Pesticide residues in muscles of some marine fish species and seaweeds of Iskenderun Bay (Northeastern Mediterranean), Turkey

Pesticide residues in muscles of nine marine fish and four seaweed species of Iskenderun Bay (Northeastern Mediterranean) have been investigated. In sampled fish species, two herbicides, three insecticides, two fungicides, and one synergist were identified and quantified. Metribuzin DADK, propamocarb HCl, and piperonyl butoxide (PBO) were detected in all the muscles of sampled fish species. Metribuzin DADK was the most abundant pesticide residue in fish muscles and the highest metribuzin DADK concentration was found in sardine (311.20 μg/kg). Propamocarb HCl concentrations varied greatly among species; from 0.530 ± 0.020 μg/kg in striped sea bream to 34.170 μg/kg in sea bass. The level of PBO ranged from 0.001 μg/kg for fourlined terapon to 0.013 μg/kg for sardine. No measurable oxamyl residue was found in any of the muscles of sampled fish species (except sardine). In seaweeds, two herbicides and two insecticides were identified and quantified. Metribuzin DADK was the most abundant and found in Cystoseira corniculata (5.01 mg/kg), Corallina elongata (0.703 mg/kg), and Jania rubens (3.85 mg/kg). Molinate was a minor contaminant and only found in Corallina elongata (0.002 mg/kg). Pyrethrin I was determined only in Padina pavonia to be 0.567 mg/kg. Pyrethrine II was found in Padina pavonia and Corallina elongate to be 1.214 and 0.229 mg/kg, respectively. The most hazardous pesticide residues of organochlorines and organophosphorus were not detected in both sampled fish muscles and seaweeds. There are no clear maximum residue limits for the detected eight pesticide residues declared for fish muscle by European Union MRL (2017). In conclusion, it can be considered that observed concentrations of pesticides in sampled nine marine fish species do not have a potential health risk for consumers. Some of the detected pesticide residues can be toxic for algae and aquatic life and regular monitoring studies are therefore essential to control the pesticide concentrations of aquatic biota in the region.

Bioaccumulation, distribution and elimination of lindane in Eisenia foetida: The aging effect

Soil aging will influence the chemical speciation of pesticides, thus affecting the uptake route to be bioavailable to the organism. So far, studies on the possible effects of the uptake route on the distribution and elimination of pesticides in the organism that also considers effects of aging are limited. In our study, Eisenia fetida was exposed to 4.5 mg kg^-1 lindane aging for 0, 30 and 180 d, and the accumulation, distribution and elimination of lindane in the earthworms were analyzed. The results showed that the 6 h Tenax-extracted fraction exhibited a good linear correlation with the lindane accumulated in the earthworms. With aging time increasing, the bioaccumulation of lindane decreased and the accumulative balance was more easily reached in the earthworms. Lindane distributions were found in the whole earthworm and the proportions of lindane content at sub-organism level and the mass distribution of each fraction were similar for 0 d and 180 d aged groups. The foregut accumulated the highest content of lindane (20%) relative to its low mass distribution proportion (10%). The elimination rate of lindane in the earthworms decreased with aging time extending. Our conclusion was that the 6 h Tenax extraction could be used to assess the bioavailability of aging lindane. Although soil aging decreased the bioavailability of lindane, the soil-bound lindane entered the earthworm through dietary route would take longer to depurate from the organisms than free lindane, which implied the potential ecological risk of bound pesticide residues.

Liquid chromatography-mass spectrometry method for evaluating the dissipation dynamics of cyromazine and its metabolite in Agaricus bisporus and dietary risk assessment

Providing guidance on the reasonable use of pesticide in agricultural production is of particular importance for ensuring food safety. In the present study, a field trial was performed to study the dissipation and accumulative pattern of cyromazine (CA) and its metabolite in Agaricus bisporus (A. bisporus) cultivation. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was first developed and validated for the determination of CA and melamine (MEL) in the casing soil and fruiting body. During the cultivation period, the dissipation rates of CA in the casing soil were between 51.57 and 63.48% at three dose groups. The fruiting body presented higher accumulation ability for MEL compared with CA. The terminal residues of MEL never exceeded the maximum residue limits (MRLs) in food. In addition, the intake health risk from the CA and MEL residues in the fruiting body were negligible to humans. This study will help to provide valuable guidance on the application strategies of CA in A. bisporus cultivation.

Residue analysis and risk assessment of pyrethrins in open field and greenhouse turnips

A sensitive and selective method was developed and validated for the determination of pyrethrin residues in turnips (turnip leaves, turnip tubers, and the whole of plant) and cultivated soil using gas chromatography coupled with mass spectrometry (GC-MS). Six major components of pyrethrins (pyrethrin I and II, cinerin I and II, and jasmolin I and II) were separated and identified. The method involving solid-phase extraction (SPE) cleanup led to satisfactory average recoveries (88.1-104%) with limits of quantification (LOQs) of 0.05 mg/kg. The dissipation and final residue of pyrethrins in six provinces (among these places, two experiments were conducted in greenhouse and other four experiments in open filed) in China were studied. The trial results suggested that the half-lives of pyrethrins in the whole of turnips and soil were 0.5-1.6 and 1.0-1.3 days, respectively, and the degradation of pyrethrins in the greenhouse was quicker than that in open fields. The final residues of pyrethrins in turnip leaves and tubers were all below the maximum residue limit (MRL) established by the EU (1.0 mg/kg). A pre-harvest interval of 2 days and MRL of 1.0 mg/kg are recommended to ensure food safety standards for pyrethrins in turnips. Long-term risk assessment and short-term risk assessment of turnip tubers were evaluated. Hazard quotient (HQ) and acute hazard index (aHI) were significantly less than 100%, indicating negligible risk for consumption of turnip tubers.

Organochlorine pesticide, antibiotic and heavy metal residues in mussel, crayfish and fish species from a reservoir on the Euphrates River, Turkey

This study investigated the residues of 19 organochlorine pesticides, 37 antibiotics and 5 heavy metals in biota samples (one mussel species, one crayfish species, six wild fish species and one farmed fish species) from the Keban Dam Reservoir on the Euphrates River, Turkey. Among monitored OCPs, only p,p'-DDE was detected in biota samples. It was found only in mussel, fish muscle and fish gill samples. The highest concentration of p,p'-DDE (0.032 mg/kg ww) was determined in the gill of common carp, which was found to be below the maximum residue limit (MRL). Only sulfadimethoxine was detected among antibiotics in biota samples. Its maximum concentration (0.0044 mg/kg ww) did not exceed the MRL of 0.1 mg/kg. Sulfadimethoxine was found only in muscle and gill of common carp collected from site S6, where there are many rainbow trout cage farms. However, no detectable residue of sulfadimethoxine was found in farmed rainbow trout. The highest concentrations of As, Cd and Pb were detected in mussels, while the highest concentrations Cu and Zn were determined in crayfish. Metal concentrations in biota samples did not exceed the maximum permissible levels. According to these results, the consumption of biota samples from the Keban Dam Reservoir is safe for human health.

Decline patterns and risk assessment of 10 multi-class pesticides in young sprout amaranth (Amaranthus mangostanus) under greenhouse growing conditions

The present study was designed to investigate the residual decline pattern and the risk assessment of 10 different class pesticides, namely azoxystrobin, boscalid, diazinon, diethofencarb, difenoconazole, etofenprox, flubendiamide, paclobutrazol, and pyraclostrobin in young vegetative amaranth (Amaranthus mangostanus) sprayed once or twice under greenhouse growing conditions. Field-incurred samples, collected at 3, 7, or 10 days after application of both treatments, were extracted and purified with the quick, easy, cheap, effective, rugged, and safe "QuEChERS" citrate-buffered method and analyzed with liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) in positive ion mode. The linearity was satisfactory with determination coefficients (R ²) falling between 0.9817 and 0.9999 and limits of detection (LOD) and quantification (LOQ) values of 0.0007 and 0.002 mg/kg, respectively. The mean recovery rate at four spiking levels (equivalent to 5, 10, 50, and 100 × LOQ) ranged from 78.1 to 131.6% with a relative standard deviation (RSD) of < 11%. Substantial differences in the initial deposit between the tested analytes were observed and clearly indicated that the structure, as well as the initial concentration of applied products, greatly affected the residue deposit. From the obtained residual data, the provisional marginal maximum residue limits (MRLs) and the pre-harvest intervals (PHI) were proposed. Risk assessment was evaluated by comparing the theoretical maximum daily intake (TMDI) with the acceptable daily intake (ADI). Herein, the TMDI was lower than the ADI (TMDI/ADI ratio ≤ 80% set by the Korean Ministry of Food and Drug Safety) except for difenoconazole (80.92%, marginally higher), indicating that the vegetative amaranth is not hazardous and can be consumed safely by Korean consumers.

