Porous sulfur polymers for effective aqueous-phase organic contaminant removal.

Sulfur polymers produced through 'inverse vulcanization' exhibit various attributes, such as photocatalytic activity and a high capacity to adsorb heavy metals. Nevertheless, there is a lack of research investigating the use of sulfur polymers as materials for the removal of organic contaminants. In this work, porous sulfur polymers (PSPs) were synthesized from elemental sulfur and 1,3-diisopropenylbenzene, with porosity introduced via salt templating. The result is a material that can strongly adsorb and chemically neutralize a model organic contaminant (caffeine). PSPs show adsorption up to 5 times higher than a leading adsorption material (activated carbon). Furthermore, either the adsorption or degradation processes can govern the removal efficiency depending on the synthesis parameters of PSPs. This is the first-ever report demonstrating sulfur polymers as effective materials for removing emerging contaminants from water. The versatile synthesis of sulfur polymers offers variation, which means that there is much more to explore in this exciting research area.

Evaluating the persistence of malachite green residues in tilapia and pacu fish.

Although banned in food-producing animals, residues of malachite green (MG) and its primary metabolite, leucomalachite green (LMG), have been found in fish due to illegal use in aquaculture and the release of industrial wastewater, which represent a serious risk to food and environmental securities. This study aimed to investigate the residue depletion profile of MG and LMG in edible tissues of Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus) cultured simultaneously under the same environmental conditions to support control measures in case of abuse. An analytical method involving QuEChERS sample preparation and liquid chromatography coupled to tandem mass spectrometry was developed, validated, and applied to quantify MG and LMG residues in fish fillets from two depletion experiments after treatment by immersion bath (MG at 0.10 mg L-1 for 60 min). During the experiment, the average water temperature was 30 ºC, while the pH was 6.9. The method is selective, precise (CV = 0.4 - 22%) and accurate (recovery 92 - 114%). The limits of detection and quantification are 0.15 and 0.5 ng g-1, respectively. In both species, the sum of MG and LMG residues were quantified up to the 32nd day post-exposure, and the concentrations were significantly higher in the pacu fillets (up to 3284 ng g-1) than in Nile tilapia (up to 432 ng g-1). The sums of MG and LMG residues were below 2 ng g-1 at 44 days and 342 days for Nile tilapia and pacu, respectively - the Minimum Required Performance Limit (MRPL) for analytical methods intended to monitor forbidden substances in food according to old European Commission guidelines. The persistence of MG residues in pacu may be attributed to its higher lipid content, which favors the accumulation of the non-polar metabolite LMG. These results provide insights into the concern about human, animal, and environmental health risks resulting from unauthorized use or aquatic contamination by industrial wastewater containing MG residues.

Assessment of tropane alkaloid levels in Brazilian buckwheat flour products: A novel LC-UHPLC-MS/MS approach using solid-liquid extraction at low temperature.

In recent years, the monitoring of tropane alkaloids, specifically hyoscyamine and scopolamine, in food has become a pressing concern. This is due to increasing reports of food contamination with these compounds worldwide, raising awareness about the potential risks associated with their consumption. A novel method is proposed here for the determination of the sum of (+)-hyoscyamine, (-)-hyoscyamine, and (-)-scopolamine in buckwheat-based matrices, using solid-liquid extraction at low temperature and quantification by bidimensional chromatography coupled to tandem mass spectrometry. The validated method presented a linear response in the concentration range of 2.5-15 µg kg-1 (r > 0.99). The precision and accuracy were in the ranges from 0.8 to 11.0 % and from 96 to 103 %, respectively. The limit of quantification (LOQ) was 2.5 µg kg-1. No contamination was found at levels above the LOQ in any of the 18 samples analyzed (buckwheat flour, grains, and gluten-free mix).

Levamisole incorporation in fish feed - Ensuring the medication dose and avoidance of leaching into the water.

