Metabolite Endosulfan Sulfate Research Articles

Organochlorine Pesticides in Soil–Groundwater–Plant System in a Famous Agricultural Production Area in China: Spatial Distribution, Source Identification and Migration Prediction

Being a famous hometown of vegetables in China, Shouguang City has a long history of vegetable cultivation and is a comprehensive national commodity base for vegetables and fruits. In recent decades, with the expansion of agricultural production, the use of pesticides is increasing. Although organochlorine pesticides (OCPs) have been banned, there are still some residues in soil, groundwater and other media. The study on the migration of the OCPs in soil and groundwater is of great importance for the maintenance of food security. Using methods of hydrogeological survey, laboratory testing and numerical simulation, the spatial distribution characteristics, sources and pollution degree of OCPs in soil and groundwater were analyzed, and the migration and transformation of OCPs in soil–groundwater was dynamically simulated and predicted. The study showed that there were many kinds of OCPs residual in the soil environment. The hexachlorocyclohexane (HCHs) in the topsoil of the study area were mainly due to the use of lindane, and the main source of dichlorodiphenyltrichloroethane (DDTs) in soil was the use of DDTs in history. The contents of HCHs, DDTs and hexachlorobenzene in the topsoil of the study area were at a low level, while the content of endosulfan metabolite endosulfan sulfate was comparatively higher. In recent years, the content of organochlorine pesticides in soil has generally decreased. The indexes of OCPs in groundwater can meet the Standards for Drinking Water quality of China. It was predicted that the HCH pollutants would mainly be distributed in Gucheng Street, Shangkou Town, and its south area where the concentration exceeds 3 ng/L exceeds that of 240 km2. DDT pollutants would mainly be distributed in the east and north of Shouguang City, where the concentration beyond 0.6 ng/L exceeds that of 200 km2. Endosulfan sulfate pollutants would mainly be distributed in the Gucheng Street Office, Shangkou Town, and its south area where the concentration exceeds 1.5 ng/L will exceed that of 150 km2. Hexachlorobenzene (HCB) pollutants would mainly be distributed in Fengcheng in the west of Shouguang City and Nancha River in the northeast, where the concentration exceeds 0.2 ng/L will exceed that of 200 km2. The study enriched the monitoring data of OCPs in agricultural planting areas and provided reference for source analysis, migration prediction, and pollution prevention of OCPs.

Determination of selected neurotoxic insecticides in small amounts of animal tissue utilizing a newly constructed mini-extractor.

We developed a simple analytical method for the simultaneous determination of representatives of various groups of neurotoxic insecticides (carbaryl, chlorpyrifos, cypermethrin, and α-endosulfan and β-endosulfan and their metabolite endosulfan sulfate) in limited amounts of animal tissues containing different amounts of lipids. Selected tissues (rodent fat, liver, and brain) were extracted in a special in-house-designed mini-extractor constructed on the basis of the Soxhlet and Twisselmann extractors. A dried tissue sample placed in a small cartridge was extracted, while the nascent extract was simultaneously filtered through a layer of sodium sulfate. The extraction was followed by combined clean-up, including gel permeation chromatography (in case of high lipid content), ultrasonication, and solid-phase extraction chromatography using C18 on silica and aluminum oxide. Gas chromatography coupled with high-resolution mass spectrometry was used for analyte separation, detection, and quantification. Average recoveries for individual insecticides ranged from 82 to 111%. Expanded measurement uncertainties were generally lower than 35%. The developed method was successfully applied to rat tissue samples obtained from an animal model dealing with insecticide exposure during brain development. This method may also be applied to the analytical treatment of small amounts of various types of animal and human tissue samples. A significant advantage achieved using this method is high sample throughput due to the simultaneous treatment of many samples. Graphical abstract Optimized workflow for the determination of selected insecticides in small amounts of animal tissue including newly developed mini-extractor.

Endosulfan, Short-Chain Chlorinated Paraffins (SCCPs) and Octachlorostyrene in Wildlife from Greenland: Levels, Trends and Methodological Challenges.

