were determined by gas‐liquid chromatography equipped with a flame ionization detector (GC‐FID) and were confirmed by nitrogen phosphorus detector (GC‐NPD). The dissipation curves of the residues followed first‐order kinetics (R²> 0.96). Initial residues of acephate on fruits varied between pepper (15.12 ppm) and cucumber (2.16 ppm) . Total residues in fruits and leaves determined at intervals following application revealed the greater persistence of acephate on pepper fruits (half‐life [t_1/2] of 6 d) than on cucumber fruits (t_1/2 was 3.7 d) . T_1/2 values for the applied methamidophos were 4.7 and 5.3 d on pepper and cucumber fruits, respectively. Deacety‐lation of acephate (formation of its metabolite) was detectable 1 d following acephate treatment and reached a maximum of 2.05% of initial acephate residues 3 d after application on pepper fruits. On cucumber fruits, acephate metabolite reached a maximum of 2.12% one wk following application. No acephate residues were detected above the limit of detection of 0.001 ppm in pepper fruits 50 d following acephate application while its metabolite was detectable at that time (detectability limit was 0.0001 ppm).     

Studies on the residues of phosalone on chilli by GLC after multiband plate cleanup

Abstract

Four sprays of 0.05 ana 0.10% phosalone were given on chilli (Capsicum annuum Linn.) crop at an interval of 15 days starting from 21 days after transplanting. Residues were determined in the green chilli fruits by GLC after cleanup of extract on multiband thin‐layer plate. The half‐lives of residues were 1.55 and 1.68 days on chilli fruits from the crop treated with four sprays of 0.05 and 0.10% phosalone respectively. The time required to reach the tolerance limit of 1 ppm after last spray with 0.05 and 0.10 % emulsion was 4.75 and 7.62 days respectively. Washing of fruits under tap water was found effective in bringing down the level of phosalone residues by 21.64 to 75.11 %.     

Simultaneous determination of fenitrothion and aminocarb in blueberry foliage and fruits: Application to the analysis of residues in field samples

Abstract

Samples of blueberry foliage and fruits were collected from spray blocks in Ontario after aerial application of fenitrothion and aminocarb at dosage rates of 210 g active ingredient (AI)/ha and 70 g AI/ha respectively. Residues were extracted from the samples by homogenizing with ethyl acetate, cleaned up by microcolumn chromatography using alumina as adsorbent, and analyzed by GLC‐AFID with a glass column packed with 1.5% OV‐17 and 1.95% OV‐210 on 80–100 mesh Chromosorb W‐HP. Average recoveries for fenitrothion and aminocarb from foliage at three fortification levels (1.0, 0.10 and 0.01 ppm) were respectively 99 and 96%. The corresponding values for the fruits were 99 and 95%. Foliage samples collected 1 h post‐spray contained on average 1.13 ppm of fe‐nitrothion and 1.14 ppm of aminocarb. However, residue levels reached below the detection limit (<0.01 ppm) in foliage collected 15 d after treatment. In addition, the fruit samples collected after 15 d post‐spray contained extremely low levels (0.03 ppm for fenitrothion and 0.02 ppm for aminocarb) of residues, and were barely above the detection limit.     

Studies of methamidophos-C-14 in Costa Rican vegetables and soils

In order to see the effect of time lapse between the last application of methamidophos and harvesting insecticide was applied on lettuce plants (6,84 μCi in one experiment and 4,03 μCi in the other experiment). Analysis of the crops harvested 3 days after last application showed 9,7 ppm residues on leaves, while crops harvested 1 day after application showed residues of 12,7 ppm (25% more). Treatment of tomato plants (39,65 μCi, 1,01 kg/ha) gave residues in fruits 4,92 ppm after 8 days interval between last application and harvesting. 40 days gap between the last application and harvesting leaved residues of 0,7 ppm in fruits which is much less as recommended by FAO/WHO (1 – 2 ppm).Degradation of this insecticide is dependent on the matrix of the soil, this breakdown is observed in the first ten days and than after it remains constant. C-14 radioactivity extracted from soil and plant analysis was methamidophos (92%)     

Phosmet residues in an orchard and adjacent recreational area

Two cover sprays of phosmet were applied to an orchard adjoining a camping area and a bird sanctuary with a resident goose population. Insecticide residues were monitored on orchard leaves, orchard ground cover, ground cover in the camp-site and along the adjacent lakeshore. Despite attempts to minimize drift, significant spray residues were found outside the target area. Residues on ground cover and leaves were reduced by sprinkler irrigation subsequent to spray application.     

