Environmental Toxicology and Chemistry最新文献

As a representative agent of bicyclic antidepressants, venlafaxine (VEN) has become widely used worldwide and is frequently detected in surface waters with concentrations ranging from ng/L to µg/L. To evaluate the toxicological effects of such medications on aquatic species, studies on environmentally relevant concentrations are essential. Zebrafish were used as a model organism to assess growth and development in larvae and examine tissue accumulation, oxidative stress, and DNA methylation in adults. The results showed adverse effects, including an 18.5% decrease in embryo hatching rate and an increase in mortality by 18.5%. There was also a reduction in body length (4.5%) and eye area (12.2%) in the larvae, along with abnormal developmental issues, such as pericardial edema, yolk sac edema, and spinal curvature. Venlafaxine and its metabolites induced oxidative stress, leading to observable toxic effects. In adult zebrafish, VEN and O-desmethylvenlafaxine (ODV) accumulated primarily in the liver, followed by the brain and intestines, and caused a reduction in DNA methyltransferase activity, leading to DNA hypomethylation. VEN had the most significant impact on DNA methyltransferase 1 and altered its conformation more than ODV. Overall, venlafaxine was found to be more toxic than its metabolites, providing a scientific basis for evaluating the toxic effects and ecological risks of antidepressant residues on aquatic organisms.

Plastic pollution constitutes one of the major environmental problems of our time, and in recent years, it has emerged as a significant threat to the environment and to various organisms, including bird species. In this context, this study, which provides the first data in Türkiye, aimed to determine the level of microplastic (MP) pollution in 12 bird species (Eurasian buzzard; short-toed snake-eagle; white stork; northern long-eared owl; common barn-owl; ruddy shelduck; Eurasian eagle-owl; scarlet macaw; common pheasant; Indian peafowl; common kestrel; and gray parrot). The results indicate that MPs were detected in 50% of the specimens (n = 20), with an average of one MP/item per individual. With an average of three MPs per individual, the short-toed snake-eagle was found to be the species with the highest MP accumulation. Fibers (range: 51-534 µm) were the most common type of plastic found in the gastrointestinal tract of birds, with ethylene vinyl acetate and navy blue being the most common polymer type and color, respectively. It was also found that the abundance of MPs increased with the weight of specimens, contributing to the hypothesis that there is a correlation between the size/weight of animals and increased levels of MP accumulation. These findings highlight the impact of plastic pollution on birdlife and the need for further monitoring to assess the ecological impact of pollution.

Occurrence of microplastics in the environment is well studied, but our knowledge of their distribution in specific locations, such as the sandboxes, which are integral parts of popular playgrounds for children, is limited. Pioneering research on the factors affecting the microplastic pollution of sandboxes in urban residential areas was conducted within three estates in Kielce, Poland. Sand samples (Σ27) were collected from nine sandboxes and examined for the presence of microplastics, using a simple quality control methodology proposed by the authors. Microplastics were found in each sample and their contents ranged from 60 to 5,540 items/kg of sand. Fragments and fibers were the most prevalent types of microplastics in the samples. They contributed to approximately 95% of all microplastics found. Transparent fibers were the most abundant among fibers (63%) and red particles (57%) among fragments. A strong, positive, and significant correlation (rSpearman = 0.90) was found between the number of microplastic items and the location of sandboxes (above sea level). There was no correlation between the population density of the estates (rSpearman  =  0.03), the distance of the estates from the center (rSpearman  =  0.02), and the distance of the estates from main roads (rSpearman  =  0.43). Considering that sandboxes can be a potential source of microplastics for children, and assuming that sand ingestion by children is similar to the estimated daily soil ingestion rate, our results indicate that the number of microplastics ingested could be 1,106. Inhalation, dermal transport, and ingestion of microplastic particles from sandboxes pose a potential threat to children's health. However, more research is needed to better understand the health risks associated with this source of microplastics.

