Risk Assessment Of Antibiotics Research Articles

Occurrence and Risk Assessment of Antibiotics in Urban River–Wetland–Lake Systems in Southwest China

Antibiotics in the aquatic environment are of great concern as novel contaminants. In this study, we investigated the occurrence, distribution, potential sources, and risk assessment of antibiotics in an interconnected river–wetland–lake system. Thirty-three target antibiotics, including sulfonamides (SAs), macrolides (MLs), fluoroquinolones (FQs), tetracyclines (TCs), and chloramphenicol (CLs) belong to five common groups of antibiotics, were tested from water samples collected in the Panlong River, Xinghai Wetland, and Lake Dian (or Dianchi). Mass spectrophotometry was used to detect the target antibiotics, and the water quality parameters were measured in situ. We found four antibiotics, lincomycin (LIN), trimethoprim (TMP), sulfamethoxazole (SMX), and ofloxacin (OFL), with relatively low concentrations at the ng/L level, and detection rates among sample sites ranged from 42.3% to 76.9%, with maximum concentrations of 0.71 ng/L~5.53 ng/L. TMP was not detected in the Panlong River but appeared in the wetlands and Lake Dian. Midstream urban areas of the Panlong River showed the highest pollution among sites. Antibiotic concentrations were positively correlated with total nitrogen (TN) (p < 0.05) and showed some negative correlation with pH, salinity, and DO. According to the risk assessment, antibiotics in water do not pose a threat to human health and aquatic ecosystems, but a potentially harmful combined effect cannot be excluded. Our research offers a geographical summary of the distribution of antibiotics in urban river, wetland, and lake ecosystems in the plateau (PWL), which is important for predicting the distribution characteristics of antibiotics in the plateau water environment and establishing a standardized antibiotic monitoring and management system for the government.

Distribution and Probabilistic Risk Assessment of Antibiotics, Illegal Drugs, and Toxic Elements in Gastropods from Southeast China.

We investigated fourteen antibiotics, three illegal drugs, and two toxic elements in commercially available gastropods from southeast China. The data revealed high detection frequencies (DFs) for florfenicol (61.32%), florfenicol amine (47.33%), and thiamphenicol (39.88%), with maximum concentrations of 1110, 2222, and 136 μg/kg wet weight (ww), respectively. The DFs of illegal drugs were 3.54% for leucomalachite green and 0.3% for chloramphenicol. The average levels of Cd and As were 1.17 and 6.12 mg/kg ww, respectively. All chemicals presented diverse DFs in different sampling months. The highest DFs of florfenicol, florfenicol amine, and thiamphenicol were in July. The health risk assessment showed that targeted hazard quotients (THQs) of antibiotics, Cd, and As for children, teens, and adults were all less than one. Notably, the toxic elements (Cd and As) were identified as the primary health risk in gastropods, contributing to over 90% of the total THQs.

Preliminary investigation on the occurrence and health risk assessment of antibiotics in cultured tilapia retailed at a commercial outlet in Tema, Ghana

In Ghana, Nile tilapia is one of the most commonly cultivated fish species. Bacterial infections, which mostly occur in intensive fish farming, are considered to be the most significant health issue facing these culture systems in Ghana's aquaculture industry. To prevent, and treat bacterial infections and promote fish growth, antimicrobials are often used, and in most cases at unregulated doses. However, this misuse and neglect of withdrawal durations for such antimicrobials may result in drug residues showing up in fish edible tissue, posing a risk to human consumers. To evaluate the risk to consumers, this study screened for antibiotic residues in popular tilapia fish sold at a retail outlet in Tema. Using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS), the study analysed the levels of 12 antibiotics present in 24 tilapia samples sold at a retail outlet in Tema. Erythromycin, tetracycline, oxytetracycline, and amoxicillin were detected at varying levels, with frequencies of 20.8 %, 62.5 %, 58.3 %, and 54.2 %, respectively. The highest concentration of 3.521 ± 0.32 μg/kg was found for oxytetracycline, while erythromycin had the lowest concentration (0.276 ± 0.11 μg/kg) in the samples. According to the study, the levels of antibiotics detected in the sampled tilapia were lower than the maximum residue limits (MRL) recommended by the WHO. Additionally, both the hazard quotient (HQ) and hazard index (HI) values were less than one. Therefore, consuming retail farmed tilapia purchased from the commercial outlet in Tema metropolis was deemed to pose no significant risk to human health. However, regular monitoring of antibiotics and other contaminants is necessary to minimise their potential impacts on human health.

