Ecotoxicological Risk Assessment Research Articles

Mixture toxicity study of two metal oxide nanoparticles and chlorpyrifos on Eisenia andrei earthworms.

Co-exposure soil studies of pollutants are necessary for an appropriate ecological risk assessment. Here, we examined the effects of two-component mixtures of metal oxide nanoparticles (ZnO NPs or goethite NPs) with the insecticide chlorpyrifos (CPF) under laboratory conditions in short-term artificial soil assays using Eisenia andrei earthworms. We characterized NPs and their mixtures by scanning electron microscopy, atomic force microscopy,dynamic light scattering and zeta potential, and evaluated effects on metal accumulation, oxidative stress enzymes, and neurotoxicity related biomarkers in single and combined toxicity assays. Exposure to ZnO NPs increased Zn levels compared to control in single and combined exposure (ZnO NPs + CPF) at 72h and 7days, respectively. In contrast, there was no indication of Fe increase in organisms exposed to goethite NPs. One of the most notable effects on oxidative stress biomarkers was produced by single exposure to goethite NPs, showing that the worms were more sensitive to goethite NPs than to ZnO NPs. Acetylcholinesterase and carboxylesterase activities indicated that ZnO NPs alone were not neurotoxic to earthworms, but similar degrees of inhibition were observed after single CPF and ZnO NPs + CPF exposure. Differences between single and combined exposure were found for catalase and superoxide dismutase (goethite NPs) and for glutathione S-transferase (ZnO NPs) activities, mostly at 72h. These findings suggest a necessity to evaluate mixtures of NPs with co-existing contaminants in soil, and that the nature of metal oxide NPs and exposure time are relevant factors to be considered when assessing combined toxicity, as it may have an impact on ecotoxicological risk assessment.

Human and ecotoxicological risk assessment of heavy metals in polymer post treatment sludge from Barekese Drinking Water Treatment Plant, Kumasi

The disposal of polymer post-treatment sludge (PTS) from Barekese Water Treatment Plants (WTPs) as organic fertilizer and aquatic feed is a common practice in Ghana, necessitating a thorough evaluation of its ecological and human health risks. This study aims to assess the suitability of PTS samples for soil amendment and fish feed, scrutinizing potential hazards to consumer health and soil. PTS samples were collected from five distinct lateral sections of three clariflocculator tanks. Potentially toxic metals such as Cd, Zn, Pb, Cu, Ni, and Cr were determined using a flame atomic absorption spectrophotometer. The mean concentration of 7.82 ± 2.43, 0.31 ± 0.021, and 0.78 ± 0.042 mg/kg for Mn, Zn, and Pb respectively. The concentrations of Ni, Cr, and Cd were below their detection limits (BDL) in all PTS samples. Upon detailed exposure assessment, ingestion emerged as the primary exposure route for both adults and children, with non-cancer risks (NCR) determined to be below 1 for both age groups. Additionally, an exploration of potential cancer risks (CR) associated with heavy metal exposure in the PTS samples revealed values below the tolerable intake levels ranging from 10−4 to 10−6 for both adults and children (10−8 and 10−9, respectively). This study also employs various ecological indices, such as Nemerow's synthetic pollution index (PN), single factor pollution index (PI), geo-accumulation index (Igeo), contamination factor (CF), potential ecological risk index (PERI), pollution load index (PLI), polymetallic contaminant index (IPD), and ecological risk index (ERI). These indices consistently highlight a low contamination status and ecological sensitivity. Consequently, the study indicates that the presence of metals in the PTS samples does not pose a significant threat to the surrounding environment and human health. Furthermore, this research underscores the inadequacy of relying solely on regulatory limit values in assessing the health risks of waste materials. Such comprehensive assessments are crucial for safeguarding aquatic and human populations.

