Seasonal patterns, fate and ecological risk assessment of pharmaceutical compounds in a wastewater treatment plant with Bacillus bio-reactor treatment.

Pharmaceutical compounds (PhCs) pose a growing concern with potential environmental impacts, commonly introduced into the environment via wastewater treatment plants (WWTPs). The occurrence, removal, and season variations of 60 different classes of PhCs were investigated in the baffled bioreactor (BBR) wastewater treatment process during summer and winter. The concentrations of 60 PhCs were 3400 ± 1600 ng/L in the influent, 2700 ± 930 ng/L in the effluent, and 2400 ± 120 ng/g dw in sludge. Valsartan (Val, 1800 ng/L) was the main contaminant found in the influent, declining to 520 ng/L in the effluent. The grit chamber and BBR tank were substantially conducive to the removal of VAL. Nonetheless, the BBR process showcased variable removal efficiencies across different PhC classes. Sulfadimidine had the highest removal efficiency of 87 ± 17% in the final effluent (water plus solid phase). Contrasting seasonal patterns were observed among PhC classes within BBR process units. The concentrations of many PhCs were higher in summer than in winter, while some macrolide antibiotics exhibited opposing seasonal fluctuations. A thorough mass balance analysis revealed quinolone and sulfonamide antibiotics were primarily eliminated through degradation and transformation in the BBR process. Conversely, 40.2 g/d of macrolide antibiotics was released to the natural aquatic environment via effluent discharge. Gastric acid and anticoagulants, as well as cardiovascular PhCs, primarily experienced removal through sludge adsorption. This study provides valuable insights into the intricate dynamics of PhCs in wastewater treatment, emphasizing the need for tailored strategies to effectively mitigate their release and potential environmental risks.

Suspect and Nontarget Screening Reveal the Underestimated Risks of Antibiotic Transformation Products in Wastewater Treatment Plant Effluents.

Antibiotics are anthropogenic contaminants with a global presence and of deep concern in aquatic environments, while less is known about the occurrence and risks of their transformation products (TPs). Herein, we developed a comprehensive suspect and nontarget screening workflow based on high-resolution mass spectrometry to identify unknown antibiotic TPs in wastewater treatment plant effluents. We identified 211 compounds (35 parent antibiotics and 176 TPs) at confidence levels of ≥3 and 107 TPs originated from macrolides. TPs were quantified by 17 TPs standards and semiquantified by the predicted response factors and accounted for 55.6-95.1% (76.7% on average) of the total concentrations of parents and TPs. 22.2%, 63.1%, and 18.8% of the identified TPs were estimated to be more persistent, mobile, and toxic than their parent antibiotics, respectively. Further ecological risk assessment based on concentrations and toxicity to aquatic organisms revealed that the cumulative risks of TPs were generally higher than those of parents. Despite the newly formed N-oxide TPs, the tertiary treatment process (mainly ozonation) could decrease the averaged 20.3% of concentrations and 36.2% of the risks of antibiotic-related compounds. This study highlights the necessity to include antibiotic TPs in environmental scrutiny and risk assessment of antibiotics in different aquatic environments.

An Antigen Capture Assay for the Detection of Mycolactone, the Polyketide Toxin of Mycobacterium ulcerans.

Mycolactone is a cytotoxin responsible for most of the chronic necrotizing pathology of Mycobacterium ulcerans disease (Buruli ulcer). The polyketide toxin consists of a 12-membered lactone ring with a lower O-linked polyunsaturated acyl side chain and an upper C-linked side chain. Mycolactone is unique to M. ulcerans and an immunological Ag capture assay would represent an important tool for the study of Buruli ulcer pathogenesis and for laboratory diagnosis. When testing sets of mycolactone-specific mouse mAbs, we found that Abs against the hydrophobic lower side chain only bind mycolactone immobilized on a solid support but not when present in solution. This observation supports previous findings that mycolactone forms micellar structures in aqueous solution with the hydrophobic region sequestered into the inner core of the aggregates. Although an Ag capture assay typically requires two Abs that recognize nonoverlapping epitopes, our search for matching pairs of mAbs showed that the same mAb could be used both as capture and as detecting reagent for the detection of the mycolactone aggregates. However, the combination of a core-specific and a core/upper side chain-specific mAb constituted the most sensitive ELISA with a sensitivity in the low nanogram range. The results of a pilot experiment showed that the sensitivity of the assay is sufficient to detect mycolactone in swab samples from Buruli ulcer lesions. Although the described capture ELISA can serve as a tool for research on the biology of mycolactone, the assay system will have to be adapted for use as a diagnostic tool.

