Environmental Toxicology and Chemistry最新文献

Although banned long ago in many countries and jurisdictions, the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) and compounds related to it remain in the aquatic environment, particularly in sediments, and can pose risks to aquatic life. To inform ecological risk assessment of these compounds, we tested the toxicity of six DDT congeners, specifically the p, p' (4,4') forms of DDT, dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD), and dichlorodiphenylchloroethylene (DDMU), as well as the o, p' (2,4') isomers of DDT and DDD. The epibenthic amphipod, Hyalella azteca, was exposed for 7 days to waterborne chemical and assessed for changes in survival and growth. Median effect concentrations for biomass gain (aggregating effects on growth and survival) ranged from 0.14 µg/L (p, p'DDT) to 5.8 µg/L (o, p'DDD). Among p, p' congeners, relative toxicity was DDT ≫ DDD > DDE ≈ DDMU. Ortho-para' isomers were approximately five-fold less toxic than their p, p' analogs. Much of the observed effect was expressed as lethality, as half maximal effect concentrations based on biomass were on average only 25% lower than the corresponding median lethal concentration. Effects in parallel 7-day and 10-day exposures indicated close comparability between the two durations for o, p'-DDT. Application of these waterborne exposure endpoints in ecological risk assessment of contaminated sediments is discussed.

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.

The use of effect-based methods in water monitoring for identifying risks to aquatic organisms and human health is important for aiding regulatory decisions. In the past decades, the database on monitoring, especially in surface waters, has grown as this aquatic environment is openly exposed to various contamination sources. With regard to endocrine disruption, estrogenic and androgenic effects have been primarily investigated. Here, yeast-based bioassays emerged as potent tools, offering sensitivity to environmentally relevant concentrations and high robustness. The objectives of this study were to investigate further endocrine endpoints and extend the monitoring to ground waters. The inclusion of progestagenic effects is crucial due to their multifaceted roles in various functions of organisms. Hence, three different Arxula-yeast hormone screens (estrogen, androgen, and progesterone receptors) were applied, revealing simultaneous exposure to diverse endocrine effects in surface and ground water matrices. Although effect profiles in surface waters showed mainly activation of hormone receptors, in-ground water samples inhibitory effects clearly predominate. Although toxicological thresholds are not yet legally binding, they are essential for effective regulatory measures and risk management to ensure the good ecological status of aquatic ecosystems. The results were compared with effect-based trigger values for ecological as well as human risk assessment depending on the sample matrix, none of which were exceeded.

Copper (Cu) is an essential trace element and can accumulate in sedimentary environments. However, beyond a certain concentration threshold, Cu can pose toxicity risks to biota. Benthic foraminifera are widely distributed and exhibit characteristics such as high biodiversity, short life cycle, good preservation potential, and high pollutant sensitivity, making them good bioindicators. In this study, we investigated the responses of benthic foraminiferal communities to various Cu concentrations through environmental RNA metabarcoding under controlled laboratory conditions. Some foraminiferal genera-Glandulina, Pyrgo, Quinqueloculina, Sorites, and Vellaria-exhibited sensitivity to high Cu concentrations. Other genera-Ammonia, Operculina, Reophax, Bolivina, Glabratella, Miliammina, and Parasorites-displayed tolerance to high Cu concentrations. Moreover, high Cu levels led to reduced living benthic foraminifera abundance and interspecific interactions, albeit without inducing test deformities. Our findings provide a novel and efficient approach for exploring the responses of benthic foraminiferal communities to heavy metal pollution.

More than 30% of human food crop yield requires animal pollination. In addition, successful crop production depends on agrochemicals to control pests. However, agrochemicals can have negative consequences on beneficial insect pollinators, such as bees. We investigated the effects of an emerging class of pesticides, sulfoximines, on the common eastern bumblebee, Bombus impatiens. We performed a series of 96-hour toxicity tests on microcolonies of laboratory-reared B. impatiens. Our data showed that sulfoxaflor (SFX) is significantly less toxic to B. impatiens than historically used neonicotinoid pesticides, such as thiamethoxam. Further, for the first time, we found significant differences among castes in sensitivity to SFX; workers and drones were more sensitive than queens. These findings are notable because they reveal both caste and sex-specific differences in bumblebee sensitivity to pesticides. Interestingly, we found no evidence that bumblebees avoid SFX-contaminated sugar syrup. To the contrary, B. impatiens workers had an apparent preference for SFX-contaminated sugar syrup over sugar syrup alone. Overall, our investigation provides novel information on an important pesticide and may help inform regulatory decisions regarding pesticide use.

Methyl mercury (MeHg) is a widespread environmental contaminant that can have adverse effects on the health of vertebrate wildlife. This study focused on diets and MeHg contamination of nestling red-winged blackbirds (Agelaius phoeniceus) from a wetland in north Texas, USA. In previous research at the study site, a risk assessment model suggested that if emergent aquatic insects (i.e., odonates) were the dominant prey item in nestling diets, the health of nestling red-winged blackbirds could be negatively affected. The purpose of this study was to follow up on an earlier risk assessment and determine whether nestling red-winged blackbirds were accumulating elevated concentrations of MeHg at our study site. We had four objectives: (1) estimate the proportion of emergent aquatic insects, spiders, and terrestrial insects in diets of nestling red-winged blackbirds using a stable isotope-based dietary mixing model; (2) assess the concentrations of MeHg in emergent aquatic insects, spiders, and terrestrial insects; (3) assess the concentrations of MeHg in blood of nestling red-winged blackbirds; and (4) determine whether nestling red-winged blackbirds had MeHg concentrations that were high enough to pose a health risk. We found that nestling red-winged blackbirds had a diet dominated by terrestrial insect prey with low concentrations of MeHg and that the nestlings had low concentrations of MeHg in their blood, well below hazardous levels. The results of the study suggest that caution must be used when interpreting risk assessment models for nestling red-winged blackbirds. Because their diets can consist of varying proportions of emergent aquatic insects, spiders, and terrestrial insects, risk assessments based on estimates of diet from the literature that suggest nestlings could be at risk from Hg contamination should be followed up with studies to assess diet and/or the actual level of contamination of nestlings.