Mono and polycyclic aromatic hydrocarbons in waterpipe wastewater: Level and ecotoxicological risk assessment

Increasing of tobacco consumption around the world has led to the production of a large volume of waterpipe wastewater that enter the environment (e.g., coastal areas)and threaten aquatic creatures. However, until now, no research has been carried out on the amounts of monocyclic and polycyclic aromatic hydrocarbons (PAHs) in hookah wastewater. In the current study, the levels of PAHs and BTEX compounds in waterpipe wastewater resulting from the use of different tobacco brands were determined and their eco-toxicological effects were also evaluated. The mean levels of ƩPAHs in waterpipe wastewater of Al Tawareg, Al-Fakher, Nakhla, Tangiers and traditional tobacco brands samples were 3.48 ± 1.65, 3.33 ± 1.52, 3.08 ± 1.25, 2.41 ± 0.87 and 0.70 ± 0.13 μg/L, respectively. The mean levels of ƩBTEX in waterpipe wastewater of Al Tawareg, Al-Fakher, Nakhla, Tangiers and traditional tobacco brands samples were also 2.53 ± 0.61, 2.65 ± 0.78, 2.51 ± 0.72, 2.35 ± 0.56, and 0.78 ± 0.12 μg/L, respectively. The maximum level of PAHs and BTEX compounds in all brands/flavors samples were for naphthalene (Naph) and toluene, respectively. The concentrations of some PAHs (fluoranthene (Flrt), anthracene (Ant), benzo(b)fluoranthene (BbF), benzo(b)fluoranthene (BkF), benzo (g,h,i)perylene (BghiP) and dibenzo (a, h) anthracene (DahA)) and BTEX compounds (benzene) in the waterpipe wastewater samples were more than recommended guidelines and standards by the international reputable organizations such as World Health Organization (WHO) for water quality. Waterpipe wastewater can be introduced as an important origin for the release of these dangerous contaminants into the environmental matrixes. Therefore, more stringent regulations should be considered for the safe disposal of such hazardous wastes including waterpipe wastewater.

Modeling pesticides and ecotoxicological risk assessment in an intermittent river using SWAT

The present work aimed to predict the fate of two pesticides, copper (Cu) and glyphosate in a Mediterranean basin with an intermittent river and to assess the ecotoxicological risk related to their presence in water bodies coupling field measurements of streamflow and pesticide concentrations, and an eco-hydrological model. The Soil and Water Assessment Tool (SWAT) model was calibrated and, subsequently used to assess predicted environmental concentrations of pesticides in surface waters. The ecotoxicological risk related to the presence of Cu and glyphosate in surface water was assessed at the reach scale by using the Toxicity to Exposure Ratio approach (TER). Measurements of glyphosate concentrations (< 0.5 μg l−1) exceeded the maximum European threshold of environmental quality standards for pesticides (EQS) of 0.1 μg l−1. High concentrations of glyphosate were predicted in the wet season and in September, when glyphosate is mostly used in vineyards and olive grove productions. Acute risk (TER < 100) associated with the presence of glyphosate was detected for several reaches. High concentrations of Cu (< 6.5 μg l−1), mainly used as a fungicide in vineyards, were predicted in several river reaches. The results of the ecotoxicological risk assessment revealed that November and January were the critical months during which most of the river reaches showed a chronic risk associated with the presence of Cu.

Ecotoxicological soil risk assessment under the new soil exposure framework – an impact assessment

For the European risk assessment (RA) for soil organisms exposed to plant protection products (PPPs) endpoints from ecotoxicological laboratory studies are compared with predicted environmental concentrations in soil (PECSOIL) at first tier. A safety margin must be met; otherwise, a higher tier RA is triggered (usually soil organism field studies). A new tiered exposure modeling guidance was published by EFSA to determine PECSOIL. This work investigates its potential impact on future soil RA. PECSOIL values for >50 active substances and metabolites were calculated and compared with the respective endpoints for soil organisms to calculate the RA failure rate. Compared to the current (FOCUS) exposure modeling, PECSOIL values for all EU regulatory zones considerably increased, e.g., resulting in active substance RA failure rates of 67%, 58% and 36% for modeling Tier-1, Tier-2 and Tier-3A, respectively. The main driving factors for elevated PECSOIL were soil bulk density, crop interception and wash-off, next to obligatory modeling and scenario adjustment factors. Spatial PECSOIL scenario selection procedures result in agronomically atypical soil characteristics (e.g., soil bulk density values in Tier-3A scenarios far below typical European agricultural areas). Consequently, exposure modeling and ecotoxicological study characteristics are inconsistent, which hinders scientifically reasonable comparison of both in the RA.

