Select antibiotics in leachate from closed and active landfills exceed thresholds for antibiotic resistance development

Emerging contaminants: A One Health perspective

Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health. Despite global efforts to mitigate legacy pollutants, the continuous introduction of new substances remains a major threat to both people and the planet. In response, global initiatives are focusing on risk assessment and regulation of emerging contaminants, as demonstrated by the ongoing efforts to establish the UN's Intergovernmental Science-Policy Panel on Chemicals, Waste, and Pollution Prevention. This review identifies the sources and impacts of emerging contaminants on planetary health, emphasizing the importance of adopting a One Health approach. Strategies for monitoring and addressing these pollutants are discussed, underscoring the need for robust and socially equitable environmental policies at both regional and international levels. Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.

A picture of pharmaceutical pollution in landfill leachates: Occurrence, regional differences and influencing factors

Municipal solid waste (MSW) landfill sites have been identified as a significant source of pharmaceuticals in the environment because unused or expired pharmaceuticals are discarded into MSW, which eventually percolate into leachates. However, the contamination of pharmaceuticals in landfill leachate in China is not comprehensively understood. Previous research into factors influencing pharmaceutical concentrations focused on a limited number and type of target pollutants or restricted study area. In the present study, 66 pharmaceuticals were analyzed (including 45 antibiotic and 21 non-antibiotic pharmaceuticals, also categorized as 59 prescription and 7 non-prescription pharmaceuticals) in leachate samples from landfill sites with various characteristics in different regions of China. The results indicated that non-antibiotic pollutants were present at significantly higher concentrations than antibiotic pollutants, with median concentrations of 1.74 μg/L and 527 ng/L, respectively. Non-antibiotic pollutants also presented a higher environmental risk than antibiotic pollutants, by 2 to 4 orders of magnitude, highlighting that non-antibiotic pharmaceuticals should not be overlooked during the assessment of landfill leachate. Pharmaceutical concentrations in landfill leachate samples exhibited regional differences; the population size served by the landfills was the dominant factor contributing to the observed differences. In addition, landfill characteristics such as the solid waste composition and MSW loading can also affect pharmaceutical concentrations in landfill leachate. Despite the implementation of the classification and disposal policy of MSW in Shanghai, China since July 2019, specifying that unused or expired pharmaceuticals should be discarded as hazardous waste, high levels of pharmaceutical contaminations were detected in leachate from the main components of classified MSW (i.e., residual and food waste). These findings emphasize the importance of pharmaceutical management in solid waste systems.

A systematic review of coastal zone integrated waste management for sustainability strategies

Coastal areas stand out because of their rich biodiversity and high tourist potential due to their privileged geographical position. However, one of the main problems in these areas is the generation of waste and its management, which must consider technical and sustainable criteria. This work aims to conduct a systematic review of the scientific literature on integrated solid waste management (ISWM) by considering scientific publications on the scientific basis for the proposal of sustainability strategies in the context of use and efficiency. The overall method comprises i) Search strategy, merging and processing of the databases (Scopus and Web of Science); ii) Evolution of coastal zone waste management; iii) Systematic reviews on coastal landfills and ISWM in the context of the circular economy; and iv) Quantitative synthesis in integrated waste management. The results show 282 studies focused on coastal landfills and 59 papers on ISWM with the application of circular economy criteria. Systematic reviews allowed for the definition of criteria for the selection of favorable sites, such as i) sites far from the coastline, ii) impermeable soils at their base to avoid contamination of aquifers, iii) use of remote sensing and geographic information system tools for continuous monitoring, iv) mitigation of possible contamination of ecosystems, v) planning the possibility of restoration (reforestation) and protection of the environment. In coastal zones, it is necessary to apply the ISWM approach to avoid landfill flooding and protect the marine environment, reducing rubbish and waste on beaches and oceans. Therefore, applying the circular economy in ISWM is critical to sustainability in coastal environments, with the planet's natural processes and variations due to climate change.

Towards Precision Ecotoxicology: Leveraging Evolutionary Conservation of Pharmaceutical and Personal Care Product Targets to Understand Adverse Outcomes Across Species and Life Stages

Translation of environmental science to the practice aims to protect biodiversity and ecosystem services, and our future ability to do so relies on the development of a precision ecotoxicology approach wherein we leverage the genetics and informatics of species to better understand and manage the risks of global pollution. A little over a decade ago, a workshop focusing on the risks of pharmaceuticals and personal care products (PPCPs) in the environment identified a priority research question, "What can be learned about the evolutionary conservation of PPCP targets across species and life stages in the context of potential adverse outcomes and effects?" We review the activities in this area over the past decade, consider prospects of more recent developments, and identify future research needs to develop next-generation approaches for PPCPs and other global chemicals and waste challenges. Environ Toxicol Chem 2024;43:526-536. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Environmental pitfalls and associated human health risks and ecological impacts from landfill leachate contaminants: Current evidence, recommended interventions and future directions

The improper management of solid waste, particularly the dumping of untreated municipal solid waste, poses a growing global challenge in both developed and developing nations. The generation of leachate is one of the significant issues that arise from this practice, and it can have harmful impacts on both the environment and public health. This paper presents an overview of the primary waste types that generate landfill leachate and their characteristics. This includes examining the distribution of waste types in landfills globally and how they have changed over time, which can provide valuable insights into potential pollutants in a given area and their trends. With a lack of specific regulations and growing concerns regarding environmental and health impacts, the paper also focuses on emerging contaminants. Furthermore, the environmental and ecological impacts of leachate, along with associated health risks, are analyzed. The potential applications of landfill leachate, suggested interventions and future directions are also discussed in the manuscript. Finally, this work addresses future research directions in landfill leachate studies, with attention, for the first time to the potentialities that artificial intelligence can offer for landfill leachate management, studies, and applications.

