Occurrence and risks of triclosan and triclocarban in the Pearl River system, South China: from source to the receiving environment

Pharmaceuticals and personal care products and heavy metals in the Ganga River, India: Distribution, ecological and human health risk assessment

In the present study, pharmaceuticals and personal care products (PPCPs), endocrine disrupting compounds (EDCs), and heavy metals (HMs), were measured in water and sediment of the Ganga River during summer and winter seasons for two consecutive years. Additionally, this study estimated the ecological and human health risks associated with PPCPs, EDCs, and HMs. HMs detected in the range of not detected (n.d.) to 23.59 μg/L and 0.01-391.44 μg/g in water and sediment samples, respectively. All studied HMs were within the permissible limits, except for As in water, and Cr and Ni in sediment. The geo-accumulation index (Igeo) indicated that Cr (0.71-5.98) and Pb (0.90-3.90) had high Igeo compared to other metals in sediment samples. Pb showed the highest ecological risk, followed by Cd, Co, Ni, Cu, Cr, As, and Zn. The maximum potential ecological risk index was observed at site G8. The hazard index (HI) value for water (0.08-0.89) and sediment (0.02-0.29) intake by adults remained within the acceptable limits, except at sites G8 (1.27) and G9 (1.34) for water intake. However, for children, the HI value was above the acceptable limit for water intake at sites G4 to G13 and for sediment at site G8. Among the studied compounds, metformin, triclosan, triclocarban, diclofenac, and methylparaben were the most abundant compounds present in the Ganga River. PPCPs and EDCs detected in the range of n.d. to 5850.04 ng/L and n.d. to 1080.41 ng/g in water and sediment samples, respectively. The environmental risk assessment identifies the maximum ecological risk in water exhibited by triclocarban followed by 17α-ethinylestradiol (EE2), diclofenac, and triclosan, while in sediment, the maximum ecological risk exhibited by triclocarban, followed by EE2, 17 β-estradiol (E2), triclosan, and diclofenac. However, none of the compounds showed human health risk, except for EE2, E2, and atenolol.

Pulsed electric field enhanced Bacillus sp. DL4 biodegradation of triclosan: focusing on operational performance and metabolomic analysis

Electrochemical-assisted microbial degradation technology was considered a crucial strategy to reduce micropollutants, but the mechanism of the pulsed electric field (PEF) in affecting biodegradation had not been systematically studied. This study aimed to construct a bio-electrochemical system (BES) using PEF to investigate its effect on the degradation of triclosan (TCS) by the aerobic bacterium Bacillus sp. DL4. The operating optimal parameters for the BES (i.e. 0.01 A of the pulsed current, 1000 Hz of the pulse frequency, Fe (+)-C (-) of the plate materials, 4 cm of the plate spacing) were obtained by batch experiments. The maximum biomass (OD600 = 1.0 ± 0.05) was achieved and the removal efficiency of TCS reached above 95% in 24 h under the obtained operating conditions. Meanwhile, a thorough and methodical investigation of the metabolites in strain DL4 stimulated by PEF using untargeted Liquid Chromatography - Mass Spectrometry (LC-MS). In multivariate analysis, the experimental groups showed a notable separation in Principal Components Analysis (PCA) and Orthogonal Partial Least Squares Analysis discriminant analysis (OPLS-DA) score plots. A total of 3181 differential metabolites were obtained, and the up-regulated metabolites were mainly related to 'Aminoacyl-tRNA biosynthesis', 'Arginine and proline metabolism', 'Lysine degradation', 'ABC transporters', and 'TCA cycle', implying that PEF enhanced the degradation efficiency of TCS by enriching functional genes with transport ability and ion migration ability in cells. This study illuminated how PEF can affect TCS biodegradation and gives insights into the application prospect of electrochemical-assisted biodegradation technology in water environment treatment.

Critical review on the environmental behaviors and toxicity of triclosan and its removal technologies

As a highly effective broad-spectrum antibacterial agent, triclosan (TCS) is widely used in personal care and medical disinfection products, resulting in its widespread occurrence in aquatic and terrestrial environments, and even in the human body. Notably, the use of TCS surged during the COVID-19 outbreak, leading to increasing environmental TCS pollution pressure. From the perspective of environmental health, it is essential to systematically understand the environmental occurrence and behavior of TCS, its toxicological effects on biota and humans, and technologies to remove TCS from the environment. This review comprehensively summarizes the current knowledge regarding the sources and behavior of TCS in surface water, groundwater, and soil systems, focusing on its toxicological effects on aquatic and terrestrial organisms. Effluent from wastewater treatment plants is the primary source of TCS in aquatic systems, whereas sewage application and/or wastewater irrigation are the major sources of TCS in soil. Human exposure pathways to TCS and associated adverse outcomes were also analyzed. Skin and oral mucosal absorption, and dietary intake are important TCS exposure pathways. Reducing or completely degrading TCS in the environment is important for alleviating environmental pollution and protecting public health. Therefore, this paper reviews the removal mechanisms, including adsorption, biotic and abiotic redox reactions, and the influencing factors. In addition, the advantages and disadvantages of the different techniques are compared, and development prospects are proposed. These findings provide a basis for the management and risk assessment of TCS and are beneficial for the application of treatment technology in TCS removal.

Tradeoffs between hygiene behaviors and triclosan loads from rivers to coastal seas in the post COVID-19 era

The use of healthcare products containing triclosan has surged globally due to the COVID-19 pandemic. In this study, we used a global spatially explicit model to simulate triclosan export by rivers to coastal seas in the post-COVID-19 era. The global triclosan model shows that the primary watersheds of triclosan export in Europe, Africa, Southeast Asia, United States, Brazil, India, and China, with river mouths presenting higher ecological risk distributed in Europe, South Asia, and America. It is estimated that triclosan concentrations in more than 77 % of global watersheds will be below the toxicity threshold by 2030 if the per capita use of triclosan is halved. Rather than completely restricting the use of triclosan, we should focus on integrating the effectiveness data of triclosan to develop recommendations for essential usage, substitutes, and wastewater treatment plants that minimize triclosan pollution in the post-COVID-19 era.

Synergistic detoxification efficiency and mechanism of triclocarban degradation by a bacterial consortium in the liver-gut-microbiota axis of zebrafish (Danio rerio)

Triclocarban (TCC), an emerging organic contaminant, poses a potential threat to human health with long-term exposure. Here, Rhodococcus rhodochrous BX2 and Pseudomonas sp. LY-1 were utilized to degrade TCC at environmental related concentrations for enhancing TCC biodegradation and investigating whether the toxicity of intermediate metabolites is lower than that of the parent compound. The results demonstrated that the bacterial consortium could degrade TCC by 82.0% within 7 days. The calculated 96 h LC50 for TCC, as well as its main degradation product 3,4-Dichloroaniline (DCA) were 0.134 mg/L and 1.318 mg/L respectively. Biodegradation also alleviated histopathological lesions induced by TCC in zebrafish liver and gut tissues. Liver transcriptome analysis revealed that biodegradation weakened differential expression of genes involved in disrupted immune regulation and lipid metabolism caused by TCC, verified through RT-qPCR analysis and measurement of related enzyme activities and protein contents. 16 S rRNA sequencing indicated that exposure to TCC led to gut microbial dysbiosis, which was efficiently improved through TCC biodegradation, resulting in decreased relative abundances of major pathogens. Overall, this study evaluated potential environmental risks associated with biodegradation of TCC and explored possible biodetoxification mechanisms, providing a theoretical foundation for efficient and harmless bioremediation of environmental pollutants.

Reproductive endocrine disruption effect and mechanism in male zebrafish after life cycle exposure to environmental relevant triclosan

Triclosan (TCS) is a wide-spectrum antibacterial agent that is found in various water environments. It has been reported to have estrogenic effects. However, the impact of TCS exposure on the reproductive system of zebrafish (Danio rerio) throughout their life cycle is not well understood. In this study, zebrafish fertilized eggs were exposed to 0, 10, and 50 μg/L TCS for 120 days. The study investigated the effects of TCS exposure on brain and testis coefficients, the expression of genes related to the hypothalamus-pituitary-gonadal (HPG) axis, hormone levels, vitellogenin (VTG) content, histopathological sections, and performed RNA sequencing of male zebrafish. The results revealed that life cycle TCS exposure had significant effects on zebrafish reproductive parameters. It increased the testis coefficient, while decreasing the brain coefficient. TCS exposure also led to a decrease in mature spermatozoa and altered the expression of genes related to the HPG axis. Furthermore, TCS disrupted the balance of sex hormone levels and increased VTG content of male zebrafish. Transcriptome sequencing analysis indicated that TCS affected reproductive endocrine related pathways, including PPAR signaling pathway, cell cycle, GnRH signaling pathway, steroid biosynthesis, cytokine-cytokine receptor interaction, and steroid hormone biosynthesis. Protein-protein interaction (PPI) network analysis confirmed the enrichment of hub genes in these pathways, including bub1bb, ccnb1, cdc20, cdk1, mcm2, mcm5, mcm6, plk1, and ttk in the brain, as well as fabp1b.1, fabp2, fabp6, ccr7, cxcl11.8, hsd11b2, and hsd3b1 in the testis. This study sheds light on the reproductive endocrine-disrupting mechanisms of life cycle exposure to TCS.