Repeated Exposure Enhanced Toxicity of Clarithromycin on Microcystis aeruginosa Versus Single Exposure through Photosynthesis, Oxidative Stress, and Energy Metabolism Shift.

Antibiotics are being increasingly detected in aquatic environments, and their potential ecological risk is of great concern. However, most antibiotic toxicity studies involve single-exposure experiments. Herein, we studied the effects and mechanisms of repeated versus single clarithromycin (CLA) exposure on Microcystis aeruginosa. The 96 h effective concentration of CLA was 13.37 μg/L upon single exposure but it reduced to 6.90 μg/L upon repeated exposure. Single-exposure CLA inhibited algal photosynthesis by disrupting energy absorption, dissipation and trapping, reaction center activation, and electron transport, thereby inducing oxidative stress and ultrastructural damage. In addition, CLA upregulated glycolysis, pyruvate metabolism, and the tricarboxylic acid cycle. Repeated exposure caused stronger inhibition of algal growth via altering photosynthetic pigments, reaction center subunits biosynthesis, and electron transport, thereby inducing more substantial oxidative damage. Furthermore, repeated exposure reduced carbohydrate utilization by blocking the pentose phosphate pathway, consequently altering the characteristics of extracellular polymeric substances and eventually impairing the defense mechanisms of M. aeruginosa. Risk quotients calculated from repeated exposure were higher than 1, indicating significant ecological risks. This study elucidated the strong influence of repeated antibiotic exposure on algae, providing new insight into antibiotic risk assessment.

Occurrence, distribution, and risk assessment of antibiotics in a typical aquaculture area around the Dongzhai Harbor mangrove forest on Hainan Island

The trees of the Dongzhai Harbor mangrove forest suffer from antibiotic contamination from surrounding aquaculture areas. Despite this being one of the largest mangrove forests in China, few studies have focused on the antibiotic pollution status in these aquaculture areas. In the present study, the occurrence, distribution, and risk assessment of 37 antibiotics in surface water and sediment samples from aquaculture areas around Dongzhai Harbor mangrove forests were analyzed. The concentration of total antibiotics (∑antibiotics) ranged from 78.4 ng/L to 225.6 ng/L in surface water (except S14-A2) and from 19.5 ng/g dry weight (dw) to 229 ng/g dw in sediment. In the sediment, the concentrations of ∑antibiotics were relatively low (19.5–52.3 ng/g dw) at 75 % of the sampling sites, while they were high (95.7–229.0 ng/g dw) at a few sampling sites (S13-A1, S13D, S8D). The correlation analysis results showed that the Kd values of the 9 antibiotics were significantly positively correlated with molecular weight (MW), Kow, and LogKow. Risk assessment revealed that sulfamethoxazole (SMX) in surface water and SMX, enoxacin (ENX), ciprofloxacin (CFX), enrofloxacin (EFX), ofloxacin (OFX), and norfloxacin (NFX) in sediment had medium/high risk quotients (RQs) at 62.5 % and 25–100 %, respectively, of the sampling sites. The antibiotic mixture in surface water (0.06–3.36) and sediment (0.43–309) posed a high risk at 37.5 % and 66.7 %, respectively, of the sampling sites. SMX was selected as an indicator of antibiotic pollution in surface water to assist regulatory authorities in monitoring and managing antibiotic pollution in the aquaculture zone of Dongzhai Harbor. Overall, the results of the present study provide a comprehensive and detailed analysis of the characteristics of antibiotics in the aquaculture environment around the Dongzhai Harbor mangrove system and provide a theoretical basis for the source control of antibiotics in mangrove systems.