Physiochemical and biological characteristics of fouling on landfill leachate treatment systems surface

Fouling of landfill leachate, a biofilm formation process on the surface of the collection system, migration pipeline and treatment system causes low efficiency of leachate transportation and treatment and increases cost for maintenance of those facilities. In addition, landfill leachate fouling might accumulate pathogens and antibiotic resistance genes (ARGs), posing threats to the environment. Characterization of the landfill leachate fouling and its associated environmental behavior is essential for the management of fouling. In this study, physicochemical and biological properties of landfill leachate fouling and the possible accumulation capacity of pathogens and ARGs were investigated in nitrification (aerobic condition) and denitrification (anaerobic condition) process during landfill leachate biological treatment, respectively. Results show that microbial (bacterial, archaeal, eukaryotic, and viral) community structure and function (carbon fixation, methanogenesis, nitrification and denitrification) differed in fouling under aerobic and anaerobic conditions, driven by the supplemental leachate water quality. Aerobic fouling had a higher abundance of nitrification and denitrification functional genes, while anaerobic fouling harbored a higher abundance of carbon fixation and methanogenesis genes. Both forms of leachate fouling had a higher abundance of pathogens and ARGs than the associated leachate, suggesting the accumulation capacity of fouling on biotic pollutants. Specifically, aerobic fouling harbored three orders of magnitude higher multidrug resistance genes mexD than its associated leachate. This finding provides fundamental knowledge on the biological properties of leachate fouling and suggests that leachate fouling might harbor significant pathogens and ARGs.

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

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

Risk ranking of macrolide antibiotics - Release levels, resistance formation potential and ecological risk

Antibiotic resistance (AR) development in natural water bodies is a significant source of concern. Macrolide antibiotics in particular have been identified as pollutants of concern for AR development throughout the literature, as well as by state and international authorities. This study utilises a probabilistic model to examine the risk of AR development arising from human-use macrolide residues, utilising administration rates from Ireland as a case study. Stages modelled included level of administration, excretion, degradation in wastewater, removal in wastewater treatment, assuming conventional activated sludge (CAS) treatment, and dilution. Release estimates per day, as well as risk quotient values for antibiotic resistance development and ecological impact, are generated for erythromycin, clarithromycin, and azithromycin. In the modelled scenario in which conventional activated sludge treatment is utilised in wastewater treatment, this model ranks risk of resistance development for each antibiotic in the order clarithromycin > azithromycin > erythromycin, with mean risk quotient values of 0.50, 0.34 and 0.12, respectively. A membrane bioreactor scenario was also modelled, which reduced risk quotient values for all three macrolides by at least 50 %. Risk of ecological impact for each antibiotic was also examined, by comparing environmental concentrations predicted to safety limits based on toxicity data for cyanobacteria and other organisms from the literature, with azithromycin being identified as the macrolide of highest risk. This study compares and quantifies the risk of resistance development and ecological impact for a high-risk antibiotic group in the Irish context, and demonstrates the potential for risk reduction achieved by adoption of alternative (e.g. membrane bioreactor) technology.

Impact of Anthropogenic Activities on the Dissemination of ARGs in the Environment-A Review

Over the past few decades, due to the excessive consumption of drugs in human and veterinary medicine, the antimicrobial resistance (AR) of microorganisms has risen considerably across the world, and this trend is predicted to intensify. Many worrying research results indicate the occurrence of pools of AR, both directly related to human activity and environmental factors. The increase of AR in the natural environment is mainly associated with the anthropogenic activity. The dissemination of AR is significantly stimulated by the operation of municipal facilities, such as wastewater treatment plants (WWTPs) or landfills, as well as biogas plants, agriculture and farming practices, including animal production and land application of manure. These activities entail a risk to public health by spreading bacteria resistant to antimicrobial products (ARB) and antibiotic resistance genes (ARGs). Furthermore, subinhibitory concentrations of antimicrobial substances additionally predispose microbial consortia and resistomes to changes in particular environments that are permeated by these micropollutants. The current state of knowledge on the fate of ARGs, their dissemination and the complexity of the AR phenomenon in relation to anthropogenic activity is inadequate. This review summarizes the state-of-the-art knowledge on AR in the environment, in particular focusing on AR spread in an anthropogenically altered environment and related environmental consequences.

