Studies of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPDQ) toxicity have identified sensitive and resistant species within the subfamily Salmoninae, but thus far fewer than 10 species, all in two genera (Oncorhynchus and Salvelinus), have shown sensitivity in experiments. The Arctic grayling (Thymallus arcticus, Salmonidae, Thymallinae) was extirpated from its range in the Great Lakes region of the United States, but because of the importance of this species to the Native American tribes of Michigan, a reintroduction effort is underway. Because high 6PPDQ concentrations have been found in Great Lakes tributaries, it is important to understand if this species is at risk from 6PPDQ exposure. Using standard methods with flow-through exposures to provide stable 6PPDQ concentrations, we exposed Arctic grayling at 3 weeks after swim-up to a series of 6PPDQ concentrations for 96 hr, evaluating mortality and measuring tissue concentrations of 6PPDQ in surviving and dying fish. We observed that grayling were sensitive to 6PPDQ, with 24- and 96-hr median lethal concentrations of 5,136 and 3,137 ng/L, respectively. Tissue concentrations were much higher than those observed in other sensitive salmonines in previous studies. While this is only the third genus found to be sensitive to 6PPDQ leading to acute lethality and the first species outside of Salmoninae, the median lethal concentrations determined for the Arctic grayling exposed in this study are at 6PPDQ water concentrations unlikely to be encountered in situ.
Emerging environmental threats increasingly challenge public health systems, and these risks often outpace the ability of scientists and policymakers to respond effectively. To address this gap, horizon scanning offers a proactive approach to identify early signals of potential threats, enabling timely research and policy action. This commentary synthesizes insights from a 2024 workshop convened by the National Institute of Environmental Health Sciences and proposes strategies to develop a horizon scanning Community of Practice (CoP) for improved identification and response to emerging environmental health risks. This commentary addresses key challenges identified during the 2024 workshop including slow risk assessment, fragmented data systems, and limited cross-agency communication. We also review existing successful frameworks for horizon scanning, including the Delphi method (using structured collective intelligence for foresight), the U.S. Interstate Technology and Regulatory Council Contaminants of Emerging Concern framework, and additional interdisciplinary collaboration models. We identify that effective models share common features: Clear objectives, structured yet flexible communication, and inclusion of diverse stakeholders, including nontraditional experts and affected communities. Empowering stakeholder "champions" and leveraging existing tools and networks enhance collaboration and efficiency. We propose that developing a horizon scanning CoP requires transdisciplinary collaboration, shared data standards, and inclusive engagement. Starting with focused, scalable efforts and building on existing frameworks can improve preparedness and enable more proactive, coordinated responses to emerging environmental health threats.
Herbicides such as chloroacetamides, chlorophenoxy acids, triazines, and bentazone are widely used in agriculture, contaminating aquatic ecosystems. However, their distribution and ecological risks in the Yangtze River are not clear. Thus, we analyzed 144 surface water samples (72 each in dry and wet season, respectively) collected from 72 sites along the Yangtze River mainstream, targeting 37 compounds, including these herbicides and their transformation products. Most compounds (31/37) were detected in > 90% of the samples. The dominant compounds were acetochlor oxanilic acid (median: 30.5 ng/L), atrazine (15.4), acetochlor ethanesulfonic acid (14.7), acetochlor (5.53), 2-methyl-4-chlorophenoxyacetic acid (5.27), followed by diaminochlorotriazine (4.72), bentazone (4.47), hydroxypropazine (3.93), prometryn (3.50), metolachlor (3.14), deethylatrazine (3.11), and others. The concentrations of the target compounds significantly increased from upstream to downstream; for example, the cumulative concentration in Shanghai (median: 660 ng/L) was approximately 300 times higher than that in Qinghai (2.18 ng/L). Significant seasonal variation was observed, with higher cumulative concentration in June (median: 198 ng/L) than December (63.9 ng/L; p < 0.05). The ecological risk assessment indicated that pretilachlor, acetochlor, prometryn, hydroxypropazine, hydroxyterbuthylazine, and butachlor oxanilic acid posed high risks (risk quotient of > 1) to aquatic organisms in some sampling sites. This study is the first to report the occurrence of some transformation products of the herbicides (e.g., hydroxysimazine, 4-chlorophenoxyacetic acid, and hydroxylated chlorophenoxy acids) in river water. Our findings highlighted the widespread occurrence of the herbicides in the Yangtze River, and targeted pollution mitigation for pretilachlor, acetochlor, prometryn and their transformation products is urgently needed, especially in the downstream reaches including Jiangsu and Shanghai, to protect the aquatic organisms.