Cross-contamination and ecological risk assessment of antibiotics between rivers and surrounding open aquaculture ponds

Antibiotics are causing widespread concern as one of the emerging contaminants. There is the abuse of antibiotics in high-density open aquaculture, and the tailwater is often discharged into surrounding rivers. At the same time, the water replenishment of open aquaculture ponds from nearby rivers containing antibiotic contamination from different sources may result in cross-contamination. However, it is still unclear which pollution intensity is greater in rivers or in open aquaculture. So in this paper, the levels of 20 antibiotics (i.e., Fluoroquinolones (FQs), Sulfonamides (SAs), Tetracyclines (TCs), Macrolides (MLs) and Lincosamides (LCs)) in rivers and high-density open aquaculture ponds were investigated in the Baini River basin in the suburbs of Guangzhou, China. The results showed that norfloxacin (NFX) was the predominant antibiotic in river and aquaculture water, with concentrations ranging from 6.12 to 156.04 ng/L and from 7.47 to 82.62 ng/L in both aquatic systems, respectively. As for the pollution intensity of antibiotics, the annual pollution contribution (28.64 kg/a) of the river water supply to open aquaculture is higher than that (10.81 kg/a) of open aquaculture to the river, which means river pollution has a greater impact on aquaculture ponds. The risk quotient (RQ) showed that the ecological risk of lincomycin (LIN), erythromycin (ERY), sulfamethoxazole (SMX), norfloxacin (NFX), ciprofloxacin (CFX) and chlortetracycline (CTC) in rivers and aquaculture environments had high ecological risks from 1.21 to 1.81. Water interactions with contaminated rivers will result in a corresponding increase in the ecological risk of antibiotics in the aquaculture environment. Overall, according to the results, the risk of polluted rivers to open aquaculture cannot be ignored, and it is recommended that open aquaculture should use these water sources with caution, and that the water quality evaluation of aquaculture water should be increased with monitoring indicators for emerging contaminants such as antibiotics.

Predictive binary mixture toxicity modeling of fluoroquinolones (FQs) and the projection of toxicity of hypothetical binary FQ mixtures: a combination of 2D-QSAR and machine-learning approaches.

All sorts of chemicals get degraded under various environmental stresses, and the degradates coexist with the parent compounds as mixtures in the environment. Antibiotics emerge as an additional concern due to the bioactive nature of both the parent compound and degradation products and their combined exposure to the environment. Therefore, environmental risk assessment of antibiotics and their degradation products is very much necessary. In this direction, we made use of in silico new approach methodologies (NAMs) and machine-learning algorithms. In this study, we have developed a robust and predictive mixture-quantitative structure-activity relationship (QSAR) model with promising quality and predictability (internal: MAETrain = 0.085, QLOO2 = 0.849, external: MAETest = 0.090, and QF12 = 0.859) for predicting the toxicity of the mixtures of a class of antibiotics and their degradation products. To obtain the predictive model, toxicity data of 78 binary fluoroquinolone mixtures in E. coli (endpoint: log 1/IC50 in molar) have been utilized. We have used only 0D-2D descriptors to efficiently encode the structural features of mixture components without any additional complexities. The optimization of the class of mixture descriptors has been performed in this study by using three different mixing rules (linear combination of molecular contributions, the squared molecular contributions, and the norm of molecular contributions). Different machine-learning approaches namely, random forest (RF), ada boost, gradient boost (GB), extreme gradient boost (XGB), support vector machine (SVM), linear support vector machine (LSVM), and ridge regression (RR) have been employed here apart from the conventional partial least squares (PLS) regression to optimize the modeling approach. A rigorous validation protocol has been used for assessing the goodness-of-fit, robustness, and external predictability of the models. Finally, the toxicity of possible untested mixtures of different photodegradation products of fluoroquinolones has been predicted using the best model reported in this study.