Occurrence of selected antibiotics in urban rivers in northwest Pakistan and assessment of ecotoxicological and antimicrobial resistance risks

Antibiotics in aquatic systems of developing countries are a growing concern, particularly with the potential ecological risks and emergence of antimicrobial resistance. In Pakistan, antibiotics are widely consumed and released untreated into rivers, however, there is little information on their occurrence and potential risks. In this study, the concentrations and risk assessment of three commonly consumed antibiotics, ciprofloxacin (CIP), amoxicillin (AMX), and cefixime (CFM) belonging to different classes of fluoroquinolone, penicillin, and cephalosporin respectively were investigated in the Kabul River and its two tributaries, Bara River and Shah Alam River in the northwest region of the country. Composite samples were collected in different sampling campaigns and analyzed using the LC-ESI-MS/MS technique. All three antibiotics were found in higher concentrations ranging from 410 to 1810 ng/L, 180–850 ng/L, and 120–600 ng/L for CIP, AMX, and CFM respectively. The Friedman and Wilcoxon signed-ranked tests revealed insignificant differences in average concentrations of each antibiotic in the three rivers and the Pearson Correlation showed a significant positive correlation of CIP with both AMX and CFM indicating their similar pollution sources. Ecotoxicological risk assessment showed a higher risk to algae and bacteria (P. putida) in the rivers with CIP posing a greater risk. The potential risk of antimicrobial resistance development (ARD) was higher in all the three rivers, particularly in Kabul River where maximum risk quotients (RQARD) of 28.3, 9.4 and 3.4 were noted for CIP, CFM and AMX respectively. The human health (HH) risk was insignificant, though the RQHH was higher for the lower age groups (0–3 months). In addition, the combined flux of the antibiotics in the Kabul River was estimated as 59 tons/year with CIP having a significant flux relative to the other antibiotics.

Developing a Novel Read-Across Concept for Ecotoxicological Risk Assessment of Phosphate Chemicals: A Case Study.

This study introduces a novel concept approach for a read-across assessment, considering species sensitivity differences among phosphate chemicals within structurally similar compound groups. Twenty-five organic chemicals, with a log Kow of 5 or less, were categorized into three functional groups based on acetylcholinesterase (AChE) inhibition as a specific mode of action (MOA). The short-term aquatic toxicity data (LC50) for fish, crustaceans, and insects were collected from the U.S. EPA Ecotoxicology (ECOTOX) Knowledgebase. A geometric mean calculation method was applied for multiple toxic endpoints. Performance metrics for the new read-across concept, including correlation coefficient, bias, precision, and accuracy, were calculated. Overall, a slightly higher overestimation (49.2%) than underestimation (48.4%) in toxicity predictions was observed in two case studies. In Case study I, a strong positive correlation (r = 0.93) between the predicted and known toxicity values of target chemicals was observed, while in Case study II, with limited information on species and their ecotoxicity, showed a moderate correlation (r = 0.75). Overall, the bias and precision for Case study I were 0.32 ± 0.01, while Case study II showed 0.65 ± 0.06; however, the relative bias (%) increased from 37.65% (Case study I) to 91.94% (Case study II). Bland-Altman plots highlight the mean differences of 1.33 (Case study I) and 1.24 (Case study II), respectively. The new read-across concept, focusing on AChE inhibition and structural similarity, demonstrated good reliability, applicability, and accuracy with minimal bias. Future studies are needed to evaluate various types of chemical substances, diverse modes of action, functional groups, toxic endpoints, and test species to ensure overall comprehensiveness and robustness in toxicity predictions.

Missing Genomic Resources for the Next Generation of Environmental Risk Assessment.

Environmental risk assessment traditionally relies on a wide range of in vivo testing to assess the potential hazards of chemicals in the environment. These tests are often time-consuming and costly and can cause test organisms' suffering. Recent developments of reliable low-cost alternatives, both in vivo- and in silico-based, opened the door to reconsider current toxicity assessment. However, many of these new approach methodologies (NAMs) rely on high-quality annotated genomes for surrogate species of regulatory risk assessment. Currently, a lack of genomic information slows the process of NAM development. Here, we present a phylogenetically resolved overview of missing genomic resources for surrogate species within a regulatory ecotoxicological risk assessment. We call for an organized and systematic effort within the (regulatory) ecotoxicological community to provide these missing genomic resources. Further, we discuss the potential of a standardized genomic surrogate species landscape to enable a robust and nonanimal-reliant ecotoxicological risk assessment in the systems ecotoxicology era.

