Maximum Residue Limits Research Articles

Metal contamination in mangrove tissues, seeds, and associated sediments from the Vattanam mangrove forest of Palk Bay, southeastern India: An ecological risk assessment

In the present work, the concentrations of toxic heavy metals in mangrove sediments, mangrove leaves, and seeds collected from five stations in the Vattanam mangrove of Palk Bay, southeastern India, as well as the effects of the monsoon season on toxic heavy metals concentrations were determined. The concentrations were 17.5 μg/g for zinc (Zn), 9.11 μg/g for copper (Cu), and 6.03 μg/g for lead (Pb) in sediments; 10.71 μg/g (Zn) and 8.94 μg/g (Cu) in mangrove leaves; and 26.24 μg/g (Zn) and 17.01 μg/g (Cu) in mangrove seeds. At all sampling stations, the Cd concentration was below the limit of detection. These mangroves seem to have adapted successfully to their environment given their selective intake of only essential metals (Cu and Zn) and the restricted movement of non-essential metals (Cd and Pb). The concentrations of metals were below the maximum residual limits regulated by national and international standard limits.

Fluorescence Entrenched Probe for Onsite Detection of Amoxicillin Residue in Bovine Milk.

A novel fluorescent probe (E)-3-(4-hydroxyphenyl)-2-((pyrene-1-ylmethylene) amino)propanoic acid (PyT) was developed for the 'turn-on' detection of amoxicillin(AM), residues. The PyT molecule was developed by a simple condensation reaction between a biologically important tyrosine amino acid and pyrene carboxaldehyde. The small fluorophore molecule has spectacular photoluminescence properties such as large stock shift, high photostability, selectivity and sensitivity toward the analytes. The PyT upon dispersion in the liquid phase becomes highly luminescent possessing the restricted intramolecular rotation (RIR) and excited stated intramolecular proton transfer (ESIPT) properties which are the major criteria for aggregation induced emission enhancement (AIEE) mechanism prevailing the aggregation caused quenching (ACQ). PyT molecule shows a binding constant of 3.285 × 104 L mol-1for amoxicillin (AM). The limit of detection(LOD) values are found to be 1.67µM. Consuming bovine milk with antibiotic residues exceeding the maximum residue limit (MRL) can lead to food toxicity and life threatening diseases in humans. The milk sample with AM antibiotic residue in presence of PyT probe shows a distinct blue colour which infers the selectivity and sensitivity of the probe towards the analyte. The fluorescence probe adheres with merits like on site and visual examination by naked eye without aid of any instruments.

Rapid identification of antibiotic residues in bovine kidney using coated blade spray-mass spectrometry.

The use of certain antibiotics in food-producing animals is allowed in Europe following Regulation (EU) 2017/625. However, use could result in antibiotic residues in foodstuffs of animal origin. Maximum residue limits (MRLs) are in place to protect consumers. For monitoring purposes, animal matrices are tested to verify their compliance with these MRLs. Initially, matrices of (slaughtered) food animals are screened, often using a microbiological assay. Faster screening tests for antibiotics would be an advantage for control laboratories. Therefore, the present study describes, for the first time, the use of coated blade spray (CBS) followed by direct mass spectrometry (MS) analysis for the screening of tetracyclines, sulfonamides, quinolones, and macrolides residues from the renal area of intact bovine kidneys. An optimized workflow using two different desorption/ionization solutions per blade allowed screening of target compounds within 1min per sample. The proof-of-principle of the CBS-MS method is validated according to (EU) 2021/808, presenting CCβ screening values of 0.1 × MRL for 43 analytes, 0.5 × MRL for 4 analytes, and 2.5µgkg-1 for the prohibited substance dapsone, respectively. The developed method was successfully applied to seven official control samples of bovine kidneys. One of these samples was found to be positive using the CBS-MS method, which was confirmed as a true positive by LC-MSMS analysis. The developed method demonstrates that CBS devices can directly extract and analyze kidney samples for food safety testing.