Environmental contaminants frequently occur as complex mixtures in agricultural systems, yet their biological effects may persist even when residues are no longer detectable in harvested soybean seeds. This study evaluated whether a single soil exposure to ciprofloxacin (CIP), applied alone or in combination with glyphosate (G), induces persistent metabolic and developmental responses in soybean (Glycine max). Soybean plants were exposed at sowing to environmentally relevant concentrations of CIP (0.10 and 1.00 mg L⁻¹), either alone or combined with G. Ciprofloxacin residues were not detected in harvested seeds. However, integrated Ultra-High-Performance Liquid Chromatography (UHPLC), Gas Chromatography-Flame Ionization Detector (GC-FID), and ^1H Nuclear Magnetic Resonance (NMR) analyses revealed treatment-dependent alterations in folic acid, isoflavones, carbohydrate-related metabolites, and selected fatty acids. Exploratory multivariate analyses revealed distinct treatment-associated patterns and identified the low-dose combined exposure treatment as the most distinct metabolic profile. Although germination remained unaffected, progeny seedlings exhibited treatment-dependent differences in primary root development, indicating carry-over effects associated with parental exposure. The observed responses were particularly evident under combined exposure conditions, suggesting metabolic modulation associated with combined exposure. Collectively, these findings indicate that early-life contaminant exposure following a single application at sowing can be associated with persistent biochemical and developmental responses. These results highlight the importance of integrating metabolomic approaches with conventional residue analysis to improve the assessment of biological responses to emerging contaminants and contaminant mixtures in agroecosystems.
Artificial soil has been used in regulatory ecotoxicology and in general chemical toxicity testing with soil organisms since 1984. Formulated standard artificial soil (SAS), consisting of 10% finely ground Sphagnum sp. peat, 20% kaolinite clay, 69% quartz sand, and 1% CaCO3, is often used for assessing the toxicity of chemicals to various terrestrial organisms, including earthworms, enchytraeids, collembola, and terrestrial plants. Recently, however, the use of peat in the SAS formulation has become less advisable due to peatland degradation. Therefore, toxicity studies have been conducted with the earthworm Eisenia andrei and the plants Medicago sativa (alfalfa), Echinochloa crus-galli (barnyard grass), and Lolium perenne (perennial ryegrass) to assess the utility of two potential organic matter (OM) alternatives to peat, including rye (Secale cereale) straw and fermented timothy grass (Phleum pratense) hay. These studies included exposing earthworms to boric acid in SAS (containing 5% peat) and in formulated soils with 5% rye straw or fermented timothy hay as OM components. Toxicity benchmarks derived from the present studies indicate that the two chosen OM alternatives have the potential to be suitable replacements for peat in SAS. However, the suitability of the alternative formulations may be species-specific and would require further testing to support regulatory acceptance of the investigated components for use in toxicity testing.
Microplastic (MP) ubiquity has led to their detection in many filter feeding organisms in aquatic environments. Interaction of MPs with filter feeding marine bivalves is known to vary with particle morphology, yet temporal dynamics, organ-specific retention and egestion patterns remain poorly characterized in freshwater bivalve species. We exposed the adult freshwater unionid mussel Megalonaias nervosa (washboard) to 150,000 MP/mL of 6 μm polystyrene (PS) spheres and 61 μm polyester (PES) fibers to determine ingestion and egestion patterns, and how these may differ between MPs. Accumulation dynamics differed markedly between particle types; PS sphere concentrations in mussel organs remained stable throughout the MP exposure period, while PES fibers increased logarithmically as time progressed. Presence of PS spheres was associated with each organ examined after only one day of exposure, while PES fibers were not detected in the gills and gonad until the third day of exposure. Counts of PS spheres in organs followed a ranking of digestive gland > gonad > gills > hemolymph > foot, while PES fiber counts ranked as digestive gland > gills > foot > gonad > hemolymph. The digestive gland was the primary site of MP accumulation, with counts being at least 60 times greater than any other organ examined. After 48 hr, M. nervosa depurated PES fibers more efficiently than PS spheres as indicated by the continuous egestion of PES, but not PS, throughout the 7-day MP exposure. Further, the feces and pseudofeces produced by M. nervosa when exposed to PES fibers was significantly higher in organic matter content. Adult M. nervosa in this study exhibited significantly different ingestion and egestion patterns according to different MP types. This suggests that MP characteristics influence availability and translocation into non-digestive organs, highlighting the importance of studying multiple particle types when considering the accumulation and depuration of MPs in filter feeding organisms.