Besides globally banned "legacy" persistent organic pollutants, other compounds might be present in Arctic wildlife, for which regulation was introduced recently (the insecticide endosulfan), is considered (short-chain chlorinated paraffins, SCCPs) or does not exist (octachlorostyrene, OCS, a byproduct of manufacturing and combustion processes involving chlorine). The purpose of this study was to analyze the time trend of endosulfan (1986-2012) in ringed seals and to address the levels of SCCPs and OCS in wildlife species from Greenland (black guillemot, glaucous gull, ringed seal, polar bear), while taking a critical standpoint to analytical methods typically applied. The metabolite endosulfan sulfate was the only endosulfan compound consistently above detection limits, with a median concentration of 0.23ng/g lipid weight (lw) and a significant annual decrease of -5.6%. The low-resolution mass spectrometry (LRMS) method appeared accurate and sufficiently precise; however, the gel permeation chromatography had to balance lipid removal and analyte loss. SCCPs and OCS were present in all samples. OCS median concentrations were between 2.8 (ringed seal blubber) and 29 (glaucous gull liver) ng/g lw, determined by a straightforward dual column electron capture detection method. SCCPs were analyzed by LRMS, following removal of potential interferences, and had median concentrations of several 100ng/g wet weight. While the method showed good precision and recovery rates as well as acceptable accuracy in control samples, the Greenland samples had high concentrations in an Arctic context, possibly indicating limited selectivity of the LRMS method.

Inducible headkidney cytochrome P450 contributes to endosulfan immunotoxicity in walking catfish Clarias gariepinus

The effect of endosulfan metabolites on fish immune system is not well known. It is also not clear whether endosulfan accumulates in fish immune organs and undergoes metabolic biotransformation in situ. In the present study we investigated the role of headkidney (HK), an important fish immune organ on endosulfan metabolism and the long term effects of endosulfan metabolites on the fish immune system. C. gariepinus (walking catfish) were exposed to 2.884ppb of endosulfan (1/10th LC50) for 30d followed by their maintenance in endosulfan-free water for 30d for recovery. Endosulfan induced time-dependent reduction in the HK somatic index and histo-pathological changes in renal and hemopoietic components of the organ. At cellular level, exposure to endosulfan led to death of HK leucocytes. Gas-liquid-chromatography documented the presence of both α- and β-isomers of endosulfan along with the toxic metabolite endosulfan sulfate (ESS) in the HK of exposed fishes. We report that β-endosulfan accumulates more readily in the HK. Depuration studies suggested the persistence of ESS in the HK. Enzyme-immunoassay and qPCR results demonstrated direct relationship between cytochrome P450 1A (CYP1A) expression and ESS levels in the HK. Pre-treatment of HKL with CYP1A specific inhibitor α-Naphthoflavone (ANF) led to reduction in CYP1A mRNA, protein levels, and inhibited ESS formation together implicating the role of CYP1A on endosulfan metabolism. When the exposed fish were transferred to endosulfan-free water (⿿recovered fish⿿) it was observed that after 30d of recovery period the concentration of endosulfan and its metabolite in the HK were significantly reduced, compared to 30-d exposed fish. We also observed improvement in HK histo-architecture but no significant recovery in HKL number and viability. Collectively, our findings suggest that HK plays an important role in endosulfan metabolism. We propose that endosulfan induces the activation of CYP1A in HK which led to the generation of persistent metabolite, ESS, resulting in immunotoxicity.

20 Years of Air–Water Gas Exchange Observations for Pesticides in the Western Arctic Ocean

The Arctic has been contaminated by legacy organochlorine pesticides (OCPs) and currently used pesticides (CUPs) through atmospheric transport and oceanic currents. Here we report the time trends and air-water exchange of OCPs and CUPs from research expeditions conducted between 1993 and 2013. Compounds determined in both air and water were trans- and cis-chlordanes (TC, CC), trans- and cis-nonachlors (TN, CN), heptachlor exo-epoxide (HEPX), dieldrin (DIEL), chlorobornanes (ΣCHBs and toxaphene), dacthal (DAC), endosulfans and metabolite endosulfan sulfate (ENDO-I, ENDO-II, and ENDO SUL), chlorothalonil (CHT), chlorpyrifos (CPF), and trifluralin (TFN). Pentachloronitrobenzene (PCNB and quintozene) and its soil metabolite pentachlorothianisole (PCTA) were also found in air. Concentrations of most OCPs declined in surface water, whereas some CUPs increased (ENDO-I, CHT, and TFN) or showed no significant change (CPF and DAC), and most compounds declined in air. Chlordane compound fractions TC/(TC + CC) and TC/(TC + CC + TN) decreased in water and air, while CC/(TC + CC + TN) increased. TN/(TC + CC + TN) also increased in air and slightly, but not significantly, in water. These changes suggest selective removal of more labile TC and/or a shift in chlordane sources. Water-air fugacity ratios indicated net volatilization (FR > 1.0) or near equilibrium (FR not significantly different from 1.0) for most OCPs but net deposition (FR < 1.0) for ΣCHBs. Net deposition was shown for ENDO-I on all expeditions, while the net exchange direction of other CUPs varied. Understanding the processes and current state of air-surface exchange helps to interpret environmental exposure and evaluate the effectiveness of international protocols and provides insights for the environmental fate of new and emerging chemicals.