Levamisole, an anthelmintic and immunostimulant drug, has been studied as a promising alternative for aquaculture use. While oral administration through feeding is the main route of administration in fish farming, no studies evaluating methods of levamisole incorporation into the feed have been reported so far. Therefore, this study aimed to evaluate potential procedures for levamisole incorporation in extruded fish feed using ethyl cellulose, gelatin, or vegetable oil, to avoid drug leaching to the water during the animal's medication. A suitable LC-MS/MS method was optimized (full factorial design), validated, and applied to evaluate the efficiency of the process, the homogeneity of the drug concentration, and the leaching rate. The method has been demonstrated to be selective, precise (RSD < 4.9%), accurate (recovery > 98.4%), and linear (r > 0.99, 125-750 mg kg-1). The incorporation procedures using the three coating agents showed high incorporation efficiency (70%) and a homogeneous drug concentration among the extruded feed pellets. A low levamisole leaching rate was verified in the feed prepared using the ethyl cellulose coating procedure (4.3% after 15 min of immersion in the water). On the other hand, fish feed coated with gelatin and oil resulted in a high leaching rate (30-35% after 15 min). Thus, this study shows that coating ethyl cellulose may be a promising procedure for levamisole incorporation in fish feed and with the potential to enhance its use in animal production while reducing environmental contamination.

Synthesis and characterization of TiO2-carbon filter materials for water decontamination by adsorption-degradation processes.

Wastewater treatment is becoming ever more challenging due to the increasing levels of molecular pollutants that are challenging for existing approaches. Innovative materials are required to help produce potable water from heavily contaminated water sources. One such material is titanium dioxide-activated carbon (TiO2/AC) heterostructures, which combine the photocatalytic properties of TiO2 with the adsorption properties of the ACs. To date, studies on TiO2/AC heterostructures for real-world water purification have yet to be performed. This study aimed to address this gap by comparing the effectiveness of titanium isopropoxide (Ti(OiPr)4) and titanium butoxide (Ti(OBu)4) for synthesizing TiO2/AC heterostructures using four different methods (sol-gel, solvothermal, and microwave-assisted hydrothermal methods [x2]). The elaborated heterostructures were compared with commercial TiO2 materials for their ability to degrade five emerging contaminants (caffeine, hydrochlorothiazide, saccharin, sulfamethoxazole, and sucralose). Hydrochlorothiazide and sulfamethoxazole were demonstrated to be rapidly degraded by UV-C irradiation within 15 min. Caffeine, saccharin, and sucralose were less susceptible to UV degradation. All the elaborated TiO2/AC heterostructures consisted of pure anatase phase, with Ti(OBu)4 syntheses generating larger average crystal sizes and lower surface areas. Sol-gel preparations produced the most effective TiO2/AC heterostructures due to their high surface area. Compared with the commercial TiO2, the heterostructures enhanced the photocatalytic activity of TiO2 by up to 10.0 times. Also, the heterostructures remained effective at environmentally relevant conditions (i.e., concentration of the contaminant and water matrices). The reuse of the materials was tested and showed no reduction in efficiency after four removal/regeneration cycles. Overall, this study presents novel TiO2/AC heterostructures with increased photocatalytic efficiency that can serve as an efficient material for removing contaminants at large scales (e.g., water treatment plants).

A comprehensive LC-UHPLC-MS/MS method for the monitoring of N-nitrosamines in lipophilic drugs: A case study with rifampicin.

In the last five years, the presence of N-nitrosamines in commonly used medicines has become a significant concern for patients, physicians, and the pharmaceutical industry, due to their carcinogenic properties, even at low concentrations. Analytical methods that enable the unequivocal monitoring of these compounds, with low detection limits and covering a range of drugs, are indispensable. The present work proposes a bidimensional liquid chromatography-tandem mass spectrometry method capable of quantifying eleven N-nitrosamines in lipophilic active pharmaceutical ingredients (APIs). The API is retained in the first chromatographic dimension, while the fraction containing the N-nitrosamines is transferred to the second chromatographic dimension and, after separation, to the mass spectrometer. The logP values for the APIs and N-nitrosamines enabled prediction of the APIs that could be separated from the target analytes. The method was validated and successfully applied for the quantification of 1-methyl-4-nitroso piperazine (MNP) and N-nitrosodimethylamine (NDMA) in rifampicin, a drug used to treat tuberculosis. Although NDMA was not detected in two pharmaceutical analyzed, MNP was found at concentrations of 0.44 ± 0.05 and 2.1 ± 0.3 µg g-1. Given the ability to apply the method to various APIs, together with its reliance solely on logP values for determining suitability, the proposed technique could be extended to the determination of N-nitrosamines in other drugs besides rifampicin.