Multi-class, multi-residue analysis of pesticide residues in fishery products using LC and GC-MS/MS

Pesticide residues in agricultural products and the environment have been studied extensively over the years. Through the excessive or illegal use of pesticides, residues enter the surrounding environment and are absorbed by animals. Livestock and fishery products are subject to pesticide residue regulation, which includes the establishment of maximum residue limits. However, currently, fishery products are regulated only for ethoxyquin, neglecting the potential for bioaccumulation. This study aims to develop a method for the multi-class, multi-residue analysis of pesticide residues in fishery products—flatfish, eel, shrimp, and Manila clam—based on the QuEChERS method. A total of 327 compounds, including 263 pesticides and their metabolites, were identified using liquid chromatography and gas chromatography–tandem mass spectrometry. The method can quantify 263 pesticide residues in flatfish, 265 in eel, 264 in shrimp, and 263 in Manila clam, respectively. Additionally, the method can be applied to quantify 244 pesticide residues in seaweed. The method proves effective and useful for monitoring both food safety and environmental contamination.

Simultaneous determination of macrolide and quinolone antibiotics in animal tissues for human consumption validated by Regulation (EU) 2021/808

In this work, an analytical method for the simultaneous detection and quantification of 11 macrolides (erythromycin A, gamithromycin, lincomycin, neospiramycin, pirlimycin, spiramycin, tildipirosin, tilmicosin, tulathromycin A and its metabolite CP-60300, and tylosin A) and 10 quinolones (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, oxolinic acid, and sarafloxacin) in muscle (bovine, ovine, porcine, equine, rabbit, poultry including laying hens, and fish) and kidney (bovine, ovine, porcine, equine) for human consumption was developed and validated according to Commission Implementing Regulation (EU) 2021/808. Sample preparation consisted of liquid extraction using a citrate–phosphate/EDTA buffer solution (McIlvaine buffer) followed by solid phase extraction for cleanup and UHPLC-MS/MS analysis. The developed method was comprehensively validated with regard to relative matrix effects (CVMF ≤ 20 %), linearity (R2 ≥ 0.98), accuracy (84–119 %), trueness (−16 to + 19 %), repeatability (2.1–20.0 %), reproducibility (3.0–25.0 %), selectivity, and robustness. The method limit of quantification values ranged from 2 to 40 µg kg−1, established as 0.1 × the lowest maximum residue limit (MRL) by species for the authorized antibiotics. Method applicability was demonstrated in six interlaboratory proficiency tests, and in the official control analyses of 1200 field samples of muscle and kidney.

Assessment of residues from common pesticides and associated risks in Pakistan.

Pesticide residues have become an escalating concern in Pakistan, raising significant risks to both public health and the environment. This review overviews the current status of pesticide contamination in the country, with a specific focus on residue levels in relation to Maximum Residue Limits (MRLs) and a comparative analysis with regional and global counterparts. Several studies reveal that 30% to 70% of tested food products, including fruits, vegetables, and animal-derived products, especially in Punjab and Sindh, exceed established MRLs. This level of contamination is considerably higher than in neighboring countries such as India, where MRL exceedance ranges from 20 to 30%, and Bangladesh, which reports lower levels due to stricter regulatory efforts. In comparison, developed countries, including those in the European Union and the United States, report less than 5% of food samples exceeding MRLs, often falling below 1% due to stringent safety standards. The high prevalence of pesticide residues in Pakistan poses severe health risks, including neurological disorders, reproductive problems, and cancer, particularly in vulnerable groups like children and pregnant women. Key factors contributing to these elevated pesticide levels include insufficient knowledge of safe pesticide use, the unregulated application of banned or expired products, improper safety protocols, and malfunctioning equipment. A prevailing reliance on pesticides as the sole pest control method further hinders the adoption of Integrated Pest Management (IPM) strategies. In conclusion, pesticide residue levels in Pakistan are above permissible MRLs compared to regional and global standards, underscoring the need for urgent improvements in pesticide regulation, enforcement, and the promotion of sustainable pest control methods like IPM to better protect human health and the environment.