Uptake and accumulation of endosulfan isomers and its metabolite endosulfan sulfate in naturally growing plants of contaminated area

Endosulfan isomers (α+β) and its main metabolite endosulfan sulfate were analyzed in naturally growing vegetation of pesticide contaminated area in Ghaziabad, India. Seven species of dominating plants were collected at different locations within the contaminated area. Endosulfan residues from plant parts and soil were extracted and determined by a gas chromatograph equipped with 63Ni electron capture detector (GC-ECD). Endosulfan isomers and endosulfan sulfate were present in almost all soil and plant samples. The concentration of total endosulfan in plant and soil samples analyzed ranged from 14 to 343ngg−1 and 13 to 938ngg−1 respectively. Out of seven plant species studied, Vetiveria zizanioides (Khus Khus) and Sphenoclea zeylamica (Chikenspike) showed the highest and lowest accumulation respectively, with a significant difference at p<0.01 level. Vetiveria zizanioides and Digitaria longiflora (Crab grass) could accumulate considerable levels of endosulfan isomers (α+β) (343 and 163ngg−1 respectively) and endosulfan sulfate (21 and 2ngg−1, respectively). The outcomes of the study reflect the value of test species in monitoring purposes and their potential for remediation of contaminated sites.

Isolation and characterization of a Bacillus subtilis strain that degrades endosulfan and endosulfan sulfate.

Endosulfan has emerged as a major environmental menace worldwide due to extensive usage and environmental persistence, seeking its remedial by a cheaper and efficient means. Therefore, natural resource (soil) was explored to search a potential candidate for biodegradation of endosulfan. A soil bacterium was enriched and isolated by applying a strong nutritional selection pressure, using a non-sulfur medium supplemented with endosulfan as sole source sulfur. The microbial strain was found to degrade endosulfan as well as its equally toxic metabolite endosulfan sulfate to non-toxic metabolites (endodiol and endosulfan lactone) very efficiently (up to 94.2 %) within 7 days, estimated qualitatively by thin layer chromatography and quantitatively by gas chromatography-electron capture detection methods. The isolate was characterized for its morphological, physiological, biochemical and 16S rRNA sequencing and identified as a new strain of Bacillus subtilis with strain designation AKPJ04, which was deposited with accession number Microbial Type Culture Collection and Gene Bank (MTCC) 8561, at MTCC, Institute of Microbial Technology, Chandigarh, India. The partial 16S rRNA sequence was submitted to Genbank, Maryland, USA, with the accession number EU 258611. The primary investigation for endosulfan degrading gene(s) localization suggested its location on chromosomal DNA.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-013-0176-7) contains supplementary material, which is available to authorized users.

Bioremediation of endosulfan-contaminated soil by using bioaugmentation treatment of fungal inoculant Aspergillus niger

The persistence of endosulfan and intermediate metabolite endosulfan sulfate in the environment and their toxic effects on biota necessitate their removal. This study investigated the bioaugmentation of endosulfan-contaminated soil by fungal inoculant Aspergillus niger ARIFCC 1053. The influence of bioaugmentation by A. niger on endosulfan-contaminated soil was evaluated with the help of change in pH and released chloride, and by thin layer chromatography and gas chromatography analysis. Its effects on soil functionality were monitored by estimating dehydrogenase and arylsulfatase enzyme activities. The endosulfan degradation reached an undetectable level on day 15. The pH of the medium was nearly neutral (6.9) at the time of inoculation and it decreased to 3.6 on day 15. The amount of chloride released at particular intervals in the endosulfan degradation ranged from 28 \mug mL^{-1} to 104 \mug mL^{-1}. Change in pH and the increase in released chloride correlated with metabolic activities involved in the simultaneous degradation of endosulfan. Endosulfan sulfate, an intermediate metabolite, was detected and had disappeared on day 11 of the process. The increase in enzyme activities is an indicator of soil fertility and suggests possible involvement of these enzymes in endosulfan degradation. These results demonstrate that bioaugmentation by A. niger may be a viable tool for the remediation of soil contaminated with endosulfan.