Adsorption of aqueous phase contaminants of emerging concern by activated carbon: Comparative fixed-bed column study and in situ regeneration methods.

This work investigated the adsorption of five model contaminants of emerging concern (CECs) that are released daily in domestic effluents (caffeine, hydrochlorothiazide, saccharin, sulfamethoxazole and sucralose) onto two activated carbons (ACs), in fixed-bed column experiments with different aqueous matrices (ultrapure water, wastewater treatment plant (WWTP) effluent and WWTP effluent pretreated by reverse osmosis and photoperoxidation (reuse water)). The ACs were chemically similar, but AC1 had smaller particles (0.7-1.7 mm) and lower surface area (551 m2 g-1) than AC2 (1.2-2.4 mm and 716 m2 g-1). AC1 had a higher adsorption capacity (qads) for the CECs in the downflow mode. Overall, the qads values of the CECs followed the order: caffeine > sulfamethoxazole > hydrochlorothiazide = saccharin > sucralose. In the downflow mode, preferential pathways reduced the hydraulic retention time (HRT) of the fixed-bed column loaded with AC, which reduced the useful lifetime of column and the adsorption capacity. Nevertheless, the adsorption capacity and useful lifetime of the fixed-bed columns remained similar in the upflow mode (no preferential pathways were observed) regardless of the AC used. Since the HRTs were also found to be similar, it was evident that the crucial factor influencing the adsorption of the CECs was the HRT, which played a pivotal role in the overall process becoming evident. Compared to ultrapure water, use of the WWTP effluent reduced qads for all the CECs by up to 4.1 times, while reuse water reduced qads by up to 1.2 times. The AC1 could be in-situ regenerated using ethanol, with a global efficiency of 97.2 %. The results showed the importance of pretreatment techniques and optimization of the operational parameters, such as HRT, for enhancing the useful lifetime and qads of fixed-bed columns.

Adsorption of recalcitrant contaminants of emerging concern onto activated carbon: A laboratory and pilot-scale study.

According to the World Health Organization (WHO), the definition of water quality indicators, including contaminants of emerging concern (CECs), associated with the development of multi-barrier approaches for wastewater treatment, are crucial steps towards direct potable reuse of water. The aims of this study were 1) quantifying twelve CECs (including pharmaceutical, stimulant, and artificial sweetener compounds) in both untreated and treated wastewater samples in a Brazilian wastewater treatment plant (WWTP) using bidimensional liquid chromatography coupled with tandem mass spectrometry, allowing the selection of five marker (i.e., priority) CECs; 2) evaluating the adsorption potential of such selected CECs [caffeine, hydrochlorothiazide, saccharin, sucralose (SUC), and sulfamethoxazole (SMX)] onto coconut-shell granular activated carbon (GAC); and 3) investigating the removal of the same CECs by a multi-barrier system (pilot-scale, 350 L h-1) treating the effluent of the WWTP and composed of reverse osmosis (RO), photoperoxidation (UV/H2O2), and filtration with GAC. Such technologies were tested separately and in binary or ternary combinations. Eleven and eight CECs were detected and quantified on the untreated and treated wastewater samples of the Brazilian WWTP, respectively. For the treated wastewater, the concentrations ranged from 499 ng L-1 (SMX) to 87,831 ng L-1 (SUC). The adsorption onto AC data fitted the Sips isotherm model, indicating monolayer chemisorption, which was also suggested by the mean adsorption energy values (>16 kJ mol-1). SMX and SUC were the most and the least adsorbed CECs (4.33 and 1.21 mg g-1, respectively). Concerning the pilot-scale treatment plant, the ternary combination (RO + UV/H2O2+GAC) removed >99% of the five marker CECs and promoted reductions on water color, turbidity, as well as on nitrogen and phosphorus concentrations. Further studies on water reuse could prioritize the selected marker CECs as quality indicators. While the removal of marker CECs is one of the WHO performance requirements, the RO + UV/H2O2+GAC system showed promising results as a first approach to direct potable reuse of water.