Ecotoxicological risk assessment of pesticides against different aquatic and terrestrial species: using mechanistic QSTR and iQSTTR modelling approaches to fill the toxicity data gap

The toxicity prediction for newly designed or untested pesticides will reduce unnecessary chemical synthesis and animal testing, and contribute to the design of “greener and safer” pesticide chemicals.

Predictionof Environmental FateandToxicityofInsecticidesUsing Multi-Target QSAR Approach.

Ecotoxicological risk assessments form the foundation of regulatory decisions for industrial chemicals used in various sectors. In this study, a multi-target-QSAR model established by a backpropagation neural network trained with the Levenberg-Marquardt (LM) algorithm was used to construct a statistically robust and easily interpretable Mt-QSAR model with high external predictability for the simultaneous prediction of the environmental fate in form of octanol-water partition coefficient (LogP), (BCF) and acute oral toxicity in mammals and birds (LD50rat ) and (LD50bird ) for a wide range of chemical structural classes of insecticides. Principal component analysis was performed on descriptors selected by the SW-MLR method, and the selected PCs were used for constructing the SW-MLR-PCA-ANN model. The developed well-trained model (RMSE=0.83, MPE=0.004, CCC=0.82, IIC=0.78, R2 =0.69) was statistically robust as indicated by the external validation parameters (RMSE=0.93, MPE=0.008, CCC=0.77, IIC=0.68, R2 =0.61). The AD of the developed Mt-QSAR model was also defined to identify the most reliable predictions. Finally, the missing values in the dataset for the aforementioned targets were predicted using the constructed Mt-QSAR model. The proposed approach can be used for simultaneous prediction of the environmental fate of new insecticides, especially ones that haven't been tested yet.

Glyphosate-Based Herbicide Formulations and Their Relevant Active Ingredients Affect Soil Springtails Even Five Months after Application

Glyphosate is the most widely used active ingredient (AI) in glyphosate-based herbicides (GBHs) worldwide and is also known to affect a variety of soil organisms. However, we know little about how the effects of glyphosate AIs differ from those of GBHs that also contain so-called inert co-formulants. We conducted a greenhouse experiment using the model cover crop white mustard (Sinapis alba) to investigate the effects of three GBHs (Roundup PowerFlex, Roundup LB Plus, and Touchdown Quattro) and their respective glyphosate AIs (glyphosate potassium, isopropylamine, and diammonium salt) on epedaphic springtails (Sminthurinus niger; Collembola) activity in soils with low (3.0%) or high (4.1%) organic matter content (SOM). Springtail activity was assessed using pitfall traps. Most GBHs and AIs reduced springtail activity compared to mechanical removal of mustard in the short-term and even up to 5 months after application. GBHs and AIs differed considerably in their effects on springtail activity, and effects were modified by SOM content. Our results highlight the need to (i) distinguish between the effects of glyphosate AIs and commercial GBH formulations, (ii) disclose all ingredients of GBHs, as co-formulants also affect non-target organisms, and (iii) include soil properties in ecotoxicological risk assessments for soil organisms to better characterize the situation in the field.

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

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

Evaluation the Toxicity of Heavy Metal Mixtures in Anecic Earthworms (Aporrectodea giardi).

Using earthworms as bioindicators of heavy metal contamination in soils is a relevant tool for environmental risk monitoring. This study examines the combined effects of four distinct concentrations mixtures (M1, M2, M3 and M4) containing Cd, Cr, Cu, Ni, Fe and Mn on Aporrectodea giardi earthworms after 12 and 24days (12D/24D) of exposure via the monitoring of certain biomarkers of stress including total protein content, glutathione (GSH), metallothionein (MT), catalase and lipoxygenase (LOX) activities. The results show a decrease in the total protein level for the M3 mixture after 24D, whereas it increases for all other treatments regardless of exposure time. Glutathione and metallothionine levels increased for M2 and M3 and decreased for M1 and M4 after 12D; they increased after 24D for all the mixtures. Regarding enzyme activities, catalase activity was decreased for all the treatments unless for M3 (P > 0.05). However, LOX increased for M1, M2 and M4 except for M3 after 12D, when inhibition of this biomarker was observed. LOX activity was inhibited for all the mixtures at the end of the treatment. All the mixtures generated oxidative stress in Aporrectodea giardi, which is minimized by increasing MT levels to remove the metal ions and triggering the antioxidant system, composed primarily of GSH and LOX to restore cellular homeostasis. These findings suggest that the species Aporrectodea giardi could be an excellent candidate for ecotoxicological risk assessment of soils contaminated by metal mixtures and it can be used in bioremediation for its fitness which allows it to tolerate high concentrations of metal mixtures.

