Environmental Toxicology and Chemistry最新文献

This pioneering study represents a comprehensive comparative analysis of naturally occurring radioactive materials (NORMs: 226Ra (≈238U),232Th, 40K) on the roadside dust samples collected from a coastal city (Khulna) and a highly urban megacity (Dhaka), Bangladesh. The corresponding radioactivity was calculated based on Instrumental Neutron Activation Analysis of elemental abundances (uranium [U], thorium [Th], and potassium [K]). Averagen=30 radioactivity levels of 226Ra (≈238U), 232Th, and 40K in the road dust of Khulna city were 46.82 ± 24, 74.79 ± 25, and 541.14 ± 160.8, whereas in Dhaka city, they were 84.4 ± 13, 126 ± 11, and 549 ± 48 (Bq.kg-1), respectively. Khulna city had 1.3, 2.5, and 1.4 times greater 226Ra (≈238U), 232Th, and 40K radioactivity than the global average values, respectively. For Dhaka city, the following values were 2.42, 4.2, and 1.4 times elevated. The levels of radioactivity in Dhaka city are significantly higher than those in Khulna city; however, both cities have exceeded the world average values. The mechanisms for the enrichment and dispersion of NORMs from their fundamental source (surface soil) were studied, considering waterlogging, relative solubility-controlled leaching and translocation, climate conditions, and aerodynamic fractionations (dry and wet air deposition). The computation of standard radiological indices indicates risks to human health. Respiratory harm can be inflicted by α-particles originating from the radioactive decay products of 232Th and 238U. In addition to public awareness, policymakers should prioritize limiting the evolution of dust particles to mitigate the associated health risks.

Microplastics are discharged by municipal wastewater treatment plants (WWTPs); however, their uptake by filter-feeding freshwater bivalves is poorly understood. This study examined the abundance and characteristics of microplastics in wild bivalves from five locations along a 155 km stretch of the Grand River (Ontario, Canada) in 2021-2022, including upstream and downstream of three municipal WWTPs. At each site, fingernail clams (Sphaeriidae spp., n = 5 composites), freshwater mussels (Lasmigona costata, n = 10; gill, digestive gland, and hemolymph), and surface water (n = 3) were sampled at a single timepoint. Microplastics (particles >38 μm to 5 mm) were isolated and visualized via stereomicroscopy, and a subset chemically analyzed using Fourier transform infrared spectroscopy. Fingernail clams contained the highest total blank corrected microparticle counts (35.5 ± 29.4 g-1 [mean ± SD]), mussel tissues ranged from 4.3 ± 4.2 mL-1 in hemolymph to 6.5 ± 8.1 g-1 in digestive gland, and water contained 5.5 ± 2.8 L-1. Fibers were the dominant morphology across all samples, most particles were between 80 μm and 2 mm in length and, of those analyzed chemically, 30.0% were a plastic polymer. At sites downstream of WWTP outfalls, elevated counts were only seen in mussel gills and not in other bivalve tissues or water compared with upstream samples. Although microplastics were found across all sites in both biotic and abiotic compartments, results suggest little impact of WWTP discharges on their uptake in downstream bivalves.

Psychopharmaceuticals are used to treat psychological disorders and other conditions relating to the nervous system and are known to affect nontarget organisms at low concentrations. Their occurrence in the water cycle remains an understudied topic, with data lacking for many compounds, and risks not accounted for in removal targets. Therefore, this study aimed to provide insights into the presence, removal, and risks of psychopharmaceuticals in wastewater. Furthermore, the use of risk assessment in the context of proposed legislation is discussed. Thirty highly used psychopharmaceuticals were studied during 1 week in the wastewater of the Amsterdam West Wastewater Treatment Plant (WWTP) using solid phase extraction and ultra high performance liquid chromatography-quadrupole time of flight-high resolution mass spectrometry. Twenty target compounds were detected in the influent (17 ng-99 µg/L) and 16 in the effluent (34 ng/L-17 µg/L). Removal efficiencies during treatment ranged from 24% to >99%. Paracetamol, amphetamine, fluoxetine, levetiracetam, phenacetin, and sertraline demonstrated almost complete removal, whereas tramadol, lidocaine, lamotrigine, fluvoxamine, and carbamazepine had removals below 50%, with lidocaine demonstrating the lowest removal (24%). Utilizing existing ecotoxicity data, a preliminary risk assessment was performed to contextualize the calculated removal efficiencies. Here, sertraline and ibuprofen still demonstrated a potential risk, despite high removal efficiencies of both compounds. This study highlights that wastewater contains abundant numbers and ecotoxicologically relevant concentrations of psychopharmaceuticals that are insufficiently removed by the WWTP. The implementation of risk-based removal targets in legislation is discussed to facilitate the reduction in emissions of psychopharmaceuticals, for example, by adequate WWTP upgrades with advanced treatments to ensure a toxic-free environment.