Competitive kinetics of adsorption onto activated carbon for emerging contaminants with contrasting physicochemical properties.

Activated carbon (AC) can be used for the removal of emerging contaminants (e.g., drugs) in water and wastewater treatment plants. In the present study, we investigated the performance of two ACs (from coconut shell and Pinnus sp.) in the adsorption of caffeine, carbamazepine, and ricobendazole considering the compounds separately and in combination in batch-scale experiments. The concentrations of the drugs were determined by a validated method using solid-phase extraction with on-line ultra-high performance liquid chromatography-tandem mass spectrometry. The most mesoporous AC provided higher drug removal. The kinetic data were described by the pseudo-second-order, Elovich, and Weber-Morris models, while the adsorption isotherms showed a better fit to the Freundlich model, indicative of multilayer adsorption. The Dubinin-Radushkevich model was used as a first approach to estimate the mean adsorption energy (E) and the results indicate that chemisorption governed the adsorption process, with E higher than 8 kJ mol-1. In the multicomponent assays, the adsorption of caffeine showed the greatest hindrance caused by the presence of other drugs. Multicomponent assays are fundamental to evaluate the potential adsorption capacity in real water treatment plants. Our study suggests that drugs with different structures and physicochemical properties may interact differently with ACs, especially in multicomponent solutions, with important implications for the design (e.g., volumes and areas of treatment plants) and operation (e.g., water residence time) of the treatment plants.

On-line solid phase extraction-ultra-high performance liquid chromatography coupled to tandem mass spectrometry for the determination of N-nitrosodiethanolamine in baby shampoo.

N-nitrosodiethanolamine (NDELA) is a carcinogenic contaminant of concern in the cosmetics industry. Contaminated raw material, degradation, reactions of ingredients of the formulation, or migration of packaging material can be responsible for the presence of NDELA in the final product. Liquid chromatography coupled to tandem mass spectrometry is the most widely accepted technique for the quantitation of NDELA in cosmetic products. Still, there is no consensus regarding the sample preparation procedure. The aim of this work was to evaluate the performance of two-dimensional liquid chromatography coupled with tandem mass spectrometry for the determination of NDELA in shampoo. In the first dimension an Oasis HLB SPE-column was used and in the second dimension a CSH C18 column. NDELA-d8 was used as an internal standard. The 2D-LC parameters were optimized by a central composite multivariate design. However, before quantitation, a sample preparation step using solid-phase extraction was necessary to eliminate compounds present in the formulation, especially surfactants that were not compatible with the chromatographic columns. Moreover, the complex matrices and singular compositions of shampoo from different manufacturers required adjustments of the sample preparation procedure for each sample. The limit of quantitation of the method for the determination of NDELA in shampoo was in the range of 5-10 ng g-1. The accuracy of the method at the LOQ (10 ng g-1) was 114 % and the inter-day precision of 15.3 % (n = 9). One sample out of 12 presented an NDELA concentration of 54 ng g-1.

Removal of low-calorie sweeteners at five Brazilian wastewater treatment plants and their occurrence in surface water.

The consumption of low-calorie sweeteners (LCSs) such as acesulfame (ACE), sucralose (SUC), saccharin (SAC), cyclamate (CYC), aspartame (ASP), neotame (NEO), and stevioside (STV) is increasing worldwide to meet the demand for reduced-calorie foods and beverages. However, there are no consumption data available in Brazil, as well as their concentration in sewage and removal on wastewater treatment plants (WWTPs). In the present study, ACE, SUC, SAC, CYC, ASP, NEO, and STV were assessed at five WWTPs located in the metropolitan region of Campinas (São Paulo State, Brazil), in operation with different treatment processes. Surface water was also analyzed. Analyses were carried out by on-line solid-phase extraction ultra-high performance liquid chromatography-tandem mass spectrometry. The major points are the following: LCS concentrations in the influents ranged from 0.25 to 189 µg L-1 and followed the order CYC > ACE > SAC > SUC. NEO, ASP, and STV were not detected at any sampling site. Sweetener concentrations in the WWTP outputs differed mainly due to the different treatment setups employed. CYC and SAC were completely removed by biodegradation-based processes, while ACE removal was favored by the anaerobic-anoxic-aerobic process. SUC presented the highest concentration in the treated sewage, even at the WWTP operating with ultrafiltration membranes and therefore could be a marker compound for evaluation of the efficiency of removal of contaminants in WWTPs. Risk quotient estimation, using the PNEC and MEC values, indicated that the levels of the LCS reported here were harmless to the biota. The consumption of ACE, CYC, SAC, and SUC was estimated to be 2634 t year-1.