The pollution and ecological risk of endosulfan in soil of Huai’an city, China

Endosulfan, a persistent organic pollutant newly listed under the Stockholm Convention, is currently widely produced and used as a pesticide in China. Concentrations of endosulfans (including α-, β-isomers, and their metabolite endosulfan sulfate) were determined in surface soil collected from Huai'an city, where the largest endosulfan producer is located. The concentrations of Σendosulfan (sum of α-endosulfan, β-endosulfan, and endosulfan sulfate) at all sites ranged from 0.28 to 44.81 ng/g dry weight (dw), following a lognormal distribution. The geometric mean was 1.09 ng/g dw, and the geometric standard deviation was 3.02. The β-endosulfan levels were consistently greater than those of α-isomer. The concentration ratios of α-endosulfan to β-endosulfan ranged from 0.03 to 0.70, which were much lower than the commercial endosulfan mixture. This is because that α-endosulfan is more volatile and degrades faster than β-endosulfan in soil. The contour map of Σendosulfan levels in soil indicates that the factory was the point pollution source with the highest endosulfan level in its surrounding area, especially the southern area. However, the non-point agricultural sources are more important. Based on Monte Carlo simulation, the Σendosulfan inventory in soil in Huai'an is estimated to be 0.8-3.0 tons. In order to understand the potential ecological risk of endosulfan, the Monte Carlo-based hazard quotient distribution was estimated and showed that Σendosulfan posed a potentially high risk to soil organisms. To our knowledge, this study is the first that reports soil pollution and risk of endosulfan around the manufacturer in China. This study will help China's implementation of Stockholm Convention for the reduction and elimination of endosulfan in future.

Degradation of endosulfan and endosulfan sulfate by white-rot fungus Trametes hirsuta

Endosulfan, an organochlorine insecticide, and its metabolite endosulfan sulfate are persistent in environments and are considered toxic. We investigate the possible nontoxic bioremediation of endosulfan. An endosulfandegrading fungus that does not produce endosulfan sulfate was selected from eight species of white-rot fungi. High degradation of endosulfan and low accumulation of endosulfan sulfate were found in cultures of Trametes hirsuta. A degradation experiment using endosulfan sulfate as the substrate revealed that T. hirsuta is able to further degrade endosulfan sulfate following the oxidative conversion of endosulfan to endosulfan sulfate. Endosulfan and endosulfan sulfate were converted to several metabolites via hydrolytic pathways. In addition, endosulfan dimethylene, previously reported as a metabolite of the soil bacterium Arthrobacter sp., was detected in T. hirsuta culture containing endosulfan sulfate. Our results suggest that T. hirsuta has multiple pathways for the degradation of endosulfan and endosulfan sulfate and thus has great potential for use as a biocatalyst in endosulfan bioremediation.

Organochlorine pesticides in the soil of a karst cave in Guilin, China

Organochlorine pesticides (OCPs) including HCH, DDT, chlordane, endosulfan, and endosulfan sulfate were analyzed in surface soil of the Dayan Cave to investigate their source and concentration levels in September 2006. Generally, the data showed that outside soil of the cave had much higher concentrations than inside soil for the most detected OCPs in the cave and both inside soil and outside soil showed much lower concentration levels (basically, the levels of OCPs were less than 0.7 ng/g) than those observed in other regions within and outside China other than TC (ranging from 3.22 to 5.00 ng/g) and CC (ranging from 3.89 to 5.08 ng/g) in the soil outside. The ratios of α-/γ-HCH ranged from 0.88 to 1.20 in the soil of the cave, together with the averaged percentages of β-HCH and δ-HCH among the total HCH isomers (accounting for 39.0% and 14.2%, respectively), implied that a historical residue of local technical HCH contamination was likely to be dominant in the soil of the cave. Based on (1) the accordance of TC/CC ratios (ranging from 0.83 to 0.98) between the values observed in the outside soil and the potentially available chlordane products in the markets, and (2) the high concentrations of TC and CC observed in the outside soil, it appeared that the illegal usage of technical chlordane was done in Guilin. The low concentrations of TC (0.02 to 0.56 ng/g) and CC (0.10 to 1.71 ng/g) in the inside soil, together with the significant distinctions of TC/CC ratios between the inside soil (ranging from 0.03 to 0.33) and the outside soil, implied that the chlordane in the inside soil of the cave was a historical residue of local technical chlordane contamination. The similar ratios of DDT isomers (o, p (')-DDT/p, p (')-DDT and p, p (')-DDE+DDD/DDT) between the outside soil and the inside soil of the cave suggested that they may have the similar DDT source. The ratios of p, p (')-DDE+DDD/DDT (ranging from 3 to 8) indicated that DDT was relatively aged. The values of o, p (')-DDT/p, p (')-DDT ratios (ranging from 3 to 7.5 with a mean value of 5.45) were found to be much higher than that of technical DDT, and very similar to that of dicofol products, implied that the primary source of DDT in the soil of the cave was most probably from dicofol-type DDT products. The low concentration levels of endosulfan and the higher levels of metabolite endosulfan sulfate indicated that the residue from historical usage of technical endosulfan was likely to be dominant in the soil of the cave.