An integrated multimedia fate modeling framework for identifying mitigation strategy of antibiotic ecological risks: A case study in a peri-urban river.

Antibiotics have been heavily used over the past decades, resulting in their frequent detections in rivers and increasing ecological risks. Recognizing characteristics of antibiotic ecological risks (AERs) and making effective strategies to mitigate the AERs are essential to ensure the safety of aquatic ecosystem and public health. In this study, an integrated technological framework has been proposed toward identifying management options for reducing AERs by jointly utilizing multimedia fugacity modelling and ecotoxicological risk assessment, and applied to characterize the AERs in a peri-urban river in Beijing. Specifically, a level III fugacity model has been successfully established to simulate the fate of antibiotics in the environment, and the manageable parameters have been screened out via sensitivity analysis of the model. Then the validated fugacity model has been used for scenario modellings to optimize mitigation strategies of AERs. Results show most of the antibiotics considered are frequently detected in the river, and pose medium or high risks to aquatic organisms. Relatively, the macrolides and fluoroquinolones present higher ecotoxicological risks than sulfonamides and tetracyclines. Furthermore, the mixture risk quotient and predictive equation of concentration addition suggest joint and synergistic/antagonistic effects of AERs for multiple or binary antibiotics in the environment. Largely, the concentrations of antibiotics in the river are determined by the source emissions into water and soil. Scenario modellings show the improvement of antibiotic removal rates would be considered preferentially to mitigate the AERs. Also, controlling human consumption is conducive to reducing the risks posed by tetracyclines, macrolides and trimethoprim, while controlling animal consumption would benefit the reduction for sulfonamides. Overall, the joint strategy presents the greatest reduction of AERs by reducing antibiotic consumption and together improving sewage treatment rate and antibiotic removal rate. The study provides us a useful guideline to make ecological risk-based mitigation strategy for reducing AERs in environment.

Occurrence, source apportionment and ecological risk assessment of thirty antibiotics in farmland system.

Antibiotics are widely used in medical care, livestock production, and aquaculture. However, antibiotic pollution has attracted increasing global concerns due to their ecological risks after entering into environmental ecosystem via animal excretion, effulent from industrial and domestic sewage treatment facilities. In this study, 30 antibiotics were investigated in soils and irrigation rivers using ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometer. This study evaluated the occurrence, source apportionment, and ecological risks of these target compounds in soils and irrigation rivers (i.e., sediments and water) of farmland system by using principal component analysis-multivariate linear regression (PCA-MLR) and risk quotients (RQ). The concentration range of antibiotics in soils, sediments, and water was 0.38-689.58 ng/g, 81.99-658.00 ng/g, and 134.45-1547.06 ng/L, respectively. In soils, the most abundant antibiotics were quinolones and antifungals with an average concentration of 30.00 ng/g and 7.69 ng/g, respectively, contributing to 40% of total antibiotics. Macrolides were the most frequently detected antibiotics in soils with an average concentration of 4.94 ng/g. In irrigation rivers, quinolones and tetracyclines, the most abundant antibiotics, accounted for 78% and 65% of antibiotics in water and sediments, respectively. Higher antibiotic contamination of irrigation water was primarily distributed in highly populated urban areas, while increasing antibiotic contamination of sediments and soils was particularly observed in rural areas. PCA-MLR analysis indicated that antibiotic contamination in soils was mainly ascribed to the irrigation of sewage-receiving water body and manure application of livestock and poultry farming, which cumulatively contributed to 76% of antibiotics. According to RQ assessment, quinolones in irrigation rivers posed high risk to algae and daphnia, contributing 85% and 72% to the mixture risk, respectively. In soils, macrolides, quinolones and sulfonamides were responsible for more than 90% to the mixture risk of antibiotics. Ultimately, these findings can improve our fundamental knowledge on contamination characteristics and source pathways towards risk management of antibiotics in farmland system.