Occurrence of pharmaceuticals and plasticizers in leachate from municipal landfills of different age

Contaminants of emerging concern (CECs), such as pharmaceuticals and plasticizers, are present in leachate due to disposal of pharmaceuticals and plastic waste. Leachate is usually released to publicly owned treatment works, but CECs could pass through and be discharged into water resources. Landfills generate leachate for many years after closure, but it is currently unknown whether CECs continue to leach over time or dissipate soon after the waste is deposited. Leachate samples from four domestic landfills with various closure status in North Carolina, United States, have been collected from summer 2019 to summer 2020 (n = 36). Samples were analyzed for 13 pharmaceuticals (7 detected), and 3 plasticizers (2 detected). Carbamazepine and ibuprofen were detected in 100% of samples at respective median concentrations of 45 and 14,867 ng/L in open cells and 100 and 3,049 ng/L in cells closed for > 13 years. 17α-ethinylestradiol, acetaminophen, bisphenol A, doxycycline, and metformin were also frequently detected at concentrations spanning over 5 orders of magnitude between the compounds. Carbamazepine was present at significantly higher concentrations in older leachate (p < 0.1), while acetaminophen, doxycycline and bisphenol S were found at significantly lower concentrations. Lower concentration of bisphenol S is likely related to its usage pattern and not to its attenuation in the landfill. This study showed that leachate could be a source of CECs many years after closure. Thus, the transport of these compounds with landfill leachate is expected to persist for as long as leachate is generated in the landfill.

The perception and disposal practices of unused and expired medicines by households in an urban municipality, southwest Nigeria: A comparative cross-sectional study

Unused, damaged, and expired medicines (UEMs) pose disposal challenges globally, despite their importance. The environmental disposal of UEMs portends public health consequences, hence, this study in high-density (HDS) and low-density (LDS) urban households in Southwest Nigeria. The comparative, cross-sectional study utilised multi-stage samplingto enrol 404 females, experienced in use and medicines safekeeping. The response rate was 93%. Data were analysed by IBM-SPSS, version 20. Continuous and categorical variableswere presentedin tables as mean(±SD), proportions (%), respectively while χ² and logistic regression statistics determined differences between LDS and HDS (P_α > 0.05). 53.4% and 71.2% of respondents respectively had good knowledge and positive attitudes to safe disposal of UEMs. At least 31.5% of households don't stock medicines while antimalarial (57.3%), analgesics (52.7%) and antibiotics (49.7%) predominate in households and significantly different between LDS and HDS. 72.9% and 67.8%; 47.9% and 55.6% respondents in LDS and HDS, respectively, disposed of solid and liquid UEMs in storage bins, though 34.9% (LDS) and 16.7% (HDS) disposed of liquid UEMs in toilet/sink. There were significant differences in medicines abundance and disposal practices between LDS and HDS for solid and liquid medicines. 37.1% of respondents perceived consequences for the poor UEMs disposal, including accidental ingestion (76.6% vs 26.7%), land pollution (69.6% vs 36.7%), water pollution (72.4% vs 32.8%) and toxicity (58.3% vs 32.8%), respectively in LDS and HDS. Respondents' good knowledge and positive attitudes contrasted with poor UEMs disposal practices, which compromise public health. Legislation, compliance monitoring and enforcement are germane for incentive-driven UEMs recovery.

Antibiotics and antibiotic resistance genes in landfills: A review

Landfill are important reservoirs of antibiotics and antibiotic resistance genes (ARGs). They harbor diverse contaminants, such as heavy metals and persistent organic chemicals, complex microbial consortia, and anaerobic degradation processes, which facilitate the occurrence, development, and transfer of ARGs and antibiotic resistant bacteria (ARB). The main concern is that antibiotics and developed ARGs and ARB may transfer to the local environment via leachate and landfill leakage. In this paper, we provide an overview of established studies on antibiotics and ARGs in landfills, summarize the origins and distribution of antibiotics and ARGs, discuss the linkages among various antibiotics, ARGs, and bacterial communities as well as the influencing factors of ARGs, and evaluate the current treatment processes of antibiotics and ARGs. Finally, future research is proposed to fill the current knowledge gaps, which include mechanisms for the development and transmission of antibiotic resistance, as well as efficient treatment approaches for antibiotic resistance.

Environmental heterogeneity determines the response patterns of microbially mediated N-reduction processes to sulfamethoxazole in river sediments

The widespread occurrence of antibiotics in aquatic ecosystems leads to potential ecological risks to organisms, in turn affecting microbially mediated processes. Here, we investigated the response of dominant N-reduction processes to the frequently detected antibiotic sulfamethoxazole (SMX) along the Chaobai River with regional environmental heterogeneity, including denitrification, anaerobic ammonium oxidation (anammox), dissimilatory nitrate reduction to ammonium (DNRA), and nitrous oxide (N₂O) release. We found two divergent SMX response patterns for denitrification in contrasting scenarios of geochemical properties. In the context of low nitrate and carbon, SMX weakened denitrification with a slightly stimulation first. Whereas SMX directly inhibited denitrification when nitrate and carbon were sufficient. High SMX concentration suppressed anammox (26-72%) and DNRA activities (48-84%) via restraining the activities of anammox and DNRA bacteria. Notably, SMX increased the contribution of denitrification to N-reduction at the expense of DNRA to N-reduction, leading to a shift in nitrogen conversion towards denitrification. Additionally, SMX stimulated N₂O emission (up to 91%) due to superior restraint on process of N₂O reduction to N₂ and an incline for N-reduction towards denitrification, thereby exacerbating greenhouse effect. Our results advance the understanding of how nitrogen cycling is affected by SMX in aquatic ecosystems with environmental heterogeneity.