Metabolic network and proteomic expression perturbed by cyclosporine A to model microbe Escherichia coli

Cyclosporine A (CsA) is a model drug that has caused great concern due to its widespread use and abuse in the environment. However, the potential harm of CsA to organisms also remains largely unknown, and this issue is exceptionally important for the health risk assessment of antibiotics. To address this concern, the crosstalk between CsA stress and cellular metabolism at the proteomic level in Escherichia coli was investigated and dissected in this study. The results showed that CsA inhibited E. coli growth in a time-dependent manner. CsA induced reactive oxygen species (ROS) overproduction in a dose- and time-dependent manner, leading to membrane depolarization followed by cell apoptosis. In addition, translation, the citric acid cycle, amino acid biosynthesis, glycolysis and responses to oxidative stress and heat were the central metabolic pathways induced by CsA stress. The upregulated proteins, including PotD, PotF and PotG, controlled cell growth. The downregulated proteins, including SspA, SspB, CstA and DpS, were regulators of self-feedback during the starvation process. And the up- and downregulated proteins, including AtpD, Adk, GroS, GroL and DnaK, controlled energy production. These results provide an important reference for the environmental health risk assessment of CsA.

Effects of Enrofloxacin and Ciprofloxacin on Growth and Toxin Production of Microcystis aeruginosa

Microcystis aeruginosa is a common cyanobacterium found in water blooms and often causes ecological harm. Antibiotics are also increasingly used for the prevention and treatment of bacterial infections in aquaculture. However, since most antibiotics cannot be fully metabolized, they enter the water environment and cause ecological impacts. In this paper, the effects of the two fluoroquinolone antibiotics (enrofloxacin and ciprofloxacin) on the population density and microcystins (MCs) production of M. aeruginosa were studied. It is of great significance for the ecological risk assessment of antibiotics in the water environment. The results showed that the 96h EC50 values of enrofloxacin and ciprofloxacin to M. aeruginosa were 56.10 mg/L and 49.80 mg/L, respectively, and the toxicity of ciprofloxacin to M. aeruginosa was slightly stronger than that of enrofloxacin. With the increase in the two antibiotic concentration, the growth inhibition rate (IR) increased, but when the concentration reached a certain level, the IR would reach its threshold. Long-term exposure to low concentrations of these two antibiotics is not only more likely to lead to the outbreak of M. aeruginosa, but also increase its toxin production capacity. The highest contents of MCs in enrofloxacin and ciprofloxacin groups were 95.539 μg/g and 93.720 μg/g, respectively. The MCs value of these three enrofloxacin treatment groups was more than above 51.8 times that of control group (CK) on the 4th day; from 8th day to 14th day, the MCs value of these three enrofloxacin treatment groups was more than above 3.2 times that of CK group. For ciprofloxacin, the MCs value of the treatment group was more than 64.98 times that of the CK group on the 4th day, and from 8th day to 14th day, the MCs value of the treatment group was more than 2.7 times that of the CK group. These findings provide crucial management rationale.

Occurrence and ecological risk assessment of antibiotics in manure and the surrounding soil from typical chicken farms in Hangzhou, China