Sources, Environmental Fate, and Ecological Risks of Antibiotics in Sediments of Asia's Longest River: A Whole-Basin Investigation.

This study conducted the first extensive and comprehensive investigation of the whole-scale sedimentary antibiotic concentration, possible drivers, environmental fate, and potential ecological risks in the Yangtze River. Totally, 20 antibiotics were detected in the sediments. Results revealed that the order of antibiotic abundance in sediment was fluoroquinolones > tetracyclines > macrolides > sulfonamides > amphenicols. The total antibiotic concentrations were 0.10-134.4 ng/g (mean: 11.88 ng/g). Of these, fluoroquinolones and tetracyclines were the two dominant antibiotic categories. The dominant occurrence of fluoroquinolones and tetracyclines in sediments suggested that the distribution coefficient (Kd) was one of the important factors to determine their fate. Correlation analysis demonstrated that antibiotic contamination was largely influenced by the local scale of animal husbandry, and the positive correlation between antibiotics and heavy metals was likely driven by their common source of contamination and the complexation. Environmental risk assessment showed that tetracycline and chlortetracycline exhibited potential risks from medium to high in the Yangtze River, although most of the compounds posed minimal and low risks. This work provided a valuable large-scale data set across the whole Yangtze River and revealed the contamination profile of antibiotics. Mitigation and management measures to reduce antibiotic inputs are needed for the Yangtze River basin.

Novel and simple analytical method for simultaneous determination of sulfonamide, quinolone, tetracycline, macrolide, and chloramphenicol antibiotics in soil.

The multiclass determination of antibiotic residues in the soil is challenging because of its complex physicochemical properties. In this study, a simple analytical method was developed to simultaneously extract and determine 58 antibiotics from the soil. A novel acidity-regulated extraction-partition-concentration protocol was established for the simultaneous extraction of five classes (23 sulfonamides, 18 quinolones, five tetracyclines, eight macrolides, and four chloramphenicols) of antibiotics from the soil. Compared to traditional methods, the sample preparation efficiency was significantly improved by four times (45 min vs. 230 min) by optimizing the extraction method and omitting the time-consuming solid-phase extraction (SPE) procedure. The ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was optimized to determine the 58 antibiotics in a single run by applying positive/negative switching acquisition mode in less than 10 min with the baseline separation of sulfameter and sulfamethoxypyridazine. Suitable recoveries, ranging between 60 and 120%, were obtained for most antibiotics, with RSD <20%. The limits of quantification (LOQ) of the method were 2 µg/kg and 5 µg/kg. Thus, this study provides a simple, reliable, and economical method for accurately and rapidly determining a multiclass of antibiotics in the soil.

Conjugates of Desmycosin with Fragments of Antimicrobial Peptide Oncocin: Synthesis, Antibacterial Activity, Interaction with Ribosome.

Design and synthesis of conjugates consisting of the macrolide antibiotic desmycosin and fragments of the antibacterial peptide oncocin were performed in attempt to develop new antimicrobial compounds. New compounds were shown to bind to the E. coli 70S ribosomes, to inhibit bacterial protein synthesis in vitro, as well as to suppress bacterial growth. The conjugates of N-terminal hexa- and tripeptide fragments of oncocin and 3,2',4''-triacetyldesmycosin were found to be active against some strains of macrolide-resistant bacteria. By simulating molecular dynamics of the complexes of these compounds with the wild-type bacterial ribosomes and with ribosomes, containing A2059G 23S RNA mutation, the specific structural features of their interactions were revealed.

Analytical Approaches in Official Food Safety Control: An LC-Orbitrap-HRMS Screening Method for the Multiresidue Determination of Antibiotics in Cow, Sheep, and Goat Milk.

