Occurrence, fate and risk assessment of biocides in wastewater treatment plants and aquatic environments in Thailand

Responses of microbial communities in coastal sediments exposed to triclocarban and triclosan

Triclocarban (TCC) and triclosan (TCS) are applied in a wide range of pharmaceutical and personal care products to prevent or reduce bacterial growth. Due to their extensive application, they are frequently detected in marine environments. In this study, marine sediment systems exposed to different concentrations of TCC and TCS were established to evaluate their effects on microbial communities. It was found that TCC and TCS increased catalase and protease activities on Day 1, but inhibited after 15 days. Microbial activity, as indicated by increased dehydrogenase activity and polysaccharide production, should be enhanced after a 15-day adaptation period. High-throughput sequencing revealed resilient α-diversity but significant shifts in community structures were observed, particularly on Day 15. Function prediction analysis confirmed that most functional profiles remained stable, and network analysis indicated that TCC and TCS enhanced the complexity of the microbial community. This study provides new insights into the impacts and risks of TCC and TCS on the marine environment.

Integrative transcriptomic analysis reveals a broad range of toxic effects of triclosan on coral Porites lutea

Triclosan (TCS) is an antimicrobial agent commonly used in personal care products. However, little is known about its toxicity to corals. Here, we examined the acute toxic effects (96 h) of TCS at different levels to the coral Porites lutea. Results showed that the bioaccumulation factors (BAFs) of TCS in Porites lutea decreased with increasing TCS exposure levels. Exposure to TCS at the level up to 100 μg/L did not induce bleaching of Porites lutea. However, by the end of the experiment, both the density and chlorophyll a content of the symbiotic zooxanthellae were 19-52 % and 19.9-45.6 % lower in the TCS treatment groups than in the control, respectively. For the coral host, its total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and catalase (CAT) activities were all significantly lower in the TCS treatment groups than the control. Transcriptome analysis showed that 942 and 1077 differentially expressed genes (DEGs) were identified in the coral host in the 0.5 and 100 μg/L TCS treatment groups, respectively. Meanwhile, TCS can interfere with pathways related to immune system and reproductive system in coral host. Overall, our results suggest that environmentally relevant concentrations of TCS can impact both the coral host and the symbiotic zooxanthellae.

Nation-wide monitoring campaign of 49 biocides and surfactants in surface waters and wastewaters

Despite their intensive use and their impact on ecosystems, biocides and surfactants are still poorly regulated and poorly monitored at large scale. In the frame of the revision of the national regulatory surveillance plan of surface waters, France planned in 2018 a monitoring campaign at national scale focused on these two types of substances of very emerging concern. Forty-nine contaminants (32 biocides and 17 surfactants) were investigated in surface water and sediment samples from 91 sampling sites, and in effluent and sludge samples of 7 wastewater treatment plants (WWTP), in mainland France and overseas regions. Between 33 and 52 % of the target contaminants were quantified at least once in water and sediment. High frequencies of quantification were observed for the surfactants (up to 91 % in water samples and up to 57 % in sediment samples for LAS C10-C13) and for the biocides (up to 64 % for fipronil in water samples and up to 90 % for methyl nonyl ketone in sediment samples). The median concentrations of surfactants were up to 2 μg/L in mainland surface water samples and up to 528 μg/kg in sediment samples, and for biocides, the median concentrations were up to 0.18 μg/L in mainland surface water samples and up to 104 μg/kg in sediment samples. PNEC exceedances in water and sediment were determined for both types of substances. The analysis of effluent and sludge suggested significant but not total removal of these substances in the WWTP. Temporal and spatial variations of the concentrations of both types of substances in surface water samples were also observed, suggesting both punctual and diffuse contamination sources of the surface water investigated.

A systematic review of the toxic potential of parabens in fish

Parabens are the most prevalent ingredients in cosmetics and personal care products (PCPs). They are colorless and tasteless and exhibit good stability when combined with other components. Because of these unique physicochemical properties, they are extensively used as antimicrobial and antifungal agents. Their release into the aquatic ecosystem poses potential threats to aquatic organisms, including fish. We conducted an electronic search in PubMed (http://www.ncbi.nlm.nih.gov/pubmed) using the search term parabens and fish and sorted 93 articles consisting of methyl paraben (MTP), ethyl paraben (ETP), propyl paraben (PPP), butyl paraben (BTP), and benzyl paraben (BNP) in several fish species. Furthermore, we confined our search to six fish species (common carp, Cyprinus carpio; fathead minnows, Pimephales promelas; Japanese medaka, Oryzias latipes; rainbow trout, Oncorhynchus mykiss; Nile tilapia, Oreochromis niloticus; and zebrafish, Danio rerio) and four common parabens (MTP, ETP, PPP, and BTP) and sorted 48 articles for review. Our search indicates that among all six fish, zebrafish was the most studied fish and the MTP was the most tested paraben in fish. Moreover, depending on the alkyl chain length and linearity, long-chained parabens were more toxic than the parabens with short chains. Parabens can be considered endocrine disruptors (EDs), targeting estrogen-androgen-thyroid-steroidogenesis (EATS) pathways, blocking the development and growth of gametes, and causing intergenerational toxicity to impact the viability of offspring/larvae. Paraben exposure can also induce behavioral changes and nervous system disorders in fish. Although the USEPA and EU limit the use of parabens in cosmetics and pharmaceuticals, their prolonged persistence in the environment may pose an additional health risk to humans.

Occurrence and Environmental Risk Assessment of Contaminants of Emerging Concern in Brazilian Surface Waters

We investigated the occurrence and the environmental risk of eight contaminants of emerging concern (CECs; acetaminophen, naproxen, diclofenac, methylparaben, 17β-estradiol, sulfathiazole, sulfadimethoxine, and sulfamethazine) in three Brazilian water bodies, namely, the Monjolinho River Basin (São Paulo State), the Mogi Guaçu River (São Paulo State), and the Itapecuru River (Maranhão State) in three sampling campaigns. The CECs were only quantified in surface water samples collected at the Monjolinho River Basin. Acetaminophen, naproxen, and methylparaben were detected in the range of <200 to 575.9 ng L-1, <200 to 224.7 ng L-1, and <200 to 303.6 ng L-1, respectively. The detection frequencies of the three measured compounds were between 33% and 67%. The highest concentrations of CECs were associated with intense urbanization and untreated sewage discharge. Furthermore, CEC concentrations were significantly correlated with total organic carbon, electrical conductivity, and dissolved oxygen levels, suggesting that domestic pollution from urban areas is an important source in the distribution of CECs in the Monjolinho River Basin. The environmental risk assessment indicated a high risk for acetaminophen (risk quotient [RQ] values between 2.1 and 5.8), a medium risk for naproxen (RQs between 0.6 and 0.7), and a low risk for methylparaben (RQs < 0.1) to the freshwater biota of the Monjolinho River Basin. Our findings show potential threats of CECs in Brazilian water bodies, especially in vulnerable areas, and reinforce the need for improvements in environmental regulations to include monitoring and control of these compounds in aquatic systems. Environ Toxicol Chem 2024;43:2199-2210. © 2024 SETAC.