The widespread use of antibiotics in animal and human medication has raised global concerns over environmental contamination caused by antibiotic residues. This research investigated the occurrence of 12 kinds of antibiotics belonging to three groups, sulfonamides (SAs), tetracyclines (TCs), and fluoroquinolones (FQs), in chicken manure and the surrounding soil from different chicken farms in Hangzhou, South China, were detected in the samples via ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS) and the contamination characteristics of each type of antibiotic and the correlations between each antibiotic and environmental factors were analyzed to identify the key influencing factors. An ecological risk assessment of antibiotics in the soil environment was conducted using the risk quotient (RQ) method to analyze the potential hazard level. The results indicated that: the total concentration of FQs was much higher than those of SAs and TCs in chicken manures and the soil samples. The mean concentration of FQs (39.17 μg·kg–1), TCs (34.37 μg·kg–1), and SAs (20.24 μg·kg–1) in chicken manure were significantly higher than those in the soil samples. Ciprofloxacin (CIP) was the main antibiotics detected in manure (19.42 μg·kg–1) and the soils samples (near soil: 18.42 μg·kg–1, far soil: 10.29 μg·kg–1), followed by enrofloxacin (ENR), tetracycline (TC), and ofloxacin (OFL). The redundancy analysis (RDA) showed that moisture content (MS), total organic carbon (TOC) and total nitrogen (TN) had a greater influence on the antibiotic concentration in the soil samples. Basis on the calculated risk quotient (RQs) values, the risk assessment indicated Sulfamerazine (SD) and Sulfamethoxazole (SMX) in soil posed a high risk, while trimethoprim (TMP), TC, CIP, and OFL in soils posed a medium or low risk. This research provides control and environmental monitoring data about chicken farms and scientific information that can be used to alleviate antibiotics pollution.

Distribution, removal and ecological risk assessment of antibiotics in leachate from municipal solid waste incineration plants in Shanghai, China

Leachate from Municipal Solid Waste (MSW) incineration plants contains multiple antibiotics. However, current knowledge of antibiotics in such leachate is very limited compared to landfill leachate. In this study, the distribution, removal and ecological risks of 8 sulfonamides (SAs), 4 quinolones (FQs), and 4 macrolides (MLs) antibiotics in leachate from three MSW incineration plants in Shanghai were investigated. The results showed that 12 types of target antibiotics were detected at high concentrations (7737.3–13,758.7 ng/L) in the fresh leachate, exceeding the concentrations reported for landfill leachate. FQs were the dominant antibiotics detected in all three fresh leachates, accounting for >60 % of the total detected concentrations. The typical “anaerobic-anoxic/aerobic-anoxic/aerobic-ultrafiltration” treatment process removed the target antibiotics effectively (89.0 %–93.4 %), of which the anaerobic unit and the primary anoxic/aerobic unit were the most important antibiotic removal units. Biodegradation was considered to be the dominant removal mechanism, removing 78.11 %–92.37 % of antibiotics, whereas sludge adsorption only removed 1.02 %–10.89 %. Antibiotic removal was significantly correlated with leachate COD, pH, TN, and NH3-N, indicating that they may be influential factors for antibiotic removal. Ecological risk assessment revealed that ofloxacin (OFX) and enrofloxacin (EFX) in the treated leachate still posed high risks to algae and crustaceans. This research provides insights into the fate of antibiotics in leachate.

Occurrence and Environmental Risk Assessment of Antibiotics in Water and Sediment from Fish Farms in the Lower Volta Lake of Ghana

Occurrence and Environmental Risk Assessment of Antibiotics in Water and Sediment from Fish Farms in the Lower Volta Lake of Ghana

Pollution Characteristics and Risk Assessment of Antibiotics in Beiyun River Basin in Beijing

To investigate the pollution characteristics and risk levels of antibiotics in water of the Beiyun River Basin in Beijing, the concentration of antibiotics was analyzed by using the solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method. The results showed that seven types of four categories of antibiotics were detected in the samples from 12 sampling points; the total concentration of antibiotics including sulfapyridine, clarithromycin, azithromycin, roxithromycin, erythromycin, ofloxacin, and lincomycin ranged from 59.19 to 703.44 ng·L-1. Among these antibiotics, the detection rate of clarithromycin, azithromycin, roxithromycin, ofloxacin, and lincomycin was 100%; that of erythromycin was 41.67%; and that of sulfapyridine was 33.33%. Compared with that in some rivers in China, the Azithromycin, Erythromycin, and Clarithromycin in the Beiyun River Basin were at a relatively high level. The ecological risk assessment results showed that the most sensitive species was algae. The health risk quotients indicated that sulfapyridine, lincomycin, roxithromycin, azithromycin, and erythromycin presented no risk for every age group, whereas the health risk of clarithromycin was at a low level.