Phosmet residues in an orchard and adjacent recreational area 1

Abstract

Two cover sprays of phosmet were applied to an orchard adjoining a camping area and a bird sanctuary with a resident goose population. Insecticide residues were monitored on orchard leaves, orchard ground cover, ground cover in the camp‐site and along the adjacent lakeshore. Despite attempts to minimize drift, significant spray residues were found outside the target area. Residues on ground cover and leaves were reduced by sprinkler irrigation subsequent to spray application.     

Disappearance of dimethoate,methamidophos and pirimicarb in lettuce

Abstract

Foliar sprays of dimethoate at 150 or 300 g a.i./ha, methamidophos at 450 or 900 g a.i./ha and pirimicarb at 140 or 280 g a.i./ha were applied for control of the green peach aphid, Myzus pericae (Sulzer), and the lettuce aphid, Nasonovia ribisnigri (Mosley), about 2 weeks before the lettuce started heading, and again about 1 week from harvest. In lettuce, dimethoate partially oxidized to its oxon and pirimicarb converted to its methylamino‐ and/or formyl methylamino‐analogues. Most residues were present in the outer leaves which were exposed directly to the sprays; only traces of residues were detected in samples of the inner head leaves. Total residues disappeared rapidly. Pirimicarb was the least persistent and only traces of residues (<0.01 ppm) were detected in marketable heads. Concentrations of dimethoate, including the oxon and of methamidophos were well below their respective tolerances of 2 and 1 ppra respectively.     

Persistence of deltamethrin and cypermethrin on wheat and sweetclover

Residues of cypermethrin and deltamethrin in wheat herbage and grain and deltamethrin in sweetclover herbage were determined. Cypermethrin was applied at 28 g/ha to wheat and the residues on the herbage declined exponentially from 3.74 ppm immediately after spraying to 0.20 ppm 27 days after spraying. No cypermethrin residues were detected in the grain. Deltamethrin was applied at 6 g/ha to wheat and the residues on the herbage declined exponentially from 0.70 ppm immediately after spraying to 0.05 ppm 27 days after spraying. No deltamethrin residues were detected in the grain. Deltamethrin was applied to sweetclover at 3, 4, 5, 10, and 16 g/ha. Residues on the herbage declined exponentially from 0.10, 0.16, 0.22, 0.40 and 0.70 ppm immediately after spraying to 0.02, 0.03, 0.04, 0.15 and 0.18 ppm 5 days after spraying, respectively.     

Degradation of disulfoton,oxydemeton‐methyl,methamidophos and demeton in asparagus plant

Abstract

Disulfoton and methamidophos (both at 1.12 kg a.i./ha), oxydemeton‐methyl and demeton, (both at 0.56 kg a.i./ha) were applied as post‐harvest foliar sprays to control the European asparagus aphid, Brachycolus asparagi. Oxidation of disulfoton, oxydemeton‐methyl and demeton to their corresponding sulfoxides and sulfones occurred in asparagus foliage 2 to 5 days after application. The total residues of these three compounds, including their toxic oxidative metabolites declined to less than 0.5 ppm about 47 days after the spray application whereas methamidophos persisted longer; 0.84 ppm of its residue was found even after 85 days. No residue was found above the limit of detection of 0.002 ppm in any asparagus spears which were produced in the following spring; the four compounds were sprayed on the asparagus plants during the previous season at realistic rates for aphid control.     