Chemical Fate and Partitioning Behavior of Antibiotics in the Aquatic Environment-A Review

Antibiotics in the aquatic environment is a major problem because of the emergence of antibiotic resistance. The long-term ecological impact on the aquatic environment is unknown. Many sources allow entry of antibiotics into the environment, including wastewater-treatment plants (WWTPs), agricultural runoff, hospital effluent, and landfill leachate. Concentrations of antibiotics in the aquatic environment vary significantly; studies have shown fluoroquinolones, tetracycline, macrolides, sulfonamides, and penicillins to reach 2900, 1500, 9700, 21 400, and 1600 ng L^-1 in wastewater effluent samples, respectively. However, concentrations are highly variable between different countries and depend on several factors including seasonal variation, prescription, and WWTP operating procedures. Likewise, the reported concentrations that cause environmental effects vary greatly between antibiotics, even within the same class; however, this predicted concentration for the antibiotics considered was frequently <1000 ngL^-1 , indicating that when discharged into the environment along with treated effluent, these antibiotics have a potentially detrimental effect on the environment. Antibiotics are generally quite hydrophilic in nature; however, they can ionize in the aquatic environment to form charged structures, such as cations, zwitterions, and anions. Certain classes, particularly fluoroquinolones and tetracyclines, can adsorb onto solid matrices, including soils, sediment, and sludge, making it difficult to fully understand their chemical fate in the aquatic environment. The adsorption coefficient (K_d ) varies between different classes of antibiotics, with tetracyclines and fluoroquinolones showing the highest K_d values. The K_d values for fluoroquinolones, tetracyclines, macrolides, and sulfonamides have been reported as 54 600, 7600, 130, and 1.37 L kg^-1 , respectively. Factors such as pH of the environment, solid matrix (sediment/soil sludge), and ionic strength can influence the K_d ; therefore, several values exist in literature for the same compound. Environ Toxicol Chem 2021;40:3275-3298. © 2021 SETAC.

Environmental antimicrobial resistance and its drivers: a potential threat to public health

Imprudent and overuse of clinically relevant antibiotics in agriculture, veterinary and medical sectors contribute to the global epidemic increase in antimicrobial resistance (AMR). There is a growing concern among researchers and stakeholders that the environment acts as an AMR reservoir and plays a key role in the dissemination of antimicrobial resistance genes (ARGs). Various drivers are contributing factors to the spread of antibiotic-resistant bacteria and their ARGs either directly through antimicrobial drug use in health care, agriculture/livestock and the environment or antibiotic residues released from various domestic settings. Resistant micro-organisms and their resistance genes enter the soil, air, water and sediments through various routes or hotspots such as hospital wastewater, agricultural waste or wastewater treatment plants. Global mitigation strategies primarily involve the identification of high-risk environments that are responsible for the evolution and spread of resistance. Subsequently, AMR transmission is affected by the standards of infection control, sanitation, access to clean water, access to assured quality antimicrobials and diagnostics, travel and migration. This review provides a brief description of AMR as a global concern and the possible contribution of different environmental drivers to the transmission of antibiotic-resistant bacteria or ARGs through various mechanisms. We also aim to highlight the key knowledge gaps that hinder environmental regulators and mitigation strategies in delivering environmental protection against AMR.

A nature-based solution to a landfill-leachate contamination of a confined aquifer

Remediation of groundwater from landfill contamination presents a serious challenge due to the complex mixture of contaminants discharged from landfills. Here, we show the significance of a nature-based solution to a landfill-contaminated aquifer in southeast Norway. Groundwater physicochemical parameters monitored for twenty-eight years were used as a proxy to infer natural remediation. Results show that concentrations of the major chemical variables decreased with time and distance until they tailed off. An exception to this was sulphate, which showed an increase, but apparently, exhibits a stationary phase. The water types were found to be most similar between samples from active landfill and post-closure stages, while samples from the stabilised stage showed a different water type. All the chemical parameters of samples from the stabilised stage were found to be within the Norwegian drinking water standards, except iron and manganese, which were only marginally above the limits, an indication of a possible recovery of this aquifer. The findings highlight the significance of natural attenuation processes in remediating contaminated aquifers and have significant consequences for future contamination management, where natural remediation can be viewed as an alternative worth exploring. This is promising in the wake of calls for sustainable remediation management strategies.

A multidisciplinary approach to the evaluation of the effects of foraging on landfills on white stork nestlings

The use of landfills as foraging areas by white storks (Ciconia ciconia) is a recent well-known behaviour. While several studies have highlighted positive effects at a populational level others suggest that the presence of pollutants, pathogens and the lower presence of antioxidants in the food could pose a health risk for individuals. The objective of this study was to evaluate potential effects of the use of landfills as a food resource on the physiology and health of white stork nestlings, by a multidisciplinary approach based on the analysis of nutritional status, body condition, blood parameters, oxidative stress balance and the presence of pathogens. Results showed better body condition in individuals associated with landfills compared to the ones feeding on natural resources, as well as better nutritional status, as indicated by higher levels of albumin, cholesterol, and triglycerides in plasma. As many pollutants have a pro-oxidant effect, we evaluated oxidative stress balance, with no differences in the indicators of damage except for methaemoglobin (metHb), significantly higher in nestlings associated with landfill-origin food. Regarding antioxidants, GSH was higher in nestlings associated with landfills, which may suggest a hormetic response induced potentially by the presence of pollutants in waste. Nestlings fed food from landfills also had a higher presence of Escherichia coli with a multiresistant phenotype to antibiotics. In conclusion, our results show that nestlings fed with a higher proportion of food from landfills present a better nutritional status and body condition than those fed with a higher proportion of natural diet, being the only indicators of negative effects of the use of this food resource the higher percentage of metHb in the peripheral blood and the presence of antibiotic-resistant E. coli.