Long-term exposure to climbazole may affect the health of stress-tolerant coral Galaxea fascicularis

The persistence of coral reefs globally is threatened by various forms of chemical pollution. Climbazole, an azole antibacterial agent extensively utilized in pharmaceuticals and personal care products (PPCPs) in everyday life, has been detected in various environment media and proved to have significant adverse effects on aquatic organism. However, the effects of climbazole on coral remain largely unknown. Therefore, in this study, we conducted a 42-day investigation to examine the effects of varying concentrations of climbazole on Galaxea fascicularis (G. fascicularis), a stress-tolerant coral species. Our investigations included coral color observations, physiological experiments, and assessments of microbial diversity. The results showed that, after 42 days of exposure, the coral color in the treatment group exposed to 100 μg/L climbazole significantly decreased by one color category on the reference chart (D6 shifted to D5), while there was no change in the control group. This was accompanied by an increase in oxidative stress and a decrease in photosynthetic capacity in coral specimens. Additionally, there was a notable alteration in microbial diversity, resulting in reduced community stability. Elevated levels of climbazole (100 μg/L) stress led to an increased abundance of potentially pathogenic bacteria such as unclassified Erysipelotrichaceae. However, at an environmentally relevant concentration of 1 μg/L, climbazole decreased the photosynthetic efficiency and induced oxidative stress in the stress-tolerant coral G. fascicularis, while not significantly impacting the microbial community diversity of the coral. The findings of our study have important implications for the protection and management of nearshore coral reefs and offer essential data for ecological risk assessment of climbazole.

Ecotoxicological study of seven pharmaceutically active compounds: Mixture effects and environmental risk assessment

Pharmaceutically active compounds (PhACs) have been detected in several aquatic compartments, which has been of environmental concern since PhACs can cause adverse effects on the aquatic ecosystem at low concentrations. Despite the variety of PhACs detected in surface water, ecotoxicological studies are non-existent for many of them, mainly regarding their mixture. In addition, water bodies can continuously receive the discharge of raw or treated wastewater with micropollutants. Thus, PhACs are subject to mixture and interactions, potentiating or reducing their toxicity. Therefore, the present study evaluated the toxicity on Aliivibrio fischeri of seven PhACs, which still needs to be explored in the literature. The effects were evaluated for the PhACs individually and for their binary and tertiary mixture. Also, the experimental effects were compared with the concentration addition (CA) and independent action (IA) models. Finally, an environmental risk assessment was carried out. Fenofibrate (FEN), loratadine (LOR), and ketoprofen (KET) were the most toxic, with EC50 of 0.32 mg L-1, 6.15 mg L-1 and 36.8 mg L-1, respectively. Synergistic effects were observed for FEN + LOR, KET + LOR, and KET + FEN + LOR, showing that the CA and IA may underestimate the toxicity. Environmental risks for KET concerning algae, and LOR e 17α-ethynylestradiol (EE2) for crustaceans and fish were high for several locations. Besides, high removals by wastewater treatment technologies are required to achieve the concentrations necessary for reducing KET and LOR risk quotients. Thus, this study contributed to a better understanding of the toxic interactions and environmental risks of PhACs.

Resistance Mechanisms of Plant Pathogenic Fungi to Fungicide, Environmental Impacts of Fungicides, and Sustainable Solutions

The significant reduction in agricultural output and the decline in product quality are two of the most glaring negative impacts caused by plant pathogenic fungi (PPF). Furthermore, contaminated food or transit might introduce mycotoxins produced by PPF directly into the food chain. Eating food tainted with mycotoxin is extremely dangerous for both human and animal health. Using fungicides is the first choice to control PPF or their toxins in food. Fungicide resistance and its effects on the environment and public health are becoming more and more of a concern, despite the fact that chemical fungicides are used to limit PPF toxicity and control growth in crops. Fungicides induce target site alteration and efflux pump activation, and mutations in PPF result in resistance. As a result, global trends are shifting away from chemically manufactured pesticides and toward managing fungal plant diseases using various biocontrol techniques, tactics, and approaches. However, surveillance programs to monitor fungicide resistance and their environmental impact are much fewer compared to bacterial antibiotic resistance surveillance programs. In this review, we discuss the PPF that contributes to disease development in plants, the fungicides used against them, factors causing the spread of PPF and the emergence of new strains, the antifungal resistance mechanisms of PPF, health, the environmental impacts of fungicides, and the use of biocontrol agents (BCAs), antimicrobial peptides (AMPs), and nanotechnologies to control PPF as a safe and eco-friendly alternative to fungicides.

Chronic toxicity of sediment-bound triclosan on freshwater walking catfish Clarias magur: Organ level accumulation and selected enzyme biomarker responses

Triclosan (TCS) is a biocide widely used in personal care and medicinal products. TCS persists in sediments and has been detected worldwide, making sediments a vital route of TCS exposure to aquatic organisms. This experiment explored the bioaccumulation and toxicological effects of TCS-contaminated sediment. The study revealed that the half-life of TCS in the sediment-water system was 21.52 days. Exposure of Clarias magur juveniles to 0.4 and 0.8 mg kg-1 TCS-spiked sediment resulted in high Biota-Sediment Accumulation Factor (BSAF) with the highest bioaccumulation in the liver (29.62-73.61 mg kg-1), followed by gill (9.22-17.57 mg kg-1), kidney (5.04-9.76 mg kg-1), muscle (2.63-4.87 mg kg-1) and brain (1.53-3.20 mg kg-1). Furthermore, a concentration-dependent increase in oxidative stress biomarkers such as superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) was documented during 45 days of exposure in gill, liver, kidney, muscle, and brain tissues of exposed fish. A similar increasing trend was also recorded for liver transaminase enzymes such as glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) during the experimental period compared to control. Serum biochemical analysis revealed a significant time and concentration-dependent increase in serum glucose, serum GOT, and serum GPT, while serum total protein and albumin decreased significantly during exposure. These findings demonstrate high bioaccumulative and toxic nature of TCS in fish, promoting multiple physiological and biochemical dysfunctions through sediment exposure. The study underscores the urgent need for strengthened regulations and robust monitoring of triclosan across various environmental matrices, including sediment, to mitigate the detrimental impacts of TCS effectively.

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.

Identification of New Hepatic Metabolites of Miconazole by Biological and Electrochemical Methods Using Ultra-High-Performance Liquid Chromatography Combined with High-Resolution Mass Spectrometry

The main objective of this study was to investigate the metabolism of miconazole, an azole antifungal drug. Miconazole was subjected to incubation with human liver microsomes (HLM) to mimic phase I metabolism reactions for the first time. Employing a combination of an HLM assay and UHPLC-HRMS analysis enabled the identification of seven metabolites of miconazole, undescribed so far. Throughout the incubation with HLM, miconazole underwent biotransformation reactions including hydroxylation of the benzene ring and oxidation of the imidazole moiety, along with its subsequent degradation. Additionally, based on the obtained results, screen-printed electrodes (SPEs) were optimized to simulate the same biotransformation reactions, by the use of a simple, fast, and cheap electrochemical method. The potential toxicity of the identified metabolites was assessed using various in silico models.

A study on the subchronic toxicity of triclocarban to the early-life development of oryzias melastigma and focused on the analysis of osmoregulatory regulation mechanisms

Triclocarban (TCC), a novel antimicrobial agent found in personal care products, has been extensively detected in marine environments. However, research on the toxic effects of TCC on marine organisms remains inadequate. This study delved into the subchronic toxic effects of TCC on the early life stages of marine medaka (Oryzias melastigma, O. melastigma), revealing that TCC could reduce embryo heart rate and hatching rate while diminishing the survival rate of larvae. Biomarker assays indicated that TCC could inflict damage on the embryos' antioxidant and nervous systems. Transcriptomic analysis suggested that TCC could impact cell growth, reproduction, and various life processes, activating cancer signaling pathways, increasing the likelihood of cancer, and exerting toxic effects on the immune and osmoregulatory systems. To validate and enhance our understanding of TCC's unique toxic impact on the osmoregulatory system of O. melastigma, we conducted homology modeling and molecular docking analyses on the protein involved in osmoregulation. The study intuitively revealed the potential binding affinity of TCC to sodium/potassium-transporting ATPase subunit alph (ATP1A1), indicating its ability to disrupt osmotic balance in marine fish by affecting this target protein. In summary, the results of this study will further enhance our comprehension of the potential toxic effects and mechanisms of TCC on the early stages of marine fish, with a specific focus on its unique toxic effects in osmoregulation.