Effect of integrated pest management practices on the occurrence of pesticide residue in okra cultivated by farmers in Kwara state.

Integrated pest management (IPM) is a sustainable approach for minimizing the negative impacts of pests on crops while reducing reliance on synthetic pesticides. This study was conducted in Kwara State Nigeria in 2023, to investigate the effects of implementation of IPM practices on the occurrence of pesticide residues in okra cultivated by the farmers in Kwara State, Nigeria, and identify the factors affecting the use of IPM practices for pest control in okra production. A sample of 245 okra farmers was selected across 4 agricultural zones of Kwara State using a multistage sampling technique. Additionally, okra samples were collected from the farmers of each community of the local government areas. The data collected from the farmers were analyzed using descriptive and inferential statistics including frequency count, percentage, mean, standard deviation, and Pearson product moment correlation (PPMC). The collected okra samples were taken to the laboratory for pesticide residue extraction and analysis was performed using gas chromatography (GC)-mass spectrometer (MS). The results showed that most okra producers in Kwara State were smallholder farmers who, despite practicing IPM, had limited knowledge of the technology. Some pesticide residues were detected in okra, out of which two were present in quantities above the maximum residue limit, while others were below the maximum residue limit. Therefore, this study recommends that the government should improve extension services in the State by providing adequate funds and training extension agents who can provide comprehensive training to farmers on the types and application of IPM as an eco-friendly technology for preventing pesticide residue in okra.

Dissipation and Residue of Chloroisobromine Cyanuric Acid in Ginger and Pepper and Its Dietary Intake Risk Assessment.

Chloroisobromine cyanuric acid is a highly effective broad-spectrum systemic fungicide for disease control in agricultural crops. In this study, the degradation, residue levels, and potential dietary risks associated with the chloroisobromine cyanuric acid residues in two widely consumed crops, pepper and ginger, were evaluated through supervised field experiments conducted at 12 sites for pepper and 4 sites for ginger in China in 2021. A QuEChERS-LC-MS/MS method was established for quantifying cyanuric acid (CYA) in both crops. The method achieved a limit of quantification (LOQ) of 0.02 mg kg-1 for ginger and 0.05 mg kg-1 for pepper, with recovery rates ranging from 91% to 96% for ginger and 84% to 89% for pepper and the relative standard deviation of 2.9% to 11.2% for ginger and 2.8%~12.9% for pepper, respectively. The results indicated that CYA had half-lives ranging from 3.1 to 8.2 days in pepper, and the terminal CYA residues at harvest were all lower than 5 mg kg-1, the maximum residue limit established in China. Furthermore, the chronic dietary risk exposure to chloroisobromine cyanuric acid in ginger and pepper, harvested at a pre-harvest interval of three days and at the normal harvesting time after the application of 50% chloroisobromine cyanuric acid soluble powder (SP), was 37.96%, which was much lower than 100%, indicating no significant health risks to the Chinese population. This study provides basic data for establishing the MRLs and serving as a reference for developing the analytical method applicable to CYA residues in different plant matrices.

Ratiometric fluorescence probe based on boric acid-modified carbon dots and alizarin red for sensitive and rapid detection of glyphosate.

Bycombining boric acid-modified carbon dots (p-CDs) and alizarin red (ARS), a double emission probe p-CDs@ARS with fluorescence at 410nm and 600nm is designed for the detection of glyphosate. When Cu2+ is added, it binds with ARS to cause ARSreleasefrom p-CDs@ARS, which decreases the fluorescence at 600nm. However, in the presence of glyphosate, glyphosate competes to thebinding ofCu2+, releasing ARS to bind with p-CDs again. Therefore, the fluorescence of 600nm recovers. Based on this, the fluorescence of 410nm and 600nm act as the reference and response signal, respectively,achieving the ratiometric fluorescence detection of glyphosate. The linear range of glyphosate detection is 0.5-50µM with a limit of detection at 0.37µM which is well below the maximum residue limit for glyphosate in food. When the probe is used to detect the glyphosate residue in Pearl River water and cucumber, the detection results are well consistent with those detected by HPLC. The established method based on p-CDs@ARS has the advantages that the assembly of ratiometric fluorescence probe is simple, and the detection speed is fast. Additionally, a typical INHIBIT logical system has been successfully constructed based on glyphosate, Cu2+, and the fluorescence signal of p-CDs@ARS.