N-Nitrosamines are a class of compounds that includes the potent mutagenicity and carcinogenicity of many of its members and is distributed widely throughout the human environment. DNA alkylation by their diazonium ions formed metabolically acts as a molecular initiating event (MIE) that links molecular chemistry to mutagenicity. However, the regiochemistry for diazonium ions reacting with DNA bases is still under debate. Hence, density functional theory calculations involving SN2 alkylation of guanine (Gua) by 14 diverse diazonium ions are presented, the results of which showed the mutagenicity-related shift from GuaN7- to GuaO6-alkylation proceeds by increasing complexity of the alkylating agents, along with a greater proportion of SN1 characteristic in SN2 transition states. Hence, "high oxyphilic" and "low oxyphilic" alkylating agents may instead be "SN1" and "SN2" species, respectively. As the degree of MIE selectivity for hard-hard interactions can be quantified by hard and soft acids and bases theory, quantitative relationships were modeled between the nucleophilic index (ω-) and hydrophobicity (log P) of diazonium ions and their carcinogenic potency. Therefore, the mechanistic link from MIE to target toxicity can be bridged by computational chemistry.

Chloride concentrations in freshwater are rising, with toxic effects on aquatic life. In temperate regions with cold winters, road salt used for deicing paved surfaces is a primary cause. There is evidence that water hardness can modify salt toxicity, but data are insufficient to inform policy. Because calcium is a primary ion influencing water hardness and there is widespread calcium decline in lakes, we examined the effects of varying calcium concentrations on acute salt toxicity in three Daphnia species to gain a greater understanding of the water hardness-salt toxicity relationship. We conducted 48-hr acute sodium chloride (NaCl) toxicity tests, using chloride concentrations as our metric, on neonates less than 24 hrs old in six calcium treatments: 1.5 to 128 mg/L (hardness ∼7 to 323 mgCaCO3/L). We determined the effective concentration of chloride that was lethal to 10%, 25%, and 50% of the sample populations from each iso-female line in each calcium treatment. Acute NaCl toxicity decreased as calcium concentrations increased. The relationship between NaCl toxicity and calcium concentration differed among Daphnia, such that Daphnia catawba and Daphnia pulex were more sensitive to NaCl in lower calcium treatments and less sensitive in higher calcium treatments compared to Daphnia pulicaria. Our results provide evidence that water quality guidelines are not protective enough for aquatic life in very soft water (≤3 mg Ca2+/L, 11.3 mg CaCO3/L) because most ECxx values we found for Daphnia were significantly lower than Canada's national guidelines for short-term chloride exposure. There are already many lakes with calcium concentrations below 3 mg/L, and global widespread calcium decline may put more aquatic ecosystems at risk of experiencing NaCl toxicity.

This study assesses the occurrence of emerging contaminants (ECs) from agricultural and livestock production activities along the Salado River (Santa Fe province, Argentina). Of the 23 ECs studied, 8 were detected and quantified in river and wastewater samples, including ciprofloxacin, enrofloxacin, chlorpyrifos-methyl, albendazole, fenbendazole, levamisole, diazepam, and thiamethoxam. In river samples, the highest concentrations corresponded to ciprofloxacin, chlorpyrifos-methyl, and enrofloxacin. In wastewater samples, albendazole, fenbendazole, ciprofloxacin, enrofloxacin, and thiamethoxam were found. The detection frequency ranged from 4.2% to 54.2% in river samples and from 11.1% to 22.2% in wastewater samples. The spatial distribution of contaminants showed different concentrations, with higher levels often found near urban and agricultural areas, suggesting anthropogenic sources. Ecological risk assessments for different organisms were conducted. Ciprofloxacin posed the highest risk, especially affecting bacteria, cyanobacteria, and algae. Diazepam also was found to pose significant risks to algae, crustaceans, and fishes. Chlorpyrifos-methyl was identified as highly hazardous to multiple living organisms, which is in agreement with the fish mortality that occurred at the sampling sites. The risk assessment in humans showed differences among children, adolescents, and adults, with infants (6 months to 1 year) being at a higher risk than adults. Children may be at a higher daily intake of contaminants than adults, raising concerns about the long-term effects of exposure. This work underscores the critical need for monitoring and regulating ECs in aquatic environments. Further studies are necessary to fully understand their impact and to develop effective strategies for mitigating their presence in water systems.