Ecotoxicological and Potential Health Risk Assess-ment in Dimna Canal, Interlinking Lentic and Lo-tic Ecosystem in Jamshedpur, India

Abstract: Heavy and Trace Elements (HTEs) pollution is a serious menace to the ecosystem. These elements are ubiquitous that can bioaccumulate and biomagnify in the food chain. This study aimed to assess the HTE pollution on different trophic level of an aquatic food chain of Dimna canal interlinking a lentic (Dimna Lake) and a lotic (Subarnarekha River) ecosystem. In this study, water, sediments, and biotic samples of molluscs (Limnaea stagnalis) and fish (Channa punctatus) were collected and analysed in an ICP-MS for six HTEs (Cu, Pb, Zn, As, CD and Cr). Then, the health risk to human through the consumption of L. stagnalis and C. Punctatus was calculated using the Target Hazard Quotient (THQ) and Hazard Index (HI). It is observed that the average level of Pb (12.96 µg/L) and Cd (3.83µg/L) in water is higher than the limit prescribed by WHO, 2004. In sediment, the average level of Zn (118.14 µg/g) and Cd (0.43 µg/g) is higher than the average shale value of the earth's crust. The higher value of Pb, Cd and Zn in the canal ecosystem may be due to the discharge of chemical, primer etc. from industries as well bricks industry. In mollusc (L. stagnalis), the average levels of HTEs are the highest in comparison to limits prescribed by FAO (1983) and account for 82.74 µg of Cu per g, 20.09 µg of Pb per g, 530.49 µg of Zn per g, and 0.86 µg of Cd per g. In edible fish (C.punctatus) parts, level of As (2.41 µg/g) and Cd (0.66 µg/g) are higher than the FAO limits. Mollusc, being the primary consumer of the aquatic food chain, accumulates more HTE than that of fish; hence mollusc can be used as a potential bioindicator. THQ values of metals due to consumption of mollusc and fish show that As contributes almost 50 % in HI. Also, among the population of two age groups (adult and children); children are found more susceptible to HTE exposure. Hence, regular monitoring and assessment are required for aquatic ecosystems for the safeguard of human health.

Ecological and Human Health Risk Assessment of Heavy Metals in Sediment of Selected Creeks in Rivers State, Nigeria

There has been much concern about the rate at which industrial and household wastes are released into Creeks in Rivers State. The study examined the status of heavy metal pollutants (Cd, Cu, Zn, Cr, Pb, and Ni) in sediment and to determine the extent of damage caused by these human factors using the most recent pollution index and Sediment quality guidelines (SQGs). The research was carried out in four important creeks along the Delta River network in Rivers State, Nigeria (Okrika, Borokiri, Eagle Island, and Kaa). Triplicate sediment samples were collected at a depth of 0-20 cm and extracted with 20cm3 of aqua ragia (a 3:1 mixture of HCl and HNO3) and 10cm3 of 30% H2O2. The metal concentrations were measured using an Atomic Absorption Spectrophotometer (AAS). The concentrations of the heavy metals ranged from 11.147–18.919mg/kg, 11.918–14.379mg/kg, 8.321–11.691 mg/kg, 6.405–11.72mg/kg, and 5.718–12.125mg/kg, and 2.429-7.725mg/kg respectively and followed the sequence Zn &gt; Pb &gt; Cr &gt; Ni &gt;Cu &gt; Cd. Geo-accumulation Index (Igeo) calculated was less than 0 i.e. uncontaminated for all metals except Pb in Borokiri Creek and Cd in all sampled creeks, showing moderate contamination. Eco-toxicological risk assessment (RI) indicated that the creeks were uncontaminated. Despite the low level of contamination, it is recommended that relevant authorities to regulate the indiscriminate dumping of domestic waste and untreated industrial effluents into the river to prevent the deterioration of the creeks