Factors Affecting the Bioaccessibility and Intestinal Transport of Difenoconazole, Hexaconazole, and Spirodiclofen in Human Caco-2 Cells Following in Vitro Digestion

This study examined how gastrointestinal conditions affect pesticide bioaccessibility and intestinal transepithelial transport of pesticides (difenoconazole, hexaconazole, and spirodiclofen) in humans. We used an in vitro model combining human gastric and intestinal digestion, followed with Caco-2 cell model for human intestinal absorption. Bioaccessibility of three tested pesticides ranged from 25.2 to 76.3% and 10.6 to 79.63% in the gastric and intestinal phases, respectively. A marked trend similar to the normal distribution was observed between bioaccessibility and pH, with highest values observed at pH 2.12 in gastric juice. No significant differences were observed with increasing digestion time; however, a significant negative correlation was observed with the solid-liquid (S/L) ratio, following a logarithmic equation. R² ranged from 0.9198 to 0.9848 and 0.9526 to 0.9951 in the simulated gastric and intestinal juices, respectively, suggesting that the S/L ratio is also a major factor affecting bioaccessibility. Moreover, significant dose- and time-response effects were subsequently observed for intestinal membrane permeability of difenoconazole, but not for hexaconazole or spirodiclofen. This is the first study to demonstrate the uptake of pesticides by human intestinal cells, aiding quantification of the likely effects on human health and highlighting the importance of considering bioaccessibility in studies of dietary exposure to pesticide residues.

Effect of the Composition and Structure of Excipient Emulsion on the Bioaccessibility of Pesticide Residue in Agricultural Products

The influence of co-ingestion of food emulsions with tomatoes on the bioaccessibility of a model pesticide (chlorpyrifos) was studied. Emulsions were fabricated with different oil contents (0-8%), lipid compositions (medium chain triglyceride (MCT) and corn oil), and particle diameters (d₃₂ = 0.17 and 10 μm). The emulsions were then mixed with chlorpyrifos-contaminated tomato puree, and the mixtures were subjected to a simulated gastrointestinal tract (GIT) consisting of mouth, stomach, and small intestine. The particle size, surface charge, and microstructure of the emulsions was measured as they passed through the GIT, and chlorpyrifos bioaccessibility was determined after digestion. The composition and structure of the emulsions had a significant impact on chlorpyrifos bioaccessibility. Bioaccessibility increased with increasing oil content and was higher for corn oil than MCT, but did not strongly depend on oil droplet size. These results suggest that co-ingestion of emulsions with fruits or vegetables could increase pesticide bioaccessibility.

Microbial growth yield estimates from thermodynamics and its importance for degradation of pesticides and formation of biogenic non-extractable residues

In biodegradation studies with isotope-labelled pesticides, fractions of non-extractable residues (NER) remain, but their nature and composition is rarely known, leading to uncertainty about their risk. Microbial growth leads to incorporation of carbon into the microbial mass, resulting in biogenic NER. Formation of microbial mass can be estimated from the microbial growth yield, but experimental data is rare. Instead, we suggest using prediction methods for the theoretical yield based on thermodynamics. Recently, we presented the Microbial Turnover to Biomass (MTB) method that needs a minimum of input data. We have estimated the growth yield of 40 organic chemicals (31 pesticides) using the MTB and two existing methods. The results were compared to experimental values, and the sensitivity of the methods was assessed. The MTB method performed best for pesticides. Having the theoretical yield and using the released CO₂ as a measure for microbial activity, we predicted a range for the formation of biogenic NER. For the majority of the pesticides, a considerable fraction of the NER was estimated to be biogenic. This novel approach provides a theoretical foundation applicable to the evaluation and prediction of biogenic NER formation during pesticide degradation experiments, and may also be employed for the interpretation of NER data from regulatory studies.

Organochlorine Pesticides Residues in Human Breast Milk from the Middle Governorates in Jordan in 2013/2014

One hundred samples of mother breast milk were gathered from six middle governorates and districts in Jordan in 2013/2014 to monitor Organochlorine pesticides pollutants. The results showed clearly that banned organochlorine pesticides are still detected in the monitored samples in low concentration despite banning of these persistent pollutants in Jordan since 36 years ago. However, the results indicated that 1% of the contaminated samples contained β-HCH, 5% γ-HCH, 3% p,p'-DDD, 2% heptachlor, 45% p,p'-DDE and 3% p,p'-DDT. In addition, these monitored samples had no residues of aldrin, dieldrin, α-endosulfan, β-endosulfan, HCB, o,p'-DD, o,p'-DDT and o,p'-DDE. In conclusion, there was a decline in the residues of Organochlorine pesticides, particularly DDT group members.

Occurrence of Chlorotriazine herbicides and their transformation products in arable soils

Chlorotriazine herbicides (CTs) are widely used pest control chemicals. In contrast to groundwater contamination, little attention has been given to the circumstances of residue formation of parent compounds and transformation products in soils. Seventy-five cultivated floodplain topsoils in the Czech Republic were sampled in early spring of 2015, corresponding to a minimum of six months (current-use terbuthylazine, TBA) and a up to a decade (banned atrazine, AT and simazine, SIM) after the last herbicide application. Soil residues of parent compounds and nine transformation products were quantified via multiple residue analysis using liquid chromatography - tandem mass spectrometry of acetonitrile partitioning extracts (QuEChERS). Using principal component analysis (PCA), their relation to soil chemistry, crops and environmental parameters was determined. Of the parent compounds, only TBA was present in more than one sample. In contrast, at least one CT transformation product, particularly hydroxylated CTs, was detected in 89% of the sites, or 54% for banned triazines. Deethylated and bi-dealkylated SIM or AT residues were not detectable. PCA suggests the formation and/or retention of CT hydroxy-metabolite residues to be related to low soil pH, and a direct relation between TBA and soil organic carbon, and between deethyl-TBA and clay or Ca contents, respectively, the latter pointing towards distinct sorption mechanisms. The low historic application of simazine contrasted by the high abundance of its residues, and the co-occurrence with AT residues suggests the post-ban application of AT and SIM banned triazines as a permitted impurity of TBA formulations as a recent, secondary source. The present data indicate that topsoils do not contain abundant extractable residues of banned parent chlorotriazines, and are thus likely not the current source for related ground- and surface water contamination. In contrast, topsoils might pose a long-term source of TBA and CT transformation products for ground and surface water contamination.

Impaired antioxidant gene expression by pesticide residues and its relation with other cellular biomarkers in Nile Tilapia (Oreochromis niloticus) from Lake Burullus

Organochlorines and Organophosphorus are the most commonly used pesticides. These pesticides constitute a considerable contaminating threat due to their excessive agricultural usage which in turn contaminates the aquatic system through agricultural drainage. The aim of this study was to evaluate water and tissue residues of both pesticides in O. niloticus obtained from three different sections in Lake Burullus, Egypt. Assessment of relative change in mRNA levels of GST and Vtg (oxidative stress indicator) was done and its relation with other cellular biomarkers including apoptosis, which is assessed by Cellular apoptosis susceptibility transcript level (CAS), comet assay and micronucleus assays (genotoxicity indicator). Pesticide residue levels in water are fluctuating. In fish tissues, most residues were higher than those found in water and were associated with down regulation of hepatic GST gene and Vtg expression. CAS gene involved in apoptosis, its transcript is down regulated in middle and western sections of the lake with higher pesticide residues. Different degrees of DNA damages in O. niloticus' liver cells were demonstrated by comet assay. Significant increase in the micronucleated cells in the three sections of the lake was observed; the western section fish showed the highest number. Persistent exposures of fish to pesticide caused impairment of antioxidant gene expression. This negatively affects apoptosis associated with damaging DNA and chromosome fragments.