A hierarchical porous Fe3O4-COOH@H-ZIF-67 composite as magnetic solid-phase extraction adsorbent for benzimidazole pesticides

A hierarchical porous structural magnetic zeolite imidazolate framework-67 composite (Fe3O4-COOH@H-ZIF-67) was prepared through directly mixing the H-ZIF-67 and glutaric anhydride functionalized Fe3O4 nanospheres, of which the H-ZIF-67 was synthesized through a double template pore size regulation method. The successful preparation of Fe3O4-COOH@H-ZIF-67 composite was confirmed based on the material characterization using different techniques. The prepared composite was applied in the efficient removal of four benzimidazole pesticides (BZDs) in water using magnetic solid-phase extraction (MSPE) process. The results of static and dynamic adsorption experiments indicate that the adsorption of BZDs on Fe3O4-COOH@H-ZIF-67 follow pseudo-second-order kinetics, the Langmuir model fitted well with the adsorption data (R2 are all higher than 0.9969), and the maximum adsorption capacity for BZDs are 7.44–31.11 mg/g. Meanwhile, the adsorption mechanism study indicate that both hydrogen bonding and coordination play important roles during the adsorption process of BZDs. Finally, the developed MSPE method was combined with HPLC analysis and applied in the removal of BZDs from simulated pesticides wastewater. The removal rate was 82.76–96.18 %, and the treated samples met the requirements of the maximum residue limits of CBZ in the national standard GB 21523–2008. In addition, the adsorbent can be used at least three times and the extraction efficiency changed within 3 % after being stored in dry atmosphere at room temperature for 90 days. The results of this work manifested that Fe3O4-COOH@H-ZIF-67 composite can be used for removal and analysis of BZDs in complex samples.

Bioaccumulation, contamination and health risks of trace elements in wild fish in Chongqing City, China: a consumer guidance regarding fish size.

Trace elements generally contaminate wild fish, particularly in megacities, necessitating guided consumption practices. This study investigated the bioaccumulation of trace elements in wild fish from Chongqing City in June 2021. We evaluated their contamination and associated health risks to establish consumption guidance based on fish size. Our results indicate that the concentrations of Zn, Pb, Cr, and As were relatively high, with some fish exceeding the maximum residue limits. Herbivorous and pelagic fish generally exhibited lower bioaccumulation of most trace elements, except for Cr and As, which were higher in pelagic species. The contamination indices (Pi) for Cr, Pb and As were consistently above 0.2, indicating widespread contamination. The most contaminated fish typically measured around 19cm in length and weighed approximately 90g. Only the maximum target hazard quotients (THQ) for As, Cr, and Hg exceeded 1, with a notably high ratio of THQ(As) > 1, highlighting concerns over arsenic contamination. The THQ(As) remained below 1 for adults across all fish species, whereas for children, species such as Onychostoma sima, Pseudohemiculter dispar, and Parabramis pekinensis exceeded this threshold. Fish safe for adult consumption generally measured 13cm in length and weighed 20g, and for children, 16cm and 25g. Consequently, selecting larger fish is likely to reduce the consumption of contaminated fish, thereby decreasing health risks to the public. The centralization of contaminated fish with high risk in specific size range confirmed fish size could be used to gauge the contamination and health risk of fish.