Global insight into the occurrence, treatment technologies and ecological risk of emerging contaminants in sanitary sewers: Effects of the SARS-CoV-2 coronavirus pandemic

The SARS-CoV-2 pandemic caused changes in the consumption of prescribed/non-prescribed drugs and the population's habits, influencing the detection and concentration of emerging contaminants (ECs) in sanitary sewage and harming environmental and health risks. Therefore, the present work sought to discuss current literature data on the effects of the "COVID-19 pandemic factor" on the quality of raw sewage produced over a five-year period (2018-2019: pre-pandemic; 2020-2022: during the pandemic) and biological, physical, chemical and hybrid treatment technologies, influencing factors in the removal of ECs and potential ecological risks (RQs). Seven hundred thirty-one publications correlating sewage and COVID-19 were identified: 184 pre-pandemic and 547 during the pandemic. Eight classes and 37 ECs were detected in sewage between 2018 and 2022, with the "COVID-19 pandemic factor" promoting an increase in estrogens (+31,775 %), antibiotics (+19,544 %), antiepileptics and antipsychotics (+722 %), pesticides (+200 %), analgesics, anti-inflammatories and anticoagulants (+173 %), and stimulant medications (+157 %) in sanitary sewage. Among the treatment systems, aerated reactors integrated into biomembranes removed >90 % of cephalexin, clarithromycin, ibuprofen, estrone, and 17β-estradiol. The absorption, adsorption, and biodegradation mechanisms of planted wetland systems contributed to better cost-benefit in reducing the polluting load of sewage ECs in the COVID-19 pandemic, individually or integrated into the WWTP. The COVID-19 pandemic factor increased the potential ecological risks (RQs) for aquatic organisms by 40 %, with emphasis on clarithromycin and sulfamethoxazole, which changed from negligible risk and low risk to (very) high risk and caffeine with RQ > 2500. Therefore, it is possible to suggest that the COVID-19 pandemic intensified physiological, metabolic, and physical changes to different organisms in aquatic biota by ECs during 2020 and 2022.

Antifungal drugs in the aquatic environment: A review on sources, occurrence, toxicity, health effects, removal strategies and future challenges

Fungal infections pose a significant global health burden, resulting in millions of severe cases and deaths annually. The escalating demand for effective antifungal treatments has led to a rise in the wholesale distribution of antifungal drugs, which consequently has led to their release into the environment, posing a threat to ecosystems and human health. This article aims to provide a comprehensive review of the presence and distribution of antifungal drugs in the environment, evaluate their potential ecological and health risks, and assess current methods for their removal. Reviewed studies from 2010 to 2023 period have revealed the widespread occurrence of 19 various antifungals in natural waters and other matrices at alarmingly high concentrations. Due to the inefficiency of conventional water treatment in removing these compounds, advanced oxidation processes, membrane filtration, and adsorption techniques have been developed as promising decontamination methods.In conclusion, this review emphasizes the urgent need for a comprehensive understanding of the presence, fate, and removal of antifungal drugs in the environment. By addressing the current knowledge gaps and exploring future prospects, this study contributes to the development of strategies for mitigating the environmental impact of antifungal drugs and protecting ecosystems and human health.

Resilience model for a destination support: Pattaya, Thailand

This research focuses on resilience and sustainable development in the tourism sector during the Covid-19 pandemic, using Pattaya - a renowned beach destination in Thailand - as the studied context. Since 2020, the pandemic has significantly impacted the tourism sector and its supply chain. The consequences include the stagnation of tourism and hospitality services and other economic activities due to lockdown measures and other restrictions. To investigate Pattaya's resilience in the face of these challenges, and post-pandemic recovery, this research adopted the conceptual framework on economic resilience and tourism recovery proposed by McCartney et al. (2021), as a theoretical lens to analyse events in Pattaya. The qualitative research method was employed, using in-depth interviews with public and private stakeholders, such as local authorities, large and small hotels, tourism business agencies and relevant organisations. The results show that the tourism industry, similarly to other sectors, was adversely affected by the Covid-19 pandemic, and the slow implementation of strategies proved inadequate in coping with the uncertainty. Local entrepreneurs require clearer and more supportive measures to reopen their businesses and resume economic activities.

Southeast Asia's environmental challenges: emergence of new contaminants and advancements in testing methods

Emerging contaminants, including pharmaceuticals, personal care products, microplastics, and per- and poly-fluoroalkyl substances, pose a major threat to both ecosystems and human health in Southeast Asia. As this region undergoes rapid industrialization and urbanization, the increasing presence of unconventional pollutants in water bodies, soil, and various organisms has become an alarming concern. This review comprehensively examines the environmental challenges posed by emerging contaminants in Southeast Asia and recent progress in toxicity testing methods. We discuss the diverse range of emerging contaminants found in Southeast Asia, shedding light on their causes and effects on ecosystems, and emphasize the need for robust toxicological testing methods. This review is a valuable resource for researchers, policymakers, and environmental practitioners working to mitigate the impacts of emerging contaminants and secure a sustainable future for Southeast Asia.

In vitro metabolism of triclosan and chemoprevention against its cytotoxicity

Triclosan (TCS), a broad-spectrum antibacterial chemical, has been extensively used in personal daily care items, household commodities, and clinical medications; therefore, humans are at risk of being exposed to TCS in their daily lives. This chemical also accumulated in food chains, and potential risks were associated with its metabolism in vivo. The aim of this study was to investigate the difference in metabolic profile of TCS by hepatic P450 enzymes and extrahepatic P450s, and also identify chemical structures of its metabolites. The results showed that RLM mediated the hydroxylation and cleavage of the ether moiety of TCS, resulting in phenolic metabolites that are more polar than the parent compound, including 4-chlorocatechol, 2,4-dichlorophenol and monohydroxylated triclosan. The major metabolite of CYP1A1 and CYP1B1 mediated TCS metabolism is 4-chlorochol. We also performed molecular docking experiments to investigate possible binding modes of TCS in the active sites of human CYP1B1, CYP1A1, and CYP3A4. In addition to in vitro experiments, we further examined the cytotoxic effects of TCS on HepG2 cells expressing hepatic P450 and MCF-7/1B1 cells expressing CYP1B1. It exhibited significant cytotoxicity on HepG2, MCF-10A and MCF-7/1B1 cells, with IC50 values of 70 ± 10 μM, 20 ± 10 μM and 60 ± 20 μM, respectively. The co-incubation of TCS with glutathione (GSH) as a chemopreventive agent could reduce the cytotoxicity of TCS in vitro. The chemopreventive effects of GSH might be ascribed to the promotion of TCS efflux mediated by membrane transporter MRP1 and also its antioxidant property, which partially neutralized the oxidative stress of TCS on mammalian cells. This study contributed to our understanding of the relationship between the P450 metabolism and the toxicity of TCS. It also had implications for the use of specific chemopreventive agents against the toxicity of TCS.