Long-term ecotoxicological effects of ciprofloxacin in combination with caffeine on the microalga Raphidocelis subcapitata.

Ciprofloxacin (CIP) is an antimicrobial "pseudo-persistent" in aquatic ecosystems. Once dispersed in the water compartments, it can also affect the microalgae. Thus, the evaluation of its long-term ecotoxicological effects is necessary. CIP interactions with other pharmaceuticals are not well known. In this study, we investigated the toxic effects of CIP alone and combined with caffeine (CAF), using the modified Gompertz model parameters and the chlorophyll-a production of the microalga Raphidocelis subcapitata as endpoints, throughout a 16-day exposure assay. The exposure to CIP alone led to significant reductions of the growth rate and the cell density of the microalgae compared to control groups. The combination with CAF lowered the adverse effects of CIP to R. subcapitata. However, as the toxicity is dynamic, our results indicated that the toxic effects in respect to the studied endpoints changed throughout the exposure period, reinforcing the need for longer-term ecotoxicity assessments.

Degradation of antidepressant pharmaceuticals by photoperoxidation in diverse water matrices: a highlight in the evaluation of acute and chronic toxicity.

Photoperoxidation (UV/H2O2) was used to degrade three of the worldwide most consumed antidepressant pharmaceuticals-bupropion, escitalopram, and fluoxetine-in ultrapure water, drinking tap water, surface water, and reclaimed water. The study was performed with antidepressants in concentration levels in which these compounds usually occur in the water matrices. Online solid-phase extraction coupled to UHPLC-MS/MS was used to quantify the analytes during degradation studies. The UV/H2O2 process was able to degrade bupropion and fluoxetine in ultrapure water, using 0.042 mmol L-1 of H2O2 and 1.9 kJ of UV-C irradiation. Nevertheless, escitalopram, which had the most recalcitrant character among the studied antidepressants, needed a tenfold more oxidant and UV-C irradiation. The primary metabolites of the antidepressants were identified as the major by-products generated by the UV/H2O2 process, and they persisted in the solution even when the parent compound was degraded. The residual toxicity of the solution was evaluated for two different trophic levels. The UV/H2O2 process reduced the toxicity of the solution to Raphidocelis. subcapitata microalgae after 30 min of reaction. On the other hand, the toxicity of the residual solution increased over the reaction time to the marine bacteria Vibrio fischeri (reaching up to 48.3% of bioluminescence inhibition after 60 min of reaction). Thus, our results evidenced that the toxicity against different trophic levels and the monitoring of the by-products formed are important aspects to be considered regarding the safety of the treated solution and the optimization of the treatment process.

Leaching of benzimidazole antiparasitics in soil columns and in soil columns amended with sheep excreta.

Benzimidazoles are anthelmintics frequently used in sheep farming due to the high susceptibility of these animals to parasitic diseases. Sheep excreta are often disposed onto soils as a fertilizer, and they may contain benzimidazole residues that can contaminate soil and water. This work aimed to assess the leaching behavior of benzimidazole drugs (albendazole, fenbendazole, and thiabendazole) and their metabolites in two Brazilian soils of different textural classifications (sandy and clay), as well as sheep excreta-amended soils, following the OECD 312 Guidelines. Ewes received a single oral dose of 10 mg kg-1 b.w. of either albendazole or fenbendazole. The feces were collected at 24, 48, 72, 96, and 120 h post-dose, and the parent drugs and their metabolites extracted using the QuEChERS approach and quantified by UHPLC-MS/MS. For the leaching assays, a benzimidazole solution was directly applied onto the soil columns, or an amount of 5 g of the medicated sheep feces was distributed over the top of the soil columns. In soil samples, benzimidazoles were extracted by solid-liquid extraction and quantified by UHPLC-MS/MS. For the leaching studies, atrazine was used as a reference substance to determine the relative mobility factor of the analytes of interest. Benzimidazoles were considered slightly to moderately mobile in both soils tested, with a leaching distance of up to 25 cm in a 30-cm soil column. Approximately 3 to 6% of the benzimidazoles present in ewe feces were able to leach into the soil columns. This finding is of concern since benzimidazoles are persistent in soil and may pose a risk to soil biota and induce the development of resistant strains of parasites.

