Environmental Toxicology and Chemistry最新文献

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.

Current standard test methods for assessing biodegradation of chemicals are laborious and not suited for high-throughput screening of chemicals because of both the required volume of the test medium and the limited possibility for automation of measurements of biodegradation. A high-throughput method (HTM) should be miniaturized, suitable for automation, and based on generic parameters that can indicate biodegradation of any chemical. The aim of this study was to develop an HTM based on bacterial proliferation (i.e., growth) as an indicator of biodegradation, measured by flow cytometry. Natural bacterial communities were exposed to reference chemicals in 96-well plates for up to 14 days at 19 °C and the results compared with parallel standard biodegradation screening tests for freshwater (Organisation for Economic Co-operation and Development [OECD] 301F) and seawater (OECD 306). Increased bacterial growth, compared with nonexposed inocula, was used as an indication of biodegradation. Sodium benzoate induced a significant growth response that corresponded to the biodegradation experiments in both freshwater and marine water. Aniline induced a lower frequency of significant growth compared with the frequency of positive biodegradation results, whereas caffeine induced a higher frequency and more rapid growth response compared with biodegradation results. This shows the potential for an HTM for biodegradation testing using bacterial growth.

Pharmaceuticals and personal care products (PPCPs) are widely detected in aquatic environments. However, recent studies on the environmental occurrence of currently used PPCPs in Japan are limited. In this study, a nationwide monitoring initiative focusing on PPCPs was undertaken to investigate the occurrence and fate of PPCPs in aquatic environments in Japan. A total of 700 samples were collected and analyzed from 2018 to 2022. Ninety-one PPCPs were detected in the analyzed samples. Three PPCPs (N, N-diethyl-meta-toluamide [DEET], salicylic acid, and crotamiton) were detected at particularly high frequencies, with a prevalence exceeding 99% of analyzed samples. Seasonal variations were observed for several PPCPs across multiple rivers, with concentrations generally increasing during fall/winter and decreasing during spring/summer (except DEET) throughout the sampling period. The detection frequencies and concentrations were higher in PPCPs with higher domestic prescription amounts. Some PPCPs, such as acetylsalicylic acid, exhibited low frequencies and concentrations despite high domestic prescription amounts, suggesting transformation into metabolites or degradates in the aquatic environment. The contribution of sewage treatment plant effluent to the PPCP concentrations in the environment was estimated by examining the correlation between each PPCP and sucralose concentration. Sewage effluents appeared to be a significant contributor to the majority of target PPCPs; however, DEET and certain other PPCPs may originate from alternate sources. This study is the first to provide a comprehensive assessment of the occurrence and fate of PPCPs in Japan's aquatic environment. Future research should assess the environmental and human health risks of these PPCPs and identify the occurrence of their metabolites or degradates in the aquatic environment.

Per- and polyfluoroalkyl substances (PFAS) are thousands of toxic synthetic chemicals that bioaccumulate and persist in the environment. They are known to cause immunotoxicity, organ damage, endocrine disruption, and reproductive impairments in wildlife such as sea otters (Enhydra lutris). However, there is limited information on the distribution of these chemicals across the northeastern Pacific, and baseline data are missing to assess their potential impacts on sea otters in regions such as British Columbia (BC), Canada. We analyzed liver (n = 11) and skeletal muscle samples (n = 5) from 11 deceased sea otters from coastal BC using the U.S. Environmental Protection Agency method 1633 with ultrahigh performance liquid chromatography coupled to a triple quadrupole mass spectrometer. We found 8 of the 40 tested PFAS were present in all sampled sea otters, although concentrations of each PFAS varied between individuals. Sea otter livers contained more PFAS compounds at higher total average concentrations than skeletal muscle (i.e., 8 PFAS totaling 10.38 ng/g wet wt vs. 1 PFAS totaling 0.38 ng/g wet wt). Only perfluorooctanesulfonamide (PFOSA) was identified in both liver and muscle tissues, whereas the remaining 7 PFAS were unique to the liver. The three PFAS that dominated the liver PFAS composition (perfluorononanoic acid, PFOSA, and perfluorooctanesulfonic acid) accounted for 84% of the contaminant load in the livers. Geographically, PFAS concentrations were more than three times higher on average in sea otters recovered near major cities and shipping routes. Identifying the contaminants accumulating in sea otters provides insights into the health threats confronted by recovering sea otter populations. Our study also establishes baseline PFAS contamination levels in BC sea otters, which can be used to monitor and regulate the presence of PFAS on marine environments in western Canada.