Microbial flora analysis for the degradation of beta-cypermethrin

In the Xinjiang region of Eurasia, sustained long-term and continuous cropping of cotton over a wide expanse of land is practiced, which requires application of high levels of pyrethroid and other classes of pesticides-resulting in high levels of pesticide residues in the soil. In this study, soil samples were collected from areas of long-term continuous cotton crops with the aim of obtaining microbial resources applicable for remediation of pyrethroid pesticide contamination suitable for the soil type and climate of that area. Soil samples were first used to culture microbial flora capable of degrading beta-cypermethrin using an enrichment culture method. Structural changes and ultimate microbial floral composition during enrichment were analyzed by high-throughput sequencing. Four strains capable of degrading beta-cypermethrin were isolated and preliminarily classified. Finally, comparative rates and speeds of degradation of beta-cypermethrin between relevant microbial flora and single strains were determined. After continuous subculture for 3 weeks, soil sample microbial flora formed a new type of microbial flora by rapid succession, which showed stable growth by utilizing beta-cypermethrin as the sole carbon source (GXzq). This microbial flora mainly consisted of Pseudomonas, Hyphomicrobium, Dokdonella, and Methyloversatilis. Analysis of the microbial flora also permitted separation of four additional strains; i.e., GXZQ4, GXZQ6, GXZQ7, and GXZQ13 that, respectively, belonged to Streptomyces, Enterobacter, Streptomyces, and Pseudomonas. Under culture conditions of 37 °C and 180 rpm, the degradation rate of beta-cypermethrin by GXzq was as high as 89.84% within 96 h, which exceeded that achieved by the single strains GXZQ4, GXZQ6, GXZQ7, and GXZQ13 and their derived microbial flora GXh.

Levels of persistent organic pollutants in breast milk of Maya women in Yucatan, Mexico

In this study, 24 breast milk samples, obtained from rural Maya women, from municipalities of Yucatan, Mexico, were analyzed for organochlorine pesticide (OCP) residues by gas chromatography. Recent studies have shown that Maya communities have a poor perception about the proper usage and handling of OCP. The karstic soil in this area has a high vulnerability to groundwater pollution by the use of OCP in agriculture and livestock activities. The impact of the ecosystem on human health is much more critical due to the prevailing poverty and a very low educational level of these communities. About 30% of the Maya population consumes water directly from contaminated wells and sinkholes, resulting in a chronic exposure to OCP. The samples served to identify and quantify high levels of OCP residues (18.43 mg/kg of heptachlor epoxide and 1.92 mg/kg of endrin in the metropolitan zone; 2.10 mg/kg of dieldrin, 0.117 mg/kg of endosulfan II, 0.103 mg/kg of heptachlor, 0.178 mg/kg of endrin, and 0.127 mg/kg of endrin aldehyde in the main agricultural zone and on the west coast). The detected levels of OCP residues are a major concern and represent a potential risk to women and children in the region. This could be associated with the high rates of cervical uterine and breast cancer mortality in Yucatan. Thus, regulations on the usage of OCP and their enforcement are necessary, and it is important to establish a yearly monitoring program for OCP residues in breast milk and groundwater, as well as to implement health promotion programs for women in particular and the general population in general.

WHO/UNEP global surveys of PCDDs, PCDFs, PCBs and DDTs in human milk and benefit-risk evaluation of breastfeeding

Since 1987, the World Health Organization (WHO) carried out global surveys on polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in human milk. This study presents a review of the three most recent surveys from 2000 to 2010, including DDT. The objective was to identify global quantitative differences and provide baseline information for 52 countries or provide time-trends for countries with previous data. Individual human milk samples were collected following a WHO-designed procedure and combined to form a national pooled sample. Here, we report global levels for PCDDs, PCDFs, PCBs and the sum of o,p'-DDT, p,p'-DDT, o,p'-DDE, p,p'-DDE, o,p'-DDD and p,p'-DDD (ΣDDTs). A concise risk-benefit evaluation related to human milk contamination with these persistent organic pollutants (POPs) was also done. Large global and regional differences were observed. Levels of PCDDs and PCDFs were highest in India and some European and African countries. PCB levels were highest in East and West Europe. The highest levels of ΣDDTs were found in less industrialized countries. A temporal downward trend for PCDDs, PCDFs and PCBs is indicated. A risk-benefit assessment indicates that human milk levels of PCDDs, PCDFs and PCBs are still significantly above those considered toxicologically safe, while ΣDDTs are below or around those considered safe. With respect to potential adverse health effects, a more dominant role of in utero exposure versus lactational exposure is indicated. If potential adverse effects are balanced against positive health aspects for (breastfed) infants, the advantages of breastfeeding far outweigh the possible disadvantages. Our observations provide a strong argument to plea for further global source-directed measures to reduce human exposure further to dioxin-like compounds.

Effective Monitoring of Fluxapyroxad and Its Three Biologically Active Metabolites in Vegetables, Fruits, and Cereals by Optimized QuEChERS Treatment Based on UPLC-MS/MS

Qualitative analysis and quantification of pesticide residues in foodstuff are essential to our health in daily life, especially regarding their metabolites, which may be more toxic and persistent. Thus, a valid analytical measure for detection of fluxapyroxad and its three metabolites (M700F002 (C-2), M700F008 (C-8), M700F048 (C-48)) in vegetables (cucumber, tomato, and pepper), fruits (grape, apple), and cereals (wheat, rice) was developed by UPLC-MS/MS with negative ion mode. The target compounds were extracted by acetonitrile contain 0.2% formic acid (v/v), and the extractions were cleaned up by octadecylsilane sorbents. The limits of quantitation and quantification were less than 0.14 μg kg^-1 and 0.47 μg kg^-1 in seven matrices. Furthermore, recoveries at levels of 0.01, 0.05, and 0.1 mg kg^-1 ranged from 74.9% to 110.5% with relative standard deviations ≤15.5% (n = 5). The method is validated to be effective and robust for the routine supervising of fluxapyroxad and its metabolites.

Metabolism and Residues of 2,4-Dichlorophenoxyacetic Acid in DAS-40278-9 Maize (Zea mays) Transformed with Aryloxyalkanoate Dioxygenase-1 Gene

DAS-40278-9 maize, which is developed by Dow AgroSciences, has been genetically modified to express the aryloxyalkanoate dioxygenase-1 (AAD-1) protein and is tolerant to phenoxy auxin herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D). To understand the metabolic route and residue distribution of 2,4-D in DAS-40278-9 maize, a metabolism study was conducted with ¹⁴C-radiolabeled 2,4-D applied at the maximum seasonal rate. Plants were grown in boxes outdoors. Forage and mature grain, cobs, and stover were collected for analysis. The metabolism study showed that 2,4-D was metabolized to 2,4-dichlorophenol (2,4-DCP), which was then rapidly conjugated with glucose. Field-scale residue studies with 2,4-D applied at the maximum seasonal rate were conducted at 25 sites in the U.S. and Canada to measure the residues of 2,4-D and free and conjugated 2,4-DCP in mature forage, grain, and stover. Residues of 2,4-D were not detectable in the majority of the grain samples and averaged <1.0 and <1.5 μg/g in forage and stover, respectively. Free plus conjugated 2,4-DCP was not observed in grain and averaged <1.0 μg/g in forage and stover.

Development of Helisoma trivolvis pond snails as biological samplers for biomonitoring of current-use pesticides

Nontarget aquatic organisms residing in wetlands are commonly exposed to current-use pesticides through spray drift and runoff. However, it is frequently challenging to measure exposure because of rapid dissipation of pesticides from water and reduced bioavailability. The authors' hypothesis is that freshwater snails can serve as bioindicators of pesticide exposure based on their capacity to passively accumulate tissue residues. Helisoma trivolvis snails were evaluated as biomonitors of pesticide exposure using a fungicide formulation that contains pyraclostrobin and metconazole and is frequently applied to crops surrounding depressional wetlands. Exposure-response studies indicate that H. trivolvis are tolerant of pyraclostrobin and metconazole at concentrations >10 times those lethal to many aquatic species, with a median lethal concentration based on pyraclostrobin of 441 μg/L (95% confidence interval of 359-555 μg/L). Bioconcentration factors ranged from 137 mL/g to 211 mL/g and from 39 mL/g to 59 mL/g for pyraclostrobin and metconazole, respectively. Elimination studies suggested one-compartmental elimination and snail tissue half-lives (t50 ) of approximately 15 h and 5 h for pyraclostrobin and metconazole, respectively. Modeling derived toxicokinetic parameters in the context of an environmentally relevant pulsed exposure suggests that residues can be measured in snails long after water concentrations fall below detection limits. With high fungicide tolerance, rapid accumulation, and slow elimination, H. trivolvis may be viable for biomonitoring of pyraclostrobin and should be investigated for other pesticides. Environ Toxicol Chem 2016;35:2320-2329. © 2016 SETAC.

