Environmental Toxicology and Chemistry最新文献

Oxytetracycline (OTC), a key antibiotic used in global aquaculture, has still unclear ecotoxicological effects. In this study, freshwater fish Piaractus mesopotamicus were fed with diets containing 750 mg kg-1 either pure OTC (ATB1) or commercial OTC (ATB2) for 10 days (treatment period-TP), followed by a 21-day withdrawal period (depuration period-DP). Fish fed with ATB2 showed decreased hematocrit (at DP) and increased glucose levels (TP and DP). In general, catalase activity increased in the liver, gills, and muscle of OTC-treated individuals at both TP and DP, particularly with ATB2. Similarly, glutathione S-transferase activity rose in the brain, gills, and muscle (TP and DP). Conversely, alkaline phosphatase activity in the liver decreased in both treated groups (TP and DP). Additionally, only ATB2 induced lactate dehydrogenase in fish muscle after 1-day depuration. Principal components analysis (PCA) identified most antioxidant enzymes, hematocrit, weight, length, and mean corpuscular hemoglobin concentration as key biomarkers, distinguishing ATB2 from control fish. These results indicate that the dietary therapeutic dose of OTC caused adverse effects in P. mesopotamicus. Differences in biomarker responses between ATB1 and ATB2 might be linked to unknown compounds in the commercial formulation, potentially influencing biological responses or altering OTC bioavailability. Further research on the toxicity of antimicrobial impurities and degradation compounds should accompany enhanced quality control measures in aquaculture to guarantee sustainable and safe products.

The use of pesticides has become a worldwide concern, and Brazil is one of the countries that release the most pesticides and is affected by them. These chemical substances, when in contact with the human body, can cause health problems such as nephrotoxicity, neurodegeneration, and even cancer. This study investigates how direct and indirect pesticide exposure interferes with acetylcholinesterase (AChE) and hematological parameters. This cross-sectional study was conducted in Sergipe, Brazil, and included 378 participants. The impact of pesticides on AChE and hematological parameters in individuals exposed to these agents was evaluated. Triazine (TZ) and Organochlorine (OC) classes combination generated the lowest AChE. A lower mean for AChE for individuals directly exposed to pesticides (p < 0.05) was observed. Men and younger individuals tended to have lower levels of AChE, as did individuals who declared themselves black or yellow or did not declare any ethnicity. As for hematological alterations, micronuclei (MN) were detected in 12.2% of farmers and 8.7% of families and neighborhoods. We found that AChE values tended to increase with the number of platelets and red blood cells (RBC). Still, we did not detect any other relationships between AChE and the type of exposure with hematological parameters. These findings contribute to evaluating the impact of pesticide exposure on human health. Thus, it allows us to infer that individuals directly exposed to pesticides tend to have lower levels of AChE, demonstrating the need to monitor these clinical parameters in individuals exposed to these agents and seek to identify the profile of this population.

The popularity of plastics in major application sectors is creating an increasing burden of pollutants in the environment in the forms of plastics and microplastics. More than 6 billion tons of plastics now reside in the environments which are now an available source of secondary microplastics. Research focused on the degradation of plastics/microplastics dealing with different environmental conditions and their change in properties. Despite being a serious pollutant, sufficient resources are still missing for the transformation of secondary microplastics from large plastics and how to detect the level of degradation before this transition. This article's brief review provides insight into the current scenario of plastics, disposed waste plastics, management system, and their limitations. In addition, a detailed explanation of the transition of plastics to microplastics, their mechanism, and the effect of different geographical conditions on degradation is also demonstrated. Moreover, the available analytical techniques to understand the degradation index of different polymers are also described in addition to the future perspectives for research in this area. This review could provide valuable insight into the formation of microplastics from waste plastics and their mechanisms in addition to a comprehensive knowledge of the quantification of the degradation.

Sea star wasting syndrome (SSWS) has affected numerous species of sea star, with populations of Pycnopodia helianthoides (Brandt, 1835) left most at risk. As their populations are struggling to recover, it is important to gain a better understanding of the impacts that the multiple stressors in their habitats can have on their populations. Contaminant stressors in particular are of increasing importance, as aquatic organisms can be exposed to a dynamic range of contaminants from nearby anthropogenic activity that may affect their future recovery efforts. This study is the first to quantify the effects of contaminant stressors on the larvae of P. helianthoides. We exposed P. helianthoides larvae to the neonicotinoid insecticide imidacloprid and polyester microfibers, both individually and in combination, at environmentally relevant concentrations (10 ng/L and 25 fibers/L, respectively) to measure the effects of these contaminants on their early life stages. Imidacloprid exposure resulted in stomach malformation in 10% of larvae and increased mortality during early development (p < 0.001), and all treatments resulted in increased larval lengths relative to controls (p < 0.001). During settlement, imidacloprid resulted in more rapid settlement responses than in the controls (p < 0.01). These findings highlight the need for further research investigating the effects of contaminant stressors to endangered organisms during reintroduction, as well as a more comprehensive understanding of the effects of pesticides to non-target organisms.