Guidelines for ecotoxicity testing with Daphnia magna specify particular feeding protocols during the exposure, yet standardization for preexposure feeding remains ambiguous despite its recognized significance in affecting organismal metabolic capacity and tolerance. This ambiguity may contribute to disparate responses and heightened uncertainty in determining the effect concentrations of test chemicals, particularly those inducing metabolic effects through narcosis. Here, we address this gap through a three-step dose-response experiment with neonates of D. magna subjected to two alternative feeding regimes in the preexposure phase: starved and moderately fed during the first 24 hr after birth. Following this treatment, the daphnids were exposed to narcosis-inducing substances (polycyclic aromatic hydrocarbons; PAHs) for 72 hr before being transferred to clean media with algal food ad libitum for a 48 hr recovery phase. Daphnid survivorship, individual protein content, and body size at the end of each experiment phase-pre-exposure, postexposure and postrecovery-were compared between the treatments. Significant treatment effects were observed, including lower and less variable protein content in the starved daphnids entering the PAH exposure phase, yet higher survivorship and greater recovery potential in these daphnids compared with the fed individuals. Our findings underscore the importance of early-life food access and advocate for mandatory reporting of pre-exposure feeding regimes, particularly when testing substances acting via nonpolar narcosis.

Riparian spiders are used in ecotoxicology as sentinels of bioavailable contaminants that are transferred from aquatic to terrestrial habitats via emergent aquatic insects. Spiders in the family Tetragnathidae are particularly of interest because a high proportion of their diet consists of emergent aquatic insects and their contaminant loads reflect the amount transferred through the food web to riparian predators. The transfer of contaminants can be determined through food web tracers such as stable isotopes and polyunsaturated fatty acids; however, it is unclear how contaminants and tracers vary over the course of a year. The objective of this study was to determine whether seasonality affected size, carbon and nitrogen stable isotopes, polyunsaturated fatty acid biomarkers, mercury, and other trace metal concentrations in tetragnathid spiders. Spiders were sampled fortnightly from a single site on the Stones River in Tennessee, USA, for an entire active season (April through October). Spider mass and length steadily increased from April to September to a maximum average value of 0.078 ± 0.03 g, then decreased in October. Seasonal trends were observed for carbon and nitrogen stable isotopes, with significantly decreased signatures occurring late in the active season. Overall, methyl mercury concentrations (range: 12.1-134.4 ng/g) and the methyl-total mercury ratio (range: 49%-98%) increased throughout the active season, with higher variability observed at the end of the active season. Collectively, our results indicate that seasonality affected several important endpoints and that spiders collected during the end of the active season may not be representative of spiders during the entire active season.

Methylmercury (MeHg) is a globally ubiquitous and persistent environmental toxicant that negatively affects animal behavior, health, and reproduction. In birds, MeHg is transferred from female to egg, contaminating embryos during sensitive stages of early embryonic development and growth. This toxic exposure in the prenatal environment not only induces mortality but also possible lasting impacts on physiology, health, and survival, even once hatched. The purpose of our study was to further elucidate the negative effects of MeHg exposure during avian embryonic development and explore how such exposure can impact offspring development, growth, and survival, both in ovo and posthatch. To assess this, we experimentally dosed fertile mallard and wood duck eggs with MeHg II chloride and reared developing embryos and ducklings to various endpoints. We found that embryos not only readily accumulated MeHg throughout incubation, but they also displayed varying dose-dependent disparities in body mass and morphometrics, with control individuals being larger during early and late embryonic stages of development (p < 0.05). Furthermore, hatched offspring exposed to MeHg exhibited increasingly slower growth rates between 7 to 10 and 10 to 15 days posthatch (p < 0.05), and were found to have lower survival probabilities both under controlled laboratory conditions (p < 0.005), and in the natural environment (p < 0.05). Our findings on the detrimental effects of MeHg on avian embryos and hatchlings emphasize the need for more proactive means of environmental protection and remediation to protect vulnerable avian populations and the ecosystems they inhabit.