DDT exposure of frogs: A case study from Limpopo Province, South Africa

Amphibians are globally under pressure with environmental contaminants contributing to this. Despite caution aired more than 80 years ago of threats posed to amphibians by DDT spraying for disease vector control, no data have been published on concentrations or effects of DDT contamination in frogs from areas where DDT is actively sprayed to control the insect vectors of malaria. In this study, we sampled fat bodies of Xenopus laevis and Xenopus muelleri naturally occurring in an area where indoor residual spraying of DDT is employed and from adjacent, non-sprayed, areas. ΣDDT concentrations ranged between <LOQ and 280 ng/g ww (wet weight) from the non-sprayed area, and 5.5-910 ng/g ww from the sprayed area, but statistical significance could not be shown. We observed significant asymmetric testicular morphology in frogs from the sprayed area, possibly due to endocrine disruption by compounds such as the DDTs. A previous study from the same area found very high concentrations of DDT in the eggs of the Grey Heron Ardea cinerea. This suggests that the DDT we found in frogs may have contributed to DDT loadings higher in the food web. These findings, combined with other studies from this area, support the need to reduce and eventually move away from DDT in malaria control safely and sustainably.

High-Throughput Analytical Techniques for Determination of Residues of 653 Multiclass Pesticides and Chemical Pollutants in Tea, Part VI: Study of the Degradation of 271 Pesticide Residues in Aged Oolong Tea by Gas Chromatography-Tandem Mass Spectrometry and Its Application in Predicting the Residue Concentrations of Target Pesticides

The degradation rate of 271 pesticide residues in aged Oolong tea at two spray concentrations, named a and b (a < b), were monitored for 120 days using GC-tandem MS (GC-MS/MS). To research the degradation trends and establish regression equations, determination days were plotted as horizontal ordinates and the residue concentrations of pesticide were plotted as vertical ordinates. Here, we consider the degradation equations of 271 pesticides over 40 and 120 days, summarize the degradation rates in six aspects (A-F), and discuss the degradation trends of the 271 pesticides in aged Oolong tea in detail. The results indicate that >70% of the determined pesticides coincide with the degradation regularity of trends A, B, and E, i.e., the concentration of pesticide will decrease within 4 months. Next, 20 representative pesticides were selected for further study at higher spray concentrations, named c and d (d > c > b > a), in aged Oolong tea over another 90 days. The determination days were plotted on the x-axis, and the differences between each determined result and first-time-determined value of target pesticides were plotted on the y-axis. The logarithmic function was obtained by fitting the 90-day determination results, allowing the degradation value of a target pesticide on a specific day to be calculated. These logarithmic functions at d concentration were applied to predict the residue concentrations of pesticides at c concentration. Results revealed that 70% of the 20 pesticides had the lower deviation ratios of predicted and measured results.

Peroxisome proliferator-activated receptors and biotransformation responses in relation to condition factor and contaminant burden in tilapia species from Ogun River, Nigeria

A major development in fishery science has been the Fulton's condition factor (CF) as a reliable physiological index of fish growth and health status (Fulton 1902). As a general rule, CF-value greater than 1 (>1) should be regarded as an indicator for good growth and health. Therefore, exposure of fish to contaminants in the environment will be expected to produce a reduction in scope for growth, since energy for growth will be allocated to overcome stressful conditions. In the present study, we hypothesized that tilapia species from Ogun River (Nigeria) are experiencing severe contaminant-induced obesogen effects leading to high CF (≥ 2) in fish with pathological alterations. The environmental obesogen hypothesis has related the interaction between environmental pollutants and PPAR isoform activation In this respect, peroxisome proliferator-activated receptors (PPARs) and biotransformation responses in relation to contaminant burden were investigated in a total of 1074 specimens of Tilapias species (Tilapia guineensis, Sarotherodon galileaus and Oreochromis niloticus) collected from three areas with different degrees of anthropogenic contamination and from a putative control site along the Ogun River. Liver mRNA expression of cytochrome cyp1 isoforms (cyp1a, 1b and 1c) and PPAR isoforms (ppar-α, β and γ) were analyzed using validated real-time PCR. Fish were also analyzed for CF and muscle contaminant burden (aliphatic and polycyclic aromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls). A significant increase in mRNA expression of cyp1- and ppar isoforms was observed in fish from polluted areas, and these results paralleled data on PCBs and PAHs tissue concentrations. Further, cyp1 isoforms showed clear sex-related differences, with higher mRNA expression in male fish than in females. Principal component analysis revealed a relationship between cyp1 isoforms, ppar-α, β, PCBs and PAHs and these interactions may suggest a crosstalk between AhR- and PPARs mediated pathways on metabolic and energetic processes. The PCA biplot also highlighted a positive relationship between ppar-γ, body weight, total length and PAHs. The CF for fish from all the sites was ≥ 2 indicating that this parameter may not be a reliable index for evaluating fish growth and health condition, especially in wild fish population exposed to complex cocktails of environmental pollutants.

Binding and detoxification of chlorpyrifos by lactic acid bacteria on rice straw silage fermentation

This investigation examined the reduction of pesticide residues on straw inoculated with lactic acid bacteria (LAB) during ensiling. Lactobacillus casei WYS3 was isolated from rice straw that contained pesticide residues. Non-sterilized rice straw, which was inoculated with L. casei WYS3, showed increased removal of chlorpyrifos after ensiling, compared with rice straw that was not inoculated with L. casei WYS3 or sterilized rice straw. In pure culture, these strains can bind chlorpyrifos as indicated by high-performance liquid chromatography analysis. Viable L. casei WYS3 was shown to bind 33.3-42% of exogenously added chlorpyrifos. These results are similar to those of acid-treated cells but less than those of heat-treated cells, which were found to bind 32.0% and 77.2% of the added chlorpyrifos respectively. Furthermore, gas chromatography-mass spectrometry analysis determined that L. casei WYS3 detoxified chlorpyrifos via P-O-C cleavage. Real-time polymerized chain reaction analysis determined that organophosphorus hydrolase gene expression tripled after the addition of chlorpyrifos to LAB cultures, compared with the control group (without chlorpyrifos). This paper highlights the potential use of LAB starter cultures for the detoxification and removal of chlorpyrifos residues in the environment.

Development of a regulatory testing procedure to study the metabolism of pesticides in farmed fish

BACKGROUND

Diets used in commercial fish farming use significant proportions of crop-derived commodities, and it is important to understand the potential for transfer of any pesticide residues on the crop into edible tissues in fish. It is a current requirement in the EU that fish metabolism studies must be performed when a pesticide is used in crops where commodities or processed fractions are fed to farmed fish. Fish metabolism studies in both rainbow trout and common carp have been carried out, following the new working document on the nature of pesticide residues in fish using (14) C-labelled pesticide.

RESULTS

The ingestion of experimental diets by rainbow trout and common carp resulted in the uptake and metabolism of the test item, as shown by liquid scintillation counting combined with radio-thin-layer chromatography. The metabolite profiles for trout and carp were qualitatively similar regarding the main residue. However, species-specific differences were found regarding the remaining residue with rainbow trout showing additional metabolites in comparison to carp.

CONCLUSIONS

Metabolism studies for regulatory purposes can be carried out with both fish species under laboratory conditions. The experimental design reported is suitable for quantifying the transfer of residues to edible tissues and enables characterisation of the chemical nature of residues.

The influence of effective microorganisms (EM) and yeast on the degradation of strobilurins and carboxamides in leafy vegetables monitored by LC-MS/MS and health risk assessment

The aim of this study was to determine the behaviour of strobilurin and carbocyamides commonly used in chemical protection of lettuce depending on carefully selected effective microorganisms (EM) and yeast (Y). Additionally, the assessment of the chronic health risk during a 2-week experiment was performed. The statistical method for correlation of physico-chemical parameters and time of degradation for pesticides was applied. In this study, the concentration of azoxystrobin, boscalid, pyraclostrobin and iprodione using liquid chromatography-mass spectrometry (LC-MS/MS) in the matrix of lettuce plants was performed, and there was no case of concentration above maximum residues levels. Before harvest, four fungicides and their mixture with EM (1 % and 10 %) and/or yeast 5 % were applied. In our work, the mixtures of 1%EM + Y and 10%EM + Y both stimulated and inhibited the degradation of the tested active substances. Adding 10%EM to the test substances strongly inhibited the degradation of iprodione, and its concentration decreased by 30 %, and in the case of other test substances, the degradation was approximately 60 %. Moreover, the addition of yeast stimulated the distribution of pyraclostrobin and boscalid in lettuce leaves. The risk assessment for the pesticides ranged from 0.4 to 64.8 % on day 1, but after 14 days, it ranged from 0.0 to 20.9 % for children and adults, respectively. It indicated no risk of adverse effects following exposure to individual pesticides and their mixtures with EM and yeast.