The presence of unauthorized substances, such as residues of veterinary medicines or chemical contaminants, in food can represent a possible health concern. For this reason, a complete legislative framework has been established in the European Union (EU), which defines the maximum limits allowed in food and carries out surveillance programs to control the presence of these substances. Official food control laboratories, in order to ensure a high level of consumer protection, must respond to the challenge of improving and harmonizing the performance of the analytical methods used for the analysis of residues of authorized, unauthorized, or prohibited pharmacologically active substances. Laboratories must also consider the state of the art of the analytical methodologies and the performance requirements of current legislation. The aim of this work was to develop a multiresidue method for the determination of antibiotics in milk, compliant with the criteria and procedures established by Commission Implementing Regulation (EU) 2021/808. The method uses an LC-Orbitrap-HRMS for the determination of 57 molecules of antibiotic and active antibacterial substances belonging to different chemical classes (beta-lactams, tetracyclines, sulfonamides, quinolones, pleuromutilins, macrolides, and lincosamides) in bovine, ovine, and goat milk samples. It provides a simple and quick sample pretreatment and a subsequent identification phase of analytes, at concentrations equal to or lower than the maximum residual limit (MRL), in compliance with Commission Regulation (EU) 2010/37. The validation parameters: selectivity, stability, applicability, and detection capability (ccß), are in agreement with the requirements of Commission Implementing Regulation (EU) 2021/808 and demonstrated the effectiveness of the method in detecting veterinary drug residues at the target screening concentration (at the MRL level or below), with a false positive rate of less than 5%. This method represents an effective solution for detecting antibiotics in milk, which can be successfully applied in routine analyses for official food control plans.

Distribution of quinolone and macrolide resistance genes and their co-occurrence with heavy metal resistance genes in vegetable soils with long-term application of manure.

The spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has become an increasingly serious global public health issue. This study investigated the distribution characteristics and influencing factors of ARB and ARGs in greenhouse vegetable soils with long-term application of manure. Five typical ARGs, four heavy metal resistance genes (MRGs), and two mobile genetic elements (MGEs) were quantified by real-time quantitative polymerase chain reaction (qPCR). The amount of ARB in manure-improved soil greatly exceeded that in control soil, and the bacterial resistance rate decreased significantly with increases in antibiotic concentrations. In addition, the resistance rate of ARB to enrofloxacin (ENR) was lower than that of tylosin (TYL). Real-time qPCR results showed that long-term application of manure enhanced the relative abundance of ARGs in vegetable soils, and the content and proportion of quinolone resistance genes were higher than those of macrolide resistance genes. Redundancy analysis (RDA) showed that qepA and qnrS significantly correlated with total and available amounts of Cu and Zn, highlighting that certain heavy metals can influence persistence of ARGs. Integrase gene intI1 correlated significantly with the relative abundance of qepA, qnrS, and ermF, suggesting that intI1 played an important role in the horizontal transfer of ARGs. Furthermore, there was a weakly but not significantly positive correlation between specific detected MRGs and ARGs and MGEs. The results of this study enhance understanding the potential for increasing ARGs in manure-applied soil, assessing ecological risk and reducing the spread of ARGs.

Quantification of spinosyn A and spinosyn D in animal-derived products using multiwalled carbon nanotubes coupled with LC-MS/MS for analysis.

An analytical method was developed for the quantification of spinosad (sum of spinosyns A and D) in five animal-derived products (chicken breast, pork, beef, egg, and milk) using LC-MS/MS. The sample was extracted using acetonitrile/1% acetic acid and a combination of magnesium sulfate and sodium acetate salts. The sample was purified using multiwalled carbon nanotubes as sorbent via a dispersive-solid-phase extraction procedure. Matrix-matched calibration (seven-point) provided good linearity with coefficient of determination (R2 ) ≥0.99 for each product. The limits of detection and quantification (LOQs) ranged between 0.0003-0.03 and 0.001-0.1 mg/kg, respectively. Method validation was carried out after spiking the target standard to blank matrices at the concentration levels of LOQ, 2 × LOQ, and 10 × LOQ with three replicates for each. The average recoveries were between 74 and 104%, with relative standard deviations ≤9.68, which were within the acceptable range designated by the international organizations. The developed method was successfully applied for monitoring market samples collected throughout the Korean Peninsula, and none of the samples tested positive for the target analytes. It has therefore been shown that dehydration and acidification were effective to extract spinosad from animal-derived products.