Persistence of deltamethrin and cypermethrin on wheat and sweetclover

Abstract

Residues of cypermethrin and deltamethrin in wheat herbage and grain and deltamethrin in sweetclover herbage were determined. Cypermethrin was applied at 28 g/ha to wheat and the residues on the herbage declined exponentially from 3.74 ppm immediately after spraying to 0.20 ppm 27 days after spraying. No cypermethrin residues were detected in the grain. Deltamethrin was applied at 6 g/ha to wheat and the residues on the herbage declined exponentially from 0.70 ppm immediatly after spraying to 0.05 ppm 27 days after spraying. No deltamethrin residues were detected in the grain. Deltamethrin was applied to sweetclover at 3, 4, 5, 10, and 16 g/ha. Residues on the herbage declined exponentially from 0.10, 0.16, 0.22, 0.40 and 0.70 ppm immediatly after spraying to 0.02, 0.03, 0.04, 0.15 and 0.18 ppm 5 days after spraying, respectively.     

Benzene accumulation in horticultural crops

In this study apple, blackberry and cucumber crops were exposed to elevated levels of benzene under controlled conditions. Benzene was retained in fruits of all crops, but only accumulated in leaves of blackberries and apples. The retention by cucumber fruits is suggested to result from the longer pathway for the desorption of benzene as a consequence of their increased tissue depth compared to leaves. The process of accumulation in blackberry and apple leaves is unknown. The ingestion of benzene via the food-chain pathway on the basis of this study is concluded not to be significant.     

Bioavailability and biological activity of wheat-bound chlorpyrifos-methyl residues in rats.

Wheat grain was treated with 14C-chlorpyrifos-methyl to generate bound residues for determining their bioavailability to rats. In a parallel experiment, bound residues were prepared with non-labelled chlorpyrifos-methyl to determine possible adverse effects in rats fed the grain-bound residue for 28 and 90 days. Two dose levels of 10 and 50 ppm were initially used on the grain. The 10 ppm led to the formation of 25.1% bound residues (2.51 ppm) after 6 months as determined by radiomeasurement. The higher dose was assumed to form 12.55 ppm bound residues. When 14C-bound residues were fed to male rats for 24 hours, the animals eliminated 75% of the radioactivity in urine, 7% in expired air and 8% in faeces after 3 days, indicating that the bound residues were highly bioavailable. A further "bioavailable" amount (4%) was found in selected organs.     

Distribution and persistence of carbaryl in some terrestrial and aquatic components of a forest environment

Abstract

An oil‐based formulation of carbaryl (1‐naphthyl N‐methyl‐carbamate) (Sevin‐2‐Oil) was applied twice by a fixed‐wing aircraft at a dosage rate of 280 g of A.I./ha/application to a coniferous forest near Allardville, New Brunswick. The highest concentrations of the chemical in fir foliage, litter and forest soil 1 h after application were respectively 4.20, 1.21 and 0.59 ppm (fresh weight). The residues dissipated rapidly and the DT50 values obtained from the depletion curves were 2.3 d for foliage and 1.5 d for litter and soil samples. Very low levels (<0.1 ppm) of carbaryl persisted in foliage and litter beyond the 10 d sampling period. The maximum residue level found in stream water was 0.314 ppm and more than 50% of it had dissipated within 1 h. Low but detectable levels (0.001 ppm) of the chemical persisted in water until the end of the 10 d sampling period. Sediment samples contained a maximum level of 0.04 ppm, which dissipated below the detection limit within 5 h. Brook trout and slimy sculpins captured in the stream 1 d after the spray contained on average about 0.04 ppm of carbaryl and none of it was found in 3 d postspray samples.     