Residues of endosulfan in surface and subsurface agricultural soil and its bioremediation

The persistence of many hydrophobic pesticides has been reported by various workers in various soil environments and its bioremediation is a major concern due to less bioavailability. In the present study, the pesticide residues in the surface and subsurface soil in an area of intense agricultural activity in Pakkam Village of Thiruvallur District, Tamilnadu, India, and its bioremediation using a novel bacterial consortium was investigated. Surface (0-15 cm) and subsurface soils (15-30 cm and 30-40 cm) were sampled, and pesticides in different layers of the soil were analyzed. Alpha endosulfan and beta endosulfan concentrations ranged from 1.42 to 3.4 mg/g and 1.28-3.1 mg/g in the surface soil, 0.6-1.4 mg/g and 0.3-0.6 mg/g in the subsurface soil (15-30 cm), and 0.9-1.5 mg/g and 0.34-1.3 mg/g in the subsurface soil (30-40 cm) respectively. Residues of other persistent pesticides were also detected in minor concentrations. These soil layers were subjected to bioremediation using a novel bacterial consortium under a simulated soil profile condition in a soil reactor. The complete removal of alpha and beta endosulfan was observed over 25 days. Residues of endosulfate were also detected during bioremediation, which was subsequently degraded on the 30th day. This study revealed the existence of endosulfan in the surface and subsurface soils and also proved that the removal of such a ubiquitous pesticide in the surface and subsurface environment can be achieved in the field by bioaugumenting a biosurfactant-producing bacterial consortium that degrades pesticides.

Enhanced Dissipation of Triazole and Multiclass Pesticide Residues on Grapes after Foliar Application of Grapevine-Associated Bacillus Species

Disease management in vineyards with fungicides sometimes results in undesirable residue accumulations in grapes at harvest. Bioaugmentation of the grape fructosphere can be a useful approach for enhancing the degradation rate and reducing the residues to safe levels. This paper reports the in vitro and in vivo biodegradation of three triazole fungicides commonly used in Indian vineyards, by Bacillus strains, namely, DR-39, CS-126, TL-171, and TS-204, which were earlier found to enhance the dissipation rate of profenophos and carbendazim. The strains utilized the triazoles as carbon source and enhanced their in vitro rate of degradation. Myclobutanil, tetraconazole, and flusilazole were applied in separate vineyard plots at field doses of 0.40 g L(-1), 0.75 mL L(-1), and 0.125 mL L(-1), respectively. Residue analysis of field samples from the treated fields reflected 87.38 and >99% degradations of myclobutanil and tetraconazole, respectively, by the strain DR-39, and 90.82% degradation of flusilazole by the strain CS-126 after 15-20 days of treatment. In the respective controls, the corresponding percent degradations were 72.07, 58.88, and 54.28, respectively. These Bacillus strains could also simultaneously degrade the residues of profenofos, carbendazim, and tetraconazole on the grape berries and can be useful in multiclass pesticide residue biodegradation.

The key microorganisms for anaerobic degradation of pentachlorophenol in paddy soil as revealed by stable isotope probing

Pentachlorophenol (PCP) is a common residual persistent pesticide in paddy soil and has resulted in harmful effect on soil ecosystem. The anaerobic microbial transformation of PCP, therefore, has been received much attentions, especially the functional microbial communities for the reductive transformation. However, the key functional microorganisms for PCP mineralization in the paddy soil still remain unknown. In this work, DNA-based stable isotope probing (SIP) was applied to explore the key microorganisms responsible for PCP mineralization in paddy soil. The SIP results indicated that the dominant bacteria responsible for PCP biodegradation belonged to the genus Dechloromonas of the class β-Proteobacteria. In addition, the increased production of (13)CH4 and (13)CO2 indicated that the addition of lactate enhanced the rate of biodegradation and mineralization of PCP. Two archaea classified as the genera of Methanosaeta and Methanocella of class Methanobacteria were enriched in the heavy fraction when with lactate, whereas no archaea was detected in the absence of lactate. These findings provide direct evidence for the species of bacteria and archaea responsible for anaerobic PCP or its breakdown products mineralization and reveal a new insight into the microorganisms linked with PCP degradation in paddy soil.

Dissipation kinetics and degradation mechanism of amicarbazone in soil revealed by a reliable LC-MS/MS method

A sensitive and reliable analytical method was developed for simultaneous determination of amicarbazone (AMZ) and its two major metabolites including desamino amicarbazone (DA) and isopropyl-2-hydroxy-DA-amicarbazone (Ipr-2-OH-DA-AMZ) in soil for the first time. Targeted analytes were extracted and purified using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure, and then analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with a total run time of 9 min. The established approach was extensively validated by determining the linearity (R (2) ≥ 0.99), recovery (84-96 ), sensitivity (limits of quantification at 5-10 μg kg(-1)), and precision (RSDs ≤12 %). Based on the methodological advances, the subsequent dissipation kinetics and degradation mechanism of amicarbazone in soil were thoroughly investigated in an illumination incubator. As revealed, AMZ was easily degraded with the half-lives of 13.9-19.7 days in soil. Field trial results of AMZ (40 g a.i. ha(-1)) in Shanghai showed that the residues of AMZ and its metabolite Ipr-2-OH-DA-AMZ decreased from 0.505 mg kg(-1) (day 50) to 0.038 mg kg(-1) (day 365) and from 0.099 mg kg(-1) (day 50) to 0.028 mg kg(-1) (day 365), respectively, while the content of DA increased from 0.097 mg kg(-1) (day 50) to 0.245 mg kg(-1) (day 365). This study provided valuable data to understand the toxicity of AMZ and substantially promote its safe application to protect environment and human health.

Environmental behavior and analysis of agricultural sulfur

Sulfur has been widely used for centuries as a staple for pest and disease management in agriculture. Presently, it is the largest-volume pesticide in use worldwide. This review describes the sources and recovery methods for sulfur, its allotropic forms and properties and its agricultural uses, including development and potential advantages of nanosulfur as a fungicide. Chemical and microbial reactivity, interactions in soil and water and analytical methods for determination in environmental samples and foodstuffs, including inexpensive analytical methods for sulfur residues in wine, beer and other food/beverage substrates, will be reviewed. The toxicology of sulfur towards humans and agriculturally important fungi is included, with some restrictions on use to promote safety. The review concludes with areas for which more research is warranted.

Dissipation behavior of octachlorodipropyl ether residues during tea planting and brewing process

The dissipation behavior of octachlorodipropyl ether (OCDPE) residues in fresh tea shoots and in tea prepared under field conditions was investigated, and the transfer of residues from brewed tea to tea infusion was determined. OCDPE levels in tea shoots, prepared tea, tea infusion, and spent tea leaves were determined using a sensitive and simple method. The dissipation of OCDPE is fairly slow in tea shoots and prepared tea, with half-life values of 5.10 and 5.46 days, respectively. The degradation rates of OCDPE residues in tea processing were 23.9-43.1 %. The terminal residues of OCDPE in tea shoots and prepared tea samples after 20 and 30 days of OCDPE application were higher than 0.01 mg/kg. However, OCDPE's transfer rates from brewed tea to tea infusion were only 6.0-14.8 %. Further studies on risk assessment of OCDPE residue in tea on the basis of the relationship of OCDPE in prepared tea and infusion are warranted.

Evaluation of chlorpyrifos transferred from contaminated feed to duck commodities and dietary risks to Chinese consumers

The present study describes chlorpyrifos residues in duck commodities through the duck food chain, transfer factors, and dietary risks to Chinese consumers. After duck feeding experiments with pellet feed that lasted for 42 days, chlorpyrifos residues found in all samples collected from the ducks on maximum estimated dose group (3.20 mg/kg level) were from <0.0005 to 0.019 mg/kg. The residue levels of the fat, intestine, and tongue were obviously higher than those of the meat and other edible tissues. The transfer factors of all duck commodities were from 0.0001 to 0.0049 among different contamination levels, which indicated that chlorpyrifos had a low persistency in duck meat and metabolism organs. The chronic exposure assessment revealed that only 0.034-0.150% of the acceptable daily intake (ADI; 0-0.01 mg/kg/bw/day) of chlorpyrifos was consumed via the duck commodities for different age and gender groups in China. The acute exposure assessments of different age and gender groups were only 0.019-0.082% of the acute reference dose (ARfD; 0-0.1 mg/kg/bw). The results show that the single dietary exposure risk of chlorpyrifos raised by the intake of duck commodities was quite low in China.