Formation of halogenated chloroxylenols through chlorination and their photochemical activity

Trace organic contaminants usually go through multiple treatment units in a modern water treatment train. Structural modification triggered by pretreatment (e.g., prechlorination) may influence the further transformation and fate of contaminants in downstream units. However, knowledge on this aspect is still limited. In this contribution, we investigated the chlorination of chloroxylenol (PCMX), an antimicrobial agent extensively used during COVID-19 pandemic, and the photoreactivity of its halogenated derivatives. Results indicate that chlorination of PCMX mainly proceeded through electrophilic substitution to give chlorinated products, including Cl- and 2Cl-PCMX. The presence of bromide (Br-) resulted in brominated analogues. Owing to the bathochromic and "heavy atom" effects of halogen substituents, these products show increased light absorption and photoreactivity. Toxicity evaluation suggest that these halo-derivatives have higher persistence, bioaccumulation, and toxicity (PBT) than the parent PCMX. Results of this contribution advance our understanding of the transformation of PCMX during chlorination and the photochemical activity of its halogenated derivatives in subsequent UV disinfection process or sunlit surface waters.

Review on Microbially Influenced Concrete Corrosion

Microbially influenced concrete corrosion (MICC) causes substantial financial losses to modern societies. Concrete corrosion with various environmental factors has been studied extensively over several decades. With the enhancement of public awareness on the environmental and economic impacts of microbial corrosion, MICC draws increasingly public attention. In this review, the roles of various microbial communities on MICC and corresponding protective measures against MICC are described. Also, the current status and research methodology of MICC are discussed. Thus, this review aims at providing insight into MICC and its mechanisms as well as the development of protection possibilities.

Antibiotic, Heavy Metal, and Biocide Concentrations in a Wastewater Treatment Plant and Its Receiving Water Body Exceed PNEC Limits: Potential for Antimicrobial Resistance Selective Pressure

Although the rise in antimicrobial resistance has been attributed mainly to the extensive and indiscriminate use of antimicrobials such as antibiotics and biocides in humans, animals and on plants, studies investigating the impact of this use on water environments in Africa are minimal. This study quantified selected antibiotics, heavy metals, and biocides in an urban wastewater treatment plant (WWTP) and its receiving water body in Kwazulu-Natal, South Africa, in the context of the predicted no-effect concentrations (PNEC) for the selection of antimicrobial resistance (AMR). Water samples were collected from the WWTP effluent discharge point and upstream and downstream from this point. Heavy metals were identified and quantified using the United States Environmental Protection Agency (US EPA) method 200.7. Biocides and antibiotic residues were determined using validated ultra-high-performance liquid chromatography with tandem mass spectrometry-based methods. The overall highest mean antibiotic, metal and biocide concentrations were observed for sulfamethoxazole (286.180 µg/L), neodymium (Nd; 27.734 mg/L), and benzalkonium chloride (BAC 12) (7.805 µg/L), respectively. In decreasing order per sampling site, the pollutant concentrations were effluent > downstream > upstream. This implies that the WWTP significantly contributed to the observed pollution in the receiving water. Furthermore, most of the pollutants measured recorded values exceeding the recommended predicted no-effect concentration (PNEC) values, suggesting that the microbes in such water environments were at risk of developing resistance due to the selection pressure exerted by these antimicrobials. Further studies are required to establish such a relationship.

Does climbazole instigate a threat in the environment as persistent, mobile and toxic compound? Unveiling the occurrence and potential ecological risks of its phototransformation products in the water cycle

Persistent, mobile, and toxic chemicals (PMT), such as the antimycotic climbazole-(CBZ), proliferate in water cycle and imperil drinking water quality, sparking off research about their environmental fate. Unlike the parent compound, its transformation products-(TPs) are scarcely investigated, much less as PMTs. To this end, phototransformation of CBZ was investigated. A novel suspect-screening workflow was developed and optimized by cross-comparing the results of the identified photo-TPs against literature data to create an enhanced HRMS-database for environmental investigations of CBZ/TPs in the water cycle. In total, 24 TPs were identified, 14 of which are reported for the first time. Isomerism, dechlorination, hydroxylation, and cleavage of the ether or C-N bond are suggested as the main transformation routes. A screening of CBZ/TPs was conducted in wastewater, leachates, surface, and groundwater, revealing a maximum concentration of 464.8 ng/L in groundwater. In silico and in vitro methods were used for toxicity assessment, indicating toxicity for CBZ and some TPs. Seemingly, CBZ is rightly considered as PMT, and a higher potential to occur in surface or groundwater than non-PM chemicals appears. Likewise, the occurrence of TPs due to PMT properties or emission patterns was evaluated.

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.

Benzimidazole fungicide biotransformation by comammox Nitrospira bacteria: Transformation pathways and associated proteomic responses

Benzimidazole fungicides are frequently detected in aquatic environments and pose a serious health risk. Here, we investigated the metabolic capacity of the recently discovered complete ammonia-oxidizing (comammox) Nitrospira inopinata and kreftii to transform a representative set of benzimidazole fungicides (i.e., benzimidazole, albendazole, carbendazim, fuberidazole, and thiabendazole). Ammonia-oxidizing bacteria and archaea, as well as the canonical nitrite-oxidizing Nitrospira exhibited no or minor biotransformation activity towards all the five benzimidazole fungicides. In contrast, the investigated comammox bacteria actively transformed all the five benzimidazole fungicides, except for thiabendazole. The identified transformation products indicated hydroxylation, S-oxidation, and glycosylation as the major biotransformation pathways of benzimidazole fungicides. We speculated that these reactions were catalyzed by comammox-specific ammonia monooxygenase, cytochrome P450 monooxygenases, and glycosylases, respectively. Interestingly, the exposure to albendazole enhanced the expression of the antibiotic resistance gene acrB of Nitrospira inopinata, suggesting that some benzimidazole fungicides could act as environmental stressors that trigger cellular defense mechanisms. Altogether, this study demonstrated the distinct substrate specificity of comammox bacteria towards benzimidazole fungicides and implies their significant roles in the biotransformation of these fungicides in nitrifying environments.

Comprehensive insight into triclosan-from widespread occurrence to health outcomes

Humans are exposed to the variety of emerging environmental pollutant in everyday life. The special concern is paid to endocrine disrupting chemicals especially to triclosan which could interfere with normal hormonal functions. Triclosan could be found in numerous commercial products such as mouthwashes, toothpastes and disinfectants due to its antibacterial and antifungal effects. Considering the excessive use and disposal, wastewaters are recognized as the main source of triclosan in the aquatic environment. As a result of the incomplete removal, triclosan residues reach surface water and even groundwater. Triclosan has potential to accumulate in sediment and aquatic organisms. Therefore, the detectable concentrations of triclosan in various environmental and biological matrices emerged concerns about the potential toxicity. Triclosan impairs thyroid homeostasis and could be associated with neurodevelopment impairment, metabolic disorders, cardiotoxicity and the increased cancer risk. The growing resistance of the vast groups of bacteria, the evidenced toxicity on different aquatic organisms, its adverse health effects observed in vitro, in vivo as well as the available epidemiological studies suggest that further efforts to monitor triclosan toxicity at environmental levels are necessary. The safety precaution measures and full commitment to proper legislation in compliance with the environmental protection are needed in order to obtain triclosan good ecological status. This paper is an overview of the possible negative triclosan effects on human health. Sources of exposure to triclosan, methods and levels of detection in aquatic environment are also discussed.