An integrated multimedia fate modeling framework for identifying mitigation strategy of antibiotic ecological risks: A case study in a peri-urban river

Antibiotics have been heavily used over the past decades, resulting in their frequent detections in rivers and increasing ecological risks. Recognizing characteristics of antibiotic ecological risks (AERs) and making effective strategies to mitigate the AERs are essential to ensure the safety of aquatic ecosystem and public health. In this study, an integrated technological framework has been proposed toward identifying management options for reducing AERs by jointly utilizing multimedia fugacity modelling and ecotoxicological risk assessment, and applied to characterize the AERs in a peri-urban river in Beijing. Specifically, a level III fugacity model has been successfully established to simulate the fate of antibiotics in the environment, and the manageable parameters have been screened out via sensitivity analysis of the model. Then the validated fugacity model has been used for scenario modellings to optimize mitigation strategies of AERs. Results show most of the antibiotics considered are frequently detected in the river, and pose medium or high risks to aquatic organisms. Relatively, the macrolides and fluoroquinolones present higher ecotoxicological risks than sulfonamides and tetracyclines. Furthermore, the mixture risk quotient and predictive equation of concentration addition suggest joint and synergistic/antagonistic effects of AERs for multiple or binary antibiotics in the environment. Largely, the concentrations of antibiotics in the river are determined by the source emissions into water and soil. Scenario modellings show the improvement of antibiotic removal rates would be considered preferentially to mitigate the AERs. Also, controlling human consumption is conducive to reducing the risks posed by tetracyclines, macrolides and trimethoprim, while controlling animal consumption would benefit the reduction for sulfonamides. Overall, the joint strategy presents the greatest reduction of AERs by reducing antibiotic consumption and together improving sewage treatment rate and antibiotic removal rate. The study provides us a useful guideline to make ecological risk-based mitigation strategy for reducing AERs in environment.

Eco-Toxicological Risk Assessment of Possible Effects of Potentially Toxic Heavy Metals on Water Quality and Performance of Nile Tilapia (Oreochromis niloticus) in Burullus Lake, North Delta, Egypt

Eco-Toxicological Risk Assessment of Possible Effects of Potentially Toxic Heavy Metals on Water Quality and Performance of Nile Tilapia (Oreochromis niloticus) in Burullus Lake, North Delta, Egypt

Ecotoxicological mixture risk assessment of 35 pharmaceuticals in wastewater effluents following post-treatment with ozone and/or granulated activated carbon

Reducing the risk posed by mixtures of pharmaceuticals is a goal of current initiatives such as the European Green Deal to reduce anthropological environmental impacts. Wastewater effluent typically contains large numbers of active pharmaceutical ingredients (APIs). For some APIs, existing technology such as conventional activated sludge (CAS) wastewater treatment plants (WWTPs) have removal rates below 20 %, thus the WWTP discharges are adding to the toxic burden of receiving waters.We present an environmental risk assessment of mixtures of 35 APIs in effluent samples from 82 Northern European WWTPs using the concentration addition model, and identify the respective risk-driving APIs. This is then compared to a corresponding mixture risk assessment of effluent samples from the Danish Hillerød WWTP subjected to post-treatment with varying specific ozone doses (0.15–1.05 mgO3/mgDOC) and/or granulated activated carbon (GAC).All 82 WWTP effluent samples exceeded risk thresholds by at least a factor of 30, with a median RQSUM of 92.9, highlighting the need for effluent post-treatment and/or a substantial dilution in the recipient waters. Antibiotics, analgesics and anti-depressants were among the top risk drivers with 99 % of the average mixture risk attributable to azithromycin, diclofenac, venlafaxine, clarithromycin and mycophenolic acid. Effluent mixture risk was reduced by ozonation in a concentration-dependent manner, decreasing below threshold levels to a median RQSUM of 0.83 following treatment with 0.65 mgO3/mg DOC. Fresh GAC was also effective at reducing the mixture risk both alone and with ozone treatment, with median RQSUM of 0.04 and 0.07 respectively.To our knowledge, this is the first study to present a risk assessment of pharmaceutical mixtures in effluent comparing “conventional” WWTP processes with additional post-treatment with ozone and/or GAC for reducing the joint risks of pharmaceutical mixtures for recipient waters. We demonstrate the need for additional WWTP treatment technologies, and the efficacy of GAC and ozonation in decreasing the risk to the aquatic environment from pharmaceutical mixtures to below acceptable threshold limits.