Honey bees are important pollinators of wild and cultivated plants. They are therefore a key species in the environmental risk assessment of plant protection products in the European Union. As empirical assessments of effects on honey bees on field and landscape level are challenging, mechanistic modelling offers a powerful complement. Such models can predict exposure and effects in the field and are therefore increasingly accepted within the regulatory framework. The BEEHAVEecotox model is a model which links exposure to colony effects in a mechanistic manner. It uses standard regulatory data to derive individual-level dose-response functions and includes larval mortality. However, it requires separate exposure pathways to be represented using pathway-specific dose-response parameters, making parameterization challenging. We developed an alternative based on the general unified threshold model of survival (GUTS), a generic toxicokinetic-toxicodynamic (TKTD) model. It combines exposure pathways into one effect module with one set of parameters. We present BEEHAVEecoGUTS, the integration of GUTS as an optional effect module in the modular design of BEEHAVEecotox. We found that the effect predictions of the original dose-response and the GUTS module are broadly comparable in semi-field tunnel scenarios, while exploratory repeated exposure scenarios revealed stronger divergences between the modules, particularly at higher application rates. GUTS is therefore a viable alternative with simpler and more robust compound specific parameterization and a broader scope for further expansion. It moves from single point estimates of toxicity and exposure to a holistic exposure-effect link.
Risk assessment of antibiotics in water typically relies on chemical target analysis and hazards of individual compounds. This traditional approach may underestimate the total toxic pressure of this large group of compounds, as neither all classes of antibiotics nor their biologically active transformation products are fully represented in common target analysis methods. In this study, the MicroGLO panel, the WaterSCAN panel, and the Escherichia coli FhuAT bioassay were applied to extracts of different water types to evaluate the potential of in vitro bioassays to study the occurrence and fate of antibiotics in water. All three tools detected activity, representing the mechanisms of action of antibiotics in the extracts of spiked water and no or negligible activity in those of procedural blanks. This demonstrated their ability to distinguish between extracts that contain antibiotics and those that do not. All three tools detected activity in wastewater influent and effluent from different wastewater treatment plants and in several surface water bodies. Effect-based trigger values were exceeded at least once in all wastewater effluents, indicating potential risk to the environment even after wastewater treatment. This was not observed for surface water. Comparison with chemical analysis revealed that bioassays often detected activity when antibiotics were absent and vice versa, highlighting their complementary value. The E. coli FhuAT bioassay is recommended for initial screening for the presence of antibiotics, as it detects activity across different water types. This may be followed by the use of effect-directed analysis to identify the biologically active compounds causing the bioassay response, which is particularly recommended in cases where effect-based trigger values are exceeded. Alternatively, the MicroGLO panel and the WaterSCAN panel can serve to pinpoint which classes of antibiotics may be most relevant for further monitoring, as these bioassays can provide responses linked to specific mechanisms of action.