Antibiotic residues in the aquatic environment - current perspective and risk considerations

Antimicrobial resistance is a major concern for human and animal health, projected to deteriorate with time and given current trends of antimicrobial usage. Antimicrobial use, particularly in healthcare and agriculture, can result in the release of antimicrobials into surface waters, promoting the development of antibiotic resistance in the environment, and potentially leading to human health risks. This study reviews relevant literature, and investigates current European and Irish antimicrobial usage trends in humans and animals, as well as potential pathways that antibiotics can take into surface waters following use. Reported levels in the aquatic environment are summarized, with particular focus on Ireland. There are relatively few studies examining Irish water bodies or sewage effluent for antibiotic residues, however, five antibiotics, namely azithromycin, ciprofloxacin, clarithromycin, metronidazole, and trimethoprim, have been measured in Irish waters, in concentrations predicted to select for resistance. Numerous isolates of multi-drug resistant bacteria have also been found in water bodies throughout Ireland and Europe. The value of risk assessment methodologies in understanding risks posed by antibiotic residues is reviewed including the advantages and disadvantages of specific approaches. Hazard quotient and bespoke Monte Carlo approaches are predominant risk assessment tools used to examine antimicrobial release and their complex pathways. This study highlights the need for monitoring of antimicrobial releases and the potential for resistance development, persistence and transmission while highlighting the role of risk assessment methodologies in assessing potential human and environmental health impacts.

Rainfall Influences Occurrence of Pharmaceutical and Personal Care Products in Landfill Leachates: Evidence from Seasonal Variations and Extreme Rainfall Episodes

Unused or expired pharmaceutical and personal care products (PPCPs) are usually discharged into municipal solid wastes, then travel to landfills, and eventually percolate into leachates. However, knowledge of their occurrence and temporal dynamics in leachates is limited, making landfill leachate an underappreciated emission source of PPCPs. Furthermore, the differences in PPCP variations in landfill leachates emphasize the necessity for identifying the influencing factors and elucidating the mechanisms for PPCP fluctuations. In this study, successive monthly monitoring of PPCPs in leachates throughout an entire year was performed to determine their seasonal variations and identify their influencing factors. Furthermore, five pairs of additional sampling campaigns were conducted before and after rainfall events during wet seasons to elucidate the influencing mechanisms. The results showed that there was a distinct seasonal variation in PPCPs in landfill leachates-elevated levels during the wet period (from April to September, with a mean concentration of 17.0 μg/L for total monitored PPCPs)-when compared to other months (mean concentration of 3.8 μg/L). Rainfall played a considerable role in mediating PPCP concentrations in leachates. The PPCP responses to five rainfall episodes further verified the influence of rainfall and demonstrated that the tendency to PPCP concentration increase was related to rainfall precipitation. Torrential rain events (i.e., 24 h cumulative precipitation of 50-99.9 mm) led to the most significant increases in PPCP concentrations in landfill leachates. In addition, the hydrophilicity of PPCPs contributed to the different fluctuations during the 1 year investigation and different responses to rainfall. To the best of our knowledge, this study provides the first direct evidence supporting the influence of rainfall on PPCPs in landfill leachates, which can help better understand the occurrence and behavior of emerging contaminants in this underappreciated emission source.

Antibiotics in surface water of East and Southeast Asian countries: A focused review on contamination status, pollution sources, potential risks, and future perspectives

This review provides focused insights into the contamination status, sources, and ecological risks associated with multiple classes of antibiotics in surface water from the East and Southeast Asia based on publications over the period 2007 to 2020. Antibiotics are ubiquitous in surface water of these countries with concentrations ranging from <1 ng/L to hundreds μg/L and median values from 10 to 100 ng/L. Wider ranges and higher maximum concentrations of certain antibiotics were found in surface water of the East Asian countries like China and South Korea than in the Southeast Asian nations. Environmental behavior and fate of antibiotics in surface water is discussed. The reviewed occurrence of antibiotics in their sources suggests that effluent from wastewater treatment plants, wastewater from aquaculture and livestock production activities, and untreated urban sewage are principal sources of antibiotics in surface water. Ecological risks associated with antibiotic residues were estimated for aquatic organisms and the prevalence of antibiotic resistance genes and antibiotic-resistant bacteria were reviewed. Such findings underline the need for synergistic efforts from scientists, engineers, policy makers, government managers, entrepreneurs, and communities to manage and reduce the burden of antibiotics and antibiotic resistance in water bodies of East and Southeast Asian countries.