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.

Toxic effects of triclosan on hepatic and intestinal lipid accumulation in zebrafish via regulation of m6A-RNA methylation

Triclosan (TCS), recognized as an endocrine disruptor, has raised significant concerns due to its widespread use and potential health risks. To explore the impact of TCS on lipid metabolism, both larval and adult zebrafish were subjected to acute and chronic exposure to TCS. Through analyzes of biochemical and physiological markers, as well as Oil Red O (ORO) and hematoxylin and eosin (H&E) staining, our investigation revealed that TCS exposure induced hepatic and intestinal lipid accumulation in larval and adult zebrafish, leading to structural damage and inflammatory responses in these tissues. The strong affinity of TCS with PPARγ and subsequent pathway activation indicate that PPARγ pathway plays a crucial role in TCS-induced lipid buildup. Furthermore, we observed a decrease in m6A-RNA methylation levels in the TCS-treated group, which attributed to the increased activity of the demethylase FTO and concurrent suppression of the methyltransferase METTL3 gene expression by TCS. The alteration in methylation dynamics is identified as a potential underlying mechanism behind TCS-induced lipid accumulation. To address this concern, we explored the impact of folic acid-a methyl donor for m6A-RNA methylation-on lipid accumulation in zebrafish. Remarkably, folic acid administration partially alleviated lipid accumulation by restoring m6A-RNA methylation. This restoration, in turn, contributed to a reduction in inflammatory damage observed in both the liver and intestines. Additionally, folic acid partially mitigates the up-regulation of PPARγ and related genes induced by TCS. These findings carry substantial implications for understanding the adverse effects of environmental pollutants such as TCS. They also emphasize the promising potential of folic acid as a therapeutic intervention to alleviate disturbances in lipid metabolism induced by environmental pollutants.

Ecotoxicological and human health risk assessment of triclosan antibacterial agent from municipal wastewater treatment plants

In this study, the occurrence and environmental risks related to triclosan (TCS) in the two wastewater treatment plants (WWTPs) were investigated in Isfahan, Iran. Influent and effluent samples were collected and analyzed by dispersive liquid-liquid microextraction (DLLME)-GC-MS method with derivatization. Moreover, the risk of TCS exposure was conducted for aquatic organisms (algae, crustaceans, and fishes) and humans (males and females). TCS mean concentrations in influent and effluent of WWTPs were in the range of 3.70-52.99 and 0.83-1.09 μg/L, respectively. There were also no differences in the quantity of TCS and physicochemical parameters among the two WWTPs. The mean risk quotient (RQ) for TCS was higher than 1 (in algae) with dilution factors (DFs) equal to 1 in WWTP1. Moreover, the RQ value was higher than 1 for humans based on the reference dose of MDH (RFDMDH) in WWTP1. Furthermore, TCS concentration in wastewater effluent was the influential factor in varying the risk of TCS exposure. The results of the present study showed the risk of TCS exposure from the discharge of effluent of WWTP1 was higher than WWTP2. Moreover, the results of this study may be suitable for promoting WWTP processes to completely remove micropollutants.

Toxicity of triclosan, an antimicrobial agent, to a nontarget freshwater zooplankton species, Moina macrocopa

The toxicity of triclosan (TCS) on the freshwater cladoceran Moina macrocopa was investigated by acute and chronic toxicity assessments followed by genotoxicity and oxidative stress response analyses. The 48-h LC50 of TCS for ≤24-h-old M. macrocopa was determined as 539 μg L-1 . Chronic exposure to TCS at concentrations ranging from 5 to 100 μg L-1 showed a stimulatory effect at low concentrations (≤10 μg L-1 ) and an inhibitory effect at high concentrations (≥50 μg L-1 ) on growth, reproduction, and population-growth-related parameters of M. macrocopa. The genotoxicity test results indicated that TCS concentrations ranging from 50 to 100 μg L-1 can alter individuals' DNA. Analysis of the antioxidant enzymes catalase (CAT) and glutathione s-transferase (GST) demonstrated increased levels of these enzymes at high TCS concentrations. Our results indicated that TCS concentrations found in the natural environment have minimal acute toxicity to M. macrocopa. However, TCS at even low concentrations can significantly affect its growth, reproduction, and population-growth-related characteristics. The observed responses suggest a hormetic dose-response pattern and imply a potential endocrine-disrupting effect of TCS. Our molecular and biochemical findings indicated that high concentrations of TCS have the potential to induce oxidative stress that may lead to DNA alterations in M. macrocopa.

Toxic effects of triclocarban on the histological morphology, physiological and immune response in the gills of the black tiger shrimp Penaeus monodon

Triclocarban (TCC) is a widely used broad-spectrum antimicrobial agent that has become a pollutant threatening the health of aquatic animals. However, the toxic effects of TCC on Penaeus monodon are still lacking. In this study, we exposed P. monodon to 1 μg/L (TCC-1) and 10 μg/L TCC (TCC-10) for 14 days, and the changes of histological morphology, physiological and immune responses in the gills were investigated. The results showed that TCC exposure caused the deformation of the gill vessels and the disordered arrangement of the gill filaments. Oxidative stress biochemical indexes such as H2O2 content, CAT and GPx activity and the relative expression levels of antioxidant-related genes (SOD, GPx and Nrf2) were increased in the TCC-1 and TCC-10 groups; the levels of CAT and HSP70 genes were increased but POD activity was decreased in the TCC-10 group. The relative expression levels of endoplasmic reticulum (ER) stress indexes such as ERP15 and ATF-6 genes were increased in the TCC-10 group, while the level of GRP78 gene was decreased in the TCC-1 and TCC-10 groups. The relative expression levels of apoptosis indexes such as p53 and JNK genes were increased, but CytC and Casp-3 genes were decreased in the TCC-1 and TCC-10 groups. Furthermore, the relative expression levels of detoxification metabolism-related genes (cytP450 and GST) and osmotic regulation-related genes (NKA-α, NKA-β, CA, AQP, CLC and CCP) were increased in the TCC-10 group. The results showed that TCC exposure could affect the physiological homeostasis in the gills of P. monodon, probably via damaging histological morphology, inducing oxidative stress, and disordering ER stress, apoptosis, detoxification and osmotic regulation.

Cetaceans as bio-indicators revealed the increased risks of triclosan exposure and associated thyroid hormone disruption during the COVID-19 pandemic

The global surge in disinfection practices from the COVID-19 response has raised concerns about the marine exposure to the hazardous ingredients in disinfectant products, including triclosan (TCS) and triclocarban (TCC). However, there are very limited studies on the response of marine TCS and TCC (TCs) loading to the COVID-19 pandemic. Here we used cetaceans as bio-indicators for a long-term retrospective analysis of TCs loading to the South China Sea (SCS) between 2004 and 2022. Hepatic TCs was 100% detected in all nine cetacean species (n = 120). Interestingly, TCS concentrations decreased in Indo-Pacific humpback dolphins (IPHD) before the pandemic from 2010 to 2017. However, after 2019, TCS concentrations in IPHD significantly increased several-fold. Similarly, post-pandemic TCS concentrations in Indo-Pacific finless porpoises (IPFP) and two fish species were significantly higher than pre-pandemic levels. There were significant relationships between thyroid hormones (THs) and TCs in IPHD and IPFP, suggesting that increased TCs may worsen the interference of THs homeostasis and nutritional conditions in cetaceans. These findings demonstrate the profound impact of the surging use of TCs-containing products from the COVID-19 response on marine ecosystems.