Spatial Distribution and Risk Assessment of Antibiotics in 15 Pharmaceutical Plants in the Pearl River Delta.

Pharmaceutical plants are an essential source of antibiotics emitted into the aqueous environment. The monitoring of target antibiotics in pharmaceutical plants through various regions is vital to optimize contaminant release. The occurrence, distribution, removal, and ecological risk of 30 kinds of selected antibiotics in 15 pharmaceutical plants in the Pearl River Delta (PRD) were investigated in this study. Lincomycin (LIN) showed the highest concentration (up to 56,258.3 ng/L) in the pharmaceutical plant influents from Zhongshan city. Norfloxacin (NFX) showed a higher detection frequency than other antibiotics. In addition, the spatial distribution of antibiotics in pharmaceutical plants showed significant differences, with higher concentrations of total antibiotics found in pharmaceutical plant influents in Shenzhen City than those of different regions in PRD. The treatment processes adopted by pharmaceutical plants were commonly ineffective in removing antibiotics, with only 26.7% of antibiotics being effectively removed (average removal greater than 70%), while 55.6% of antibiotics had removal rates of below 60%. The anaerobic/anoxic/oxic (AAO)-membrane bioreactor (MBR) combined process exhibited better treatment performance than the single treatment process. Sulfamethoxazole (SMX), ofloxacin (OFL), erythromycin-H2O (ETM-H2O), sulfadiazine (SDZ), sulfamethazine (SMZ), norfloxacin (NFX), and ciprofloxacin (CIP) in pharmaceutical plant effluents posed high or moderate ecological risk and deserve particular attention.

Pollution Characteristics and Risk Assessment of Antibiotics and Resistance Genes in Different Water Sources in the Wuhan Section of the Yangtze River

The distribution characteristics, correlations, and potential ecological risks of 13 antibiotics and 10 antibiotic resistance genes (ARGs) in 16 water sources in Wuhan were analyzed using solid-phase extraction-ultra-high performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) and real-time quantitative PCR technology. The distribution characteristics and correlations and potential ecological risks of antibiotics and resistance genes in this region were analyzed. The results showed that a total of nine antibiotics were detected in the 16 water source samples, and the concentration range was ND-177.36 ng·L-1. The concentration distribution presented as follows:Tributary Jushui River<lower reaches of the main stream of the Yangtze River<upstream of the main stream of the Yangtze River<Tributary Hanjiang River<Tributary Sheshui River. The total absolute abundance of ARGs after the Yangtze River and Hanjiang River confluence was significantly higher than that before the confluence, and the average abundance of sulfa ARGs was significantly higher than that of the other three ARGs resistance genes (P<0.05). There was a significant positive correlation between sul1 and sul2, ermB, qnrS, tetW, and intI1 in ARGs (P<0.01), and the correlation coefficients were 0.768, 0.648, 0.824, 0.678, and 0.790, respectively. The correlation within the sulfonamide ARGs group was weak. Correlation of ARGs between groups. Four antibiotics, sulfamethoxazole, aureomycin, roxithromycin, and enrofloxacin, had a medium risk to aquatic sensitive organisms, and the proportion of each risk area in the ecological risk map was 9.0% (medium risk), 30.6% (low risk), and 60.4% (no risk). The combined ecological risk assessment (RQsum) of the 16 water sources indicated medium risk, and the RQsum (mean) of the rivers involved was 0.222 (Tributary Hanjiang River)<0.267 (main stream of the Yangtze River)<0.299 (other tributaries).