Wastewater reclamation trends in Thailand

Thailand constantly faces the problem of water scarcity, resulting from an imbalance between available water supply and increasing water demand for economic and community expansion, as well as climate change. To address this shortage, wastewater reclamation is being planned and implemented throughout the country, along with a 20-year, long-term integrated water resource management plan. Significant opportunities from municipal wastewater treatment plants (WWTPs) are dependent on the following factors: the establishment of a reuse water framework and a tangible target for treated wastewater set by local government authorities; widespread recognition and adaptation of wastewater reuse measures in the agriculture, industry, tourism and service sectors regarding climate change and water stress; and the implementation of joint investment water reuse projects between private and government agencies. However, wastewater reclamation faces some significant challenges, specifically: the limitations of regulation and monitoring for specific reuse purposes; a lack of public confidence in the water quality; the limited commercial development of reclaimed wastewater research; and difficulties in self-sustaining business models through adapting circular economy principles. This study aims to provide an overview of the wastewater reclamation, present research trends, currently operating WWTPs as well as opportunities and challenges to speed up water reuse activities in Thailand.

Cosmetic Preservatives: Hazardous Micropollutants in Need of Greater Attention?

In recent years, personal care products (PCPs) have surfaced as a novel class of pollutants due to their release into wastewater treatment plants (WWTPs) and receiving environments by sewage effluent and biosolid-augmentation soil, which poses potential risks to non-target organisms. Among PCPs, there are preservatives that are added to cosmetics for protection against microbial spoilage. This paper presents a review of the occurrence in different environmental matrices, toxicological effects, and mechanisms of microbial degradation of four selected preservatives (triclocarban, chloroxylenol, methylisothiazolinone, and benzalkonium chloride). Due to the insufficient removal from WWTPs, cosmetic preservatives have been widely detected in aquatic environments and sewage sludge at concentrations mainly below tens of µg L-1. These compounds are toxic to aquatic organisms, such as fish, algae, daphnids, and rotifers, as well as terrestrial organisms. A summary of the mechanisms of preservative biodegradation by micro-organisms and analysis of emerging intermediates is also provided. Formed metabolites are often characterized by lower toxicity compared to the parent compounds. Further studies are needed for an evaluation of environmental concentrations of preservatives in diverse matrices and toxicity to more species of aquatic and terrestrial organisms, and for an understanding of the mechanisms of microbial degradation. The research should focus on chloroxylenol and methylisothiazolinone because these compounds are the least understood.

Effect of Iron Complex Source on MWWTP Effluent Treatment by Solar Photo-Fenton: Micropollutant Degradation, Toxicity Removal and Operating Costs

Benzophenone-3, fipronil and propylparaben are micropollutants that are potential threats to ecosystems and have been detected in aquatic environments. However, studies involving the investigation of new technologies aiming at their elimination from these matrices, such as advanced oxidation processes, remain scarce. In this study, different iron complexes (FeCit, FeEDTA, FeEDDS and FeNTA) were evaluated for the degradation of a mixture of these micropollutants (100 µg L−1 each) spiked in municipal wastewater treatment plant (MWWTP) effluent at pH 6.9 by solar photo-Fenton. Operational parameters (iron and H2O2 concentration and Fe/L molar ratio) were optimized for each complex. Degradation efficiencies improved significantly by increasing the concentration of iron complexes (1:1 Fe/L) from 12.5 to 100 µmol L−1 for FeEDDS, FeEDTA and FeNTA. The maximum degradation reached with FeCit for all iron concentrations was limited to 30%. Different Fe/L molar ratios were required to maximize the degradation efficiency for each ligand: 1:1 for FeNTA and FeEDTA, 1:3 for FeEDDS and 1:5 for FeCit. Considering the best Fe/L molar ratios, higher degradation rates were reached using 5.9 mmol L−1 H2O2 for FeNTA and FeEDTA compared to 1.5 and 2.9 mmol L−1 H2O2 for FeEDDS and FeCit, respectively. Acute toxicity to Canton S. strain D. melanogaster flies reduced significantly after treatment for all iron complexes, indicating the formation of low-toxicity by-products. FeNTA was considered the best iron complex source in terms of the kinetic constant (0.10 > 0.063 > 0.051 > 0.036 min−1 for FeCit, FeNTA, FeEDTA and FeEDDS, respectively), organic carbon input and cost-benefit (USD 327 m−3 > USD 20 m−3 > USD 16 m−3 > USD 13 m−3 for FeEDDS, FeCit, FeEDTA and FeNTA, respectively) when compared to the other tested complexes.

Occurrence and Transport of Isothiazolinone-Type Biocides from Commercial Products to Aquatic Environment and Environmental Risk Assessment

This study investigated the occurrence and transport of four isothiazolinone-type biocides from commercial products to wastewater treatment plants (influents, sludges, and effluents) and to natural emissaries (upstream and downstream the wastewater treatment plants) in Romania. All four biocides were determined in personal care and household products, with the highest concentration of 76.4 µg/L OIT (2-octyl-4-isothiazolin-3-one). For environmental samples, three of the four isothiazolinones were determined, CMI (5-chloro-2-methyl-4-isothiazolin-3-one) being the prominent compound for water samples. The maximum concentration of 84.0 µg/L in influent, 122 µg/L upstream, and 144 µg/L downstream the wastewater treatment plants were obtained for CMI. Unlike water samples, in the sewage sludge samples, OIT proved to be the dominant compound, with concentration up to 5.80 µg/g d.w. The extremely high levels of isothiazolinone determined in different WWTPs from Romania may be due to the COVID-19 pandemic situation, during which a much larger amount of cleaning, hygiene, and personal care products was used. The isothiazolinone-type biocides were readily removed from the influents of the five WWTPs, with the mean removal rate up to 67.5%. The mean mass loading value for the targeted biocides based on influent was 20.4 μg/day/1000 people, while the average environmental emissions were 6.93 μg/day/1000 people for effluents. The results obtained for riverine water combine with statistical analysis showed that the anthropogenic activities are the major contamination sources of the surface waters. Preliminary ecological risk evaluation showed that BIT (1,2-benzisothiazol-3(2H)-one), OIT, and CMI could pose a very high risks to different aquatic species living in the receiving aquatic environments.

Pesticides in surface freshwater: a critical review

The objective of this study was to critically review studies published up to November 2021 that investigated the presence of pesticides in surface freshwater to answer three questions: (1) in which countries were the studies conducted? (2) which pesticides are most evaluated and detected? and (3) which pesticides have the highest concentrations? Using the Prisma protocol, 146 articles published from 1976 to November 2021 were included in this analysis: 127 studies used grab sampling, 10 used passive sampling, and 9 used both sampling techniques. In the 45-year historical series, the USA, China, and Spain were the countries that conducted the highest number of studies. Atrazine was the most evaluated pesticide (56% of the studies), detected in 43% of the studies using grab sampling, and the most detected in passive sampling studies (68%). The compounds with the highest maximum and mean concentrations in the grab sampling were molinate (211.38 µg/L) and bentazone (53 µg/L), respectively, and in passive sampling, they were oxyfluorfen (16.8 µg/L) and atrazine (4.8 μg/L), respectively. The levels found for atrazine, p,p'-DDD, and heptachlor in Brazil were higher than the regulatory levels for superficial water in the country. The concentrations exceeded the toxicological endpoint for at least 11 pesticides, including atrazine (Daphnia LC₅₀ and fish NOAEC), cypermethrin (algae EC50, Daphnia and fish LC₅₀; fish NOAEC), and chlorpyrifos (Daphnia and fish LC₅₀; fish NOAEC). These results can be used for planning pesticide monitoring programs in surface freshwater, at regional and global levels, and for establishing or updating water quality regulations.