A survey of sub-inhibitory concentrations of antibiotics in the environment

Antibiotics are poorly metabolized, and can enter the environment via human waste streams, agricultural run-off and pharmaceutical effluent. We consequently expect to see a concentration gradient of antibiotic compounds radiating from areas of human population. Such antibiotics should be thought of as pollutants, as they can accumulate, and have biological effects. These antibiotic pollutants can increase rates of mutation and lateral transfer events, and continue to exert selection pressure even at sub-inhibitory concentrations. Here, we conducted a literature survey on environmental concentrations of antibiotics. We collated 887 data points from 40 peer-reviewed papers. We then determined whether these concentrations were biologically relevant by comparing them to their minimum selective concentrations, usually defined as between 1/4 and 1/230 of the minimum inhibitory concentration. Environmental concentrations of antibiotics surveyed often fall into this range. In general, the antibiotic concentrations recorded in aquatic and sediment samples were similar. These findings indicate that environmental concentrations of antibiotics are likely to be influencing microbial ecology, and to be driving the selection of antibiotic resistant bacteria.

A critical review on the effects of antibiotics on anammox process in wastewater

Anaerobic ammonium oxidation (anammox) has recently become of significant interest due to its capability for cost-effective nitrogen elimination from wastewater. However, anaerobic ammonia-oxidizing bacteria (AnAOB) are sensitive to environmental changes and toxic substances. In particular, the presence of antibiotics in wastewater, which is considered unfavorable to the anammox process, has become a growing concern. Therefore, it is necessary to evaluate the effects of these inhibitors to acquire information on the applicability of the anammox process. Hence, this review summarizes our knowledge of the effects of commonly detected antibiotics in water matrices, including fluoroquinolone, macrolide, β-lactam, chloramphenicol, tetracycline, sulfonamide, glycopeptide, and aminoglycoside, on the anammox process. According to the literature, the presence of antibiotics in wastewater could partially or completely inhibit anammox reactions, in which antibiotics targeting protein synthesis or DNA replication (excluding aminoglycoside) were the most effective against the AnAOB strains.

Is Disposal of Unused Pharmaceuticals as Municipal Solid Waste by Landfilling a Good Option? A Case Study in China

Properly disposing of unused pharmaceuticals is essential to minimize emissions of active pharmaceutical ingredients (APIs). The aim of this study was to determine whether disposing of unused pharmaceuticals in household solid waste is a cost-effective way of attenuating pharmaceutical emissions. We calculated attenuation rates (ARs) for unused pharmaceuticals by performing mass balance calculations for disposal to landfill. The results indicated that the average ARs for disposal as household solid waste reached 63% to 100% for our investigated pharmaceuticals at the worst scenario, indicating that disposal as household solid waste strongly attenuated emissions of APIs. Disposing of unused pharmaceuticals as household solid waste could be a cost-effective disposal method from the view of reducing APIs emission, but should be used with caution.

Sustainable landfill leachate treatment: Optimize use of guar gum as natural coagulant and floc characterization

Sustainable wastewater treatment necessitates the application of natural and green material in the approach. Thus, selecting a natural coagulant in leachate treatment is a crucial step in landfill operation to prevent secondary environmental pollution due to residual inorganic coagulant in treated effluent. Current study investigated the application of guar gum in landfill leachate treatment. Central composite design in response surface methodology was used to optimize the performance of Chemical Oxygen Demand (COD) removal. Quadratic model developed indicated the optimum COD removal 22.57% at guar gum dosage of 44.39 mg/L, pH 8.56 (natural pH of leachate) and mixing speed 79.27 rpm. Scanning electron microscopy showed that floc was compact and energy-dispersive-x-ray analysis showed that guar gum was capable to adsorb multiple ions from the leachate. Structural characterization using Fourier Transform Infrared analysis demonstrated that hydrogen bonding between guar and pollutant particles was involved in coagulation and flocculation process. Therefore, guar gum coagulant present potential to be an alternative in leachate treatment where pH requirement is not required during treatment. Simultaneously, adsorption by guar gum offers added pollutant removal advantage.

Municipal Solid Waste Landfills: An Underestimated Source of Pharmaceutical and Personal Care Products in the Water Environment

Pharmaceutical and personal care products (PPCPs) have been the focus of increasing concern in recent decades due to their ubiquity in the environment and potential risks. Out-of-date PPCPs are usually discharged into municipal solid wastes (MSWs), enter the leachates in MSW landfills, and have serious adverse effects on the surrounding water environment. However, the occurrence and removal of PPCPs from landfill leachates have rarely been examined to date. This lack of knowledge makes the landfill an underestimated source of PPCPs in the environment. In this review, we collected the relevant publications of PPCPs in landfill leachates, systematically summarized the occurrence of PPCPs in landfill leachates globally, evaluated the removal performances for various PPCPs by different types of on-site full-scale leachate treatment processes, and assessed the impacts of landfill leachates on PPCPs in the adjacent groundwater. In particular, influencing factors for PPCPs in landfill leachates, including the physicochemical properties of PPCPs, climate conditions, and characteristics of landfill sites (i.e., landfill ages) as well as sociological factors (i.e., economic development), were extensively discussed to understand their occurrence patterns. Future perspectives were also proposed in light of the identified knowledge gaps. To the best of our knowledge, this is the first review regarding the occurrence and removal of PPCPs from landfill leachates worldwide.