The widespread use of acephate, a common insecticide, raises concerns about its potential impacts on nontarget soil organisms. This study investigated the chronic effects of acephate on the reproduction of two key soil fauna species, the springtail Folsomia candida and the enchytraeid Enchytraeus crypticus. We exposed these organisms to acephate in both natural Cambisol soil and tropical artificial soil (TAS) to assess potential impacts under different environmental conditions. Our results revealed significant reductions in reproduction for both species, with effects ranging from 38% to 49% (based on control and lowest observed effect concentration values). Furthermore, the observed effects were dependent on both the organism and the soil type. Springtails exhibited greater sensitivity in TAS than in Cambisol (0.09 and 15.0 mg a.i. kg-1 soil dry wt, respectively), whereas enchytraeids were more sensitive in Cambisol than in TAS (1 and 100 mg a.i. kg-1 soil dry wt, respectively). These findings highlight the importance of considering species-specific responses and soil properties when evaluating the ecological risks of pesticides on soil fauna communities.

Monitoring of genotoxic chemicals released into the water cycle or formed through transformation processes is critical to prevent harm to human health. The development of the high-performance thin-layer chromatography (HPTLC)-umu bioassay combines sample separation and detection of genotoxic substances in the low ng/L concentration range. In this study, raw, process, and drinking water samples from 11 different waterworks in Germany were analyzed using the HPTLC-umu. A genotoxic response was detected in three out of 42 samples (one raw water sample and two drinking water samples). Genotoxicity testing using the micronucleus and p53-CALUX (chemical activated luciferase gene expression) assays revealed genotoxic effects for the raw water sample and one of the drinking water samples. Fortunately, only minor genotoxic effects could be detected in the two drinking water samples, with estimated 4-nitroquinoline-N-oxide equivalency concentrations of 0.12 ng/L and 0.17 ng/L, respectively. After extraction of the genotoxic zones from HPTLC plates, identification attempts were conducted with nontarget analysis (NTA). A prioritization approach based on chlorine and bromine isotope pattern revealed several halogenated features for both drinking water samples. These tentatively identified substances were previously reported in the literature as possible carcinogens. Although the detected features could not be conclusively identified, the presence of halogenated features in the genotoxic effective zone of the HPTLC-umu assay strongly suggests that the chlorine disinfection process in both waterworks was responsible for the formation of the genotoxic substances in the drinking water samples. These findings emphasize that the HPTLC-umu in combination with additional genotoxicity assays and NTA can be used to evaluate even relatively clean samples, such as drinking water.

In contrast to microplastics, studying the interactions of nanoplastics (NPs) with primary producers such as marine microalgae remains challenging. This is attributed to the lack of adequate visualization methods that can distinguish NPs from autofluorescent biological material such as marine algae. The aim of this study was to develop a method for labeling and visualizing nonfluorescent micro- and nanoplastics (MNPs) of various polymer types, shapes, and sizes, in interaction with marine primary producers, which are autofluorescent. A labeling technique for plastics was refined, using a swell incorporation method with the commercial dye "IDye." Comprehensive quality control measures, including toxicity, leaching, and dye longevity tests, were applied to ensure the robustness of the method. Although stimulated emission depletion (STED) microscopy successfully enabled the visualization of the diverse labeled NPs smaller than 200 nm, it could not distinguish NPs from autofluorescent organic material such as marine microalgae, due to overlapping excitation and emission spectra with the photosynthetically active molecule chlorophyll-a. This study is the first to advance the field by coupling STED with fluorescence lifetime imaging microscopy (FLIM). The FLIM technique, based on the differing lifetimes of fluorescent signals, allowed us to overcome the challenge of overlapping spectra. Our work not only refines and expands existing plastic labeling protocols to accommodate a wide range of polymer types, but also introduces a more precise method for studying interactions between MNPs and autofluorescent organisms. This combined STED-FLIM approach provides a reproducible and reliable framework for examining MNP impacts in complex, ecologically relevant environments, particularly highlighting its potential for investigating MNP-microalgae interactions.