Phycoremediation integrated approach for the removal of pharmaceuticals and personal care products from wastewater - A review

Pharmaceuticals and personal care products (PPCPs) are of emerging concerns because of their large usage, persistent nature which promised their continuous disposal into the environment, as these pollutants are stable enough to pass through wastewater treatment plants causing hazardous effects on all the organisms through bioaccumulation, biomagnification, and bioconcentration. The available technologies are not capable of eliminating all the PPCPs along with their degraded products but phycoremediation has the advantage over these technologies by biodegrading the pollutants without developing resistant genes. Even though phycoremediation has many advantages, industries have found difficulty in adapting this technology as a single-stage treatment process. To overcome these drawbacks recent research studies have focused on developing technology that integrated phycoremediation with the commonly employed treatment processes that are in operation for treating the PPCPs effectively. This review paper focuses on such research approaches that focused on integrating phycoremediation with other technologies such as activated sludge process (ASP), advanced oxidation process (AOP), Up-flow anaerobic sludge blanket reactor (UASBR), UV irradiation, and constructed wetland (CW) with the advantages and limitations of each integration processes. Furthermore, augmenting phycoremediation by co-metabolic mechanism with the addition of sodium chloride, sodium acetate, and glucose for the removal of PPCPs has been highlighted in this review paper.

Biodegradability, environmental risk assessment and ecological footprint in wastewater technologies for pharmaceutically active compounds removal

Several studies have investigated the removal of pharmaceutically active compounds (PhACs) by wastewater treatment technologies due to the risk that these compounds pose to the environment. In this sense, advanced biological processes have been developed for micropollutants removal, such as membrane bioreactors and moving bed biofilm reactors. Thus, this review holistically evaluated the biodegradation of 18 environmentally hazardous PhACs. Biological processes were assessed including removal efficiencies, environmental risk, and ecological footprint (consumption of resources and energy, atmospheric emissions, and waste generation). The maximum concentration of PhACs for a low or negligible risk scenario in treated wastewater and the potential of biological processes to meet this goal were assessed. Among the evaluated PhACs, the most biodegradable was paracetamol, while the most recalcitrant was diclofenac. Combination of conventional processes and advanced biological processes proved to be the most efficient way to remove several PhACs, mainly the osmotic membrane bioreactor.

Azole fungicides: (Bio)degradation, transformation products and toxicity elucidation

The increasing consumption of azole antifungal agents leads to their uncontrolled release into the environment. Therefore, it is crucial to remove their residues from natural ecosystems. This study aimed to examine the biological and chemical degradation of four typical azole fungicides: fluconazole (Fc), clotrimazole (Cl), climbazole (Cb), and epoxiconazole (Ep). The biodegradation was investigated using activated sludge and two novel Gram-negative bacterial strains. The chemical degradation experiments aimed to assess the efficiency of fungicides removal through UV treatment, the Fenton reaction, and a combination of these methods. Transformation products of Cb, Ep, and Cl photocatalytic removal were identified by mass spectrometry. In addition, the AlamarBlue® Assay and the MTT Assay allowed careful evaluation of the toxicity of azole derivatives and their transformation products towards newly isolated strains, Stenotrophomonas maltophilia AsPCl2.3 and Pseudomonas monteilii LB2. Among all azole fungicides, Cb was the most susceptible to biological removal while Fc, Ep, and Cl were basically resistant to biodegradation. Cl and Ep showed a significant biosorption on the activated sludge. Under optimized photolysis conditions, the removal efficiency of Cl, Cb, and Ep was significantly higher than that of biodegradation. The Fenton reaction supported by the UV-irradiation offered the best results of fungicides elimination. After 1 min of the experiment, Cl was almost completely removed while Cb and Ep removal rates reached an average of 60%. The proposed main degradation route of azole fungicides during UV-irradiation includes halogen atoms substitution by hydroxyl moieties. The final degradation product was imidazole or triazole. Azole fungicides and their transformation products differently affected the metabolic activity of Gram-negative bacteria. Cl and Cb intermediates showed lower toxicity than parent compounds. The findings help better understand the environmental impact of azole fungicides, their degradation, and toxicity. They also stress the need for reducing their uncontrolled release to the environment.

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.

Environmental occurrence and remediation of emerging organohalides: A review

As replacements for "old" organohalides, such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), "new" organohalides have been developed, including decabromodiphenyl ethane (DBDPE), short-chain chlorinated paraffins (SCCPs), and perfluorobutyrate (PFBA). In the past decade, these emerging organohalides (EOHs) have been extensively produced as industrial and consumer products, resulting in their widespread environmental distribution. This review comprehensively summarizes the environmental occurrence and remediation methods for typical EOHs. Based on the data collected from 2015 to 2021, these EOHs are widespread in both abiotic (e.g., dust, air, soil, sediment, and water) and biotic (e.g., bird, fish, and human serum) matrices. A significant positive correlation was found between the estimated annual production amounts of EOHs and their environmental contamination levels, suggesting the prohibition of both production and usage of EOHs as a critical pollution-source control strategy. The strengths and weaknesses, as well as the future prospects of up-to-date remediation techniques, such as photodegradation, chemical oxidation, and biodegradation, are critically discussed. Of these remediation techniques, microbial reductive dehalogenation represents a promising in situ remediation method for removal of EOHs, such as perfluoroalkyl and polyfluoroalkyl substances (PFASs) and halogenated flame retardants (HFRs).

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.

Assessment of Environmental Pollution and Human Exposure to Pesticides by Wastewater Analysis in a Seven-Year Study in Athens, Greece

Pesticides have been used in large amounts around the world for decades and are responsible for environmental pollution and various adverse effects on human health. Analysis of untreated wastewater can deliver useful information on pesticides’ use in a particular area and allow the assessment of human exposure to certain substances. A wide-scope screening method, based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry, was applied, using both target and suspect screening methodologies. Daily composite influent wastewater samples were collected for seven or eight consecutive days in Athens between 2014 and 2020 and analyzed for 756 pesticides, their environmental transformation products and their human metabolites. Forty pesticides were quantified at mean concentrations up to 4.9 µg/L (tralkoxydim). The most abundant class was fungicides followed by herbicides, insect repellents, insecticides and plant growth regulators. In addition, pesticide transformation products and/or metabolites were detected with high frequency, indicating that research should be focused on them. Human exposure was evaluated using the wastewater-based epidemiology (WBE) approach and 3-ethyl-carbamoyl benzoic acid and cis-1,2,3,6-tetrahydrophthalimide were proposed as potential WBE biomarkers. Wastewater analysis revealed the presence of unapproved pesticides and indicated that there is an urgent need to include more transformation products in target databases.