The European environmental risk assessment (ERA) of pesticides to soil invertebrates applies a correction factor (CF) of 2 to endpoints derived from toxicity tests with lipophilic pesticides (log Kow > 2) to correct for differences in organic matter (OM) content between artificial soil (AS) and natural soils. Because the applicability of this CF to springtails has never been assessed, this study investigated the influence of soil OM content on the toxicity of five pesticide active substances differing in lipophilicity to the springtail Folsomia candida. Toxicity tests following Organisation for Economic Cooperation and Development guideline 232 were conducted in AS containing 10%, 5%, and 2.5% peat and a natural soil (LUFA 2.2) with 4.5% OM. For all pesticides, toxicity (median lethal and median effect concentrations [LC50s, EC50s]) differed significantly between soils and strongly negatively correlated with soil OM content in AS (r2 > 0.88). Utilizing the regression equations derived from the data, LC50s and EC50s were calculated for soils with 10% and 5% OM. For EC50s, the differences in model-estimated toxicity between these soils ranged from 1.85 to 3.23, sometimes exceeding the CF of 2. To identify differences between species, data from a sister paper on the earthworm Eisenia andrei was used. Although ratios between model-estimated EC50s in soils containing 10% and 5% OM were similar between species (2.08-3.24 for earthworms), pesticide-specific toxicity-OM relationships differed in some cases. Non-lipophilic pesticides were influenced by soil OM content in a similar manner as the lipophilic pesticides, showing that the influence of soil properties on non-lipophilic pesticides may currently be overlooked. Overall, this study shows that the CF of 2 suffers from erroneous assumptions concerning lipophilicity, OM content, and toxicity. Further research is required to improve our mechanistic understanding of the relationship between toxicity and soil OM content, ultimately increasing the ecological relevance of CFs used in ERAs.

Although not assessed in standard ecotoxicological tests, exposure to a toxicant that does not result in an observable adverse effect in the parents may lead to transgenerational effects. These are adverse effects observed in unexposed offspring as a result of their parents' exposure to a toxicant. The goal of this study was to investigate whether transgenerational effects are observed in freshwater snails exposed to a toxicant. Using copper (Cu) as a reference toxicant, this study investigated whether the magnitude of exposure to the parents of the freshwater snail Planorbella pilsbryi resulted in a change in sensitivity of juvenile snails to a subsequent aqueous exposure of Cu. This study also investigated whether transgenerational effects observed in juvenile snails born to exposed parents would change if the parents laid eggs after being given time to recover from their exposure to Cu. Juvenile snails born to parents that were exposed to Cu without being given time to recover had no change in their sensitivity to Cu exposure or in some cases they became less sensitive. This study also observed that when parents were given time to recover from the Cu exposure, juvenile snails tended to be more sensitive to a subsequent Cu exposure, that is, decrease in median lethal concentrations for juveniles with an increase adult exposure. This study demonstrates that exposure of parent snails to a toxicant does not necessarily result in a consistent and significant change in sensitivity of the offspring to the same toxicant.

Alkylcyclohexanones and alkylcyclohexanols are industrial chemicals produced in large volumes. Little is known regarding estrogenic activity of these chemicals in aquatic species. A series of para-alkyl subsituted hexanones and hexanols with varying chain length and branching were tested in a suite of in vitro rainbow trout binding assays and in an ex vivo rainbow trout liver slice/vitellogenin (Vtg) expression assay to assess estrogenic potential. Furthermore, the extent of biotransformation of these chemicals under test conditions was monitored. Cyclohexane, cyclohexanol, and 4-ethylcyclohexanol had no detectable estrogenic activity in these assays. Para substituted alkylcyclohexanones and alkylcyclohexanols with side chains containing three to six carbons were active in both assays. Alkylcyclohexanones and alkylcyclohexanols with other than para substitution were also estrogenic when tested in these assays. The binding affinity relative to estradiol in cytosol of active chemicals was low, ranging from 0.0016 to 0.000029%. Biotransformation of alkylcyclohexanones to alkylcyclohexanols occurred in the cytosol binding assay and in the liver slice assay, thus making those exposures a mixture of alcohol and ketone forms. Biotransformation did not occur in rainbow trout nuclear extract and recombinant binding assays, thus the exposure in these assays was to only the dosed chemical. Both alkylcyclohexanones and alkylcyclohexanols bound to the estrogen receptor in these metabolically limited assays. Significant induction of Vtg mRNA expression was seen in slice exposed to chemicals with measurable binding affinities. Often the induction levels were below maximum efficacy and occurred at concentrations slightly lower than toxic concentrations. Therefore, while these chemicals produced an estrogenic effect, it is considerably weaker than that of the endogenous hormone and occurred at concentrations close to those which produce toxicity.