Arthropods, abundant in farmland, have unique biological traits that make them valuable for studying the ecotoxicological impacts of pollutants. Recent advancements in multi-omics technologies have enhanced their use in assessing pollution risks and understanding toxicity mechanisms. This paper reviews recent developments in applying omics technologies-genomics, transcriptomics, proteomics, metabolomics and meta-omics to ecotoxicological research on farmland arthropods. Agricultural arthropods manage genes and proteins like metallothioneins (MTs), antioxidant enzyme systems, heat shock proteins, cytochrome P450 (CYP450), carboxylesterases (CarEs), and glutathione S-transferases (GSTs), for detoxification and antioxidant purposes. They adjust amino acid, sugar, and lipid metabolism to counteract pollutant-induced energy drain and modify gut microbiota to aid in detoxification. This study advocates for enhanced analysis of compound pollution and emerging pollutants using multi-omics, especially meta-omics, to clarify the toxicological mechanisms underlying arthropod responses to these pollutants. Furthermore, it underscores the urgent need for subsequent gene function mining and validation to support biological control strategies and promote sustainable agricultural practices. The findings of this research provide significant insights into the toxicological impacts and mechanisms of pollutants within farmland ecosystems, thereby contributing to the preservation of arthropod diversity.

The United States Environmental Protection Agency (USEPA) has a conditional requirement for a chronic toxicity test with mysids (Americamysis bahia) for registration of pesticide products. Achieving performance acceptability criteria in control treatments for this study can be challenging because the current draft test guideline, which was published in 1996 under USEPA Office of Prevention, Pesticides, and Toxic Substances (OPPTS) 850.1350, Mysid Chronic Toxicity Test, provides limited information on study design and conduct. This critical review was undertaken to 1) identify areas of inconsistency in acceptability criteria between the 1996 draft OPPTS test guideline and ASTM International test guidance, 2) highlight areas that require additional clarification, 3) discuss areas that are impractical or have uncertain scientific relevance regarding the objectives of the test, and 4) provide recommendations for revision of the draft OPPTS test guideline. To achieve this, 116 final study reports from chronic mysid toxicity tests conducted over approximately the past 30 years were collected. From these reports, survival, growth, and reproduction data from negative and solvent control groups were compiled. Through investigation of trends in the data, it became apparent that no-observed-effect-concentrations (NOECs) were most commonly based on reproductive endpoints, followed by adult growth endpoints and adult survival. Notably, less than 1% of studies had a NOEC based solely on a second-generation measurement endpoint. Analysis of this comprehensive data set provided clarity on the establishment of acceptability criteria for the study and elements of the testing procedure that can be streamlined without loss of critical information, which resulted in a set of recommendations to improve future versions of the chronic mysid toxicity test guideline.

Feeding rate alteration is one of the first observed responses when animals are exposed to toxic stress and recognized as relevant tool for studying chemical compounds toxicity. However, food substrate that are currently used for ecotoxicity tests are not always easily available compared to referenced products. Using the European freshwater amphipod Gammarus fossarum, we here proposed for ecotoxicity tests a standardized food substrate fabricated with referenced ingredients: the MUG® (Meal Unit for Gammarid). To investigate the suitability of using MUG® to study behavioural response of amphipods to toxic stress, we explored in laboratory-controlled conditions whether three chemical compounds belonging to different families of contaminants (zinc (Zn): metal; methomyl (MT): insecticide; perfluorooctanoic acid (PFOA): Per-/poly-fluoroalkyl substance (PFAS)) could affect gammarids feeding rates on MUG®. First, we explored the effects of 7-day exposure to different concentrations of each contaminant alone. While PFOA did not affect feeding rate, zinc induced feeding behaviour on MUG® at lower concentration but inhibited food consumption at higher ones, whereas methomyl decreased feeding rate with increased concentration. Then, we explored effects when gammarids were exposed during 7 days to mixtures of molecules in pairs. No effect of mixtures was observed on MUG® consumption compared to control group. Observed effects of binary mixtures were also compared to predicted values based on additive effects of contaminants. Both Zn/MT and Zn/PFOA mixtures inhibited feeding behaviour compared to predictions, resulting in feeding rate values similar to control ones. Overall, our study supports that MUG® represent a promising standardized food substrate for evaluating substances effects on amphipods behaviour during laboratory ecotoxicological bioassays.