Development and validation of an LC-MS/MS screening method for macrolide and quinolone residues in baby food.

A simple, rapid and sensitive screening method by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the identification of 7 macrolides (clarithromycin, erythromycin, oleandomycin, spiramycin, tilmicosin, troleandomycin and tylosin) and 8 quinolones (ciprofloxacin, difloxacin, enrofloxacin, flumequine, moxifloxacin, nalidixic acid, norfloxacin and ofloxacin) in meat and egg-based baby foods. Sample preparation was performed using an alkaline modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) extraction method without additional clean-up steps. A simplex-lattice mixture experimental design was used in the optimization of the QuEChERS extraction solvent. The developed method was successfully validated according to the Commission Decision 2002/657/EC and the European Community Reference Laboratories Residues Guidelines regarding the validation of screening methods 20/01/2010, adopting a fixed permited tolerance for relative ion ratio. Samples of baby food (n = 44) commercialized in Rio de Janeiro, Brazil, were analyzed using the validated method and none of them presented residues of the searched macrolides and quinolones, with a screening target value of 5 µg kg-1.

Targeted analysis of six emerging derivatives or metabolites together with 25 common macrolides in milk using Quick, Easy, Cheap, Effective, Rugged and Safe extraction and ultra-performance liquid chromatography quadrupole/electrostaticfield orbitrap mass spectrometry.

An analytical method for the determination of six emerging derivatives or metabolites together with 25 common macrolides antibiotics in milk by ultra-performance liquid chromatography quadrupole/electrostaticfield orbitrap mass spectrometry was established. The samples were purified with optimized Quick, Easy, Cheap, Effective, Rugged, Safe methods. The amounts of primary-secondary amine, C18, and sodium acetate adsorbent materials were optimized by response surface method to obtain the best purification effect. The chromatographic separation was carried out using the XBridge-C18 (2.1 × 100 mm, 3.5 µm, Waters) column with mobile phase of acetonitrile with 0.1% v/v formic acid-water solutions (containing 10 mmol/L ammonium acetate), separated by gradient elution. The instrument was operated in the detection mode of electrospray positive and negative ions with Full MS/data dependent MS2 acquisition mode detection, external standard method was used for quantitative analysis. The limits of detection and limits of quantitation of 31 compounds were 0.1-0.5 µg/L and 0.5-2.0 µg/L, respectively. A total of 31 compounds performed a good linearity in the range of 1 to 200 µg/L, and the correlation coefficient was greater than 0.990. The spiked recoveries in milk samples were 81.07-110.1% and the relative standard deviation was less than 5.1%. The method was successful applied to actual sample testing in the market.

Uncovering the Core Microbiome and Distribution of Palmerolide in Synoicum adareanum Across the Anvers Island Archipelago, Antarctica.

Polar marine ecosystems hold the potential for bioactive compound biodiscovery, based on their untapped macro- and microorganism diversity. Characterization of polar benthic marine invertebrate-associated microbiomes is limited to few studies. This study was motivated by our interest in better understanding the microbiome structure and composition of the ascidian, Synoicum adareanum, in which palmerolide A (PalA), a bioactive macrolide with specificity against melanoma, was isolated. PalA bears structural resemblance to a hybrid nonribosomal peptide-polyketide that has similarities to microbially-produced macrolides. We conducted a spatial survey to assess both PalA levels and microbiome composition in S. adareanum in a region of the Antarctic Peninsula near Anvers Island (64° 46'S, 64° 03'W). PalA was ubiquitous and abundant across a collection of 21 ascidians (3 subsamples each) sampled from seven sites across the Anvers Island Archipelago. The microbiome composition (V3-V4 16S rRNA gene sequence variants) of these 63 samples revealed a core suite of 21 bacterial amplicon sequence variants (ASVs)-20 of which were distinct from regional bacterioplankton. ASV co-occurrence analysis across all 63 samples yielded subgroups of taxa that may be interacting biologically (interacting subsystems) and, although the levels of PalA detected were not found to correlate with specific sequence variants, the core members appeared to occur in a preferred optimum and tolerance range of PalA levels. These results, together with an analysis of the biosynthetic potential of related microbiome taxa, describe a conserved, high-latitude core microbiome with unique composition and substantial promise for natural product biosynthesis that likely influences the ecology of the holobiont.