Passive samplers (PSs) deployed in the field for several months provide a time-averaged measurement of the freely dissolved concentration of pollutants, which is important for assessing ecological exposure and estimating pollutant loads. A comprehensive theoretical modeling assessment of the sampling time scale of integration (TSI) of an equilibrium PS is required to correctly interpret the results. We address this knowledge gap by modeling exchange kinetics of polychlorinated biphenyl congeners in low-density polyethylene (PE) PS based on diffusive transport and first-order kinetics. We evaluate the sampling TSI by analyzing the response of the PS to simulated pulsed concentration increases in the water column that lasted for 1 day in a total sampling period of 90 days. More hydrophobic compounds experience slower transfer into the sampler and show a longer TSI compared with less hydrophobic compounds. Similarly, a thick sampler shows longer TSI than a thinner sampler. The sampling TSI for a typical 25.4 μm PE sheet ranged widely from 14-15 days for a dichlorobiphenyl to 43-45 days for a hexachlorobiphenyl. We show that strategic deployment of a thick and thin passive sampler can be used to narrow the range of TSIs for all congeners and used to simultaneously capture episodic events along with long-term averages.

To enable risk characterization of perfluorooctane sulfonic acid (PFOS) in extended chronic and multi-generational exposures, we assessed PFOS bioconcentration in zebrafish (Danio rerio) exposed continuously to environmentally-relevant PFOS concentrations (0, 0.1, 0.6, 3.2, 20, and 100 µg/L PFOS) through 180 days postfertilization (dpf) in parental (P) and first filial generation (F1) fish. Exposures included five replicate tanks per treatment where whole-body PFOS concentrations were measured using 20-35 fish per replicate at 14 and 29 dpf in the P generation and one fish of each sex per replicate at 180 dpf for the P and F1 generations. Perfluorooctane sulfonic acid accumulation reached an apparent steady state at ≤ 14 dpf where whole-body wet-weight concentrations remained constant through 180 dpf in the P and F1 generations. The median bioconcentration factor (BCF) of 934 L/kg was observed for all PFOS exposures with a range from 255 to 2,136 L/kg which varied with PFOS exposure concentration and sex of adult fish. Significantly lower BCFs were observed in 20 and 100 µg/L PFOS exposures versus 0.1 and 0.6 µg/L indicating exposure-concentration dependance. Additionally, males had significantly increased (∼2×) PFOS accumulation and BCFs versus females in both P and F1 generations. Maternal transfer of PFOS was observed from P females to F1 eggs where maternal whole-body and egg PFOS burdens were equivalent, suggesting PFOS transfer to eggs was not a depuration pathway. Finally, a toxicokinetic model was developed that reliably reproduced PFOS whole-body burdens (data within 1.64-fold of predicted values) across all exposure durations spanning the P and F1 generations, providing a tool for PFOS bioaccumulation predictions relevant for risk assessment of acute, chronic, and multi-generational exposures.

Microplastics are widespread pollutants. Microplastics generated from the wear and tear of paints and coatings have recently been modeled to be a large source of microplastics to the environment. Yet, studies focused on microplastics broadly frequently overlook paint microplastics. In this article, we systematically reviewed the primary literature (turning up 53 relevant articles) on paint microplastic sources, identification methods, environmental concentrations, and toxicity to model organisms. Examples of sources of paint microplastics include paints from buildings and murals, crafts and hobbies, cars and roads, marine boats and structures, and industrial systems like pipes, sewers, and other infrastructure. Paint microplastics have been quantified in several marine samples from Europe and, to a lesser extent, East Asia. Reported concentrations of paint microplastics are up to 290,000 particles per kilogram of sediments, with the greatest concentration reported near a graffiti wall. Out of the toxicity studies testing paint microplastics, there have been 68 tested effects in total across all endpoints and organisms and 17 quantified lethal concentration 50% doses (ranging from 0.001 to 20 g/L). Of the tested effects, 45 observed endpoint values in the paint treatment were significantly different from the control (66%)-most of which were tests using antifouling paints. Overall, the number of studies on paint microplastics is small, limiting a holistic understanding of microplastics. Based on our synthesis of the state of the science on paint microplastics, we suggest a research agenda moving forward informed by research gaps.

Determining the impact of an oil spill on aquatic ecosystems is a challenge. Because of the chemical complexity of crude oil, risk assessments rely on quantitative structure associated relationships to group chemical classes of compounds based on similar modes of toxicity. Quantitative structure associated relationships like the target lipid model can be used to determine species sensitivity by determining the critical target lipid body burden (CTLBB) and can be used to calculate the toxic units (TU) of a mixture. In this study we used the CTLBB generated from single polycyclic aromatic compound toxicity data and the analytical chemistry of whole oil to predicted and validate toxicity of both water-accommodated fraction (WAF) of crude oil and chemically dispersed WAF (CEWAF) to American lobster (Homarus americanus) larvae. A two-step procedure for modelling whole oil partitioning was utilized to compute the dissolved components in each of the WAF and CEWAF dilutions. Then, a species and life stage specific CTLBB derived for lobster larvae was applied in PetroTox to compute the TUs of exposure solution. The approach used in this study was able to effectively predict the effects observed in the exposures and can be integrated into oil spill fate and effects models to improve the oil spill assessment and response.