Behavioral alterations in terrestrial isopods emerged as early warning signals of soil pollution, but their link to specific physicochemical properties of contaminants remains unexplored. This study investigates whether specific chemical properties can predict two ecologically relevant behavioral endpoints in the gregarious isopod Porcellionides pruinosus. A combined avoidance-disaggregation bioassay was applied to a set of twenty-four substances referred to fourteen pesticides (1,3-dichloropropene (1,3-D), azadirachtin A, chlorpyrifos, dichlobenil, dimethoate, fipronil, glyphosate, parathion, pendimethalin, S-metolachlor, sulfoxaflor, terbuthylazine, triclopyr, trifluralin), five pharmaceutical and personal care products (PPCPs: Benzophenone-1 [BP-1], carbamazepine, N,N-diethyltoluamide [DEET], galaxolide, oxybenzone [BP-3]), and five polifluoro carboxylic acid (PFCAs: Perfluorobutanoic acid [PFBA], perfluorododecanoic acid [PFDoA], perfluorooctanoic acid [PFOA], perfluoropentanoic acid [PFPeA], perfluoropropionic acid [PFPrA]). The substances were categorised according to the effects they induced: Those that induced both avoidance and disaggregation, those that triggered only one of these effects, and those showing no detectable effects. Regression models revealed a significant positive association between disaggregation and the Henry's law constant, with a threshold value estimated at 1 × 10-³ Pa m³ mol⁻¹, beyond which aggregation breaks down. This value can be proposed as a potential indicator in the regulatory field for predicting the impact of a substance on the social behaviour of woodlice, supporting management decisions in assessing the impact of contaminants on soil. Conversely, no predictive descriptors were found for avoidance responses, indicating that the mechanisms underlying migration remain to be elucidated. Furthermore, given the heterogeneity of behavioural responses, the combined use of avoidance and disaggregation endpoints is recommended for a more comprehensive investigation.
Ecological relevance of arbuscular mycorrhizal fungi (AMF) led the European Food Safety Authority (EFSA) to identify AMF as a potential group of non-target in-soil organisms to be included in environmental risk assessment (ERA) of plant protection products (PPPs). Currently, no OECD test guidelines including AMF exist, and technical specification standard documents are limited to ISO/TS 10832:2009 for pre-symbiotic phase testing and AFNOR FDX31-205-2 for symbiotic phase testing. A new methodology was developed to assess the effects of contaminants on the AMF-plant symbiosis and the method described in the ISO/TS document was updated with new methodologies and test conditions. A ring test involving nine laboratories for symbiotic-phase experiments and six laboratories for pre-symbiotic-phase experiments was performed to assess the validity of these methods using Rhizophagus irregularis, artificial soil and two fungicides (Azoxystrobin and Fluazinam). Allium ampeloprasum was the host plant used in the symbiotic phase tests. Endpoints estimated during the ring test were variable: 8-week EC10 for total colonization in the symbiotic phase varied from 0.1 to 5 mg/kg of soil for Azoxystrobin (coefficient of variation (CV)=123.5%) and 0.03 to 7.8 mg/kg for Fluazinam (CV = 185.9%); in the pre-symbiotic phase, 14-day EC10 for spore germination with Fluazinam was 0.6 mg/kg of soil and for Azoxystrobin 0.4 and 1.4 mg/kg of soil (CV = 78.6%). The outcome of the ring test suggests a potential sensitivity of AMF but the high data variability and the fact that the validity criteria are frequently not met indicate that further development of the test system is needed. Nevertheless, comparisons between these data and data from published studies suggest that AMF may be more sensitive than other non-target soil organisms currently considered in EU ERA, particularly for Azoxystrobin. Consequently, current ERA procedures may not provide sufficient protection for AMF communities, but additional data are needed to confirm this assumption.
Geotaxis is the behaviour of an organism in response to gravitational forces. Mosquito larvae display innate negative geotaxis in water. This study explored how exposure to pymetrozine (PYM) and manganese (Mn) affects the geotaxis of Culex sp. larvae in water, and whether this behaviour could be a useful endpoint in aquatic ecotoxicology. Culex sp. larvae were exposed to varying concentrations of both chemicals, and their geotaxis was monitored for ten min. Additionally, 24-hr mortality bioassays were carried out to obtain novel data on the lethal effects of both chemicals on Culex sp. larvae. Mortality experiments revealed that PYM caused significant larval mortality with an LC50 of 60.75 (54.29-67.98) mg/L. Mn showed a moderate lethal effect with an undetermined LC50 value due to insufficient mortality across the tested concentration range (i.e., 0-345.50 mg Mn/L). Geotaxis testing revealed that in the control, the mosquito larvae spent, on average, 78.23% of their time in negative geotaxis. Exposure to Mn significantly decreased this innate rate to 62.71% in the 172.75 mg Mn/L treatment (p < 0.05), whereas exposure to PYM lowered it further to 54.54% in the 8.25 mg PYM/L treatment (p < 0.05). These significant reductions in negative geotaxis in contaminated water samples suggest that geotaxis could serve as a useful endpoint for the quick assessment of water pollution. However, because the geotaxis dose-response curves were biphasic, validation using other aquatic life forms may be required, especially at lower concentrations, to ensure that systemic shutdown in the larvae at higher concentrations is not misinterpreted as genuine geotaxis responses.
