Environmental Toxicology and Chemistry最新文献

Commercial beekeepers transport colonies across the United States to provide pollination services for >100 crops, especially for almond production in California. In these agricultural settings, honey bees are exposed to adjuvant compounds that are either included as "inert ingredients" in pesticide formulations or added as a separate adjuvant product to pesticides to improve application characteristics. However, evidence suggests that some of these inert ingredients pose risks to bees. This study used a Potter spray tower to determine the 48-hr acute toxicities (lethal concentration 50) of 37 pesticide inert ingredients or adjuvant principal functioning agents. Additionally, the toxicity trends of 15 alcohol ethoxylates were determined for structural and physical metrics, including moles of ethoxylation, number of carbons in the alcohol group, and hydrophilic-lipophilic balance. Last, median lethal dose values for an organosilicone (Silwet Eco) and a nonionic surfactant (Makon 10) were determined when applied to different parts of the adult honey bee. The results show that 25 of the 37 tested inert ingredients demonstrated a significant 48-hr dose-response and that 15 of these 25 inert ingredients had a median lethal concentration value below the maximum concentration tested. For alcohol ethoxylates, moles of ethoxylation and number of carbons in the alcohol group were not significant predictors for toxicity, but hydrophilic-lipophilic balance did show a significant trend with toxicity. The body placement assay indicated that applications to the dorsal part of the head and ventral thorax were generally the most toxic but that the two adjuvants produced differing results. The findings from this study can guide the selections of adjuvants and pesticide inerts to reduce risks to honey bees.

In acute fish toxicity tests, mortality has traditionally served as the primary endpoint. However, in accordance with the "3Rs" principle-replacement, reduction, and refinement-there is a growing need to minimize the suffering and pain experienced by test fish. In this study we aimed to establish a behavioral framework for identifying the moribund state in zebrafish (Danio rerio), providing a humane and ethically refined alternative endpoint. Continual observation of zebrafish exposed to 10 representative chemicals allowed the documentation of 12 clinical signs, with the severity of the signs evaluated by the death/clinical-sign ratio, which represents the proportion of fish exhibiting a given sign that subsequently died. The signs "immobility," "immobility at surface," and "lethargy" emerged as strong predictors of imminent death, each exhibiting a death/clinical-sign ratio of 1.0 across all tested chemicals and concentrations, indicating that all fish exhibiting these signs died within the 96-hr test period. Furthermore, the survival times from the onset of these signs to death were sufficiently short to justify their definition as moribund states. Accordingly, we defined these signs as moribund endpoints and propose that fish exhibiting any of them should be euthanized during the test period. Notably, these findings align with previously reported results in Japanese medaka, indicating the potential cross-species applicability of these moribund endpoints.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used as surfactants and repellents across industries such as textiles, personal care products, and nonstick cookware. In India, rapid industrialization and urbanization have increased PFAS usage, raising concerns about environmental contamination. Per- and polyfluoroalkyl substances are persistent, bioaccumulative, and have been detected in multi-environmental matrices including humans. This widespread contamination poses health risks to millions through water and food chains. Because PFAS usually occur as complex mixtures, comprehensive toxicity assessments addressing mixtures rather than individual compounds are urgently needed. The zebrafish (Danio rerio) is an established model for rapid toxicity screening and provides predictive insights into human health risks. This study evaluates developmental effects of two PFAS mixtures on zebrafish embryos and larvae: a 2-compound mixture (2-mix) consisting of perfluorooctanoic acid and perfluorobutanesulfonic acid, and a 24-compound mixture (24-mix) including long- and short-chain PFAS and their precursors. Developmental endpoints monitored were survival, hatching success, heart rate, and deformities. Morphometric analyses of head, eye, yolk sac, and pericardial areas were conducted with ImageJ. Oxidative stress was assessed via reactive oxygen species (ROS) quantification, and histopathology evaluated tissue alterations. Results revealed significant developmental toxicity, with the 24-mix causing delayed hatching, growth inhibition, blood accumulation, and reduced heart rate, whereas the 2-mix showed milder effects. Elevated ROS levels indicated oxidative stress in both groups, and histopathology confirmed damage to the eye, brain, and muscles. These findings demonstrate that prolonged exposure to environmentally relevant PFAS concentrations can induce significant biological effects. This study provides critical insights into PFAS mixture toxicity, informing risk assessments and guiding regulatory policy development to protect public health.