Monitoring and Modeling Endosulfan in Chinese Surface Soil

Endosulfan is a currently used organochlorine pesticide in China, with annual usage of 2300 t between 1994 and 2004. Concentrations of endosulfan (including α- and β-isomers and their metabolite endosulfan sulfate) were reported for surface soil collected in 2005 at 141 sites (6 background, 95 rural, and 40 urban) across China. The concentrations of total endosulfan (sum of α-endosulfan, β-endosulfan, and endosulfan sulfate) at all sites ranged from BDL (below detection limit) to 19000 pg/g dry weight (dw), with geometric mean (GM) 120 pg/g dw. Rural soils had the highest total endosulfan concentrations, with GM 160 pg/g dw, followed by urban soils (GM = 83 pg/g dw) and background soils (GM = 38 pg/g dw). The observed soil concentrations of α-endosulfan (GM = 6.5 pg/g dw) were much lower than those of β-endosulfan (GM = 49 pg/g dw) and endosulfan sulfate (GM = 47 pg/g dw). The fractional abundance of α-endosulfan F(α-endo) [α-endosulfan/(α-endosulfan + β-endosulfan)] for all soils ranged from 0.00040 to 0.91, with GM 0.10, much lower than those in technical products (ranged from 0.67 to 0.7), which most likely reflects that α-endosulfan is more volatile and degrades faster than β-endosulfan in soil. Consequently, half-life of β-endosulfan in soil is expected longer than α-endosulfan. Significant correlation between endosulfan sulfate and its parent isomers suggested that the presence of endosulfan sulfate originated from its parent isomers. Based on multiple linear regression model, inventories of endosulfan sulfate in Chinese agricultural soil in 2004 with a 1/4° longitude × 1/6° latitude resolution are established. Comparison between field measurements and modeling results showed significant correlations between the modeled and measured endosulfan concentrations, and 89%, 83%, and 70% of monitoring data fell between the lowest and the highest modeled concentrations for α- and β-endosulfan and endosulfan sulfate, respectively. The good agreement lends credibility to modeled soil concentrations of endosulfan. To our knowledge, this is the first soil concentration inventory for endosulfan sulfate, which paves the way for further study on its environmental behavior.

Endosulfan induces CYP2B6 and CYP3A4 by activating the pregnane X receptor

Endosulfan is an organochlorine pesticide commonly used in agriculture. Endosulfan has affects on vertebrate xenobiotic metabolism pathways that may be mediated, in part, by its ability to activate the pregnane X receptor (PXR) and/or the constitutive androstane receptor (CAR) which can elevate expression of cytochrome P450 (CYP) enzymes. This study examined the dose-dependency and receptor specificity of CYP induction in vitro and in vivo. The HepG2 cell line was transiently transfected with CYP2B6- and CYP3A4-luciferase promoter reporter plasmids along with human PXR (hPXR) or hCAR expression vectors. In the presence of hPXR, endosulfan-alpha exposure caused significant induction of CYP2B6 (16-fold) and CYP3A4 (11-fold) promoter activities over control at 10 µM. The metabolite endosulfan sulfate also induced CYP2B6 (12-fold) and CYP3A4 (6-fold) promoter activities over control at 10 µM. In the presence of hCAR-3, endosulfan-alpha induced CYP2B6 (2-fold) promoter activity at 10 µM, but not at lower concentrations. These data indicate that endosulfan-alpha significantly activates hPXR strongly and hCAR weakly. Using western blot analysis of human hepatocytes, the lowest concentrations at which CYP2B6 and CYP3A4 protein levels were found to be significantly elevated by endosulfan-alpha were 1.0 µM and 10 µM, respectively. In mPXR-null/hPXR-transgenic mice, endosulfan-alpha exposure (2.5 mg/kg/day) caused a significant reduction of tribromoethanol-induced sleep times by approximately 50%, whereas no significant change in sleep times was observed in PXR-null mice. These data support the role of endosulfan-alpha as a strong activator of PXR and inducer of CYP2B6 and CYP3A4, which may impact metabolism of CYP2B6 or CYP3A4 substrates.