Toward Sustainable Environmental Quality: Priority Research Questions for Asia

Environmental and human health challenges are pronounced in Asia, an exceptionally diverse and complex region where influences of global megatrends are extensive and numerous stresses to environmental quality exist. Identifying priorities necessary to engage grand challenges can be facilitated through horizon scanning exercises, and to this end we identified and examined 23 priority research questions needed to advance toward more sustainable environmental quality in Asia, as part of the Global Horizon Scanning Project. Advances in environmental toxicology, environmental chemistry, biological monitoring, and risk-assessment methodologies are necessary to address the adverse impacts of environmental stressors on ecosystem services and biodiversity, with Asia being home to numerous biodiversity hotspots. Intersections of the food-energy-water nexus are profound in Asia; innovative and aggressive technologies are necessary to provide clean water, ensure food safety, and stimulate energy efficiency, while improving ecological integrity and addressing legacy and emerging threats to public health and the environment, particularly with increased aquaculture production. Asia is the largest chemical-producing continent globally. Accordingly, sustainable and green chemistry and engineering present decided opportunities to stimulate innovation and realize a number of the United Nations Sustainable Development Goals. Engaging the priority research questions identified herein will require transdisciplinary coordination through existing and nontraditional partnerships within and among countries and sectors. Answering these questions will not be easy but is necessary to achieve more sustainable environmental quality in Asia. Environ Toxicol Chem 2020;39:1485-1505. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

National action to combat AMR: a One-Health approach to assess policy priorities in action plans

Little is known about the overall trend and prioritisations of past and current antimicrobial resistance (AMR) policies. Here we introduce a quantitative method to analyse AMR policies. The AMR-Policy Analysis Coding Toolkit (AMR-PACT) uses several categorical variables. Thirteen AMR action plans from five countries (China, Japan, Norway, the UK and the USA) were used to develop the tool and identify possible values for each variable. The scope and capability of AMR-PACT is demonstrated through the 2015 WHO's Global Action Plan and 2017 Hong Kong AMR Action Plan (HKAP). Majority of policies were aimed at either human or animal sector with less attention given to the environment, plant or food sector. Both plans shared the same two strategic focus areas, namely the conservation of antibiotics and the improved surveillance of resistance. There were no policies dedicated to improving access to antibiotics in the HKAP. These empirical results provide useful insights into the priorities and gaps of AMR policies. The method proposed here can help understand countries' priorities regarding AMR, support the creation of AMR policy database and foster innovative policymaking.

Changes in nitrogen removal and microbiota of anammox biofilm reactors under tetracycline stress at environmentally and industrially relevant concentrations

Anammox-related processes are often applied for the wastewater treatment which contains both ammonium and antibiotics. Herein, the long-term effects of tetracycline (TC), at environmentally and industrially relevant concentrations, on the performance, anammox activity and microbial community of anammox reactors were investigated for 518 days. The control reactor (without TC exposure) was stable for nitrogen removal during the long-term operation (a nitrogen removal rate of 0.56 ± 0.05 kg-N·m^-3·d^-1). In the TC-added reactor, the nitrogen removal efficiency increased slightly at low TC levels (1-100 μg/L), whereas poor anammox performance occurred at high TC concentration (1000 μg/L). Furthermore, the concentrations of extracellular polymeric substances (EPS) were much higher at 10 μg/L than those in the control reactor (P < 0.01), whereas rapidly decreased at 1000 μg-TC/L. Furthermore, the reactor performance was highly consistent with the variations of the heme c contents. Consistently, exposure to TC changed the abundance of anammox bacteria, e.g., an increase in Candidatus Jettenia abundance occurred from 2.20 ± 0.97% (0-10 μg/L) to 12.13 ± 1.66% (100 μg/L). Similarly, the genus Denitratisoma, the most predominant denitrification bacteria, also had a higher abundance at a TC concentration of 100 μg/L (15.60 ± 6.42%) than other TC concentrations (5.40 ± 2.50% and 7.65 ± 0.55% at concentrations of 10 and 1000 μg/L, respectively). The results can explain why the exposure of anammox bacteria to a lower TC concentration (100 μg/L) resulted in a better nitrogen removal rate. In contrast, exposure to a high TC level (1000 μg/L) led to a decline in the abundance of anammox bacteria and denitrifiers (1.53 ± 0.64% and 8.18 ± 0.63%, respectively) but an increased abundance in the nitrifier population (8.07 ± 1.21%; P < 0.01). Therefore, this study can aid in the design and operation of anammox-based processes treating sewage and industrial wastewater.

Pharmaceutical residues in streams near concentrated animal feeding operations of Korea - Occurrences and associated ecological risks

Concentrated animal feeding operations (CAFOs) have been suggested to be the most significant source of pharmaceutical release into the environment. However, limited information is available on the occurrence of veterinary pharmaceutical residues and the associated ecological risks to the aquatic environment near CAFO areas. In this study, ten commonly used veterinary antibiotics, including sulfonamides, tetracyclines, and cephalosporins, along with three analgesics, were measured in water samples collected from the streams that run near two CAFOs in Korea in 2013 (n = 16) and 2014 (n = 10). In addition, the associated ecological risks were estimated by calculating risk quotient. The pharmaceuticals were detected in a higher amount in the samples collected downstream from the CAFO than in those collected upstream. Acetaminophen, sulfamethazine, sulfathiazole, and oxytetracycline were detected at maximum concentrations of 38.8 μg/L, 21.3 μg/L, 17.4 μg/L, and 16.9 μg/L, respectively. Relatively higher concentrations of pharmaceuticals were observed in locations adjacent to the CAFO and the downstream area, suggesting the influence of the CAFO. Except for acetaminophen, lower concentrations of the target pharmaceuticals were detected in the samples collected during the high-flow season. The concentrations of most of the target pharmaceuticals exceeded the risk quotient of one, suggesting potential ecological effects in the areas affected by CAFOs. Our observations show that the water environment near a CAFO could be heavily affected by veterinary pharmaceuticals and analgesic drugs that are also frequently used among humans. Hence, the ecological consequences of pharmaceutical residues in the water bodies near CAFOs warrant further investigation.