Aqueous film-forming foams (AFFFs) are widely used fire suppression products that have been identified as a direct source of environmental per- and polyfluoroalkyl substances (PFAS). Per- and polyfluoroalkyl substance exposure has demonstrated chronic and sublethal effects on biota. Ongoing efforts aim to reduce and, ideally, eliminate PFAS use in AFFF products. However, there is little known about the potential toxic effects of the new PFAS-free AFFFs, specifically on benthic organisms. The objective of this study is to quantify the effects of seven AFFFs on growth in the hard clam, Mercenaria mercenaria, over a 21-day exposure period with juvenile animals. Additionally, AFFF effects are reported from algal toxicity assays and a feeding study. Five of the PFAS-free AFFFs negatively impacted growth over the exposure period, while one PFAS-free AFFF and the reference PFAS-containing AFFF had no observable effect. Median effect concentrations (EC50) for shell growth ranged from 5.81 mg/L to >100 mg/L. Clam dry and wet weights also decreased with increasing exposure concentration (p  < 0.05). Algal growth was impacted over a 96-hr exposure. Impacts were observed to final standing biomass and overall growth rates at the highest exposure concentrations. However, complete lethality was only observed for one PFAS-free product, suggesting lack of food availability was likely not the primary driver of growth inhibition for all products. Net particle clearance rates in AFFF-exposed clams were not found to be impacted, suggesting there was no obvious AFFF influence on organismal feeding ability. The presented results identify chronic effects of exposure to these AFFFs in this economically and ecologically important bivalve species and are expected to inform decisions regarding PFAS replacement AFFF products.

Obtaining fine particulate matter (PM2.5) samples that are consistent with the natural composition of PM2.5 is crucial for toxicological research. However, current extraction methods inevitably alter the physicochemical properties of PM2.5. Based on variations in processing procedures: extraction solvent (water, ethanol, or dimethyl sulfoxide [DMSO]), sonication, and filtration steps (coarse filtration with 40 μm filters and fine filtration with10 μm filters), five PM2.5 extraction methods were developed, designated as WSF10, ESF10, DSF10, DCF10, and DCSF10, respectively. A mathematical model was developed to evaluate the similarity of PM2.5 samples, and the result showed that PM2.5 extracted by the DCF10 method (DMSO extraction, Coarse filtration, Fine filtration) were closest to that of natural PM2.5, with the highest overall similarity value of 0.70 (0.70 ± 0.01). The cytotoxicity of DCF10-extracted PM2.5 was significantly higher than other groups, inhibiting BEAS-2B cell viability by up to 60% after 9 days of exposure, which aligned best with the similarity results. The outcomes highlight that improper extraction methods may underestimate the actual toxicity of PM2.5. Therefore, optimizing and refining PM2.5 extraction protocols is critical for accurately evaluating its toxicity and providing valid evidence for health risk assessment.

Isoxazoline antiparasitic drugs are a new class of ectoparasiticides used in veterinary medicine for companion animals. Four active substances-fluralaner, (es)afoxolaner, lotilaner, and sarolaner-are marketed globally for flea and tick control. Isoxazolines exhibit long plasma half-lives in dogs and cats, with lotilaner reaching 30 days and sarolaner up to 41.5 days in cats. Their bioavailability varies with feeding; fasting significantly reduces lotilaner absorption. These drugs are primarily eliminated via the biliary/fecal route, with fluralaner showing a fecal elimination half-life of 3 to 12 days in felids and 6 to 38 days in canids. The European Medicines Agency has highlighted the risk of these substances contaminating ecosystems, though data on their environmental release are limited. Recent studies suggest that fluralaner and other parasiticides can be transferred to the environment via feces, urine, or pet hair. This study examined isoxazoline fecal elimination in dogs and cats. Elimination half-lives were determined in groups of five dogs or five cats per active substance. All animals received the drug according to label instructions. The estimated median half-lives were 15.5 and 22.0 days for fluralaner and lotilaner in cats, and 22.9, 24.6, 19.7, and 17.4 days for fluralaner, lotilaner, afoxolaner, and sarolaner in dogs, respectively. Fluralaner and lotilaner were still detected in feces after the end of the recommended treatment period. We used Monte Carlo simulations to assess the risk to nontarget arthropods. Environmental risk assessment indicated that dung-feeding insects could be highly exposed to isoxazoline parasiticides, with fluralaner and lotilaner having the greatest potential impact. These findings emphasize the need for further research on environmental contamination (pathways, quantitative estimate) and impact of veterinary parasiticides on nontarget species.