Insecticide dissipation from soil and plant surfaces in tropical horticulture of southern Benin, West Africa

In Sub-Saharan Africa, horticulture provides livelihood opportunities for millions of people, especially in urban and peri-urban areas. Although the vegetable agroecosystems are often characterized by intensive pesticide use, risks resulting therefrom are largely unknown under tropical horticultural conditions. The objective of this study therefore was to study the fate of pesticides in two representative horticultural soils (Acrisol and Arenosol) and plants (Solanum macrocarpon L.) after field application and thus to gain first insight on environmental persistence and dispersion of typical insecticides used in vegetable horticulture in Benin, West Africa. On plant surfaces, dissipation was rapid with half lives ranging from 2 to 87 h (alpha-endosulfan < beta-endosulfan < deltamethrin). Soil dissipation was considerably slower than dissipation from plant surfaces with half-lives ranging from 3 (diazinon) to 74 d (total endosulfan), but persistence of pesticides in soil was still reduced compared to temperate climates. Nevertheless, for deltamethrin and endosulfan, a tendency for mid-term accumulation in soil upon repeated applications was observed. The soil and plant surface concentrations of the metabolite endosulfan sulfate increased during the entire trial period, indicating that this compound is a potential long-term pollutant even in tropical environments.

Accumulation of Current-Use Pesticides in Neotropical Montane Forests

In Central America, chemical-intensive tropical agriculture takes place in close proximity to highly valued and biologically diverse ecosystems, yet the potential for atmospheric transport of pesticides from plantations to national parks and other reserves is poorly characterized. The specific meteorological conditions of mountain ranges can lead to contaminant convergence at high altitudes, raising particular concern for montane forest ecosystems downwind from pesticide use areas. Here we show, based on a wide-ranging air and soil sampling campaign across Costa Rica, that soils in some neotropical montane forests indeed display much higher concentrations of currently used pesticides than soils elsewhere in the country. Specifically, elevated concentrations of the fungicide chlorothalonil, the herbicide dacthal, and the insecticide metabolite endosulfan sulfate on volcanoes Barva and Poas, lying directly downwind of the extensive banana plantations of the Caribbean lowland, indicate the occurrence of atmospheric transport and wet deposition of pesticides at high altitudes. Calculations with a contaminant fate model, designed for mountain regions and parametrized to the Costa Rican environment, show that chemicals with a log K(AW) between -3 and -5 have a greater potential for accumulation at high altitudes. This enrichment behavior is quantified by the Mountain Contamination Potential and is sensitive to contaminant degradability. The modeling work supports the hypothesis suggested by the field results that it is enhanced precipitation scavenging at high elevations (caused by lower temperatures and governed by K(AW)) that causes pesticides to accumulate in tropical montane areas. By providing for the first time evidence of significant transfer of currently used pesticides to Central American montane cloud forests, this study highlights the need to evaluate the risk that tropical agricultural practices place on the region's ecological reserves.

Residual fate and persistence of endosulfan (50 WDG) in Bengal gram (Cicer arietinum)

Residual fate and dissipation pattern of endosulfan (50 WDG) in soil and plant was studied by gas liquid chromatography following twice applications (at 350 g and 700 g a.i. ha(-1)) in chick-pea, Bengal gram (Cicer arietinum) at vegetative and flowering stages of the crop. The initial residues of Endosulfan (alpha + beta + endosulfan sulfate) in plant following second application was 23.40-57.91 microg g(-1) and its maximum deposit in soil was 1.00-2.45 microg g(-1) after 1 day. Dissipation followed first order reaction kinetics and the half-life values were 2.6-2.9 days in green foliage and 4.4-5.0 days in soil. A pre-harvest interval of 14-19 days was recommended for green foliage. No residues were detected in harvested seeds. Maximum concentration of the metabolite endosulfan sulfate was 0.152-0.473 microg g(-1) in soil and 5.42-9.40 microg g(-1) in plant on third day. Endosulfan-beta was more persistent than alpha-isomer attributable to higher conversion of the later to endosulfan sulfate in soil and plant.