This study investigated 4 cyclic and 10 linear volatile methylsiloxanes (VMSs) in 155 dust samples collected across three regions in Vietnam. Despite their widespread use, research on the temporal trends of VMSs in dust within developing countries in Southeast Asia remains limited. The total concentrations of VMSs ranged from 55.1 to 20,300 ng/g (mean: 2,960 ng/g; median: 1,430 ng/g). Volatile methylsiloxane concentrations measured in indoor dust samples were significantly higher than in outdoor dust samples. Regionally, the highest concentrations were found in indoor dust collected from the north, followed by the south and central regions. Cyclic VMSs (mean: 1,850 ng/g) were more prevalent than linear VMSs (mean: 1,110 ng/g), with decamethylcyclopentasiloxane and octadecamethyloctasiloxane being the dominant compounds in their respective groups. A moderate correlation was observed between cVMS and lVMS concentrations, except in indoor dust from southern Vietnam. However, correlations between individual VMSs in indoor and outdoor samples were negligible. The positive matrix factorization analysis reveals a clear functional separation, yet active exchange between indoor and outdoor siloxane reservoirs. Indoor dust is dominated by emissions from consumer products and silicone materials, whereas outdoor siloxane profiles are primarily shaped by atmospheric aging, surface storage, and dust resuspension, favoring particle-bound linear homologues. The estimated exposure doses through dust ingestion were 2.47 ng/kg-body weight/day for adults and 3.94 ng/kg-body weight/day for children, suggesting a relatively low health risk.
Robust chronic ecotoxicological data are essential for EU pharmaceutical regulation, yet many ibuprofen studies in the public domain fail to meet quality criteria, creating uncertainty in its chronic aquatic toxicity profile. Additionally, due to the cost and complexity of full life-cycle fish tests, most studies focus on early/specific life stages rather than reproductive outcomes, limiting insights into population-level effects. The authors used a collaborative approach that included consultation with leading academic experts and regulatory authorities to develop a full life cycle test suitable for investigating the toxicological effects of ibuprofen to fish (Pimephales promelas). Fish were continuously exposed from F0 embryos (<24-hours old) through all growth and reproduction stages to the production and growth of free feeding F1 juveniles. The nominal test concentrations (0.01, 0.032, 0.10, 0.32, and 1.0 mg/L) were selected based on scientific literature and the findings of OECD 236 Fish Embryo Toxicity Tests (FET) and a larval growth test that were used as range finding tests. Ecotoxicology endpoints (NOEC, LOEC, EC10) of relevance were determined and no statistically significant effects were identified at the highest test concentration (1.0 mg/L) for all endpoints except F0 survival and F1 hatching success. These endpoints were considered to represent the most sensitive NOEC (0.32 mg/L) based on statistical significance (p < 0.05) but following additional statistics that identified an outlier the NOEC of ≥ 1.0 mg/L based on biological significance was concluded.
The Eastern oyster Crassostrea virginica is a filter feeder that is exposed to a variety of anthropogenic contaminants including pharmaceuticals in the seawater within its natural habitat. Atenolol, a β-adrenergic antagonists, is frequently detected in the marine environment. However, the impacts of atenolol on marine organisms have been understudied. This study aims to broaden our knowledge of the impact of pharmaceuticals on marine invertebrates by evaluating the impact of the β-adrenergic antagonist atenolol on oysters hemocytes and assessing the use of C. virginica hemocytes as a screening tool. Results indicate atenolol is sub-lethal with no impact on viability. However, apoptosis temporarily increased for hemocytes exposed to 266 µg/L of atenolol. Furthermore, differences in response by agranulocytes and granulocytes were observed, supporting the need to evaluate hemocyte subpopulations along with the whole population. These findings suggest oyster hemocytes may be a useful tool in addressing the gap of knowledge in ecotoxicological impacts of emerging contaminants on marine organisms and can serve as a preliminary assessment of immunotoxicity of these contaminants prior to in-vivo experiments.