In regulatory aquatic risk assessment, toxicokinetic-toxicodynamic (TKTD) methods, such as the generalized unified threshold model of survival (GUTS), are already established and considered ready for use, whereas TKTD methods for aboveground terrestrial species, like arthropods, are less developed and currently not intended for risk assessment. This could be due to the fact that exposure in aboveground terrestrial systems is more event-based (feeding, contact, overspray, etc.), whereas exposure in aquatic systems is simply related to substance concentrations in the surrounding water. To provide a generic TKTD framework for terrestrial invertebrates, we propose a new GUTS variant that includes an intermediate buffer between the external exposure and inside of the organism. This buffer can be interpreted as residues on the exoskeleton or in the stomach, depending on the uptake route. Such an uptake behavior is mechanistically reasonable and observable in laboratory experiments. This GUTS variant, BufferGUTS, is particularly suitable for discrete or discretized exposure scenarios. Testing our model on honeybee datasets for 13 pesticides reveals a similar or better reproduction of survival curves than existing models (GUTS-RED and BeeGUTS) while keeping the number of parameters the same and making no substance or species-specific assumptions. The proposed new BufferGUTS approach can prospectively be used to derive TKTD parameters for a variety of terrestrial arthropod species. A standardized model definition for terrestrial species will facilitate the comparison and extrapolation of parameters between species and the applicability for terrestrial risk assessments.

Per- and polyfluoroalkyl substances (PFAS) are synthetic organofluorine compounds used in various products, which are highly durable in the environment and may pose risks to wildlife health. We investigated the blood cell concentrations of PFAS in breeding Scopoli's shearwaters (Calonectris diomedea) from three different colonies in the central and southern Mediterranean (Linosa, Malta, and La Maddalena). Shearwaters are flexible, high trophic level foragers, and foraging areas may differ according to sex and breeding stage. We examined inter- and intracolony differences in PFAS blood concentrations and compared them with exploited foraging areas and dietary tracers. Per- and polyfluoroalkyl substances were detected in all samples, with the major congeners detected in descending order being perfluoroctanesulfonic acid (PFOS), perfluoroundecanoic acid (PFuNA), perfluorododecanoic acid (PFDoDA), and perfluorotridecanoic acid (PFTriDA). The mean sum of PFAS during the chick-rearing phase was highest in the birds from Malta (145.1 ng/g dry wt, 95% confidence interval [CI] of the mean 106.8, 183.5) compared with Linosa (91.5 ng/g dry wt, 95% CI 72.9, 110.1) and La Maddalena (84.5 ng/g dry wt, 95% CI 61.7, 107.3), and the PFAS blood composition of shearwaters from La Maddalena and Malta differed. The PFAS concentrations in shearwaters from Linosa were higher during incubation than during chick-rearing, and males had higher PFAS concentrations than females during incubation. Some PFAS were associated with carbon and nitrogen stable isotope values. After baseline adjustment of stable isotope values, no differences were observed for adjusted δ15N and δ13C between the three colonies, suggesting that differences in PFAS levels attributed to diet were minor compared with regional differences. Our study highlights that shearwaters are useful biomonitors of PFAS exposure in remote marine areas.

Selenium (Se) occurs in natural surface waters as a variety of inorganic and organic chemical species, typically dominated by the oxyanions selenate and selenite. Organoselenium species, although hypothesized to be more bioavailable than oxyanions, have rarely been identified or quantified in natural waters and little is known about their fate or bioaccumulative potential. We studied spatial patterns of bioaccumulation in relation to aqueous Se speciation over 5 years at more than 100 locations near coal mine operations in southeast British Columbia, Canada. We used a sequential approach to fitting bioaccumulation model coefficients, first using sites with no detectable organic Se species (< 0.01 µg L-1) to describe the bioaccumulation of selenate and selenite, then applying those relationships to the remaining sites to infer the bioavailability of detectable organoselenium species. Our analysis indicated that the methylated species methylseleninic acid was the most bioaccumulative form, followed by dimethylselenoxide. Organoselenium species were associated primarily with mine sedimentation ponds and are presumed to be products of Se metabolism by algae and bacteria. Highly bioavailable organoselenium species exported from the ponds appear to be responsible for enhanced Se bioaccumulation in biota in downstream lotic reaches, with this influence diminishing with distance from ponds as concentrations decline. Our findings indicate that managing biological productivity in mine sedimentation ponds could help manage Se risk in the receiving environment.