Environmental fate of chlorothalonil in a Costa Rican banana plantation

The environmental fate of chlorothalonil (CHT) and its metabolites were studied under field-variable conditions in a commercial banana plantation in Costa Rica. Weather conditions were representative of a tropical environment and the fungicide applications were typical of those in banana production. The test plots were treated with Bravo 720 at 1.2 l ha(-1) of formulated product. Field persistence of CHT in soil and on banana leaves was measured during five consecutive months and after three aerial applications of the fungicide. Residues were analyzed in soil, sediment, water, banana leaves and drift cards by gas and liquid chromatography coupled to mass spectrometry. In soil and on the surface of banana leaves, CHT dissipated rapidly with half-lives of 2.2 and 3.9 d, respectively. Soil residues persisted and were detected 85 d after application. The main metabolite found in soil, 4-hydroxy-chlorothalonil, accounted for approximately 65% of residues detected and was measured up to 6d after application.     

Environmental fate of synthetic pyrethroids during spray drift and field runoff treatments in aquatic microcosms.

The aquatic fate and persistence of synthetic pyrethroids under spray drift and field runoff treatment regimens were determined in outdoor pond microcosms. In this paper, the experimental design and construction of outdoor microcosms is presented, as well as the aquatic fate of tralomethrin and deltamethrin. Tralomethrin is rapidly degraded to deltamethrin, with a half-life of 12.7 hours under spray drift conditions. Degradation profiles of tralomethrin in water indicated rapid conversion of deltamethrin and to less active isomers and then to decamethrinic acid (BR2CA). After 24 hours, the percent radioactivity of tralomethrin was 25% of the test material in the water column. In sediment, tralomethrin was immediately converted to deltamethrin. Deltamethrin is rapidly degraded with a half-life of 8 to 48 hours, depending on mechanisms of introduction into water. Degradation profiles of deltamethrin in water indicated rapid conversion of deltamethrin to decamethrinic acid (BR2CA), comprising approximately 90% of the radioactivity in the aqueous phase at 168 hours. Extraction and analysis of fathead minnows (Pimephales promelas) after 96 hours revealed that tissue residues contained parent compounds and metabolites alpha-R-deltamethrin, trans-deltamethrin and Br2CA. Fish residues are directly related to aqueous concentrations, thus bioavailability under field runoff regimes were an order of magnitude lower than tissue residues under spray drift conditions. Plant tissue was found to significantly accumulate pyrethroids.     

Disappearance of bromopropylate residues in artichokes, strawberries and beans

Residues of Bromopropylate were determine in artichokes, strawberries and beans after foliar spray of acaricide at two rates. The rates used were 1 g/l formulated product (normal recommended) and 1.5 g/l. The residue levels of bromopropylate in the three crops after 14 days were lower than 0.7 ppm and did not exceed the Maximum Residual Level (MRL) recommended by FAO. In the artichokes and strawberries, the total concentration of residues decreased by 50% of the initial level after 2-3 days. Only trace levels of the bromopropylate residues (less than 0.01 ppm) were detected in the "hearts" of the artichokes. Bromopropylate residues in the green beans were also less than 0.8 ppm after the first day of foliar spraying. The kinetic of degradation occurred in two different steps. In the first step (4-6 days) the dissipation of bromopropylate was faster whereas in the second step (7-14 days) the loss of residues was much slower.     

Dissipation pattern of flubendiamide residues on capsicum fruit (Capsicum annuum L.) under field and controlled environmental conditions

This investigation was undertaken to compare the dissipation pattern of flubendiamide in capsicum fruits under poly-house and open field after giving spray applications at the recommended and double doses of 48 g a.i. ha^?1 and 96 g a.i. ha^?1. Extraction and purification of capsicum fruit samples were carried out by the QuEChERS method. Residues of flubendiamide and its metabolite, des-iodo flubendiamide, were analyzed by high-performance liquid chromatography–photodiode array, and confirmed by liquid chromatography–mass spectrometry/mass spectrometry. Limit of quantification of the method was 0.05 mg kg^?1, and recovery of the insecticides was in the range of 89.6–104.3%, with relative standard deviation being 4.5–11.5%. The measurement uncertainty of the analytical method was in the range of 10.7–15.7%. Initial residue deposits of flubendiamide on capsicum fruits grown under poly-house conditions were (0.977 and 1.834 mg kg^?1) higher than that grown in the field (0.665 and 1.545 mg kg^?1). Flubendiamide residues persisted for 15 days in field-grown and for 25 days in poly-house-grown capsicum fruits. The residues were degraded with the half-lives of 4.3–4.7 and 5.6–6.6 days in field and poly-house respectively. Des-iodo flubendiamide was not detected in capsicum fruits or soil. The residues of flubendiamide degraded to below the maximum residue limit notified by Codex Alimentarius Commission (FAO/WHO) after 1 and 6 days in open field, and 3 and 10 days in poly-house. The results of the study indicated that flubendiamide applied to capsicum under controlled environmental conditions required longer pre-harvest interval to allow its residues to dissipate to the safe level.     