Determination and dissipation of fipronil and its metabolites in peanut and soil

In this study, a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was established for the extraction and cleanup of fipronil and its three metabolites (fipronil solfone, sulfide, and desulfinyl) in peanut kernel, shell, straw, seedling, and soil samples, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for analysis. The average recoveries were 66-116% at the level of 0.001-0.1 mg/kg with the RSD <19%, and the limit of detection was 0.3 ng/g for all matrices. The dissipation experiment results demonstrated that fipronil dissipated more rapidly in peanut seedling than in soil, with half-lives of <1 day in peanut seedling and 32-57 days in soil depending on the soil pH. The final residues at harvest of peanut kernels were all below 0.02 mg/kg, whereas in peanut shell and straw, the total highest residues were 0.99 and 0.30 mg/kg, respectively. Fipronil-desulfinyl and fipronil-sulfone were the highest residue metabolites in peanut plant (seedling and straw) and soil samples, respectively.

Interspecific and geographical differences in anticoagulant rodenticide residues of predatory wildlife from the Mediterranean region of Spain

We studied the prevalence of anticoagulant rodenticides (ARs) in the liver of 344 individuals representing 11 species of predatory wildlife that were found dead in the Mediterranean region of Spain (Catalonia and Majorca Island). Six different ARs (brodifacoum, bromadiolone, difenacoum, flocoumafen, difethialone, warfarin) were found in the liver of 216 (62.8%) animals and >1 AR co-occurred in 119 individuals (34.6%). The occurrence of ARs was positively correlated with the human population density. Catalonia and Majorca showed similar prevalence of AR detection (64.4 and 60.4%, respectively), but a higher prevalence was found in the resident population of Eurasian scops owl (Otus scops) from Majorca (57.7%) compared to the migratory population from Catalonia (14.3%). Birds of prey had lower levels of bromadiolone than hedgehogs, whereas no difference was found for other ARs. The risk of SGAR poisoning in wild predators in NE Spain is believed to be elevated, because 23.3% of the individuals exhibited hepatic concentration of ARs exceeding 200 ng/g.

Assessment of pesticide residues and gene expression in common carp exposed to atrazine and chlorpyrifos: Health risk assessments

This study assessed the impacts of atrazine (ATR), chlorpyrifos (CPF) and combined ATR/CPF exposure on the kidney of common carp (Cyprinus carpio L.). The carp were sampled after a 40-d exposure to CPF and ATR, individually or in combination, followed by a 40-d recovery to measure the expression levels of heat shock proteins genes (HSP60, HSP70 and HSP90) and pesticide residues in the kidney tissue. The results revealed that the mRNA and protein levels of HSP60, HSP70 and HSP90 were induced in the kidney of common carp by ATR, CPF, and ATR/CPF mixture. The accumulated amounts of ATR, CPF, and their metabolites in the kidney tissues exhibited dose-dependency. These results exhibited that increasing concentration of ATR and CPF in the environment causes considerable stress for common carp, suggesting that the expression levels of HSP60, HSP70 and HSP90 may act as potential biomarkers for assessing the environmental ATR and CPF risk for carp.

Examining pyrethroids, carbamates and neonicotenoids in fish, water and sediments from the Indus River for potential health risks

This 3 × 3 factorial study assessed pyrethroids, carbamates and neonicotenoids groups of pesticides in replicated samples of three fish species from low (S1, reference), medium (S2) and heavy (S3) polluted sites receiving agricultural run-offs around the Indus River. Water and sediment samples from the same sites were also analysed for these pesticides by using high-performance liquid chromatography. Out of nine investigated pesticides, only three pesticides (deltamethrin, carbofuran and cypermethrin) were detected in fish and sediment samples. Deltamethrin in Cyprinus carpio ranged from 0.490 to 0.839 μg/g, mostly exceeding 0.5 μg/g as the maximum residual limit suggested by FAO-WHO, whereas it ranged from 0.214 to 0.318 μg/g in the sampled sediments. The carbofuran concentrations were 0.0425-0.066 and 0.613-0.946 μg/g in Labeo rohita and Channa marulius muscles respectively and 0.069-0.081 μg/g in the corresponding sediment samples. These values were either higher or lower than the maximum limit (0.1 μg/g) as suggested by FAO-WHO. Conversely, the cypermethrin concentration ranged from 0.141 to 0.174 in Ch. marulius and 0.183-0.197 μg/g in sediments which were both below the FAO-WHO maximum limit of 2 μg/g. No pesticide residues were detected in water from these sampling sites. Most selected physicochemical variables were within the acceptable range of World Health Organization for the water quality for aquatic life. The detected pesticide contents were mostly higher in fish muscles from heavily polluted sites. This is worrying because these pesticides may pose health risks for the fish and people of the study area. However, a preliminary risk assessment indicated that the calculated daily intake of detected pesticides by people consuming fish from the Indus River was low and did not present an immediate risk to the fish-consuming people. This study may be used as a benchmark to determine the safety of fish meat in order to develop intervention strategies to maintain the water quality and to protect the health of fish and fish-consuming people.

Distribution and uptake pathways of organochlorine pesticides in greenhouse and conventional vegetables

The application of greenhouse vegetable cultivation has dramatically expanded worldwide during the last several decades. However, little information is available on the distribution and uptake of pesticides in greenhouse vegetables. To bridge this knowledge gap, the present study was initiated to investigate the distribution and uptake of organochlorine pesticides (OCPs) in vegetables from plastic greenhouse and conventional cultivation methods. The uptake pathways of OCPs were not significantly different between these two cultivation methods. The arithmetic means of OCP concentrations in greenhouse vegetables were higher than those in conventional vegetables, although there was no significant difference. This small difference raised the concern of whether the tiny difference could be magnified to a significant difference by bioaccumulation in the food chain. The issue should be addressed by a well-designed scheme in future studies.

MISCANTHUS X GIGANTEUS AS A NEW HIGHLY EFFICIENT PHYTOREMEDIATION AGENT FOR IMPROVING SOILS CONTAMINATED BY PESTICIDES RESIDUES AND SUPPLEMENTED CONTAMINANTS

Soil monitoring was accomplished at 76 former pesticide storehouses in Kazakhstan. Gas chromatography analysis was limited to the organochlorine pesticides DDT (p,p'-dichloro-diphenyl-trichloroethane) and HCH (hexachlorocyclohexane), and their associated metabolites and isomers: 2.4'-DDD (p,p'-dichlorodiphenyl dichloroethane); 4.4'-DDD; 4.4'-DDT; 4.4'-DDE (p,p'-dichlorodiphenyl-dichloroethylene); α-HCH; β-HCH and γ-HCH. The studies showed exceeding of Maximum Acceptable Concentration (MAC) by 10 times at soil samples taken at 24 former pesticide storehouses, and the basic pollutants were isomers of α-HCH, β-HCH and metabolite of 4.4'-DDE, 4.4'-DDT, supplemented by heavy metals. Monitoring data demonstrated the potential ecological danger and health risk posed by the sites, especially those located near populated areas. In order to eliminate the negative environmental and health effect it was proposed to use phytotechnology with second generation biofuel crop Miscanthus x giganteus. The technology applied directly at the contaminated area (in situ), helping to decrease costs and to reduce exposure from polluted sites. The plant shows good growing at the soil contaminated by pesticides during vegetation season.

Determination of pesticide residues in fish tissues by modified QuEChERS method and dual-d-SPE clean-up coupled to gas chromatography-mass spectrometry

The aim of this research was to modify the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the determination of organochlorine and organophosphate pesticides in fatty animal matrices such as fish muscle tissues of carp and sturgeon collected from Carp Valley, Lesser Poland. Pesticides extraction effectiveness was evaluated at 0.030 mg kg(-1) spiking level and efficiency of the dispersive-solid-phase extraction (d-SPE) clean-up step was evaluated by comparison testing two different d-SPE clean-up stages, first the addition of the d-SPE sorbent combination (PSA + SAX + NH2), and secondly the addition of C18 after extracts enrichment with the d-SPE sorbent combination (PSA + SAX + NH2), introducing a novel concept of clean-up named dual-d-SPE clean-up. Analysis of pesticide residues was performed by Gas Chromatography Quadrupole Mass Spectrometry (GC/Q-MS) working in selected-ion monitoring (SIM) mode. Linear relation was observed from 0 to 200 ng mL(-1) and determination coefficient R(2) > 0.997 in all instances for all target analytes. Better recoveries and cleanliness of extracts in both samples, carp and sturgeon tissues, were obtained after C18 addition during the dual-d-SPE clean-up step. Recoveries were in the range 70-120%, with relative standard deviation lower than 10% at 0.030 mg kg(-1) spiking level for most pesticides. LODs ranged 0.001-0.003 mg kg(-1), while LOQs ranged 0.004-0.009 mg kg(-1). The proposed method was successfully applied analyzing pesticide residues in real carp and sturgeon muscle samples; detectable pesticide residues were observed, but in all of the cases contamination level was lower than the default maximum residue levels (MRLs) set by the European Union (EU), Regulation (EC) N 396/2005.