The residue levels of spinosad and abamectin in eggs and tissues of laying hens following spray application.

Spinosad (SPN) and abamectin (ABM) are used in poultry premises to control external parasites including red mites (Dermanyssus gallinae). This study aimed to determine levels of SPN (spinosyn A + spinosyn D) and ABM residues in egg and edible tissues of laying hens following spray application. A total of 36 laying hens were divided into four groups of nine birds each, and they were kept in individual cages. Two different concentrations of SPN (2 and 4 g/l) and ABM (0.025 and 0.033 g/l) were applied in stocked and empty cages, respectively. Eggs were collected individually for 30 days. All hens were sacrificed at day 30 post-treatment, and tissue samples (liver, breast muscle, fat and skin) were collected. The residue levels in eggs and tissues were determined by high pressure liquid chromatography. ABM residues were not detectable in egg samples. SPN residues in eggs and residues of both ABM and SPN in liver, muscle and fat were under the maximum residue limits (MRLs) following low and high concentration applications. However, although the MRLs have not been established for SPN and ABM in skin tissue of chicken, residues in the skin detected at the low and high concentrations were greater than the MRLs for other edible tissues (except fat tissue) indicating that a withdrawal period would be necessary for the skin tissue after ABM and SPN use in laying hens.

Simultaneous determination of spinosad, temephos, and piperonyl butoxide in animal-derived foods using LC-MS/MS.

Pesticides, which are used as plant protection products, can enter the food chain, and exposure to these xenobiotics can cause a wide array of health problems in humans. Therefore, the objective of the present study was to develop an analytical method for the simultaneous determination of residual spinosad (sum of spinosyn A and D), temephos and piperonyl butoxide in porcine muscle, egg, milk, eel, flatfish and shrimp (sampling period: February to June 2018) using liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS). The target analytes were extracted with a combination of acidified acetonitrile and ethyl acetate and subsequently purified with original QuEChERS kits (composed of magnesium sulfate and sodium chloride) as well as n-hexane. All analytes were separated on a reversed-phase analytical column using a mobile phase of (A) 0.1% formic acid containing 10 mm ammonium formate in distilled water and (B) methanol. Good linearity (R2 ≥ 0.980) was achieved over the tested concentration range (3.5-35 µg/kg for spinosyn A; 1.5-15 µg/kg for spinosyn D; 5-50 µg/kg for temephos and piperonyl butoxide) in matrix-matched standard calibrations. Fortified samples at three spiking levels yielded recoveries in the range of 71-105% with relative standard deviations ≤9.2%. The applicability of the method was evaluated via evaluating samples collected from a large wholesale market located in Seoul, and none of the samples contained any of the target analytes. In conclusion, the current approach is simple, efficient and reliable and can successfully determine the residual levels of spinosad, temephos and piperonyl butoxide in complex animal-derived food products.

A microbiological inhibition method for the rapid, broad-spectrum, and high-throughput screening of 34 antibiotic residues in milk.

In this study, we developed a microbiological inhibition method for the rapid screening of antibiotics in milk with Geobacillus stearothermophilus ATCC12980 as an indicator bacterium and an easy sample pretreatment. We observed that the limits of detection of the kit for 34 common antibiotic residues in milk, including ß-lactams (13), aminoglycosides (6), tetracyclines (4), sulfonamides (6), macrolides (4), lincosamides (1), were lower than or close to the maximum residue limits formulated by the European Union and China. Moreover, the false-positive rate was 1% and the false-negative rates were less than 5%. The ruggedness of the method (the reproducibility of detection capability of different batches of medium) met requirements at determined levels and residual limits. The shelf life of the kit was more than 6 mo at 4°C. Additionally, we observed good correlations between the kit results and ultra-high-performance liquid chromatography-tandem mass spectrometry results for incurred milk (samples taken from animals treated with antibiotics according to the pre-slaughter medication data), which indicated that the kit was reliable for screening antibiotics in incurred samples. In conclusion, the kit has a broad application potential with high sensitivity, specificity, and reproducibility, stability, and reliability, combined with simple operation, low cost, and high-throughput capacity.