Distribution and risk assessment of antibiotics under water level fluctuation in the riparian zone of the Hanjiang River

The riparian zone (RZ) is an important region connecting surface water and groundwater, and it has widely been acknowledged for its pollutant buffering capacity. However, the decontaminating effect of RZ on trace organic compounds such as antibiotics has received little attention. This study explored the distribution of 21 antibiotics and 4 sulfonamide metabolites in river water and groundwater in the lower reaches of the Hanjiang River. The diffusion and exchange of contaminants between the river and riverbanks under the influence of water conservancy projects (Xinglong Dam and the Yangtze-Hanjiang Water Diversion Project) were investigated. Macrolide antibiotics were prevalent in river water (62.5–100%) and groundwater samples (42.9–80.4%). Ofloxacin and chlortetracycline were detected with the highest concentrations in river water (12.2 ng L−1) and groundwater (9.3 ng L−1) respectively. Higher levels of antibiotics were observed in spring and winter than in other seasons. The river-groundwater interaction has a certain interception effect on antibiotics, especially near riverbanks. Redox sensitive element Fe2+ showed significantly positive correlations with some tetracycline and macrolide antibiotics (p < 0.05), and thus the migration mechanism between Fe2+ and antibiotics under the condition of redox change should be investigated further. Environmental risks posed by antibiotics were assessed for algae, daphnids, and fish in surface water and groundwater. Only clarithromycin and chlortetracycline presented a medium risk to algae (0.1 < RQ < 1), and the rest presented low risk (RQ < 0.1). Nevertheless, the risk range may be further extended by interactions between groundwater and surface water. Accurate understanding of antibiotic transport in RZ is critical for developing management strategies aimed at reducing the pollution load on the watershed.

Mechanism of time-dependent toxicity of quinolone antibiotics on luminescent bacteria Vibrio qinghaiensis sp.-Q67

Four quinolone antibiotics (ciprofloxacin (CIP), enrofloxacin (ENR), sparfloxacin (SPA), gatifloxacin (GAT)) and their binary mixtures at environmentally relevant concentrations exhibited time-dependent hormesis on Vibrio qinghaiensis sp.-Q67 (Q67). The study aims to investigate the time-dependent toxicity of low-dose pollutants and the occurrence of hormesis. These indicators, total protein (TP), reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and luminescence-related chemicals flavin mononucleotide (FMN), nicotinamide adenine dinucleotide (NADH), were measured to explore the mechanism of hormesis. The results showed a trend of increases in all indicators after 12 h of exposure, reaching maximal effects at 60 h and then decreasing as time progressed. At 36 h, 60 h and 84 h, the results showed a gradual increase followed by a decreasing trend in TP, FMN and NADH as the concentration in the group increased, whereas ROS, CAT, SOD and MDA showed the opposite trend. Notably, the degree of changes was related to the magnitude of hormesis. At low concentrations, the content of ROS and MDA decreased, the activity of CAT and SOD was lower, but the content of TP, FMN, NADH gradually increased, positively correlated with the promotion of Q67. At high concentrations, ROS and MDA content in Q67 increased, triggering the antioxidant defense mechanism (CAT and SOD activity increased), but TP, FMN, NADH content decreased, negatively correlated with the inhibited Q67. Therefore, our findings demonstrated two common patterns in these seven biochemical indicators on Q67. These findings have important practical implications for the ecological risk assessment of antibiotics in aquatic environment.