Photocatalytic degradation of acephate in pak choi, Brassica chinensis, with Ce-doped TiO2

The photocatalytic degradation of acephate was investigated using Ce-doped TiO2 (TiO2/Ce) hydrosol. In contrast to previous research conducted under artificial light in the laboratory, this study investigated the decomposition of acephate in a field trial. The results show that acephate can be efficiently degraded by the TiO2/Ce system under natural field conditions; the degradation efficiency was affected by the dosage of the photocatalyst and acephate. The optimum dosage of TiO2/Ce was 2400 g a.i.ha(-1), and the photodegradation efficiency of acephate reached 93.5% after 20 h at an acephate dosage of 675 g a.i.ha(-1). Ultra-performance liquid chromatography/mass spectrometry (UPLC/MS) analysis detected and identified four degradation products-methamidophos, phosphorothioic acid O,O,S-trimethyl ester, S-methyl methanethiosulfonate and phosphorous acid-that were formed during the TiO2/Ce photodegradation of acephate. Based on the structural identification of the degradation products, a probable photodegradation pathway was proposed, and the first decomposition step may be the cleavage of the C‒N bond of acephate. Subsequently, the P‒S and P‒O bonds may be oxidized gradually or simultaneously to complete the mineralization.

Analysing half-lives for pesticide dissipation in plants

Overall dissipation of pesticides from plants is frequently measured, but the contribution of individual loss processes is largely unknown. We use a pesticide fate model for the quantification of dissipation by processes other than degradation. The model was parameterised using field studies. Scenarios were established for Copenhagen/Denmark and Shanghai/PR China, and calibrated with measured results. The simulated dissipation rates of 42 pesticides were then compared with measured overall dissipation from field studies using tomato and wheat. The difference between measured overall dissipation and calculated dissipation by non-degradative processes should ideally be contributable to degradation in plants. In 11% of the cases, calculated dissipation was above the measured dissipation. For the remaining cases, the non-explained dissipation ranged from 30% to 83%, depending on crop type, plant part and scenario. Accordingly, degradation is the most relevant dissipation process for these 42 pesticides, followed by growth dilution. Volatilisation was less relevant, which can be explained by the design of plant protection agents. Uptake of active compound from soil into plants leads to a negative dissipation process (i.e. a gain) that is difficult to quantify because it depends largely on interception, precipitation and plant stage. This process is particularly relevant for soluble compounds.

Fate of 14C-ethion insecticide in the presence of deltamethrin and dimilin pesticides in cotton seeds and oils, removal of ethion residues in oils, and bioavailability of its bound residues to experimental animals

Ethyl-1-(14)C-ethion and some of its degradation products have been prepared for comparison purposes. Cotton plants were treated with (14)C-ethion alone and in the presence of deltamethrin and dimilin pesticides under conditions simulating local agricultural practice. (14)C-Residues in seeds were determined at harvest time; about 47.5% of (14)C-activity was associated with oil. After further extraction of seeds with ethanol, the ethanol-soluble (14)C-residues accounted for 10.6% of the total seed residues, whereas the cake contained about 37.3% of the total residues as bound residues in the case of ethion only. The bound residues decreased in the presence of deltamethrin and dimilin pesticides and amounted to 8.1 and 10.4% of the total residues, respectively. About 95% of the (14)C-activity in the crude oil could be eliminated by simulated commercial processes locally used for oil refining. Chromatographic analysis of crude cotton oil revealed the presence of ethion monooxon, O,O-diethyl phosphorothioate, and O,O-diethyl phosphoric acid in addition to one unknown compound in the case of ethion alone or ethion and dimilin. The same degradation products are found in the case of ethion and deltamethrin in addition to ethion dioxon, whereas ethanol extract revealed the presence of ethion dioxon and O,O-diethyl phosphoric acid as free metabolites. Acid hydrolysis of the conjugated metabolites in the ethanol extract yielded O,O-diethyl S-hydroxymethyl phosphorodithioate. The bound residues were quite readily bioavailable to the rats. After feeding rats with the cake containing ethion-bound residues, a substantial amount (60%) of (14)C-residues was eliminated in the urine, whereas the (14)C-residues excreted in expired air and feces were 10 and 9%, respectively. About 11% of the radioactive residues were distributed among various organs.

Biodegradation of imidacloprid by consortium of two soil isolated Bacillus sp

Imidacloprid degradation potential of bacterial cultures from sugarcane growing soils was studied in liquid culture and Bacillus aerophilus and Bacillus alkalinitrilicus showed maximum potential to degrade imidacloprid. Hence, into a clay loam soil imidacloprid was added at 50, 100, and 150 mg kg(-1) along with 45 × 10(7) cells g(-1) soil of both species under autoclaved and unautoclaved conditions. Under autoclaved conditions imidacloprid residues were degraded after 56 days to 3.18, 5.83 and 10.48 mg kg(-1) and under unautoclaved conditions to 5.17, 6.23 and 10.31 mg kg(-1). 6-chloronicotinic acid, nitrosimine and imidacloprid-NTG metabolites were detected in measurable concentrations under both conditions. Dissipation pattern of imidacloprid did not follow first order kinetics under both sets of conditions. The half life value of imidacloprid ranged from 13 to 16 days after bacterial inoculation. This is first report of use of mixed culture of native soil bacterial isolates for remediation of imidacloprid contaminated soils.

Degradation kinetics of anilofos in soil and residues in rice crop at harvest

BACKGROUND

Pesticides used on rice, which is widely grown in India in the rainy season, must be investigated for the persistence and magnitude of their residues in the crop and soil to ensure human and environmental safety. Anilofos is widely used in rice, and its persistence and dissipation behaviour in soil and rice was investigated in field trials under subhumid and subtropical conditions.

RESULTS

The persistence of anilofos in soil, husk, grain and rice straw was evaluated at two application rates (0.4 and 0.8 kg AI ha(-1) ) by RP-HPLC. In soil, residues were detected up to 45 and 75 days after application at 0.4 and 0.8 kg AI ha(-1) respectively. No residue was observed in soil, husk, grain or rice straw at the time of harvest at either application rate. Detector response was linear within the concentration range 0.1-5.0 µg mL(-1) at 2.22% standard deviation. The limit of detection was 0.003 µg mL(-1) , and the limit of quantification of the method for soil, straw, grain and husk was 0.007, 0.01, 0.008 and 0.01 µg g(-1) respectively.

CONCLUSION

The dissipation of herbicide from soil appeared to occur in a single phase and conformed to pseudo-first-order kinetics. The calculated half-life values of anilofos residue in soil were 13 days for the lower rate of application (0.4 kg AI ha(-1) ) and 15.5 days for the higher rate (0.8 kg AI ha(-1) ). Anilofos residues were below the maximum residue level in soil, husk, rice grain and rice straw at harvest.

Determination of organochlorine pesticide residue levels in chewable parts of the khat (Catha edulis) plant

In this study, the levels of DDT and its metabolite residues were determined in chewable parts of Catha edulis plants grown in the southern part of Ethiopia. The levels of p,p'-DDT and p,p'-DDE were found to be in the range of 10.8-19.7 and 3.5-18.6 μg/kg, respectively. These data revealed that the residue being detected is from recent applications. The estimated daily intake of total DDT from C. edulis consumption was calculated to be in the range between 0.0278 and 0.0747 μg/kg, which is significantly lower than the FAO/WHO guideline. However, this may not guarantee safety, as the application of DDT extends to vegetables as well. Even though the use of DDT was banned in Ethiopia for agriculture purposes, detectable levels are still being observed. The results of the study necessitate the need for awareness creation among the people in the community.