Phytoplankton Biological Pump Controls the Spatiotemporal Bioaccumulation and Trophic Transfer of Antibiotics in a Large Subtropical River

The spatiotemporal bioaccumulation, trophic transfer of antibiotics, and regulation of the phytoplankton biological pump were quantitatively evaluated in the Pearl River, South China. The occurrence of antibiotics in organisms indicated a significant spatiotemporal trend associated with the life cycle of phytoplankton. Higher temporal bioaccumulation factors (BAFs) were found in phytoplankton at the bloom site, while lower BAFs of antibiotics in organisms could not be explained by phytoplankton biomass dilution but were attributed to the low bioavailability of antibiotics, which was highly associated with distribution coefficients (R2 = 0.480-0.595, p < 0.05). Such lower BAFs of antibiotics in phytoplankton at higher biomass sites hampered the entry of antibiotics into food webs, and trophic dilutions were subsequently observed for antibiotics except for ciprofloxacin (CFX) and sulfamerazine (SMZ) at sites with blooms in all seasons. Distribution of CFX, norfloxacin (NFX), and sulfapyridine (SPD) showed further significant positive relationships with the plasma protein fraction (R2 = 0.275-0.216, p < 0.05). Both mean BAFs and trophic magnification factors (TMFs) were significantly negatively correlated with phytoplankton biomass (R2 = 0.661-0.741, p < 0.05). This study highlights the importance of the biological pump in the regulation of spatiotemporal variations in bioaccumulation and trophic transfer of antibiotics in anthropogenic-impacted eutrophic rivers in subtropical regions.

Toxicity of microplastics and triclosan, alone and in combination, to the fertilisation success of a broadcast spawning bivalve Tegillarca granosa

Since most marine invertebrates adopted external fertilisation, their fertilisation process is particularly vulnerable to aquatic pollutants. Both antimicrobial ingredients and microplastics (MPs) are ubiquitous in aquatic environments; however, their synergistic effects on the fertilisation of marine invertebrates remain unclear. Therefore, in this study, the fertilisation toxicity of MPs and triclosan (TCS), alone and in combination, was investigated in the broadcast spawning bivalve Tegillarca granosa. Results showed that MPs and TCS significantly suppressed the fertilisation success of T. granosa. As the fertilisation success of broadcast spawning invertebrates depends on successful gamete collisions, gamete fusion, and egg activation, sperm swimming velocity, viability, gamete collision probability, ATP status, and ion-transport enzyme activities were also analysed to further ascertain the underlying toxicity mechanisms. In summary, our findings indicate that the presence of MPs may enhance the fertilisation toxicity of TCS by hampering sperm-egg collision probability, reducing gamete fusion efficiency, and restricting Ca²⁺ oscillation formation.

Emerging contaminant triclosan incites endocrine disruption, reproductive impairments and oxidative stress in the commercially important carp, Catla (Labeo catla): An insight through molecular, histopathological and bioinformatic approach

Triclosan (TCS), a broad-spectrum antimicrobial agent is ubiquitous in aquatic ecosystems; however, the mechanisms regarding TCS-induced reproductive toxicity in the teleost still remains uncertain. In this context, Labeo catla were subjected to sub-lethal doses of TCS for 30 days and variations in expression of genes and hormones comprising the hypothalamic-pituitary-gonadal (HPG) axis along with alterations in sex steroids were evaluated. Moreover, manifestation of oxidative stress, histopathological alterations, in silico docking and the potential to bioaccumulate were also investigated. Exposure to TCS may lead to an inevitable onset of the steroidogenic pathway through its interaction at several loci along the reproductive axis: TCS stimulated synthesis of kisspeptin 2 (Kiss 2) mRNAs which in turn prompts the hypothalamus to secrete gonadotropin-releasing hormone (GnRH), resulting in elevated serum 17β-estradiol (E₂) as a consequence; TCS exposure increased aromatase synthesis by brain, which by converting androgens to oestrogens may raise E₂ levels; Moreover, TCS treatment resulted in elevated production of GnRH and gonadotropins by the hypothalamus and pituitary, respectively resulting in the induction of E₂. The elevation in serum E₂ may be linked to abnormally elevated levels of vitellogenin (Vtg) with harmful consequences evident as hypertrophy of hepatocytes and increment in hepatosomatic indices. Additionally, molecular docking studies revealed potential interactions with multiple targets viz. Vtg and luteinizing hormone (LH). Furthermore, TCS exposure induced oxidative stress and caused extensive damage to tissue architecture. This study elucidated molecular mechanisms underlying TCS-induced reproductive toxicity and the need for regulated use and efficient alternatives which could suffice for TCS.

Calibration of a microporous polyethylene tube passive sampler for polar organic compounds in wastewater effluent

Water resources are vulnerable to contamination from polar organic compounds (POCs) originating from sources such as wastewater effluent. Two configurations of a microporous polyethylene tube (MPT) passive sampler were investigated for the time-integrative detection and quantification of POCs in effluent. One configuration contained the polymeric reversed phase sorbent Strata-X (SX) and the other Strata-X suspended in agarose gel (SX-Gel). These were deployed for up to 29 days and analysed for forty-nine POCs including pesticides, pharmaceuticals and personal care products (PPCPs) together with illicit drugs. Complementary composite samples were collected on days 6, 12, 20 and 26 representing the previous 24 h. Thirty-eight contaminants were detected in composite samples and MPT extracts, with MPT sampling rates (R_s) for 11 pesticides and 9 PPCPs/drugs ranging from 0.81 to 10.32 mL d^-1 in SX and 1.35-32.83 mL d^-1 in SX-Gel. Half-times to equilibrium of contaminants with the SX and SX-Gel equipped samplers ranged from two days to >29 days. MPT (SX) samplers were also deployed at 10 wastewater treatment effluent discharge sites across Australia for 7 days (again with complementary composite samples), to validate the sampler performance under varying conditions. Extracts from these MPTs detected 48 contaminants in comparison with 46 in composite samples, with concentrations ranging from 0.1 to 138 ng mL^-1. An advantage of the MPT was preconcentration of contaminants, resulting in extract levels often markedly above instrument analytical detection limits. The validation study demonstrated a high correlation between accumulated contaminant mass in the MPTs and wastewater concentrations from composite samples (r² > 0.70, where concentrations in composite samples were > 3× LOD). The MPT sampler shows promise as a sensitive tool for detecting POCs at trace levels in wastewater effluent and also quantifying these levels if temporal concentration variations are not significant.

Triclosan and related compounds in the environment: Recent updates on sources, fates, distribution, analytical extraction, analysis, and removal techniques

Triclosan (TCS) has been widely used in daily life because of its broad-spectrum antibacterial activities. The residue of TCS and related compounds in the environment is one of the critical environmental safety problems, and the pandemic of COVID-19 aggravates the accumulation of TCS and related compounds in the environment. Therefore, detecting TCS and related compound residues in the environment is of great significance to human health and environmental safety. The distribution of TCS and related compounds are slightly different worldwide, and the removal methods also have advantages and disadvantages. This paper summarized the research progress on the source, distribution, degradation, analytical extraction, detection, and removal techniques of TCS and related compounds in different environmental samples. The commonly used analytical extraction methods for TCS and related compounds include solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, liquid-phase microextraction, and so on. The determination methods include liquid chromatography coupled with different detectors, gas chromatography and related methods, sensors, electrochemical method, capillary electrophoresis. The removal techniques in various environmental samples mainly include biodegradation, advanced oxidation, and adsorption methods. Besides, both the pros and cons of different techniques have been compared and summarized, and the development and prospect of each technique have been given.

Evaluating the spatial and temporal distribution of emerging contaminants in the Pearl River Basin for regulating purposes

Little information is available on how the types, concentrations, and distribution of chemicals have evolved over the years. The objective of the present study is therefore to review the spatial and temporal distribution profile of emerging contaminants with limited toxicology data in the pearl river basin over the years to build up the emerging contaminants database in this region for risk assessment and regulatory purposes. The result revealed that seven groups of emerging contaminants were abundant in this region, and many emerging contaminants had been detected at much higher concentrations before 2011. Specifically, antibiotics, phenolic compounds, and acidic pharmaceuticals were the most abundant emerging contaminants detected in the aquatic compartment, while phenolic compounds were of the most profound concern in soil. Flame retardants and plastics were the most frequently studied chemicals in organisms. The abundance of the field concentrations and frequencies varied considerably over the years, and currently available data can hardly be used for regulation purposes. It is suggested that watershed management should establish a regular monitoring scheme and comprehensive database to monitor the distribution of emerging contaminants considering the highly condensed population in this region. The priority monitoring list should be formed in consideration of historical abundance, potential toxic effects of emerging contaminants as well as the distribution of heavily polluting industries in the region.