Aquatic and terrestrial food webs are linked by movements of aquatic insects during their development from larvae to adults. Contaminants can affect these linkages by reducing insect survival and increasing tissue contaminant concentrations through adult metamorphosis, thus changing contaminant flux from water to land. Most anthropogenically influenced freshwater ecosystems are exposed to multiple contaminants. To better understand the combined effects of contaminants on aquatic-terrestrial linkages, we investigated how adult aquatic insect emergence and tissue contaminant concentrations affect insect-mediated contaminant flux of mercury and pesticides from wetlands. In a field survey of 15 wetlands in the Prairie Pothole Region, an important agricultural region of North America, we found that insect-mediated mercury flux was 3.5 times more strongly predicted by emergence biomass than tissue mercury concentration. Thus, factors that were previously found to influence aquatic insect emergence biomass in this system-including insecticide tissue concentrations in adult insects, open water surface area, and agricultural land use-were the most likely to drive insect-mediated mercury flux. Pesticide flux, however, was 3.3 times more strongly predicted by the tissue pesticide concentration than by emergence. Thus, factors that influence pesticide exposure and, to a smaller extent, emergence biomass were the most likely to drive pesticide flux. Our results show how factors driving contaminant fluxes by adult aquatic insects differ by contaminant class, and they suggest one mechanism by which toxic effects of one contaminant (pesticides) could influence the flux of another (mercury). Predicting contaminant fluxes in areas where different mixtures of contaminants are present can aid in identifying risk to insectivores.

The per and polyfluoroalkyl substance (PFAS) precursor alternative, 6:2 fluorotelomer sulfonate (6:2 FTS), has been detected globally. The central aim of this work was to evaluate the chronic toxicity of 6:2 FTS for this understudied PFAS. Using the amphibian African clawed frog Xenopus laevis, we tested the main hypothesis that, regardless of sex, the sensitivity of this model to 6:2 FTS would be comparable with that of North American amphibians. Larvae were exposed to 6:2 FTS (1.2-1,200 ppb) from Niewkoop and Faber (NF) stages 51 to 65, which took a range of 24 to 42 days. We found significant growth stimulation at 120 ppb (26% mass increase, 6% snout-vent-length increase) without traditional dose-dependency. This growth stimulation coincided with a nonsignificant developmental delay at 120 ppb (38.0 ± 2.9 vs. 35.5 ± 1.8 days to NF 65). The nonmonotonic response yielded dual no observed effect concentration/lowest observed effect concentration (NOEC/LOEC) interpretations: (1) growth stimulation with a NOEC = 12 ppb and a LOEC = 120 ppb; and (2) adverse effects with a NOEC = 1,200 ppb. Xenopus laevis sensitivity to 6:2 FTS appears comparable with North American native amphibians (reported NOECs: 800-1,800 ppb), although the stimulation response and lack of a dose response complicates their application for assessing ecological risks. Although genetic sexing enabled sex-specific analysis in this species, no differences in sensitivity or accumulation rates were detected. These findings highlight the critical importance of endpoint selection in PFAS risk evaluation and supports previous findings with other amphibians showing that exposure to environmentally relevant 6:2 FTS concentrations should not adversely affect growth and development.

The Society of Environmental Toxicology and Chemistry (SETAC) is a global organization whose mission is the advancement of environmental science and management through collaboration, leadership, communication, and education. On SETAC's 45th anniversary, the following question was raised: Are the 1979 founding principles of SETAC, multidisciplinary approaches to solving environmental problems, multisector engagement, and scientific objectivity, still useful, adequate, and effective in fulfilling its mission? In a special session held at the 45th Annual Meeting in Fort Worth, Texas, United States, a critical evaluation of the founding principles was initiated by reviewing SETAC's history and ongoing activities, and recommendations were made for the future. With few exceptions, participants appreciated SETAC's purposeful efforts to approach challenging environmental issues through multisectoral balance, an approach that is unique among scientific societies. We recognized that scientists have biases and views of what they find important, regardless of employing organization, and that objectivity is best served by being aware of these biases and views. SETAC's founding principles have stood the test of time and continue to provide a strong foundation for the Society's mission, and with a few suggested improvements, will continue to be instrumental in guiding environmental science, stewardship, and policy into the future. The significance of SETAC's contribution of robust science grounded in reliable evidence and data was recognized as being especially crucial at this time of triple planetary crisis (climate change, pollution, and biodiversity loss), compounded by rapid technological developments and geopolitical issues.