Environmental Toxicology and Chemistry最新文献

Methyl 2-{[1-(5-fluoropentyl)-1H-indazole-3-carbonyl]amino}-3,3-dimethylbutanoate (5F-ADB), a potent synthetic cannabinoid, induces intense euphoria, hallucinations, and addiction, posing significant risks to human health. Current drug surveillance efforts lack data to identify drug abuse, and the environmental impacts of 5F-ADB entering aquatic systems via synthesis or use remain uncharacterized. To address these gaps, a multi-level assessment system (in vitro-invertebrate-vertebrate) was established to elucidate 5F-ADB metabolic pathways and identify robust biomarkers. Human liver microsomes (HLM), Daphnia magna, and zebrafish were exposed to 5F-ADB, with metabolites profiled using high performance liquid chromatography coupled with mass spectrometry (HPLC-MS). Metabolic pathways were inferred, and metabolite toxicity was evaluated. Results revealed 9, 11, and 22 metabolites in HLM, D. magna, and zebrafish models, respectively. Dominant pathways in HLM and zebrafish included ester hydrolysis, defluorinated-hydroxylation, and combined ester hydrolysis/defluorinated-hydroxylation. D. magna metabolism primarily featured defluorinated-hydroxylation, depentylation, and ester hydrolysis coupled with hydroxylation. Glucuronidation metabolites were exclusive to zebrafish. Based on abundance and stability, H-M4 (ester hydrolysis), D-M1 (ester hydrolysis/depentylation), and Z-M15 (ester hydrolysis/condensation) were identified as key biomarkers for HLM, D. magna, and zebrafish, respectively. Toxicity assessments indicated reduced toxicity for most metabolites versus 5F-ADB. However, H-M7, D-M7, D-M11, and Z-M15 (products of ester hydrolysis/condensation or defluorinated-hydroxylation/oxidation) exhibited comparable toxicity to the parent compound. Critically, D-M7 (defluorinated-hydroxylation/oxidation) demonstrated heightened hydrophilicity and potentially elevated ecotoxicity in D. magna, warranting further ecological risk investigation. This study provides the first multi-trophic metabolic characterization of 5F-ADB, delivering critical data for tracing illicit synthesis, monitoring drug-use distribution, and evaluating environmental hazards of synthetic cannabinoids.

The environmental impact of tire and road wear particles (TRWPs), arising from tire-road friction, has raised significant concerns. Like microplastics, TRWPs contaminate air, water, and soil, with considerable annual emissions and runoff into freshwater ecosystems. Among TRWP compounds, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q), leached from tire particles, shows varying toxicity across species, notably affecting fish and invertebrates. This study investigates the effects of 6PPD-Q on Gammarus amphipods, a key species in freshwater ecosystems, to better understand its potential ecological and policy implications. Using recirculating water systems with nine independent incubators, Gammarus amphipods were exposed to 6PPD-Q at concentrations (1.5 and 3.0 µg/L) relevant to peri-alpine lakes. Males and females were separately tested across treatments, and multiple biodemographic endpoints were monitored, including survival, feeding rate, behavior, and reproductive traits. Results revealed sublethal effects included a significant reduction in feeding rate and behavioral alterations at 1.5 µg/L, such as decreased swimming speed and reduced distance travelled. Furthermore, a moderate increase in male mortality (14%) was observed at 3 µg/L. Although oocyte size increased at 3 µg/L, the number of oocytes and embryos did not significantly differ between treatments. These results suggest that even at low concentrations, 6PPD-Q may impair key physiological and behavioral functions in Gammarus, potentially through neurotoxic mechanisms. Given the ecological role of amphipods in detritus processing and trophic transfer, such impairments could compromise energy flow within freshwater food webs. Although some observed effects showed high variability, they warrant further investigation to assess potential long-term and population-level consequences.

Concerns about the toxic effects of chemical mixtures have led to regulatory organizations considering how best to address exposures to complex mixtures in the environment. The ubiquitous nature of metals means that they are always present in the environment, even if only at very low levels. It is appropriate to consider whether the mixtures of commonly regulated metals in the environment are likely to cause adverse effects on ecosystems if the environmental quality standards (EQSs) for all the individual metals are complied with. The total risk from four metals (copper, lead, nickel, and zinc) was evaluated in terms of the potential effects on freshwater benthic macroinvertebrate communities from the United Kingdom. The total risk was expressed as the sum of the individual risk characterization ratios for each metal (∑RCR). The ecological data are expressed relative to predicted reference conditions to provide an ecological quality ratio, which indicates whether the local community has been affected by any stressors by comparison to unaffected reference conditions. Very high metal exposures, expressed as the ∑RCR value, were found to be associated with reduced ecosystem diversity. However, a 10% reduction in community diversity relative to the predicted unaffected reference conditions is expected to occur only at ∑RCR values of greater than 8 ∑RCR units. This indicates that in "real world" situations, where a suite of inorganic and organic pollutants may be present, if the EQS for each of the individual metals is complied with (in this case, a ∑RCR value no higher than 4), there will likely not be any observable impact on benthic invertebrate community diversity despite the presence of these metals and other contaminants.