Triclosan and triclocarban weaken the olfactory capacity of goldfish by constraining odorant recognition, disrupting olfactory signal transduction, and disturbing olfactory information processing

Recently, increased production and consumption of disinfectants such as triclosan (TCS) and triclocarban (TCC) have led to massive pollution of the environment, which draws global concern over the potential risk to aquatic organisms. However, the olfactory toxicity of disinfectants in fish remains elusive to date. In the present study, the impact of TCS and TCC on the olfactory capacity of goldfish was assessed by neurophysiological and behavioral approaches. As shown by the reduced distribution shifts toward amino acid stimuli and hampered electro-olfactogram responses, our results demonstrated that TCS/TCC treatment would cause deterioration of the olfactory ability of goldfish. Our further analysis found that TCS/TCC exposure suppressed the expression of olfactory G protein-coupled receptors in the olfactory epithelium, restricted the transformation of odorant stimulation into electrical responses by disturbing the cAMP signaling pathway and ion transportation, and induced apoptosis and inflammation in the olfactory bulb. In conclusion, our results demonstrated that an environmentally realistic level of TCS/TCC would weaken the olfactory capacity of goldfish by constraining odorant recognition efficiency, disrupting olfactory signal generation and transduction, and disturbing olfactory information processing.

Personal Care Products as a Contributing Factor to Antimicrobial Resistance: Current State and Novel Approach to Investigation

Antimicrobial resistance (AMR) is one of the world's industrialized nations' biggest issues. It has a significant influence on the ecosystem and negatively affects human health. The overuse of antibiotics in the healthcare and agri-food industries has historically been defined as a leading factor, although the use of antimicrobial-containing personal care products plays a significant role in the spread of AMR. Lotions, creams, shampoos, soaps, shower gels, toothpaste, fragrances, and other items are used for everyday grooming and hygiene. However, in addition to the primary ingredients, additives are included to help preserve the product by lowering its microbial load and provide disinfection properties. These same substances are released into the environment, escaping traditional wastewater treatment methods and remaining in ecosystems where they contact microbial communities and promote the spread of resistance. The study of antimicrobial compounds, which are often solely researched from a toxicological point of view, must be resumed considering the recent discoveries, to highlight their contribution to AMR. Parabens, triclocarban, and triclosan are among the most worrying chemicals. To investigate this issue, more effective models must be chosen. Among them, zebrafish is a crucial study system because it allows for the assessment of both the risks associated with exposure to these substances as well as environmental monitoring. Furthermore, artificial intelligence-based computer systems are useful in simplifying the handling of antibiotic resistance data and speeding up drug discovery processes.

Acute toxicity, oxidative stress, and apoptosis due to short-term triclosan exposure and multi- and transgenerational effects on in vivo endpoints, antioxidant defense, and DNA damage response in the freshwater water flea Daphnia magna

In this study, we measured the acute toxicity of triclosan (TCS) in neonate and adult Daphnia magna water fleas. The median lethal concentrations were 184.689 and 349.511 μg/L, respectively. Oxidative stress induced by TCS was analyzed based on changes in reactive oxygen species (ROS) content and antioxidant enzymatic activities in D. magna. Based on these endpoints, TCS concentrations of 50 and 100 μg/L induced oxidative stress. However, several apoptosis-mediated proteins showed TCS-induced oxidative-stress damage in response to 25 μg/L, indicating that apoptotic proteins were the most sensitive mediators. We also evaluated the multi- and transgenerational effects of TCS on D. magna over three generations in terms of various in vivo endpoints, DNA damage responses, and biochemical reactions. The transgenerational group exposed to TCS exhibited greater negative impacts on antioxidant responses, DNA fragmentation status, and biological endpoints compared with the multigenerational exposure group, leading to decreased reproductive rates and higher ROS content. The transcriptional expression levels of glutathione S-transferase genes in the transgenerational exposure group were upregulated compared to those in the multigenerational group but were fully recovered in F2 offspring. Our findings provide an in-depth understanding of the adaptive effects of multigenerational exposure to TCS.

Applications of biochar in sulfate radical-based advanced oxidation processes for the removal of pharmaceuticals and personal care products

Recently, biochar (BC) has been increasingly used as a catalyst for the degradation of 'emerging pollutants' (EPs). Pharmaceuticals and personal care products (PPCPs), which come under 'EPs', can be harmful to the aquatic ecosystem despite being present in very low concentrations (ng/L-μg/L). Advanced oxidation processes (AOPs), which produce sulfate radical (SR-AOPs), show a great potential to degrade PPCPs effectively from wastewater. It is mainly due to the higher stability, long half-lives and better non-selectivity of SO₄^{• -} compared with AOPs with •OH generation. Furthermore, research focus is now given on AOPs coupled with BC-supported catalyst to enhance the degradation of PPCPs because of quicker generation of radicals (•OH, SO₄^•-) by the activation of persulfate (PS) and peroxymonosulfate (PMS). This article sheds light on the catalytic ability of BC after its physical and chemical modifications such as acid/alkali treatment and metal doping. The role of persistent free radicals (PFRs) in the BC for effective removal of PPCPs has been elaborated. Its potential applications in synthetic as well as real wastewater have also been discussed.

Physiological Impairment and Biochemical Modifications Induced by Triclosan in Mediterranean Mussels

The effects of pharmaceutical under aquatic biota are still not well established. In this investigation, we assessed the results of a common pharmaceutical's, triclosan (TCS), treatment on physiological and biochemical status of the Mediterranean mussels. Filtration and respiration rates were statistically reduced after treatment with highest considered concentration TCS2 = 100 µg·L^-1. However, no modification (p > 0.05) was detected after treatment with TCS1 = 50 µg·L^-1. For biochemical responses, oxidative stress parameters including H₂O₂ level and antioxidant enzymes were enhanced following concentration in considered organs. In parallel, Malondialdheyde content was measured in mussels after TCS treatment and lipid peroxidation occurred at high TCS concentration. Neurotoxicity evaluated by acetylcholinesterase (AChE) activity was induced in gills and digestive glands after exposure to TCS2. Overall, physiological impairment, oxidative stress, lipid peroxidation and neurotoxicity could be induced by triclosan in mussels. The association of physiological and biochemical biomarkers constitute a useful tool to measure the impact of pharmaceuticals in marine organism.

Neurotoxic mechanisms of triclosan: The antimicrobial agent emerging as a toxicant

Several scientific studies have suggested a link between increased exposure to pollutants and a rise in the number of neurodegenerative disorders of unknown origin. Notably, triclosan (an antimicrobial agent) is used in concentrations ranging from 0.3% to 1% in various consumer products. Recent studies have also highlighted triclosan as an emerging toxic pollutant due to its increasing global use. However, a definitive link is missing to associate the rising use of triclosan and the growing number of neurodegenerative disorders or neurotoxicity. In this article, we present systematic scientific evidence which are otherwise scattered to suggest that triclosan can indeed induce neurotoxic effects, especially in vertebrate organisms including humans. Mechanistically, triclosan affected important developmental and differentiation genes, structural genes, genes for signaling receptors and genes for neurotransmitter controlling enzymes. Triclosan-induced oxidative stress impacting cellular proteins and homeostasis which triggers apoptosis. Though the scientific evidence collated in this article unequivocally indicates that triclosan can cause neurotoxicity, further epidemiological studies may be needed to confirm the effects on humans.

The last 50 years of organic contamination of a highly anthropized tributary of the Po River (Italy)

We examined the temporal profiles of many organic micropollutants analysed in a sediment core sampled from a highly anthropized tributary of the Po River, the Lambro River. Analysed for extractable organic halogens (EOX), total petroleum hydrocarbons (C₁₀-C₄₀TPH), polycyclic aromatic hydrocarbons (PAHs), common legacy pollutants (DDTs, PCBs), halogenated flame retardants (PBDEs, DBDPE, TBBPA-bis, TCBPA, TBBPA, HBCDs), organotins (TBT, TPhT), antimicrobials (TCS, TCC), fragrances (AHTN, HHCB) and phthalates (DMP, DEP, DnBP, BBP, DEHP, DnOP), the dated sediment core revealed the historical record of 50 years of chemical contamination discharged into the Lambro and thereby the Po River. In this regard, the peak levels of PCBs and DDTs found in Lambro sediments were also identified in other sediment cores collected from the Po River prodelta in the Adriatic Sea, thus hundreds of kilometres downstream (Combi et al., 2020). The highest risk to aquatic organisms was associated with decades of high levels of C₁₀-C₄₀ TPH, PBDEs, PCBs, PAHs, DDTs, EOX, TCC, AHTN and DEHP, which in different periods of the contamination history, showed exceedances of guideline/threshold values. C₁₀-C₄₀ TPH and TCC, for example, were very high in the 1960s, whereas PCBs, DDTs, and PBDEs, peaked from the 1980s onward. The corresponding sums of PEC quotients ranged between 0.48 and 28.63, with a mean value (±SD) for the entire recording period of 10.62 ± 9.83. Environmental legislations and improved wastewater treatments were the main drivers of the recent downward trends observed for most of the chemicals investigated. Floods in turn resulted in macroscopic yet temporary improvements in the chemical quality of the tributary, conveying contaminated sediments into the Po River.