Trace level nitrite sensitized photolysis of the antimicrobial agents parachlormetaxylenol and chlorophene in water

Nitrite (NO₂^-)-sensitized photolysis plays an important role in the attenuation of effluent-derived trace organic contaminants (e.g., anilines, phenolic compounds, etc.) in surface waters. However, the kinetics, mechanisms, and influencing factors of photolysis of many emerging contaminants sensitized by NO₂^- still remain largely unknown. Herein, we report that NO₂^--sensitized photolysis of the antimicrobial agents parachlormetaxylenol (PCMX) and chlorophene (CP) in aqueous solution under ultraviolet 365 nm (UV₃₆₅) radiation. A nonlinear increase in photolysis rate constants of PCMX and CP was observed with increasing NO₂^- concentration. Radical quenching studies and kinetic modeling revealed that hydroxyl radical (HO•) and nitrogen dioxide radicals (NO₂^•) contributed dominantly to the removal of PCMX and CP. Solid phase extraction (SPE) combined with high resolution-mass spectrometry (HR-MS) analysis identified a series of intermediate products including hydroxylated, nitrated, nitrosated, and dimerized derivatives. Experiments with isotopically labelled nitrite (¹⁵NO₂^-) showed that the nitro- and nitroso-substituents of intermediate products were derived from the nitrite nitrogen. Based on the identified products and theoretical computations, the mechanisms and pathways of NO₂^--sensitized photolysis of PCMX and CP are elucidated. Deoxygenation partially inhibited the formation of 4-chloro-3,5-dimethyl-2-nitrophenol (nitro-PCMX) while the presence of HO• scavenger such as isopropanol (i-PrOH) suppressed the further transformation of nitro-PCMX. The presence of Mississippi River natural organic matter (MRNOM) inhibited the removal of PCMX and CP, likely due to light screening and radical quenching. However, appreciable degradation of PCMX and CP was still observed in wastewater and wetland water matrices. Results of this study shed some light on the transformation and fate of PCMX and CP in NO₂^--rich wastewater effluents or effluent-impacted surface waters under solar radiation.

Parabens as chemicals of emerging concern in the environment and humans: A review

Parabens are one of the most widely used preservatives in food, pharmaceuticals and personal care products (PCPs) because of their advantageous properties and low toxicity based on the early assessments. However, recent research indicates that parabens may act as endocrine-disrupting chemicals (EDCs) and thus, are considered as chemicals of emerging concern that have adverse human health effects. To provide the basis for future human health studies, we reviewed relevant literature, published between 2005 and 2020, regarding the levels of parabens in the consumer products (pharmaceuticals, PCPs and food), environmental matrices and humans, including susceptible populations, such as pregnant women and children. The analysis showed that paraben detection rates in consumer products, environmental compartments and human populations are high, while the levels vary greatly by country and paraben type. The concentrations of parabens reported in pregnant women (~20-120 μg/L) were an order of magnitude higher than in the general population. Paraben concentrations in food and pharmaceuticals were at the ng/g level, while the levels in PCPs reached mg/g levels. Environmental concentrations ranged from ng/L-μg/L in surface waters to tens of μg/g in wastewater and indoor dust. The levels of human exposure to parabens appear to be higher in the U.S. and EU countries than in China and India, which may change with the increasing production of parabens in the latter countries. The review provides context for future studies to connect paraben exposure levels with human health effects.

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.

Environmental Spread of Antibiotic Resistance

Antibiotic resistance represents a global health concern. Soil, water, livestock and plant foods are directly or indirectly exposed to antibiotics due to their agricultural use or contamination. This selective pressure has acted synergistically to bacterial competition in nature to breed antibiotic-resistant (AR) bacteria. Research over the past few decades has focused on the emergence of AR pathogens in food products that can cause disease outbreaks and the spread of antibiotic resistance genes (ARGs), but One Health approaches have lately expanded the focus to include commensal bacteria as ARG donors. Despite the attempts of national and international authorities of developed and developing countries to reduce the over-prescription of antibiotics to humans and the use of antibiotics as livestock growth promoters, the selective flow of antibiotic resistance transmission from the environment to the clinic (and vice-versa) is increasing. This review focuses on the mechanisms of ARG transmission and the hotspots of antibiotic contamination resulting in the subsequent emergence of ARGs. It follows the transmission of ARGs from farm to plant and animal food products and provides examples of the impact of ARG flow to clinical settings. Understudied and emerging antibiotic resistance selection determinants, such as heavy metal and biocide contamination, are also discussed here.

Pharmaceuticals and personal care products in a Mediterranean coastal wetland: Impact of anthropogenic and spatial factors and environmental risk assessment

The present study focused on the occurrence, distribution and risk assessment of 32 pharmaceuticals and personal care products (PPCPs) in water and sediment, as well as the surrounding soil of the irrigation channels and lake of a Mediterranean coastal wetland, the Albufera Natural Park (Valencia, Spain). Moreover, the influent and effluent of ten wastewater treatment plants (WWTPs) that treat wastewater from Valencia and the surrounding areas were also studied. BPA, caffeine, diclofenac, ethyl paraben, methyl paraben, metformin, tramadol and salicylic acid were the predominant PPCPs detected in the channels and the lake, and are in good agreement with those detected in the effluent. Furthermore, 22 PPCPs were detected in >47% of the sediment samples. Of them, BPA, ethyl paraben, furosemide, ibuprofen and salicylic acid were at higher concentrations. In contrast, only seven PPCPs were detected in >44% of the soil samples. Spatial variation showed that the concentration of many PPCPs was higher in the northern area of the park, whereas the ibuprofen concentrations were higher in the south. Differences were also observed according to the type of water used for irrigation and the land uses of the area. A risk assessment based on the hazardous quotient (HQ) indicated that caffeine is a compound of concern, and tramadol at the highest concentration showed a moderate risk for the organisms assessed. Considering the mixture of the PPCPs found at each sampling point, the green algae are at risk, particularly in those points located near the city of Valencia (the most important nearby human settlement). These results indicate the need for further studies.

Urban pathways of biocides towards surface waters during dry and wet weathers: Assessment at the Paris conurbation scale

Eighteen biocides used in building materials and domestic products were monitored in wastewater treatment plants (WWTPs) during dry weather and in combined sewer overflows (CSOs) during wet weather in the Paris conurbation. The aims of this study were to (i) acquire data on biocides in urban waters, which are very scarce up to now, (ii) identify their origins in CSOs with the perspective of reducing these contaminants at source, and (iii) compare and rank biocide pathways to the river (dry vs. wet weather) at the annual and conurbation scales. The results showed the ubiquity of the 18-targeted biocides in WWTP waters and CSOs. High concentrations of methylisothiazolinone, benzisothiazolinone (0.2-0.9 μg/L) and benzalkonium C12 (0.5-6 μg/L) were measured in wastewater. Poor WWTP removals (< 50 %) were observed for most of the biocides. Both wastewater (mainly domestic uses) and stormwater (leaching from building materials) contributed to the CSO contamination. However, benzisothiazolinone mainly came from wastewater whereas diuron, isoproturon, terbutryn, carbendazim, tebuconazole, and mecoprop mainly came from stormwater. Annual mass loads discharged by WWTPs and CSOs into the Seine River were estimated using a stochastic approach (Monte Carlo simulations) at the conurbation scale and showed that WWTP discharges are the major entry pathway.

Purification of malachite green as a model biocidal agent from aqueous system by using a natural widespread coastal biowaste (Zostera marina)

The present paper aimed to perform an environmentally friendly and effective study on the purification of biocidal material using bioremediation technique, and in this context, a natural widespread coastal biowaste (Zostera marina) was applied to remove a model biocide from aqueous system. Herein, malachite green was selected as a common agent to evaluate the biosorption efficiency of waste biomaterial. The bioremediation properties of biosorbent were studied in a controlled batch experiment system by the optimization practice of operating parameters like biosorbent quantity, medium pH, time, pollutant concentration and temperature, and kinetic, thermodynamic, equilibrium, and characterization operations. The optimum operating conditions were considered as 10 mg, 4, 6 h, 15 mg L^-1, and 25 °C, respectively. Elovich and Langmuir were found to be the best-fitted models, describing the experimental biosorption data. Thermodynamic study revealed a favorable nature of the cleanup process. The characterization analysis indicated the presence of various functional groups on the layered biosorbent surface involved on the pollutant treatment. The untreated biosorbent showed a good biocide purification performance with a value of 97.584 mg g^-1, and it could thus be employed as an eco-friendly and cost-effective cleaning agent in environmental bioremediation studies.