Effects of Sulfamethazine in Soil on Rice Growth

For the sake of investigating the effects of residual antibiotics in soil on plant growth, sulfamethazine, which is commonly detected in soil, was selected in this project. In general, the growth index of rice at the seedling and mature stages, physiological/biochemical characteristics of roots and leaves, antibiotic residues, enrichment factors, and transport coefficients in various rice organs were respectively tested and analyzed to evaluate the ecological effects of sulfamethazine residues on rice. The results revealed that the inhibitory effect of sulfamethazine on plant height and biomass was maintained during the whole growth cycle. Moreover, the effect at the seedling stage was greater than that at the growth maturity stage, and the root part was more easily influenced than the seedling section. The root activity, nitrate reductase activity, and leaf chlorophyll content at the seedling stage were hindered by the increase in antibiotic content. By contrast, the antioxidant enzyme change showed a different tendency, in which the superoxide was activated, and the catalase and peroxidase were firstly activated and then inhibited. The sulfamethazine accumulation in various rice organs was in the order of root>leaf>sti>grain. The results of antibiotic risk assessment of rice grains exhibited that EDI/ADI was less than 0.1, indicating no health risk. The effect of sulfamethazine on enrichment factors and transport coefficients at the growth maturity stage was more obvious than that at the seedling stage. Considering the adverse effects of sulfamethazine on rice, we need to take the ecological effects of sulfamethazine on plants into consideration when applying livestock manure as organic fertilizer or using aquaculture water for irrigation, to ensure crop production safety.

Occurrence and risk assessment of antibiotics in feces of elderly individuals in Shenzhen.

The occurrence of antibiotics in the feces of elderly individuals in Shenzhen, China, was investigated by monitoring 78 compounds to understand the adverse effects and its association with antibiotic residues in animal products collected from local markets. In total, 18 compounds belonging to 5 classes of antibiotics were identified in 74 of 140 fecal samples. Furthermore, 17.9% of the fecal samples contained at least two antibiotics, and 14.3% of the samples showed antibiotic concentrations higher than 100μg/kg. Cephalothin exhibited the highest detection frequency (22.1%), followed by azithromycin (15.7%) and tilmicosin (12.9%). Oxytetracycline, norfloxacin, and azithromycin showed extremely high concentrations (> 1000μg/kg). Eight antibiotics were detected in the animal products, with detection frequencies ranging from 4.8 to 40.0%. Five antibiotics exhibited similar detection frequencies and strong correlations between the human fecal and animal product samples. Health risk assessment based on hazard quotients showed that ciprofloxacin in animal products and human feces posed a medium and high risk, respectively. The hazard quotients of oxytetracycline, norfloxacin, and azithromycin in the feces were greater than 1, indicating a high health risk. These findings suggest that the elderly individuals were frequently exposed to antibiotics via the food chain and faced health risks posed by these antibiotics.

Occurrence, fate, and risk assessment of antibiotics in typical pharmaceutical manufactories and receiving water bodies from different regions.

This study aimed to investigate the presence and persistence of antibiotics in wastewater of four typical pharmaceutical manufactories in China and receiving water bodies and suggest the removal of antibiotics by the wastewater treatment process. It also evaluated the environmental impact of antibiotic residues through wastewater discharge into receiving water bodies. The results indicated that thirteen antibiotics were detected in wastewater samples with concentrations ranging from 57.03 to 726.79 ng/L. Fluoroquinolones and macrolides were the most abundant antibiotic classes found in wastewater samples, accounting for 42.5% and 38.7% of total antibiotic concentrations, respectively, followed by sulfonamides (16.4%) and tetracyclines (2.4%). Erythromycin-H2O, lincomycin, ofloxacin, and trimethoprim were the most frequently detected antibiotics; among these antibiotics, the concentration of ofloxacin was the highest in most wastewater samples. No significant difference was found in different treatment processes used to remove antibiotics in wastewater samples. More than 50% of antibiotics were not completely removed with a removal efficiency of less than 70%. The concentration of detected antibiotics in the receiving water bodies was an order of magnitude lower than that in the wastewater sample due to dilution. An environmental risk assessment showed that lincomycin and ofloxacin could pose a high risk at the concentrations detected in effluents and a medium risk in their receiving water bodies, highlighting a potential hazard to the health of the aquatic ecosystem. Overall, The investigation was aimed to determine and monitor the concentration of selected antibiotics in 4 typical PMFs and their receiving water bodies, and to study the removal of these substances in PMFs. This study will provide significant data and findings for future studies on antibiotics-related pollution control and management in water bodies.