The Influence of the Chemical Composition of Natural Waters about the Triclocarban Sorption on Pristine and Irradiated MWCNTs

The influence of the chemical composition of natural waters on triclocarban (TCC) sorption on pristine and irradiated multi-walled carbon nanotubes (MWCNTs) at different temperatures was studied. Natural waters have been characterized in terms of the concentrations of cations and anions, pH, and electric conductivity. The sorption process of TCC on MWCNTs is influenced by both the chemical composition of natural waters and the variation of the temperature. The adsorption capacity of TCC on pristine and irradiated MWCNTs in the studied natural waters increased by increasing the temperature. The increase of the concentration of monovalent cations (Na+ and K+) in natural waters determined a significant decrease of the adsorption capacity of TCC on both pristine and irradiated MWCNTs while the increase of the bivalent cations (Ca2+ and Mg2+) determined an easy increase adsorption capacity. Freundlich and Langmuir models were selected to describe the steady adsorption of the TCC on the pristine and irradiated MWCNTs.

Screening of antimicrobials, fragrances, UV stabilizers, plasticizers and preservatives in sewage treatment plants (STPs) and their risk assessment in India

Community/industrial wastewater is the prime source of anthropogenic chemicals, its treatment is often a daunting task and unaffordable for many countries. Emerging Contaminants (ECs) have been drained into wastewater after continuous use/misuse and Conventional treatments in STPs do not remove them completely. ECs including antimicrobial agents, synthetic musks, Benzotriazole UV stabilizers (BUVSs), plasticizers, and preservatives are frequently reported in environment, and cause health effects to non-target organisms. Monitoring of ECs is important to understand their status in aquatic environment. Hence, it was aimed to monitor ECs (n = 21) from 11 STPs in Tamil Nadu, India. The detection frequency of most of these analytes was >90%. Antimicrobials ranged from 247 to 22,714 ng/L and 11-14,369 ng/L in influents and effluents, respectively. The synthetic musks were in the order of Tonalide > Galaxolide > Musk Ketone. BUVSs ranged from 4 to 1632 ng/L (influents) and < LOD to 29,853 ng/L (effluents). Concentration of phthalates in influents and effluents were < LOD - 11,311 ng/L and < LOD - 17,618 ng/L, respectively. Parabens were found in the order of Prophyl > Methyl > Ethyl > Butyl in influents and Methyl > Prophyl > Butyl > Ethyl in effluents. Mass loads of ECs through STPs were found as antimicrobials > plasticizers > fragrances > BUVSs > Preservatives. This study reveals increasing usage of ECs and inadequate treatment processes at STPs in India. Also helps to adopt suitable treatment processes to remove ECs from wastewater and to reuse the wastewater.

Occurrence and distribution of triclosan and its transformation products in Taihu Lake, China

The transformation products of triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) may be more persistent and toxic than their parent compound, yet their occurrence in aquatic environments is poorly understood. In this study, we identified three transformation products in sediment samples from Taihu Lake and compared their concentrations with the parent compound triclosan. Triclosan in Taihu Lake was at low level, ranging from 0.086 to 1.1 ng/L in surface water and 0.0058-8.3 ng/g in sediments. The three detected transformation products included methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives. Those transformation products constituted 0.73-87.5% of the total triclosan (total triclosan is the sum of triclosan, methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives on a molar basis), indicating that the ecological risk of transformation products should be considered in addition to the parent compound. Different transformation products had distinct spatial distributions. Chlorinated triclosan derivatives had the highest concentration in samples from the northwest region (0.016-0.21 ng/g) of the lake and were positively correlated with triclosan, which may indicate the possible transformation from triclosan to chlorinated triclosan derivatives. Methyl triclosan and methyl chlorinated triclosan derivatives were generally higher in samples from the center of the lake (0.22-0.28 ng/g for methyl triclosan and 0.017-0.021 ng/g for methyl chlorinated triclosan derivatives, respectively), indicating the possible occurrence of in situ microbial methylation of triclosan and chlorinated triclosan derivatives and the accumulation of those methylated analogues in Taihu Lake.

The distribution and ecological risks of antibiotics in the sediments from a diverging area of the bifurcated river: Effects of hydrological properties

The hydrodynamics in the diverging area become complicated because of the basin hydrological conditions, making the distribution of antibiotics largely uncertain and thus bringing uncertain ecological risks of antibiotics. Through field sampling, experiments and numerical simulations, the distribution of antibiotics, its responses to hydrological conditions were studied. Antibiotics in the bifurcated river sediments was mainly distributed in the branch mouth. The hydrodynamic regions were affected by the hydrological frequency. Notably, the center of the low-velocity area moved upstream and gradually expands to the entire tributary as the hydrological frequency shifted from high to low. ENRO (enrofloxacin) and OFC (ofloxacin) were the key hazardous antibiotics affecting the ecological health in the diverging area, and their concentrations are mainly affected by sediment particle size (D < 0.15 mm) and oxygen content. The ecological risk of antibiotics in the diverging area were gradually decreased with the increase of the distance from the central area. The water physical and chemical properties, altered by the river basin hydrological conditions, play an important role in influencing the distribution of antibiotic concentrations, and ultimately posing great threat to aquatic ecosystem. The research provides a scientific basis for antibiotic risk control in the diverging area under different hydrological conditions.

Pharmaceuticals and personal care products (PPCPs) in water, sediment and freshwater mollusks of the Dongting Lake downstream the Three Gorges Dam

Pharmaceuticals and personal care products (PPCPs) are a group of emerging anthropogenic pollutants. Here we investigated the occurrence and concentrations of 35 typical PPCPs in water, sediment, and freshwater mollusks (Hyriopsis cumingii, Unio douglasiae, Sinanodonta woodiana, Lamprotula leai and Corbicula fluminea) of the Dongting Lake downstream of the Three Gorges Dam. As results, 33 PPCPs were detected in water and sediment of the lake. Ketoprofen (not detected (ND)-292.8 ng/L, mean 91.1 ng/L) and roxithromycin (13.7-141.9 ng/L, mean 30.4 ng/L) were the primary PPCPs measured in lake water, while ibuprofen (ND-105.0 ng/g, mean 30.0 ng/g) and ketoprofen (ND-142.9 ng/g, mean 27.6 ng/g) were dominant in the sediment. Distinct seasonal difference in PPCP compositions was observed in both water and sediment of the Dongting Lake, potentially associated with the water-level fluctuations driven by the Three Gorges Dam operations. Ketoprofen and ibuprofen were also frequently detected in the soft tissues of freshwater mollusks, with concentrations of 42.5-1206.6 and 44.9-992.7 ng/g, respectively. Significant species-specific accumulation characteristics of PPCPs in mollusks were observed, with the highest total contents being reported for Corbicula fluminea (3.18 ± 1.13 μg/g). Moreover, gonads of mollusks were identified as the target organ to accumulate these compounds. Correlation analysis further revealed the strong associations of PPCP concentrations in mollusks with those in water and sediment, suggesting the importance of controlling dissolved and sedimentary bioavailability of PPCPs for ecological risk management in this freshwater lake ecosystems.

Impairment of the gut health in Danio rerio exposed to triclocarban

Triclocarban (TCC) is the principal component in personal and health care products because it is a highly effective, broad-spectrum, and safe antibacterial agent. TCC has recently been discovered in aquatic creatures and has been shown to constitute a health danger to aquatic animals. Although several studies have looked into the toxicological effects of TCC on a variety of aquatic animals from algae to fish, the possible gut-toxicity molecular pathway in zebrafish has never been thoroughly explored. We investigated the gut-toxic effects of TCC on zebrafish by exposing them to different TCC concentrations (100 and 1000 μg/L) for 21 days. We discovered for the first time that the MAPK and TLR signaling pathways related to gut diseases were significantly altered, and inflammation (up-regulation of TNF-α, IL-6, and IL-1β) caused by TCC was confirmed to be largely mediated by the aryl hydrocarbon receptor (AHR) and its related cytokines. This was found using the results of qPCR, a transcriptome analysis, and molecular docking (AHR, AHRR, CYP1A1 and CYP1B1). Furthermore, high-throughput 16S rDNA sequencing demonstrated that TCC exposure reduced the bacterial diversity and changed the gut microbial composition, with the primary phyla Fusobacteria and Proteobacteria, as well as the genera Cetobacterium and Rhodobacteraceae, being the most affected. TCC exposure also caused damage to the gut tissue, including an increase in the number of goblet cells and a reduction in the height of the columnar epithelium and the thickness of the muscular layer, as shown by hematoxylin and eosin staining. Our findings will aid in understanding of the mechanism TCC-induced aquatic toxicity in aquatic species.