Towards Understanding the Factors behind the Limited Integration of Multispecies Ecotoxicity Assessment in Environmental Risk Characterisation of Graphene-Family Materials—A Bibliometric Review

Even though graphene-family materials (GFMs) hold great promise for various applications, there are still significant knowledge gaps in ecotoxicology and environmental risk assessment associated with their potential environmental impacts. Here, we provide a critical perspective on published ecotoxicity studies of GFMs based on meticulous bibliometric research. Based on the results of our review paper, in order to fill in the current critical knowledge gaps, the following issues are recommended for consideration: performing more studies on GFMs’ effects at environmentally relevant concentrations and more field and laboratory studies with marine and terrestrial organisms. It is also recommended to assess the ecotoxicity of GFMs in more environmentally relevant conditions, such as in trophic chain transfer studies and by multispecies exposure in micro- or mesocosms, as well as gaining insights into the interactive effects between GFMs and environmental pollutants. It was also revealed that despite their widespread detection in different environmental compartments the potential impacts of GFMs in complex test systems where hierarchical trophic organisation or trophic transfer studies are significantly under-represented. One of the main causes was identified as the difficulties in the physicochemical characterisation of GFMs in complex terrestrial test systems or aquatic micro- and mesocosm studies containing a sediment phase. The lack of tools for adequate characterisation of GFMs in these complex test systems may discourage researchers from conducting experiments under environmentally relevant test conditions. In the coming years, fundamental research about these complex test systems will continue to better understand the mechanism behind GFM toxicity affecting organisms in different environmental compartments and to ensure their safe and sustainable use in the future.

Polychlorinated biphenyls (PCBs) in intertidal sediment and water from Lagos lagoon: Baseline report on occurrence, distribution and ecotoxicological risk assessment

To assess the occurrence and potential ecological risk associated with organic micropollutants in Lagos lagoon, 27 polychlorinated biphenyls (PCBs) were analysed in sediments and surface water. Sediment samples were obtained from 18 designated sites (SD1 – SD18) using a Van Veen grab sampler and extracted following standard procedures. Cleaned extracts were analysed using gas chromatography with electron capture detector (ECD). The concentration of ∑PCBs in sediment samples ranged between 6757.61 and 273.46 µg/kg. The PCB homologues distribution patterns in sediments indicated that the low-chlorinated (∑di-PCB - ∑penta-PCB) PCBs were more dominant with 61.1 % occurrence than the high-chlorinated ((∑hexa-PCB - ∑nona-PCB) PCBs with 38.9 % relative abundance. The following is the decreasing order of the average homologue composition of PCBs in sediment samples: ∑tetra-PCB (24.6%) > ∑octa-PCB (21 %) > ∑hexa-PCB (13.8 %) > ∑penta-PCB (12.8) > ∑tri-PCB (11.4 %) > ∑hepta-PCB (7.8 %) > ∑nona-PCB (4.9 %) > ∑di-PCB (2.9 %). More so, the ∑PCBs in surface water samples ranged from 69.28 to 440.90 ng/L, with the mean ranging between 7.21 and 16.33 ng/L. The class distribution of PCB homologue profiles in water samples indicated that highly-chlorinated (∑hexa-PCB to ∑nona-PCB) PCBs were the dominant homologues, with 94.4 % occurrence, compared to the very low occurrence rate (5.6 %) of the low-chlorinated (∑di-PCB to ∑penta-PCB) PCBs. Hexa-PCBs (PCB-138 and PCB-153) were the dominant congeners in most water samples. The concentrations of ∑PCBs in sediments and surface water were unprecedentedly high at almost all locations. The total toxicity equivalent concentrations (TTECs) of dioxin-like PCBs for the sediment samples ranged from 0.001 to 2.43 µg/kg, with an average of 0.34 µg/kg. These findings suggest that PCB congeners are pervasive from anthropogenic point sources of pollution. Intensive site-specific monitoring and remediation are recommended.