Endosulfan degradation by a Rhodococcus strain isolated from earthworm gut

A Rhodococcus MTCC 6716 bacterial strain was isolated apparently for the first time from the gut microflora of an Indian earthworm ( Metaphire posthuma). Endosulfan was used as a carbon source by the strain and degraded it up to 92.58% within 15 days. Furthermore, the isolated strain of the bacterium did not produce the persistent form of the toxic metabolite endosulfan sulfate. This strain exhibits luxury growth in minimal medium with high concentrations of endosulfan (80 μg mL −1). Degradation of the endosulfan occurred simultaneously with bacterial growth and an increase in chloride ion (87.1%) in the growth medium, suggesting nearly complete degradation of the insecticide. This strain is able to tolerate 45 °C and retain its degradation potential even under sunlight exposure. Since endosulfan is used worldwide for pest control and its residues have been retained for long periods in soil, water, and agricultural products, the strain isolated by us is valuable for bioremediation of endosulfan-contaminated soil and water.

Distribution of multiple pesticide residues in apple segments after home processing

The effects of washing, storing, boiling, peeling, coring and juicing on pesticide residue were investigated for field-sprayed Discovery and Jonagold apples. Residues of chlorpyrifos, cypermethrin, deltamethrin, diazinon, endosulfan, endosulfan sulfate, fenitrothion, fenpropathrin, iprodione, kresoxim-methyl, lambda-cyhalothrin, quinalphos, tolylfluanid and vinclozolin in the processed apples were analysed by gas chromatography. Statistical analysis showed that reductions of 18–38% were required to obtain significant effects of processing practices, depending on pesticide and apple variety. Juicing and peeling the apples significantly reduced all pesticide residues. In the case of detectable pesticide residues, 1–24% were distributed in the juice and in the peeled apple. None of the pesticide residues was significantly reduced when the apples were subject to simple washing or coring. Storing significantly reduced five of the pesticide residues: diazinon, chlorpyrifos, fenitrothion, kresoxim-methyl and tolylfluanid, by 25–69%. Residues of the metabolite endosulfan sulfate were increased by 34% during storage. Boiling significantly reduced residues of fenitrothion and tolylfluanid by 32 and 81%, respectively. Only a few of the observed effects of processing could be explained by the physical or chemical characteristics of the pesticides. No differences in effect of processing due to apple variety were identified.

Analysis of pesticide residues in fruit juices by matrix-solid phase dispersion and gas chromatographic determination

A rapid multiresidue method has been developed for the analysis of pesticides in fruit juices. The compounds studied were two insecticides (endosulfan I, endosulfan II and their metabolite endosulfan sulfate), five fungicides (chlorothalonil, vinclozolin, procymidone, hexaconazole and fenarimol) and two acaricides (dicofol and tetradifon). The method is based on the dispersion of fruit juices on the adsorbent, Florisil, placed in small glass columns, and subsequent extraction of pesticides using a small volume of ethyl acetate. Residue levels were determined by gas chromatography with electron-capture detection. The ECD response for all pesticides was linear in the range of concentrations studied, with correlation coefficients higher than 0.99. Recoveries obtained for pesticides in different fruit juices at various fortification levels were higher than 74%, with relative standard deviations between 1 and 12%. The detection limits ranged from 1 to 5 μg kg1. The identity of the pesticides was confirmed by GC-MS.

Degradation of beta‐endosulfan byAspergillus Niger

Abstract The organochlorine insecticide endosulfan is a mixture of two stereoisomers, alpha and beta. The degradation of the more persistent beta isomer was shown using the soil microorganism Aspergillus niger. The relatively rapid rate of degradation of beta‐endosulfan as compared to control, formation of endosulfan diol and absence of formation of the toxic metabolite endosulfan sulfate suggest the possibility of developing a non‐chemical method for degrading endosulfan.