Determination and study on dissipation and residue determination of cyhalofop-butyl and its metabolite using HPLC-MS/MS in a rice ecosystem

Cyhalofop-butyl is an aryloxyphenoxypropionate postemergence herbicide with good control of barnyard grass in rice paddies. In this study, method for the determination of cyhalofop-butyl and its metabolite was developed with high-performance liquid chromatography tandem mass spectrometry. Dissipation and residue levels of cyhalofop-butyl and its metabolite in rice ecosystems were also investigated. Recoveries and relative standard deviations of cyhalofop-butyl and cyhalofop acid in six matrices at three spiking levels ranged from 76.1 to 107.5% and 1.1 to 8.2%, respectively. The limit of quantitation (LOQ) of cyhalofop-butyl and cyhalofop acid was 0.01 mg/kg in paddy water, paddy soil, rice plant, rice straw, rice hulls, and husked rice. For field experiments, the results showed that cyhalofop-butyl degraded to cyhalofop acid quickly, and the half-lives of cyhalofop acid in paddy water, paddy soil, and rice plant were 1.01-1.53, 0.88-0.97, and 2.09-2.42 days, respectively. Ultimate residues of cyhalofop-butyl and its metabolite in the rice samples were not detectable or below 0.01 mg/kg at harvest.

Degradation pattern and risk assessment of chlorantraniliprole on berseem (Trifolium alexandrinum L.) using high performance liquid chromatography

The persistence pattern of chlorantraniliprole on berseem leaves and its risk assessment for the safety of cattle were studied. QuEChERS method was used for the extraction and cleanup of samples and the residues of chlorantraniliprole were estimated using high performance liquid chromatography (HPLC) and confirmed by Liquid Chromatograph-Mass Spectrometer (LCMS-MS). The dissipation studies on berseem were carried out by application of chlorantraniliprole at five different dosages i.e. 11.6, 17.1, 23.1, 34.7 and 46.2 g a.i. ha(-1). Average initial deposits of chlorantraniliprole were found to be 0.47, 0.61, 0.78, 1.15 and 1.31 mg kg(-1), respectively. The residues reached below determination limit (BDL) of 0.01 mg kg(-1) in 5, 7, 7, 10 and 10 days for 11.6, 17.1, 23.1, 34.7 and 46.2 g a.i. ha(-1) dosages, respectively. Half-life (t1/2) of chlorantraniliprole on berseem was observed to be 0.93, 1.14, 1.06, 1.00 and 1.33 days, respectively, at 11.6, 17.1, 23.1, 34.7 and 46.2 g a.i. ha(-1). It was found that the theoretical maximum residue contributions (TMRC) values reached below maximum permissible intake (MPI) on 0 day in berseem samples treated with chlorantraniliprole. These studies, therefore suggest that the use of chlorantraniliprole formulation at different dosages does not seem to pose any hazards to the consumers and a waiting period of one day is suggested to reduce the risk before consumption of berseem leaves. These data could provide guidance for the proper and safe use of this pesticide on berseem in India.

Sensitive methodology for simultaneous determination of residues of imidacloprid and its metabolites in sugarcane leaves and soil

An analytical method to quantify imidacloprid and its metabolites in sugarcane leaves and soil using HPLC has been developed. The samples were extracted with acetonitrile + water (80 + 20, v/v), soil samples partitioned with dichloromethane, and leaf samples with hexane + ethyl acetate (9 + 1, v/v) and dichloromethane. Further, the extracts were dried, filtered, and concentrated under vacuum into HPLC-grade acetonitrile. Residues were estimated using an HPLC equipped with a photodiode array detector system, C18 column with a mobile phase of acetonitrile + water (40 + 60, v/v) at 0.3 mL/min to separate imidacloprid and its six metabolites in single run of 20 min. The mean percent recoveries of imidacloprid and its metabolites ranged from 80.45 to 99.80 from sugarcane leaves and 80.20 to 99.70 from sugarcane soils. The analytical method was validated in terms of selectivity, linearity, reproducibility, repeatability, and accuracy. The repeatability values ranged from 0.24 to 3.15% and 1.69 to 4.94%, along with 2.73 to 3.82% and 1.12 to 4.96%, for imidacloprid and its metabolites in leaves and soil, respectively. The reproducibility of imidacloprid and its metabolites in leaves and soil ranged from 2.20 to 4.27% and 2.53 to 4.08%, respectively, and all measurements were within 15% at all concentration levels.

Organochlorine pesticide level differences among female inhabitants from Veracruz, Puebla and Tabasco, Mexico

Organochlorine pesticides have been used in Mexico in malaria control programs and against ectoparasites. The objective of this study was to compare the levels of organochlorine pesticides: HCB, α-β-γ-HCH, pp'-DDE, op'-DDT and pp'-DDT in adipose tissue of female inhabitants from three Mexican states: Veracruz, Puebla and Tabasco. Data analyses indicated higher β-HCH levels in Puebla inhabitants. When comparing the mean values of the pp'-DDE concentrations among the three states, no statistically significant differences were noted. A trend of increasing concentrations of op'-DDT from Veracruz to Puebla and Tabasco was observed. Significantly higher pp'-DDT concentrations in Veracruz as compared to Puebla and Tabasco were determined. Using factorial analysis of three age categories (>30, 31-50, <51) organochlorine pesticide concentrations increases with age of participants, indicating time of exposure as a principal factor of organochlorine pesticides accumulation in adipose tissue.

Persistence and dissipation of chlorpyrifos in Brassica chinensis, lettuce, celery, asparagus lettuce, eggplant, and pepper in a greenhouse

The residue behavior of chlorpyrifos, which is one of the extensively used insecticides all around the world, in six vegetable crops was assessed under greenhouse conditions. Each of the vegetables was subjected to a foliar treatment with chlorpyrifos. Two analytical methods were developed using gas chromatography equipped with a micro-ECD detector (LOQ = 0.05 mg kg(-1)) and liquid chromatography with a tandem mass spectrometry (LOQ = 0.01 mg kg(-1)). The initial foliar deposited concentration of chlorpyrifos (mg kg(-1)) on the six vegetables followed the increasing order of brassica chinensis Collapse

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MESH Headings

• Apium/metabolism
• Brassica/metabolism
• Chlorpyrifos/chemistry
• Chlorpyrifos/metabolism
• Crops, Agricultural/metabolism
• Environment, Controlled
• Food Safety
• Lactuca/metabolism
• Pesticide Residues/chemistry
• Pesticide Residues/metabolism
• Piper/chemistry
• Piper/metabolism
• Soil/chemistry
• Solanum melongena/metabolism

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Affiliation(s)

Meng-Xiao Lu Pesticide Biology and Ecology Research Center, Nanjing, Jiangsu, China Key Laboratory of Food Safety Monitoring and Management of Ministry of Agriculture, Nanjing, Jiangsu, China
Wayne W. Jiang Department of Entomology, Michigan State University, East Lansing, Michigan, United States of America
Jia-Lei Wang Pesticide Biology and Ecology Research Center, Nanjing, Jiangsu, China
Qiu Jian Institute for the Control of Agrochemicals, Ministry of Agriculture, Beijing, China
Yan Shen Key Laboratory of Food Safety Monitoring and Management of Ministry of Agriculture, Nanjing, Jiangsu, China
Xian-Jin Liu Pesticide Biology and Ecology Research Center, Nanjing, Jiangsu, China Key Laboratory of Food Safety Monitoring and Management of Ministry of Agriculture, Nanjing, Jiangsu, China
Xiang-Yang Yu Pesticide Biology and Ecology Research Center, Nanjing, Jiangsu, China Key Laboratory of Food Safety Monitoring and Management of Ministry of Agriculture, Nanjing, Jiangsu, China

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[Residue decline dynamics and safety utilization of carbendazim in cultivation of Anoectochilus roxburghii]

The paper aimed to study the residue decline dynamic and standards for safety utilization of carbendazim in roots, stems, leaves of Anoectochilus roxburghii and in growth media. Samples extracted with methanol were purified by liquid-liquid extraction and analysed by HPLC. The results showed that average rate of recovery was 82.9% - 95.7% and RSD were 2.0% - 6.3% with add of carbendazim in respectively diverse concentration, which meets inspection requirement of pesticide residue. Two kinds of dosages of carbendazim were treated, varying from recommended dosage (1.0 kg x hm(-2)) to 1.5 times recommended dosage (1.5 kg x hm(-2)). Results of two years test showed that the half-life period of carbendazim were 7.01 - 8.51 d in the growth media of A. roxburghii, 3.58 - 4.27 d in stems and 3.50 - 3.91 d in leaves, 4.93 - 5.71 d in roots. Providing max recommended residue of carbendazim in the cultivation of A. roxburghii is 0.5 mg x kg(-1), sprayed 4 times a year with the dosage of 1.0 kg x hm(-2), 28 days is proposed for the safety interval of the last pesticide application's and harvest's date.