To protect marine environments, standardized whole effluent toxicity (WET) testing methods using a diverse range of aquatic organisms have been developed. A predominant method of WET testing is the fish larval growth and survival (LGS) test, which uses sheepshead minnow (Cyprinodon variegatus) or inland silverside (Menidia beryllina) larvae. Although fish LGS tests have been effective in the identification of potentially toxic effluents, animal welfare concerns have spurred efforts to develop and implement new approach methods, such as fish embryo toxicity (FET) and mysid (Americamysis bahia) survival and growth tests, which feature fish embryos and invertebrates, respectively. The goal of this study was to advance the development of marine testing alternatives by assessing the sensitivity of marine FET and mysid tests relative to that of standardized fish tests (i.e., fish LGS tests) for two environmentally relevant chemicals (i.e., Ni and phenanthrene [Phe]). In addition, the utility of sublethal endpoints as additional FET test metrics was explored. The findings of this study indicate that the mysid test is more sensitive than the other test methods evaluated for the assessment of Ni and Phe acute toxicity. Further, the mysid test showed comparable or greater sensitivity relative to the standardized fish LGS tests for the evaluation of chronic toxicity. Although the marine FET tests were less sensitive than the most sensitive fish LGS test for Ni and Phe, the inclusion of sublethal endpoints (i.e., pericardial edema and hatchability) increased FET test sensitivity. These findings indicate the predictive power of marine FET and mysid tests relative to fish LGS tests for the chemicals tested and suggest that FET test performance can be improved through the inclusion of additional endpoints. The results of this study lay the groundwork for future studies that aim to compare the performance of these test types using complex whole effluent mixtures.

Year-round neonicotinoids detections in waterways pose a threat to aquatic ecosystems and drinking water supplies. Neonicotinoids, and increasingly diamides, are being used in the Canadian Prairies, but there is a paucity of detection and concentration data in streams and rivers. We report on neonicotinoids and diamides in 16 streams in southern Saskatchewan, Canada between 2017 and 2019. Approximately half of all samples had measurable levels of at least one insecticide, generally below guidelines. Thiamethoxam was most frequently detected across sites (42%), followed by clothianidin (18%) and imidacloprid (9%), while diamide detections differed with location. Most samples with detections contained at least one of thiamethoxam, clothianidin, or imidacloprid (98%). About 15% of samples between 2018 and 2019 detected diamides, reflecting their increasing use in Canada. While thiamethoxam and clothianidin concentrations were similar between rain events and snowmelt, their average daily loads were greatest during snowmelt (p < 0.05); suggesting overwintering and spring freshet as a significant source to streams. Generally, agriculturally intensive subwatersheds dominated by canola and cereals had higher neonicotinoid concentrations, yet crop cover and sites explained a small proportion of the variance. Neither site, crop, flow, or year considerably accounted for the large variation in detections, suggesting a complexity of factors. Based on probability distributions, exceedances of 7% to 15% were observed for thiamethoxam, clothianidin, and imidacloprid when compared to a highly protective chronic predicted no-effect concentration guideline value, suggesting limited acute or chronic risk in these systems. The variation of insecticide concentrations reflects crop practices, precipitation, prairie hydrology, agricultural practices, and environmental conditions, and highlights the need for improved monitoring across Canada to better understand processes affecting their distribution and risk.

Of the many hypotheses attributed to the global decline in shorebirds, an important one is the exposure to contaminants, particularly to wintering shorebirds. However, there is limited information available on contaminant levels in winter migrant shorebirds, especially within the Central Asian Flyway (CAF). This research gap is addressed in this study on total mercury (THg) contamination in 10 species of long-distance migrant shorebirds along the west coast of India from 2019 to 2021. Of the 10 species studied, the highest concentration of THg was reported in the droppings of Common Redshank in the mangroves (81.29 ± 6.82 mg/kg wet wt) and the lowest was reported in Little Stint in sand beach (17.40 ± 2.14 mg/kg wet wt). The Kadalundi-Vallikunnu Community Reserve (KVCR) and its adjacent sand beaches serve as vital stop-over sites within the CAF, catering to the nutritional needs of various migratory shorebirds, including transoceanic, oversummering, and locally moving species. This research offers solid evidence of THg concentration in predators occupying high trophic levels of the coastal ecosystems in the KVCR and surrounding areas. Understanding the extent and impact of THg concentration on both organisms and their habitat is crucial. The study highlights a significant increase of THg concentration across the years. Additionally, it provides essential information to support extensive, long-term biomonitoring efforts aimed at conserving shorebirds regionally and globally.