Distribution and Ecological Risk Assessment of Pharmaceuticals and Personal Care Products in Sediments of North Canal, China

The pollution of water bodies by pharmaceuticals and personal care products (PPCPs) has attracted widespread concern due to their widespread use and pseudo-persistence, but their effects on sediments are less known. In this study, solid-phase extraction-high performance liquid chromatography–tandem mass spectrometry (SPE-LC/MSMS) was used to investigate the occurrence and ecological risks of five typical pharmaceuticals and personal care products (PPCPs) in thirteen key reservoirs, sluices, dams, and estuaries in the Haihe River Basin. At the same time, the PPCP exchanges of surface water, groundwater, and sediments in three typical sections were studied. Finally, the PPCP’s environmental risk is evaluated through the environmental risk quotient. The results showed that the five PPCPs were tri-methoprazine (TMP), sinolamine (SMX), ibuprofen (IBU), triclosan (TCS), and caffeine (CAF). The average concentration of these PPCPs ranged from 0 to 481.19 μg/kg, with relatively high concentrations of TCS and CAF. The relationship between PPCPs in the surface sediments was analyzed to reveal correlations between SMX and TMP, CAF and IBU, CAF and TCS. The risk quotients (RQ) method was used to evaluate the ecological risk of the five detected PPCPs. The major contributors of potential environmental risks were IBU, TCS and CAF, among which all the potential environmental risks at the TCS samples were high risk. This study supplemented the research on the ecological risk of PPCPs in sediments of important reaches of the North Canal to reveal the importance of PPCP control in the North Canal and provided a scientific basis for pollution control and risk prevention of PPCPs.

Critical review on negative emerging contaminant removal efficiency of wastewater treatment systems: Concept, consistency and consequences

Emerging contaminants (ECs) are not completely removed by wastewater treatment owing to their capabilities of making complexes, toxic derivatives, byproduct formation, and dynamic partitioning. Negative contaminant removal i.e., higher concentrations (up to 5731%) of these ECs in the effluent with respect to the influent sampled on the same occasions, is globally prevalent in almost all types of treatment systems. Conventional WWTPs showed the highest negative removal (NR) for Carbamazepine, and Carbadox. Conjugation-deconjugation, types of WWTPs, transformations, leaching, operational parameters, sampling schemes, and nature of substance governs the NR efficiencies. Among the various categories of micropollutants, pesticides and beta-blockers are reported to exhibit the maximum percentage of NR, posing threat to human and the environment. With > 200% of NR for beta-blockers, low blood-pressure related symptoms may likely to get more prevalent in the near future. Study red-flags this phenomenon of negative removal that needs urgent attention.

Research on freshwater water quality criteria, sediment quality criteria and ecological risk assessment of triclosan in China

Triclosan (TCS) is a broad-spectrum antimicrobial agent commonly used in pharmaceuticals and personal care products (PPCPs). The widespread use of TCS makes it frequently detected in various environmental mediums. In view of the high detection frequency of TCS in the aquatic environment and sediments, and its toxic effects on aquatic species, it is critical and necessary to derive Chinese TCS water quality criteria (WQC) and sediment quality criteria (SQC) for protecting Chinese aquatic organisms, and perform the ecological risk assessment. In fact, former research had derived the WQC of TCS mainly based on acute and chronic toxicity data. As an endocrine disrupting chemical (EDC), TCS poses adverse effects on the growth, development and reproduction of aquatic organisms at much lower concentration. Considering nonlethal endpoints are sensitive endpoints for EDCs, TCS long-term water quality criteria (LWQC) was derived based on reproduction and growth related endpoints. In this work, the acute toxicity data of 19 aquatic organisms and the chronic toxicity data of 15 aquatic organisms were obtained through collection and screening. The best fitting model of species sensitivity distribution (SSD) models including Normal, Log-Normal, Logistic and Log-Logistic of toxicity data was selected to derive WQC. The short-term and long-term WQC of TCS for Chinese aquatic organisms were 6.22 μg/L and 0.25 μg/L, respectively. Furthermore, through the phase-equilibrium partitioning method, SQC was derived based on WQC. SQC-low (SQC-L) and SQC-high (SQCH) were 0.13 mg/kg and 3.26 mg/kg, respectively. Moreover, the exposure concentration (EPC) data of TCS in Chinese rivers and sediments were collected. And through the hazard quotient (HQ) method and the joint probability curve (JPC) method we found that there were certain TCS ecological risks in Chinese rivers and sediments. Our work will provide a valuable reference for protecting aquatic organisms and minimizing TCS ecological risk in China.

Antibiotics in aquaculture ponds from Guilin, South of China: Occurrence, distribution, and health risk assessment

Antibiotics have been widely used to prevent or treat bacterial infections in aquaculture in the past decades. However, large proportions of these compounds are excreted unchanged in feces and urine of animals, given incomplete metabolism, leading to the residual of unmetabolized compounds, and posing a potential risk to the environment. This study investigated the occurrence and distribution of seven antibiotics in surface water, sediments, fish muscle, and fish feed by high-performance liquid chromatography from the aquaculture areas in Guilin, South of China. The highest concentrations of the target antibiotics in water, sediment, fish muscle, and fish feed were 2047.53 ng/L, 13.32 μg/kg, 35.90 μg/kg, and 2203.97 μg/kg, respectively. In contrast, the most abundant antibiotic was enrofloxacin (ENR), followed by ofloxacin (OFL), sulfadimidine (SMZ), and ciprofloxacin (CIP). In this work, the concentrations of antibiotics were lower than those in other breeding areas. Correlation analyses showed significant relationships between sulfadiazine (SDZ) and TP, TN, and COD_Cr in water. In sediment, the release of SDZ was significantly related to TN, TP, and organic matter. The risk quotient (RQ) results revealed that sulfamethoxazole (SMX), CIP, and ENR were at high risk to microorganisms in water; while, SMX and NOR were at high risk in sediments. The result from the estimated daily intakes (health risk quotient, HQ < 1) suggested that the antibiotics might not pose a risk to human health by dietary exposure assessment; however, sediments may become an accumulation reservoir of antibiotics and cause secondary pollution, of which the local management should raise awareness.

Insights into the distribution, partitioning and influencing factors of antibiotics concentration and ecological risk in typical bays of the East China Sea

In order to obtain in-depth insight of the behavioral fate and ecological risks of antibiotics in coastal environment, this study investigated the distribution, partitioning and primary influencing factors of antibiotics in water and sediment in the East China Sea. After quantification of 77 target antibiotics in 6 categories, ten antibiotics were detected simultaneously with a detection frequency >50.0% in water and sediment; the concentrations of these ten antibiotics were 0.1-1508.0 ng L^-1 and 0.01-9.4 ng g^-1 in water and dry sediment, respectively. Sulfadiazine and Azithromycin (Pseudo partitioning coefficient were 28-3814 L kg^-1 and 21-2405 L kg^-1, respectively.) had the largest partitioning coefficient between sediment and water. In addition, pseudo partitioning coefficient of Sulfadiazine and Clindamycin were higher than the values of corresponding equilibrium partitioning constant (K_d), which would likely cause them to re-release from sediment to water. Compared to the physiochemical properties of the sediment, water quality has a greater impact on antibiotic partitioning. We found that the partitioning of antibiotics was significantly positively correlated with salinity, suspended solids, pH, NH₄⁺-N and Zn; and negatively correlated with temperature, dissolved oxygen, PO₄^3-, chemical oxygen demand, NO₃^--N, oil, Cu and Cd. The ecological risks of antibiotics in water and sediment were also evaluated for revealing their relationship with the concentration partitioning of antibiotics. Results showed that the target antibiotics mainly pose ecological risks to Daphnia with low and median chronic toxicity risk rather than fish and green algae. The antibiotics in sediment were more chronically toxic to Daphnia than that in water. The risk quotient ratio of sediment and water (RQ_s/RQ_w) ranged from 0 to 1154.0, which were exactly opposite of the values of organic carbon normalized partition coefficient (K_oc), suggesting that the physical properties of antibiotics drove the ecological risk allocation of antibiotics in sediment and water.