Monitoring and Risk Assessment of Multi-Pesticide Residues in Apples: A Focus on Consumer Safety

Pesticide residues in human diets pose significant health hazards, particularly for vulnerable populations such as infants and children. This study aimed to determine pesticide residues in apples and to assess the cumulatively chronic risk posed to adult and child consumers from simultaneous exposure to multiple residues. During the 2022–2023 harvest seasons, 100 apple samples from Turkey were analyzed for the presence of 225 different pesticide residues. Pesticide extraction was performed using the QuEChERS method, followed by detection through liquid chromatography coupled with tandem mass spectrometry. Fifteen distinct pesticides (ten insecticides and five fungicides) were detected in 64 out of the 100 apple samples analyzed. Eleven samples contained pesticide residues that exceeded the maximum residue limit (MRL) set by the Turkish Food Codex and the European Union. Thiophanate-methyl was the most frequently detected pesticide (34%) in apples, with concentrations ranging from 0.012 to 0.108 mg kg−1, all of which were well below the MRL of 0.5 mg kg−1. Other commonly detected residues included chlorantraniliprole (28%), acetamiprid (24%), sulfoxaflor (22%), bifenazate (18%), indoxacarb (13%), diflubenzuron (12%), and carbendazim (10%). Under a worst-case scenario, the hazard index (HI) values for adults and children were 0.85% and 2.60%, respectively, indicating that these values remain significantly below the risk threshold of 100%, suggesting no associated health risks from apple consumption. However, regular monitoring of pesticide residues in fresh fruits and vegetables remains critically important.

An integrated approach for assessing the health risks of pesticide residues on apple: From field dynamics to human exposure

The apple (Malus domestica), a cultivated fruit extensively grown in temperate regions worldwide, is abundant in nutrients and phytochemicals that promote health. However, the application of pesticides in apple cultivation raises significant concern regarding their influence on food safety. This study investigated the dynamic behavior of five pesticides, including chlorpyrifos, imidacloprid, acetamiprid, carbendazim, prochloraz, in apple trees, utilizing both field experiments and predictive modeling to analyze their distribution, transfer, and degradation patterns. Results from the field experiment revealed that at harvest, the residue levels of the five pesticides on apple were below international and national maximum residue limits. The dynamiCROP modeling results, corresponding to the field trial findings, demonstrated that these pesticides exhibited comparable dissipation patterns across various environmental compartments. The primary sources of pesticides in apples were the air and the fruit surface up to 10 days after application, while the soil and leaf surface became the main sources over time. The transferred pesticides adhered to the apple fruits at varying rates and persist therein. Choosing pesticides with lower impact scores helped reduce the impacts on human health and the environment. The assessment of health risks associated with consuming apples containing pesticide residues suggested that the impact on human health is acceptable. These findings were crucial for apple producers, as they enable the optimization of pesticide application timing to ensure compliance with food safety standards and help improve pesticide management strategies in agriculture. This study is essential for minimizing the environmental impact of pesticides and enhancing sustainable agricultural practices.

Investigation of insecticide residues in fig and health risk assessment

This study aimed to detect insecticide, acaricide, and nematicide residues in 92 fresh and 50 dried fig samples collected from locations with intensive fig, Ficus carica L. (Rosales: Moraceae) production in Aydın, Türkiye in 2022. The analysis method was validated according to SANTE 11312/2021 guidelines. The recoveries ranged between 70% and 120%, with repeatability (RSDr) and within-laboratory reproducibility (RSDwR) ≤ 20% and expanded measurement uncertainties below 50% for all insecticides indicating satisfactory analytical performance. In total, 114 different insecticides were screened, revealing residues in 27 samples. Bifenazate was detected in 13 samples, etoxazole in 3 samples, spiromesifen in 5 samples, and both bifenazate and spiromesifen in 6 samples. No detectable residues were found in the dried fig samples. All samples in which bifenazate was detected were above the European Union Maximum Residue Limits (EU-MRL). Etoxazole and spiromesifen, unauthorized in figs, showed etoxazole residues above EU-MRLs, while spiromesifen residues were below EU-MRLs. The acute and chronic health risk indices for the insecticides were found to be below 1, indicating low health risks associated with fig consumption. The risk assessment suggests that fig consumption is safe for consumers.