Tracking the occurrence of psychotropic pharmaceuticals in Brazilian wastewater treatment plants and surface water, with assessment of environmental risks.

According to the World Health Organization, >360 million people worldwide suffer from mental diseases such as depression, anxiety, or bipolar disorder, for which psychotropic drugs are frequently prescribed. Despite being highly metabolized in the human organism, non-metabolized portions of these drugs are excreted, subsequently reaching wastewater treatment plants (WWTPs), where they may be incompletely removed during treatment, leading to the contamination of surface waters. In this work, ten psychotropic drugs widely consumed in Brazil (alprazolam, amitriptyline, bupropion, carbamazepine, clonazepam, escitalopram, fluoxetine, nortriptyline, sertraline, and trazadone) were monitored at five WWTPs located in the metropolitan region of Campinas (São Paulo State, Brazil). The drugs were determined in the influents, at different stages of the treatments, and in the effluents. Surface waters from the Atibaia River and the Anhumas Creek were also monitored. Quantitation of the pharmaceuticals was carried out by online solid-phase extraction coupled with ultra-high performance liquid chromatography and tandem mass spectrometry. The method was validated and presented a limit of quantitation of 50 ng L-1 for all the drugs assessed. Six of the substances monitored were quantified in the samples collected from the different treatment processes employed at the WWTPs. These technologies were unable to act as barriers for these psychotropics drugs. The concentrations ranged from 50 to 3000 ng L-1 in the WWTP effluents, while the main contaminants were found in surface waters at concentrations from 25 to 3530 ng L-1. The levels of the psychotropic detected in this work did not appear to present risks to the aquatic biota.

On-Flow LC-MS/MS method for screening of xanthine oxidase inhibitors.

The screening of compounds is the initial step in research for the development of new drugs. For this reason, the availability of fast and reliable tools for the screening of a large number of compounds becomes essential. Among the therapeutic targets, the enzyme xanthine oxidase (XO) is of great interest for its importance as a biological source of superoxide radicals, which contribute to the oxidative stress on organisms and are involved in many pathological processes. In the present study, we validated a new method using an immobilized capillary enzyme reactor in an LC system directly coupled to triple quadrupole mass spectrometry to screen for XO ligands. The use of mass spectrometry provided selectivity and speed to the system, eliminating the analytical separation step. The Michaelis-Menten constant (KM) value determined for the immobilized enzyme was 14.5 ±â€¯0.4 µmol L-1, which is consistent with the value previously reported for the XO-ICER with UV detection in a 2D LC method. The on-line approach was successfully applied to assay the XO inhibitory activities of thirty isolated compounds from different classes of natural products and provided greater productivity (288 analysis/day) than 2D LC method (84 analysis/day) of screened samples.

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.

Oral administration of antibiotics increased the potential mobility of bacterial resistance genes in the gut of the fish Piaractus mesopotamicus.