Residues and mutagenicity of captan applied to apple trees and potential human exposure

The fungicide captan (cis-N-((trichloromethyl)thio) 4-cyclo-hexene-1,2-dicarboximide) was applied at the rate of 2.4 g/l to apple trees (c.v. Golden Delicious) individually or as part of a standard treatment program where it was applied eight times during the growing season together with several pesticides. Leaf samples (100 discs of 2.2 cm diameter) were collected from treated and control trees before treatment and at 0, 1, 3, 7, 14, 28, 56, 90 and 112 days after treatment. Fruit samples were taken at mid-season (56 days) and at harvest (112 days). The objective of this study was to determine the captan residue and mutagenicity of leaf and fruit extracts to ascertain the potential health hazard to agricultural workers in these orchards. Surface residues were extracted from leaves and fruits with methylene chloride. These extracts were subsequently analyzed for captan by gas-liquid chromatography (GLC) utilizing an electron-capture detector, and for mutagenicity with two strains (TA98 and TA100) of Salmonella typhimurium, with and without microsomal enzyme activation. Positive mutagenic effects were observed with strain TA100 at 0-14 days post spray, even with extracts from one leaf disc's surface (3.8 cm2) of the single treatment. Captan residues in these samples indicated a decline from 9.3 micrograms/cm2 at 0 days to 0.80 micrograms/cm2 at 14 days and a trace after 112 days. With the standard treatment, in which captan was incorporated eight times in the program starting at the 7-day interval, leaf extracts showed mutagenic activity at 7, 14, 28 and 90 days. Captan residues at these intervals were 11.4, 5.0, 4.1 and 3.4 micrograms/cm2, respectively. Fruit sample extracts of the standard spray were mutagenic to the tester strains TA100 and TA98 both at mid-season and at harvest. Residues of captan on fruits declined from 10.4 micrograms/cm2 at mid-season to 1.1 micrograms/cm2 at harvest. No mutagenic activity was detected with extracts from fruit samples from the single captan application.     

Dissipation, half-lives, and mass spectrometric identification of endosulfan isomers and the sulfate metabolite on three field-grown vegetables

Endosulfan 3 EC, a mixture of α- and β-stereo isomers, was sprayed on field-grown pepper, melon, and sweet potato plants at the recommended rate of 0.44 kg A.I. acre(-1). Plant tissue samples (leaves, fruits, or edible roots) were collected 1 h to 30 days following spraying and analyzed for endosulfan isomers (α- and β-isomers). Analysis of samples was accomplished using a gas chromatograph (GC) equipped with a mass detector in total ion mode. The results indicated the formation of endosulfan sulfate as the major metabolite of endosulfan sulfite and the relatively higher persistence of the β-isomers as compared to the α-isomer. The initial total residues (α- and β-isomers plus endosulfan sulfate) were higher on leaves than on fruits. On pepper and melon fruits, the α-isomer, which is the more toxic to mammals, dissipated faster (T(1/2) = 1.22 and 0.95 d, respectively) than the less toxic β-isomer (T(1/2) = 3.0 and 2.5 d, respectively). These results confirm the greater loss of the α-isomer compared to the β-isomer, which can ultimately impact endosulfan dissipation in the environment. Additionally, the higher initial residues of endosulfan on pepper and sweet potato leaves should be considered of great importance for timing field operations and the safe entry of harvesters due to the high mammalian toxicity of endosulfan.