Efficacy and Residual Analysis of Three Insecticides against Spodoptera littoralis (Boisd.) on Field-grown Tomatoes

Spodoptera littoralis (Boisd.) is among the most destructive insect pests in Egypt, the field study was conducted at El-Beheira Governorate, Egypt to evaluate the toxicity of three insecticides against 2nd and 4th larval instars of these insect and residual effect in tomato fruit into open field application. The outcomes demonstrated that spinosad, methoxyfenzide and diflubenzuron proved to be very toxic. Semi-field application showed that spinosad was the most effective with 91.38 % and 100% insect pest mortalities at initial and residual effects against second instar larvae, respectively. The initial effect manifested higher morality (90.25%) for fourth instar larvae when treated with diflubenzuron followed by spinosad (86.50%), then methoxyfenzide (84.25%), while the residual effects of all tested insecticides were 100% mortality. The findings additionally demonstrated that the pre-harvest intervals (PHI) for diflubenzuron, spinosad, and methoxyfenzide were 3,7 and 10 days, respectively, for tomato fruits. Following this PHI, the products are considered safe for export and local consumption, as the residue level satisfies the maximum residue limit, which is the level documented by the European Union.

Peer review of the pesticide risk assessment of the active substance pyrimethanil.

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Czech Republic and co-rapporteur Member State Austria for the pesticide active substance pyrimethanil and of confirmatory data following the maximum residue limit (MRL) review under Article 12 of Regulation (EC) No 396/2005 are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of pyrimethanil as a fungicide on grapevine and pome fruit (field uses), strawberry and lettuce (field and greenhouse uses). The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

Infant and Toddler Health Risks Associated with Pesticide Residue Exposure Through Fruit- and Vegetable-Based Baby Food

This research specifically delves into the potential health risks associated with pesticide residues in fruit- and vegetable-based foods for Turkish infants and toddlers.A total of 36 baby food samples were analyzed using a validated method covering 355 pesticide residues, employing liquid chromatography-tandem mass spectrometry (LCMS/ MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). Notably, 72.2% of the samples revealed no pesticide residues, while 10 samples exceeded the Maximum Residue Limits (MRLs) stipulated by the EU Directives. Specifically,pyriproxyfen had the greatest average concentration in pear fruits (0.573mg/kg). Notably, both pyrimethanil and pyriproxyfen were the most frequently detected analytes in all positive samples. The study further simulated a population, considering age-specific energy requirements for infants and toddlers. Pyriproxyfen demonstrated the highest average exposure (1.58±2.20μg/kg bw/day) across all age groups. Notably, for 6-month-old infants, the toxicological contribution as a percentage of the ADI for pesticides remained below 14.73%. It emphasizes the necessity for regulatory measures to ensure the safety of foods intended for infants and toddlers in the Turkish market. These findings support ongoing efforts to uphold pesticide levels within acceptable safety limits.

Dissipation and persistence behaviour of fipronil and its metabolites in chilli fruits using GC-ECD, confirmed by GC-MS, under semi-arid conditions