A Review on the Fate of Legacy and Alternative Antimicrobials and Their Metabolites during Wastewater and Sludge Treatment

Antimicrobial compounds are used in a broad range of personal care, consumer and healthcare products and are frequently encountered in modern life. The use of these compounds is being reexamined as their safety, effectiveness and necessity are increasingly being questioned by regulators and consumers alike. Wastewater often contains significant amounts of these chemicals, much of which ends up being released into the environment as existing wastewater and sludge treatment processes are simply not designed to treat many of these contaminants. Furthermore, many biotic and abiotic processes during wastewater treatment can generate significant quantities of potentially toxic and persistent antimicrobial metabolites and byproducts, many of which may be even more concerning than their parent antimicrobials. This review article explores the occurrence and fate of two of the most common legacy antimicrobials, triclosan and triclocarban, their metabolites/byproducts during wastewater and sludge treatment and their potential impacts on the environment. This article also explores the fate and transformation of emerging alternative antimicrobials and addresses some of the growing concerns regarding these compounds. This is becoming increasingly important as consumers and regulators alike shift away from legacy antimicrobials to alternative chemicals which may have similar environmental and human health concerns.

Detection, occurrence, and fate of emerging contaminants in agricultural environments (2020)

A review of 79 papers published in 2019 is presented. The topics ranged from detailed descriptions of analytical methods, to fate and occurrence studies, to ecological effects and sampling techniques for a wide variety of emerging contaminants likely to occur in agricultural environments. New methods and studies on veterinary pharmaceuticals, antibiotics, anthelmintics, and engineered nanomaterials in agricultural environments continue to expand our knowledge base on the occurrence and potential impacts of these compounds. This review is divided into the following sections: Introduction, Analytical Methods, Antibiotics in Agroecosystems, Pharmaceutical Fate and Occurrence, Anthelmintics and Engineered Nanomaterials. PRACTITIONER POINTS: New research describes innovative new techniques for emerging contaminant detection in agricultural settings Newer classes of contaminants include human and veterinary pharmaceuticals Research in nanomaterials show that these also occur in agricultural environments and will likely be topics of future work.

Pharmaceuticals and personal care products in a Brazilian wetland of international importance: Occurrence and environmental risk assessment

Despite the fact that the occurrence of emerging contaminants in the environment has become frequent in recent decades, the seasonal dynamics of contaminants in different environmental compartments are little studied in protected areas influenced by effluent discharges. In this study, the seasonal and spatial occurrence of 33 pharmaceuticals and personal care products (PPCPs) was investigated in surface waters and sediments from Anil and Bacanga rivers (northeast of Brazil). The studied area is located within a Wetland of International Importance by Ramsar Convention (Amazon Estuary and its Mangroves). Sample preparation was carried out using solid-phase extraction and QuEChERS, for water and sediment samples, respectively and all determinations were performed by liquid chromatography tandem mass spectrometry. Eleven PPCPs were detected in water samples and 14 in sediments. In aqueous samples, caffeine was the most occurring compound reaching 13,798 ng L^-1. In addition, high levels of acetaminophen, ibuprofen, sulfamethoxazole, carbamazepine and diclofenac were also observed. In the sediment samples, triclocarban, benzophenone-3, ketoconazole and methylparaben were also detected. The spatial and temporal distribution of the assessed molecules indicates urbanization and anthropic activities as relevant sources of PPCPs in the region. Moreover, the levels of acetaminophen, caffeine, diclofenac, ibuprofen, benzophenone-3, triclosan and triclocarban measured within the Ramsar site pose a high risk to aquatic and terrestrial organisms. These findings indicate potential threats to the allegedly protected biodiversity and, therefore, urgent actions are needed to effectively protect this unique and vulnerable area.

Removal, seasonal variation, and environmental impact of parabens in a municipal wastewater treatment facility in Guangzhou, China

The occurrence, seasonal variation, and environmental impact of five widely used parabens, methyl-(MeP), ethyl-(EtP), n-propyl-(n-PrP), n-butyl-(n-BuP), and benzyl-(BzP) parabens, were investigated in a municipal wastewater treatment plant (WWTP) located in Guangzhou, China, for 1 year. The concentrations of ∑₅parabens in the influent and the effluent were 94.2-957 and 0.89-14.7 ng L^-1, respectively. The influent paraben concentrations in autumn were significantly lower than in winter, spring, and summer, and the concentrations were generally higher in spring. The removal efficiencies of ∑₅parabens in the dissolved phase were over 96%, with high efficiencies in MeP, EtP, and n-PrP. Risk assessment indicated that parabens in the effluent were not likely to pose an environmental risk to aquatic ecosystems. The present study indicates that the treatment processes employed in full-scale WWTPs are effective at removing parabens and highlights the possibility of utilizing WWTPs for restoring water quality in riverine and coastal regions heavily impacted by paraben contamination.

Triclocarban impairs autophagy in neuronal cells and disrupts estrogen receptor signaling via hypermethylation of specific genes

Although an increasing body of evidence suggests that triclocarban, a phenyl ether classified as a contaminant of emerging concern, presents a risk to development, there is limited data available on the potential interplay of triclocarban with the developing mammalian nervous system. This study was aimed to investigate the impact of environmentally pervasive chemical triclocarban on autophagy and estrogen receptor-mediated signaling pathways in mouse neurons. The study showed that triclocarban impaired autophagy and disrupted estrogen receptor signaling in mouse embryonic neurons in primary culture. Triclocarban used at environmentally relevant concentrations inhibited the mRNA and protein expression of ESR1 and GPER1 but not ESR2. The triclocarban-induced decrease in the expression of estrogen receptors was supported by the colocalization of the receptors in mouse neurons and corresponded to hypermethylation of the Esr1 and Gper1 genes. Selective antagonists increased the effects of triclocarban, which suggests that the neurotoxic effects of triclocarban, in addition to decreasing estrogen receptor expression, are mediated via inhibition of the neuroprotective capacity of the receptors. Furthermore, Becn1 and Atg7 siRNAs potentiated the caspase-3-dependent effect of triclocarban, which points to triclocarban-induced impairment of autophagy. Indeed, triclocarban dysregulated the expression of autophagy-related genes, and caused a time-dependent inhibition of the mRNA expression of Becn1, Map1lc3a, Map1lc3b, Nup62, and Atg7, which was correlated with a decrease in the protein levels of MAP1LC3B, BECN1 and autophagosomes, but not NUP62 protein level which was increased. Intriguingly, the Esr1 and Gper1 siRNAs did not affect the level of autophagosomes, suggesting that the triclocarban-induced impairment of autophagy is independent of the triclocarban-induced disruption of estrogen receptor signaling in mammalian neurons. Because our data provided evidence that triclocarban has the capacity to impair autophagy and disrupt estrogen receptor signaling in brain neurons at an early developmental stage, we postulate to categorize the compound as a neurodevelopmental risk factor.