Groote Eylandt, Australia, is an island of international conservation significance as well as the site of one of the world's largest manganese (Mn) mines. Endangered northern quolls (Dasyurus hallucatus) living near active Mn mining sites on Groote Eylandt accumulate Mn at higher concentrations in the hair, testes, and brain than do animals living far from the mine. However, little is known about the potential developmental effects of Mn exposure on the tissues of quolls or other marsupials, and marsupial histology and ecotoxicology are relatively under-studied. We examined relationships between exposure to Mn and other toxic metals with histological endpoints of quolls and northern brown bandicoots (Isoodon macrourus). Male quolls (n = 18) and bandicoots (n = 9) were live trapped both near and far from mining activities, euthanized, and then dissected for target tissues (liver, lung, muscles [bicep, quadricep, skull], olfactory bulb), which were preserved in formalin for histology. Tissues were prepared using H&E staining and analyzed with Leica imaging software. Although we did not find differences in most tissues between animals collected near vs. far from the mine, we found that Mn exposure was associated with altered muscle histomorphology of quolls, potentially affecting their ability to find food and avoid predators. Our results showed clear differences between the muscle histology of quolls and bandicoots. Given the ecological importance of Groote Eylandt and the conservation needs of species such as quolls and bandicoots, information on exposure to contaminants and effects on health and development is critical to successful management, including environmental remediation.
Antiviral drugs (ATVs), such as oseltamivir carboxylate (OTC), are widely used to treat viral infections. Although environmental levels are in the ng/L to µg/L range, knowledge on risks posed by this substance class is hindered by limited assessments. Evidence on effects on microbially-driven ecosystem processes is especially scarce, which is concerning because viruses are omnipresent in the microbiome and likely to influence microbial functioning. We assessed the influence of OTC on anaerobic methane production, a greenhouse gas largely emitted from natural systems and responsible for around one third of greenhouse gas-driven warming, as a proxy for microbial ecosystem function. Oseltamivir carboxylate inhibited initial methanogenesis between 15% and 40% even at nanotrace levels (i.e., 0.006-600 µg/L). Given that in most treatments methane levels returned to those of the control, the initial inhibition is potentially attributed to a temporally limited OTC-induced shift from a neutral/temperate viral infection of prokaryotes toward a lytic viral replication. Mostly unaffected 16S rRNA metabarcoding community data indicate that this effect might be uniform throughout the community. This study points to ecosystem-level effects at the ng/L range of ATVs, suggesting a significant knowledge gap, which warrants further attention to this group of chemicals.
Copper (Cu) is an essential trace element but is often anthropogenically elevated to toxic concentrations, requiring organisms to adapt or perish. Wetland treatment systems (WTS) exemplify these conditions and are frequently colonized by amphibians. Previously, an acute Cu exposure study with southern toad (Anaxyrus terrestris) larvae from a WTS called A-01 exhibited high survival compared to reference populations, suggesting Cu tolerance. Conversely, embryos from another WTS called H-02 showed reduced survival in Cu treatments compared to reference populations, suggesting Cu intolerance. We conducted a chronic exposure trial with southern toads from A-01, H-02, and two reference wetlands 24 and 17 years since colonization of A-01 and H-02, respectively. We used nominal Cu concentrations of 0, 10, and 15 µg/L to assess survival, time-to and size-at metamorphosis throughout the embryonic and larval stage. Embryo survival did not differ by population, though the 15 µg/L treatment significantly reduced survival. However, in the 15 µg/L Cu treatment, the H-02 larval mortality risk was double that of the reference population (HR = 1.98; 95% CI [1.01-3.9], p = 0.047) and the odds of mortality were 3.3 times higher (Odds Ratio = 3.29, 95% CI [1.29-8.39], p = 0.013). In contrast, A-01 larval mortality did not diverge from the reference population. Our results indicate that 1) there is no evidence for Cu tolerance in either WTS population 2) the experimental approach for tolerance testing may impact outcomes, and 3) WTSs may have the potential to become ecological traps - an important consideration for amphibian conservation.