Aerobic dissipation of avermectins and moxidectin in subtropical soils and dissipation of abamectin in a field study.

Avermectins and moxidectin are antiparasitics widely used as active pharmaceutical ingredients in veterinary medicine, as well as in pesticide formulations for pest control in agriculture. Although the use of these compounds provides benefits to agribusiness, they can impact the environment, since a large part of these substances may reach the soil and water from the excreta of treated animals and following direct applications to crops. The present work had the objective of evaluating the dissipation behaviors of abamectin, doramectin, eprinomectin, ivermectin, and moxidectin in four native Brazilian soils of different textural classes (clay, sandy-clay, sandy, and sandy-clay-loam), following OECD Guideline 307. The studies were conducted in a climate chamber at 22 °C, 71% relative humidity, and protected from light. The dissipation studies were carried out with all drugs together, since no difference was verified when studies were done with each drug separately. The concentrations of the drugs in the soils were determined using an ultra-high performance liquid chromatograph coupled to a fluorescence detector or a tandem mass spectrometer. The dissipation half-life (DT50) values ranged from 9 to 16 days and the calculated GUS index values were in the range from -1.10 to 0.08, indicating low mobility of the drugs in the soils evaluated and low tendency for leaching. In addition, a field study was carried out to evaluate the dissipation of abamectin after application of a foliar pesticide in an orange crop. A DT50 of 9 days was determined, which was similar to that obtained under controlled conditions in the climate chamber (12 days), indicating that biotransformation was the primary process influencing the overall dissipation.

Residue distribution and risk assessment of two macrocyclic lactone insecticides in green onion using micro-liquid-liquid extraction (MLLE) technique coupled with liquid chromatography tandem mass spectrometry.

A micro-liquid-liquid extraction (MLLE) technique coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis was established and validated to determine the residues of two macrocyclic lactone insecticides (spinetoram and spinosad) in green onion. The limit of quantification (LOQ) of the method, as demonstrated by the lowest acceptable recovery level, was 0.01 mg kg-1, and the obtained recoveries were 78.3-93.4% with relative standard deviations (RSDs) < 12.5%. The method was then applied for analyzing field samples collected after treatment with the tested insecticides under Egyptian open-field condition. The decline pattern, terminal residues, and dietary risk assessment of spinetoram and spinosad residues in green onion were evaluated for food safety. Spinetoram and spinosad residues' decline in green onion followed first-order kinetics with the half-lives of 1.2 and 1.42 days, respectively. Based on the results, the required period to reach their respective maximum residue limits (MRLs) was 1 and 0 days for spinetoram and spinosad residues in green onion, respectively, which indicates a short persistence level and high degradation rate. The results suggest that there is no unacceptable chronic or acute risk to human health from the consumption of green onion treated with spinetoram and spinosad according to the uses considered.

Occurrence and Risk Assessment of Antibiotics in Manure, Soil, Wastewater, Groundwater from Livestock and Poultry Farms in Xuzhou, China.

Antibiotics in manure, soil, wastewater, and groundwater samples from the livestock and poultry farms in Xuzhou City were investigated in the present study. The concentrations of antibiotics in all matrices varied greatly among farms. Total concentrations of fluoroquinolones and macrolides were much higher than those of sulfonamides in manures and soil samples. Total concentrations of antibiotics in wastewater of livestock farms were higher than those of poultry farm. Josamycin (JM) and tilmicosin (TIL) accounted for more than 74% of the nine macrolides in all groundwater samples. Sulfamethizole (SMT), fleroxacin (FLE), cinoxacin (CIN) and JM were the main antibiotics detected in manure and soil samples, while sulfamethoxypyridazine (SMP), sulfameter (SME), SMT, FLE, JM and TIL accounted for a large proportion of antibiotics in surface and groundwater. The risk assessment of target antibiotics revealed that JM in wastewater showed relatively high RQs for aquatic organisms.