Pharmaceuticals and personal care products in aquatic environments and their removal by algae-based systems

The consumption of pharmaceuticals and personal care products (PPCPs) has been widely increasing, yet up to 90-95% of PPCPs consumed by human are excreted unmetabolized. Moreover, the most of PPCPs cannot be fully removed by wastewater treatment plants (WWTPs), which release PPCPs to natural water bodies, affecting aquatic ecosystems and potentially humans. This study sought to review the occurrence of PPCPs in natural water bodies globally, and assess the effects of important factors on the fluxes of pollutants into receiving waterways. The highest ibuprofen concentration (3738 ng/L) in tap water was reported in Nigeria, and the highest naproxen concentration (37,700 ng/L) was reported in groundwater wells in Penn State, USA. Moreover, the PPCPs have affected aquatic organisms such as fish. For instance, up to 24.4 × 10³ ng/g of atenolol was detected in P. lineatus. Amongst different technologies to eliminate PPCPs, algae-based systems are environmentally friendly and effective because of the photosynthetic ability of algae to absorb CO₂ and their flexibility to grow in different wastewater. Up to 99% of triclosan and less than 10% of trimethoprim were removed by Nannochloris sp., green algae. Moreover, variable concentrations of PPCPs might adversely affect the growth and production of algae. The exposure of algae to high concentrations of PPCPs can reduce the content of chlorophyll and protein due to producing reactive oxygen species (ROS), and affecting expression of some genes in chlorophyll (rbcL, psbA, psaB and psbc).

Triclosan detoxification through dechlorination and oxidation via microbial Pd-NPs under aerobic conditions

The present study focuses on the successful preparation of microbial palladium nanoparticles (Pd-NPs). The even distribution of Pd in the periplasmic space of B. megaterium Y-4 cells is characterized using a transmission electronic microscopy (TEM) and scanning electron microscope (SEM). X-Ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed the domination of Pd (0) in Pd-NPs. The microbial Pd-NPs were selected to detoxify triclosan (TCS). Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the intermediate products of dechlorination and oxidization. Free radicals quenching and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) capturing experiments confirmed the crucial contribution of atomic H• and O₂^·- to TCS degradation. Besides, TCS degradation by microbial Pd-NPs could alleviate the cytotoxicity of TCS polluted water. Meanwhile, great circulating utilization of microbial Pd-NPs was obtained in degrading TCS. Corresponding findings in the present study could provide new insight into the role of microbial Pd-NPs in detoxifying pollutants.

Occurrence and partitioning of bisphenol analogues, triclocarban, and triclosan in seawater and sediment from East China Sea

Bisphenol analogues (BPs), triclocarban (TCC), and triclosan (TCS) are well-known environmental endocrine disrupters. Many studies have characterized their occurrence in the freshwater environment. However, their environmental behaviors in the coastal marine environment remain poorly understood. Here, matched seawater and sediment samples were collected from East China Sea, and analyzed for 13 BPs (including halogenated derivatives of bisphenol A), TCC, and TCS. Bisphenol A (BPA; mean 23 ng/L) was the predominant BP in seawaters, followed by tetrabromobisphenol A (TBBPA; 2.3 ng/L) and bisphenol S (BPS; 2.2 ng/L). Seawater concentrations of TCS (<LOD-8.7 ng/L) were much higher (p < 0.01) than that of TCC (<LOD-0.33 ng/L). In sediments BPA was still the major BP (mean 13 ng/g dw, dry weight), followed by bisphenol F (1.6 ng/g dw) and BPS (0.69 ng/g dw). All sediment samples contained measurable TCC (0.12-6.6 ng/g dw), while TCS was occasionally detected. For the first time, this study reports the environmental occurrence of bisphenol M and 4,4'-sulfonylbis (2-aminophenol) (a first discovered BPS analogue) in seawaters and sediments. Spatially, inshore seawater and sediment samples contained higher (p < 0.01) BPA and BPS concentrations, compared with offshore samples. The mean log-transformed sediment-seawater partitioning coefficients (log K_oc) ranged from 2.3 (TBBPA) to 4.0 (TCC). The log K_oc values of BPA, BPS, and BPAF were lower than those previously reported in the freshwater environment. Overall, this study provides first data on the spatial distribution patterns and partitioning behaviors of BPs, TCC, and TCS in marine environment.

Pharmaceuticals and personal care products' (PPCPs) impact on enriched nitrifying cultures

The impact of pharmaceutical and personal care products (PPCPs) on the performance of biological wastewater treatment plants (WWTPs) has been widely studied using whole-community approaches. These contaminants affect the capacity of microbial communities to transform nutrients; however, most have neither honed their examination on the nitrifying communities directly nor considered the impact on individual populations. In this study, six PPCPs commonly found in WWTPs, including a stimulant (caffeine), an antimicrobial agent (triclosan), an insect repellent ingredient (N,N-diethyl-m-toluamide (DEET)) and antibiotics (ampicillin, colistin and ofloxacin), were selected to assess their short-term toxic effect on enriched nitrifying cultures: Nitrosomonas sp. and Nitrobacter sp. The results showed that triclosan exhibited the greatest inhibition on nitrification with EC₅₀ of 89.1 μg L^-1. From the selected antibiotics, colistin significantly affected the overall nitrification with the lowest EC₅₀ of 1 mg L^-1, and a more pronounced inhibitory effect on ammonia-oxidizing bacteria (AOB) compared to nitrite-oxidizing bacteria (NOB). The EC₅₀ of ampicillin and ofloxacin was 23.7 and 12.7 mg L^-1, respectively. Additionally, experimental data suggested that nitrifying bacteria were insensitive to the presence of caffeine. In the case of DEET, moderate inhibition of nitrification (<40%) was observed at 10 mg L^-1. These findings contribute to the understanding of the response of nitrifying communities in presence of PPCPs, which play an essential role in biological nitrification in WWTPs. Knowing specific community responses helps develop mitigation measures to improve system resilience.

Development of an in vivo acute bioassay using the marine medaka Oryzias melastigma

To determine whether the marine medaka Oryzias melastigma is a suitable model organism for in vivo acute toxicity bioassay in seawater, we first determined whether there were differences in the concentrations of chemicals that were toxic to marine medaka (O. melastigma) and freshwater medaka (O. latipes). We performed in vivo acute toxicity bioassay with 3-chloroaniline, triclosan, 3,4-dichloroaniline, fenitrothion, and pyriproxyfen on larvae of both species. Although the concentrations of 3-chloroaniline and fenitrothion that were lethal to the larvae were identical for both species, the toxic concentrations of triclosan, 3,4-dichloroaniline, and pyriproxyfen were lower for O. melastigma than for O. latipes. We then used an in vivo acute toxicity bioassay to monitor the quality of coastal seawater in Akita, Japan. No lethal effects were observed in the harbor and canal in 2019. O. melastigma could be used to monitor the quality of seawater with salinities in the range 2-25. Our findings suggest that O. melastigma can be used as the test fish for in vivo acute toxicity bioassay intended for water quality monitoring.

Exploration of the developmental toxicity of TCS and PFOS to zebrafish embryos by whole-genome gene expression analyses

Triclosan (TCS) and perfluorooctane sulfonate (PFOS) are known to have both endocrine disrupting and developmental toxicity effects on zebrafish embryos. Currently, potential molecular mechanisms underlying these toxicological phenomena require further studies. To address this gap in the literature, we used whole transcriptome microarrays to being to address the potential molecular mechanisms underlying developmental toxicity of TCS and PFOS on zebrafish embryos. Zebrafish embryos were exposed to 300 μg/L TCS and 500 μg/L PFOS from 4 to 120 h post fertilization (hpf). Phenotypically, the hatching rate of zebrafish embryos was significantly reduced after TCS exposure at 72 hpf. Additionally, body length was significantly decreased in the TCS treatment group at 120 hpf. Gene ontology analysis of differentially expressed genes revealed that lipid metabolism, steroid metabolism, and organ development-related biological processes were significantly enriched in TCS- and PFOS-treated zebrafish embryos. Furthermore, signaling network analysis indicated that the steroid biosynthesis process was the most significant biological process disrupted by TCS in 120 hpf zebrafish embryos, while organ development was the most significant biological process disrupted by PFOS exposure. Our findings enhance the understanding of the specific types of embryotoxicity elicited by TCS and PFOS, and also provide information that can be used to inform future mechanistic studies.