Commentary: Perspectives on aquaculture, urbanization and water quality

Aquaculture presents essential opportunities to meet global food security needs, but adverse effects of aquaculture practices on ecological integrity and influences of existing waste management infrastructure on product safety must be understood in rapidly expanding urban and peri-urban regions. Concentration of, access to and use of chemical products is increasing in many urban areas faster than interventions are being implemented. Aquaculture farming is employing "non-traditional" (e.g., treated or untreated sewage) waters in some regions, but the spatial extent of these intentional or de facto water reuse practices with associated water quality and food safety systems are poorly understood around the world. Integrative water reuse, aquaculture product safety, ecological and public health research and advanced surveillance systems are needed. Such efforts appear particularly important because noncommunicable diseases are increasing and pollution is now recognized as one of the major global health threats, particularly in lower and middle income countries. Here we provide some modest perspectives and identify several research needs to support more sustainable aquaculture practices while protecting public health and the environment.

Pharmaceuticals, illicit drugs and their metabolites in fish from Argentina: Implications for protected areas influenced by urbanization

Because an understanding of aquatic bioaccumulation of human pharmaceuticals in Latin America is limited, this area was recently identified as a priority environmental quality research need. We examined bioaccumulation of twenty-seven pharmaceuticals, illicit drugs and their metabolites in muscle, liver and gills of multiple fish species (Rhamdia quelen, Hypostomus commersoni, Hoplias lacerdae, Prochilodus lineatus) from an urban river receiving wastewater discharges (Paraná) and a lotic system (Acaraguá) without direct wastewater sources, which runs through a protected area. All samples were analyzed using isotope-dilution liquid chromatography-tandem mass spectrometry. Caffeine, which was detected up to 13 μg/kg, and antibiotics were consistently detected in all fish. Among antibiotics, erythromycin was ubiquitous (0.7-5.6 μg/kg) but its tissue concentrations were lower than levels of sulfamethoxazole, sulfathiazole and trimethoprim (0.9-5.5 μg/kg), which are used in human medicine, aquaculture and livestock. Erythromycin bioaccumulation in fish is reported here from Argentina for the first time, though levels of antibiotics in edible muscles of these species were lower than the maximum residue limits for human consumption. We observed norfluoxetine, the primary active metabolite of the antidepressant fluoxetine, ranging from 1.1-9.1 μg/kg in fish. We further identified benzoylecgonine, a primary metabolite of cocaine, in fish from both study systems, representing the first observation an illicit drug or associated metabolites bioaccumulation in aquatic life from Argentina. Interestingly, high pharmaceutical levels were observed in fish from the Acaraguá river suggesting their transport into the protected area, from the surrounding lands. Though fish from the Paraná river were sampled near WWTP discharges, pharmaceutical concentrations may have been reduced by hydrological and other environmental conditions, and biological differences among species. These findings, which observed bioaccumulation of select pharmaceuticals, their metabolites and illicit drugs in wild fish sampled inside a protected area, highlight the importance of developing an advanced understanding of urban influences on inland protected watersheds.

Global review and analysis of erythromycin in the environment: Occurrence, bioaccumulation and antibiotic resistance hazards

Environmental observations of antibiotics and other pharmaceuticals have received attention as indicators of an urbanizing global water cycle. When connections between environment and development of antibiotic resistance (ABR) are considered, it is increasingly important to understand the life cycle of antibiotics. Here we examined the global occurrence of erythromycin (ERY) in: 1. wastewater effluent, inland waters, drinking water, groundwater, and estuarine and coastal systems; 2. sewage sludge, biosolids and sediments; and 3. tissues of aquatic organisms. We then performed probabilistic environmental hazard assessments to identify probabilities of exceeding the predicted no-effect concentration (PNEC) of 1.0 μg L^-1 for promoting ABR, based on previous modeling of minimum inhibitory concentrations and minimal selective concentrations of ERY, and measured levels from different geographic regions. Marked differences were observed among geographic regions and matrices. For example, more information was available for water matrices (312 publications) than solids (97 publications). ERY has primarily been studied in Asia, North America and Europe with the majority of studies performed in China, USA, Spain and the United Kingdom. In surface waters 72.4% of the Asian studies have been performed in China, while 85.4% of the observations from North America were from the USA; Spain represented 41.9% of the European surface water studies. Remarkably, results from PEHAs indicated that the likelihood of exceeding the ERY PNEC for ABR in effluents was markedly high in Asia (33.3%) followed by Europe (20%) and North America (17.8%). Unfortunately, ERY occurrence data is comparatively limited in coastal and marine systems across large geographic regions including Southwest Asia, Eastern Europe, Africa, and Central and South America. Future studies are needed to understand risks of ERY and other antibiotics to human health and the environment, particularly in developing regions where waste management systems and treatment infrastructure are being implemented slower than access to and consumption of pharmaceuticals is occurring.