Hydroxylated polychlorinated biphenyls (OH-PCBs) are potential endocrine disruptors due to their interaction with nuclear receptors. However, experimental evaluation of their estrogenic activity is costly and time-consuming, limiting data availability. In this study, quantitative structure-activity relationship (QSAR) models were constructed using linear discriminant analysis (LDA) and decision tree (DT) with both 2D autocorrelation and arithmetic residuals in K-groups analysis (ARKA) descriptors to classify OH-PCBs as agonists or nonagonists of estrogen receptors (ERα and ERβ). For the ERα dataset, the training, test, and cross-validation set accuracies were 89.2%, 84.0%, and 88.0% for the LDA model developed with 2D autocorrelation descriptors (Model I); 89.2%, 72.0%, and 84.9% for the DT model developed with 2D autocorrelation descriptors (Model II); and 89.2%, 80.0%, and 87.0% for the ARKA-based model (Model V). Area under receiver operating characteristic (AUC-ROC) values of 0.959, 0.903, and 0.954 were obtained for Models I, II, and V respectively. For the ERβ dataset, the training, test, and cross-validation set accuracies were 90.5%, 84.0%, and 87.9% for the LDA model constructed with 2D autocorrelation descriptors (Model III); 89.2%, 68.0%, and 83.9% for the DT model constructed with 2D autocorrelation descriptors (Model IV); and 87.8%, 80.0%, and 84.9% for the ARKA-based model (Model VI). Values for AUC-ROC of 0.966, 0.892, and 0.945 were obtained for Models III, IV, and VI respectively. Overall, the QSAR models reported in this article provide a reliable and efficient approach for screening OH-PCBs for estrogenic activity, offering valuable tools for environmental risk assessment, with ARKA descriptors serving as effective alternatives to conventional descriptors.

The buildup of pollutants on impervious surfaces, and their subsequent flush into the environment within stormwater, could worsen with expected increases in prolonged dry periods and extreme rain events due to climate change. As such, the monitoring and treatment of urban stormwaters is becoming a high priority. Of particular interest is road runoff in urban areas, which has been found to be acutely lethal to salmonids and frequently contains elevated concentrations of metals and organic contaminants. In this study, samples of road runoff were collected in the Metro Vancouver area of British Columbia, Canada, and assessed for acute lethality to rainbow trout (Oncorhynchus mykiss). Three of the four stormwaters tested exhibited 100% mortality in the 96-hr test. Stormwater toxicity was demonstrated to be reduced by treatment in a rain garden. Phase I Toxicity Identification Evaluation (TIE) techniques initially identified a metal as the cause of toxicity in one stormwater, which was determined to be zinc after Phase II/III TIE testing. The second stormwater sample revealed an organic constituent to be responsible for toxicity, and subsequent TIE testing implicated N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q). The potential contribution of 6PPD-Q to toxicity was assessed by performing TIE techniques on a standard solution of 6PPD-Q in parallel with the stormwater. Chemical analysis of 6PPD-Q using Condensed-Phase Membrane Introduction Mass Spectrometry was used to support toxicity assessments. This is the first study to use the TIE approach to provide a toxicity profile for 6PPD-Q.

Obtaining clean water is a global priority, as emphasized by the United Nations Sustainable Development Goal 6, which aims to ensure availability and sustainable management of water and sanitation for all. Pharmaceutical pollutants are becoming more prevalent in aquatic environments, triggering public health concerns, negative environmental impacts, and the development of antibiotic resistance. Microalgae hold great potential for bioremediation of antibiotics, although most of the studies to date supporting these observations rely on conditions where artificial wastewater contained one or a few antibiotics. In this study, Chlorella sorokiniana was used to assess the removal of a mixture of 10 antibiotics selected and tested considering environmentally relevant antibiotic concentrations based on data from the National Health Service (United Kingdom). The selected antibiotics had a risk quotient > 1 as calculated by the ratio of predicted environmental concentration (PEC) to predicted no effect concentration. The experimental antibiotic concentration tested for each antibiotic corresponded to their PEC values. After 19 days of incubation, the β-lactam class (amoxicillin, penicillin V, cephalexin) showed the highest percentage of removal (51-85), followed by trimethoprim (24), oxytetracycline (6), metronidazole (6), and sulfamethoxazole (2). Different mechanisms, that is, biodegradation, photodegradation, bioadsorption, and bioaccumulation, were involved at variable range. Increase in algal biomass was observed concomitantly to decrease in the concentration of the tested antibiotics, suggesting their use as a carbon source for cellular growth. In addition, levels of dissolved ammonium, nitrate, phosphate, and chemical oxygen demand, decreased by 88%, 22%, 100%, and 10%, respectively. Our study confirmed the ability of C. sorokiniana to biodegrade antibiotics while also effectively reducing key nutrient loadings.