Occurrence and Ecological Risk Assessment of Perfluoroalkyl Substances (PFASs) in Water and Sediment from an Urban River in South China

The chemical substances in urban rivers influence municipal water systems and reflect the recent use of these chemicals by humans or industries around the urban center. In this study, seven perfluoroalkyl substances (PFASs)-perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), 2-perfluorohexyl ethanol (6:2 FTOH), 2-perfluorooctyl ethanol (8:2 FTOH), and 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (F-53B)-could be detected and quantified in river water and sediment samples collected from one tributary of the Liuxi River, which is part of Pearl River near Guangzhou in Guangdong province, South China. The fluxes of target PFASs into Liuxi River and their related ecological risks were further estimated. The total concentrations of PFASs (ΣPFASs) ranged from 506 to 3.16 × 10³ ng/L in water samples and 9.13 to 850 ng/L in sediment samples. The two dominant PFAS compounds were 6:2 FTOH and PFHpA, which accounted for more than 90.0% of ΣPFASs in river water and sediment. Correlation analysis showed that there was significant positive correlation (p < 0.01) between two selected PFASs (e.g., between 6:2 FTOH and PFHpA). Correlation analysis of PFASs in river water and sediment indicated most PFASs in sediment were partitioned from river water. The ecological risk assessment indicated that the detected PFASs have a low risk (HQ < 0.1) in river water and sediment to Daphnia magna in the Liuxi River.

Fate and biodegradation characteristics of triclocarban in wastewater treatment plants and sewage sludge composting processes and risk assessment after entering the ecological environment

Triclocarban (TCC) has a high detection frequency in soil, rivers, sediments, and organisms, and its ecological risks have attracted substantial attention. In this study, we analyzed the fate of TCC in four wastewater treatment plants (WWTPs) in Zhengzhou, China, the biodegradation characteristics during the composting process, and the ecological risks of TCC when entering different environmental compartments. The concentration of TCC in the influent was 731.1-812.4 ng/L. More than 53.4% of TCC was biodegraded during the wastewater treatment process, and less than 2.5% was retained in the effluent. TCC was effectively removed through microbial degradation and sewage sludge absorption, and there were only minor differences in the different wastewater treatment processes. It is worth noting that more than 38% of TCC was enriched in sewage sludge (1430.1-1663.8 ng/g). The corresponding biodegradation rates of TCC were 65.7% and 82.8% in sewage sludge after 17 days of composting treatment with sawdust and straw as bulking agents, respectively. The estimated results showed that effluent discharge into the city rivers was safe. Composting could effectively degrade TCC and decrease the ecological risk of TCC when applied to sewage sludge.

Improving urban drainage systems to mitigate PPCPs pollution in surface water: A watershed perspective

Parabens are preservatives widely used in pharmaceutical and personal care products (PPCPs). This study investigated urban water pollution by parabens from a watershed perspective. Water and sediment samples were collected from one of the most polluted urban streams in China. Six parabens and five paraben metabolites were frequently detected in the samples, whereas the overall pollution level was intermediate according to a global comparison. The spatial distributions of the chemical concentrations along the river are influenced by multiple factors, and WWTPs appear to be a major factor. In general, the target pollutants were detected at higher concentrations in the dry season than in the wet season, but extraordinary concentration peaks in water were observed downstream of wastewater treatment plants (WWTPs), indicating a dominant contribution from combined sewage overflows (CSOs) during rainfall events. In a representative WWTP-influenced reach, CSOs account for its 97.3% of ∑parabens input and 96.9% of ∑metabolites input in a typical rainfall event. Converting the existing combined sewer systems to separate stormwater drainage systems could reduce the inputs of ∑parabens and ∑metabolites by 86.9-84.5%, respectively. This study highlights the role of urban drainage systems in preventing surface water pollution by PPCPs. CAPSULE: Urban drainage systems play a critical role in controlling pollution by parabens and their metabolites in urban surface water.

Sublethal and environmentally relevant concentrations of triclosan and triclocarban induce histological, genotoxic, and embryotoxic effects in Clarias gariepinus (Burchell, 1822)

Antimicrobial additives in personal care products (PCPs) such as triclosan (TCS) and triclocarban (TCC) are of environmental concern due to their potential toxicity in non-target aquatic organisms. In this study, the histological, genotoxic (micronucleus assay), and embryotoxic effects of sublethal and environmentally relevant concentrations of TCS and TCC were evaluated in Clarias gariepinus (the African sharptooth catfish) over a period of 28 days. The 96 hLC50 values of TCS and TCC against fingerlings of C. gariepinus were 16.04 mg/L and 41.57 mg/L respectively. The 24 hLC50 and 26 hEC50 (non-hatching) values for C. gariepinus embryos were 16.48 mg/L and 11.08 mg/L for TCS and 46.08 mg/L and 41.93 mg/L for TCC respectively. TCS was ×3 to ×4 more toxic to C. gariepinus fingerlings and embryos than TCC. Gill histological alterations ranged from mild to severe lamellar necrosis in the exposed fishes with Gill Alteration Index (GAI) of 1.60 on day 14 and 3.20 on day 28. There were significant dose-dependent increases (p < 0.05) in micronuclei and binucleated cells in the erythrocytes of exposed fishes compared to control. Embryotoxic effects assessed from 0 to 72 h post fertilization showed significant decreases (p < 0.05) in hatching success and number of heartbeats per minute, and significant increase (p < 0.05) in percentage abnormalities in the exposed embryos compared to control. The study demonstrates the need for regulatory measures and monitoring of the use of TCS and TCC in PCPs in order to mitigate potential adverse effects to non-target aquatic organisms. This will support the United Nations Sustainable Development Goal 14 on sustaining life below water.

Adsorption of five emerging contaminants on activated carbon from aqueous medium: kinetic characteristics and computational modeling for plausible mechanism

Pharmaceuticals and personal care products (PPCPs) do not have standard regulations for discharge in the environment and are categorized as contaminants of emerging concern as they pose potential threats to ecology as well as humans even at low concentrations. Conventional treatment processes generally employed in the wastewater treatment plants are not adequately engineered for effective removal of PPCPs. Identifying cost-effective tertiary treatment is therefore, important for complete removal of PPCPs from wastewater prior to discharge or reuse. Present study demonstrates adsorption using granular-activated carbon (GAC) as a possible tertiary treatment for simultaneous removal of five PPCPs from aqueous media. Adsorbent was characterized in terms of morphology, surface area, surface charge distribution, and presence of functional groups. Performance of GAC was investigated for sorption of three hydrophilic (ciprofloxacin, acetaminophen, and caffeine) and two hydrophobic (benzophenone and irgasan) PPCPs from aqueous solution varying the process parameters (initial concentration, adsorbent dose, pH, agitation time). Langmuir isotherm model (correlation coefficients (R2): 0.993 to 0.998) appeared to fit the isotherm data better than Temkin isotherm model for these adsorbates. Adsorption efficiencies of these compounds (8.26 to 20.40 mg g-1) were in accordance with their log Kow values. While the adsorption kinetics was best explained in terms of a pseudo-second-order kinetic model, the data suggested that adsorption mechanism was mainly governed by the intraparticle diffusion. The role of physical factors like molecular volume, molecular size, and area of targeted PPCPs were investigated through computational studies which in turn can help predicting their uptake onto GAC.

Emerging organic contaminants and odorous compounds in secondary effluent wastewater: Identification and advanced treatment

This study aims to address organic micropollutants in secondary effluents from municipal wastewater treatment plants (WWTPs) by first identification of micropollutants in different treatment units, and second by evaluating an advanced treatment process for removals of micropollutants. In secondary effluents, 28 types of pharmaceutical and personal care products (PPCPs), 5 types of endocrine disrupting chemicals (EDCs) and 3 types of odorous compounds are detected with total concentrations of 513 ± 57.8 ng/L, 991 ± 36.5 ng/L, 553 ± 48.3 ng/L, respectively. An integrated process consisting of in-situ ozonation, ceramic membrane filtration (CMF) and biological active carbon (BAC) filtration is investigated in a pilot scale (1000 m³/d) for removal of micropollutants in secondary effluents. The total removal efficiencies of PPCPs, EDCs and odorous compounds are 98.5%, 95.4%, and 91.1%, respectively. Removal mechanisms of emerging organic contaminants (EOCs) and odorous compounds are discussed based on their physicochemical properties. The remarkable removal efficiencies of micropollutants by the pilot system is attributed to synergistic effects of combining ozonation, ceramic membrane filtration and BAC filtration. This study provides a cost-effective and robust technology with the capability of treating secondary effluents for reuse applications.