BACKGROUND: Aquaculture is on the rise worldwide, and the use of antibiotics is fostering higher production intensity. However, recent findings suggest that the use of antibiotics comes at the price of increased antibiotic resistance. Yet, the effect of the oral administration of antibiotics on the mobility of microbial resistance genes in the fish gut is not well understood. In the present study, Piaractus mesopotamicus was used as a model to evaluate the effect of the antimicrobial florfenicol on the diversity of the gut microbiome as well as antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) using a metagenomic approach. RESULTS: The total relative abundance of ARGs and MGEs significantly increased during the antibiotic exposure. Additionally, phage integrases, transposases, and transposons flanking ARGs accumulated in the gut microbiome of P. mesopotamicus because of the antibiotic exposure. MGEs co-occurring with ARGs showed a significant positive correlation with the total ARGs found. Furthermore, shifts in the gut microbiome towards well-known putative pathogens such as Salmonella, Plesiomonas, and Citrobacter were observed following florfenicol treatment. Mainly Plesiomonas and Citrobacter harbored genes that code for multidrug and phenicol efflux pumps. Moreover, several genes related to RNA processing and modification, cell motility, SOS response, and extracellular structure were enriched due to the antibiotic application. The observed effects were visible during the complete application phase and disappeared at the post-exposure phase. CONCLUSIONS: Our findings suggest that the oral administration of antibiotics increases the potential for MGE-mediated exchange of ARGs in the gut of fish and could contribute to the enrichment and dispersion of ARGs in aquaculture systems. Importantly, this increase in the potential for ARGs exchange could be an effect of changes in community structure and/or ARG mobilization.

Benzimidazoles in wastewater: Analytical method development, monitoring and degradation by photolysis and ozonation.

Pharmaceutical residues are constantly released into natural waters, mainly from wastewater treatment plants (WWTPs) whose processes are unable to completely eliminate them. Among these drugs, the occurrence of benzimidazoles, a class of antiparasitics for human and veterinary use, has been reported in WWTP effluents and surface waters. In this study, an SPE-UHPLC-MS/MS method was developed and optimized for extraction and quantitation of benzimidazoles in influents and effluents of a local WWTP and in hospital wastewater. The extraction procedure was optimized using response surface methodology (Box-Behnken design) and the optimal parameters were as follows: 2.0 mL of loading solvent consisting of a mixture of water:methanol (95:5, v/v) and temperature at 43 °C. In hospital wastewater, albendazole (ABZ) and its principal metabolite ricobendazole (RBZ) were the main benzimidazole-related contaminants and were found at concentrations of up to 3810 and 3894 ng L-1, respectively. The WWTP system was able to remove from 46% to 95% of the ABZ quantified in the influent, discharging an effluent with 16-441 ng L-1 of ABZ. The concentrations of other benzimidazoles and metabolites in the WWTP effluents remained below 350 ng L-1. WWTP effluents fortified with 50 µg L-1 of ABZ required 26.7 mgO3 L-1 to remove ABZ and RBZ. After ozonation, the COD and BOD5 of the effluents were reduced by 27%. Photolysis by UVA radiation was not effective to remove ABZ and FBZ from the effluent samples.

Sorption behaviors of antimicrobial and antiparasitic veterinary drugs on subtropical soils.

Brazil is one of the world's largest producers of animal protein, requiring the large-scale use of veterinary drugs. The administration of antimicrobials and antiparasitics is a common practice. However, there is a lack of information on how these drugs impact the environment. Antimicrobials are capable of altering the soil microbial population and are responsible for the development of multidrug-resistant microbial strains. Therefore, it is important to evaluate the fate and transport of these compounds in the environment, and one parameter used for this purpose is the soil-water partition coefficient. In this work, an assessment was made of the soil sorption behaviors of 18 drugs from seven different families, including antimicrobials (sulfonamides, fluoroquinolones, amphenicols, and macrolides) and antiparasitic drugs (milbemycin, avermectins, and benzimidazoles). Seven subtropical soils of different textural classes were tested. The Freundlich sorption coefficients, expressed as µg1-1/n (cm3)1/n g-1, were in the following ranges: 0.45 to 19 (sulfonamides), 72 to 2410 (fluoroquinolones), 9 to 58 (thiabendazole), 0.03 to 0.48 (florfenicol), 105 to 424 (moxidectin), 14 to 184 (avermectins), and 1.5 to 74 (macrolides). The results showed that the drugs belonging to the same family, with chemical structures in common, presented similar behaviors regarding sorption and desorption, for the different soils tested and are generally in agreement with soils from temperate regions. The data set obtained in this work give an overview of the fate of the veterinary drugs in Brazilian subtropical soils with different textures and composition and can be very helpful for exposure risk assessments.