Chilli, one of the most popular vegetables in the world is infested by many insect-pests and diseases. Fipronil, a phenylpyrazole class insecticide is used to manage insect-pests on chilli. The present study aimed to analyze the dissipation patterns and residual concentrations of the fipronil and its metabolites in chilli fruits during the Kharif season of 2020–21, in semi-arid environment. In the study, fipronil was applied to the plants twice, with a 10-day gap between treatments, using a 5 % suspension concentrate. The applications were undertaken using two separate concentrations i.e. the lower dosage of 40 g a.i. ha−1 and higher dosage of 80 g a.i. ha−1. There were four sets of data for each concentration. The chilli crop was systematically sampled at predetermined intervals after the application of the second spray. The procedure encompassed utilizing the modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) technique for extraction and purification, followed by analyzing the resulting residues using Gas Chromatography Electron Capture Detector. Gas Chromatography- Mass Spectrometry was subsequently conducted for the confirmation of the findings. The research revealed that the mean initial deposit of fipronil and its metabolites (desulfinyl, sulphide, and sulfone) at the authorized dosage was determined to be 0.574, 0.123, 0.031, and 0.180 mg kg−1, respectively. In contrast, when administered at twice the prescribed dosage, the mean first deposit was 1.204, 0.230, 0.067, and 0.382 mg kg−1. The half-life values of these residues exhibited a range of 1.2–4.1 days for both dosages. A prudent waiting duration was determined for the doses, leading to the conclusion that an average interval of 7 days is deemed safe for harvesting chilli peppers. The significance of this discovery is related to the maximum residue limits of 0.001 mg kg−1 for fipronil in green chilli, as established by the Food Safety and Standards Authority of India. This study provides significant insights into fipronil's persistence and proper management in chilli plant cultivation, emphasizing the importance of following prescribed dosages and designated waiting intervals to ensure the safety of food products.

Organophosphate, carbamate and synthetic pyrethroid pesticide residues in muscle tissues of fish from Loktak Lake, a Ramsar Site in Manipur, India

The muscle tissues of Channa punctatus and Anabas testudineus collected from the Loktak Lake (a Ramsar site) and its three major feeder rivers in Manipur, Northeastern India, were analyzed using high-performance liquid chromatography for the presence of residues of organophosphorus, carbamate, and synthetic pyrethroid pesticides. Pesticide residues of all the three types were detected in the fish tissues. Pesticide residues in Channa punctatus ranged from 0.002 – 0.043 µg g-1, and from 0.008 –0.027 µg g-1in Anabas testudineus from Loktak lake in pre-monsoon and post-monsoon seasons. Pesticide residues were detected only in Anabas testudineus (0.002 – 0.078 µg g-1) in Nambul river, while these were detected only in Channa puctatus (0.001 – 0.032 µg g-1) in Moirang river. In Nambol river, pesticide concentrations ranged from 0.002 – 0.026 µg g-1 in Channa punctatus, and from 0.004 – 0.005 µg g-1 in Anabas testudineus. Among the five pesticides detected, concentrations of dichlorvos residues detected in the present study (0.027 and 0.032 µg g-1 wet weight) exceeded the Codex Alimentarius maximum residue limit (MRL) of 0.01 mg kg-1 for animal tissues. The rest of the compounds were within the MRL. None of the pesticide residues was detected in the two fish species collected from the control or reference site. The present study indicates that pesticide contamination is emerging as a threat to the water quality and aquatic biodiversity of Loktak Lake, which calls for more detailed studies on the extent and magnitude of these threats.

Study on the Bioactivity, Toxicity, Stereoselective Fate, and Risk Assessment of Chiral Fungicide Isopyrazam in Five Kinds of Fruits and Vegetables.

Isopyrazam (IPZ) is a new chiral fungicide. For bioactivity, there was a 3.37-1578 times difference among the four stereoisomers. For Alternaria alternata and Phoma multirostrata, cis-(1S,4R,9S)-IPZ had the greatest activity. Using cis-IPZ might improve the efficacy and reduce the dosage of the racemate by 54.7-72.2% for A. alternata and P. multirostrata. To zebrafish, trans-IPZ showed the highest acute toxicity (LC50, 0.096 mg/L). The degradation half-lives of IPZ stereoisomers in the five crops ranged from 3.50 to 15.2 days. Cis-IPZ was preferentially degraded in grape, pear, and celery. The residual concentrations of IPZ in grape and celery were still higher than the maximum residue limit, and the acute and chronic dietary intake risks of IPZ in celery were unacceptable (RQa: 146-250%, HQ: 117-200%), which were worthy of further researching. Based on the research results, it is safer and more reasonable to use IPZ in the form of a racemate with a high ratio of cis-IPZ.