Chemical composition and ecotoxicity of plastic and car tire rubber leachates to aquatic organisms

Toxicity and intergenerational accumulation effect of tire wear particles and their leachate on Brachionus plicatilis

Tire wear particles (TWP) are one of the main sources of microplastic (MP) pollution in the marine environment, causing adverse effects on marine life and attracting increasing attention. This study aimed to investigate the chemical composition of TWP (particles and leachate) and their toxic effects on Brachionus plicatilis. The results showed that Zn and acenaphthene were the most frequently detected compounds in the three TWP treatments. In the single-generation exposure experiment, TWP leachate showed the highest toxicity potential, followed by nano-TWP (<1 μm) and micro-TWP (1-20 μm). Both nano-TWP and leachate had negative effects on the lifespan and population of rotifers. High-concentration TWP leachate significantly shortened the reproductive period of rotifers, slowed down their swimming speed, and reduced the number of offspring. These negative effects were mainly attributed to the toxic mixture of nano-TWP with additives in the leachate. Furthermore, in multi-generation exposure experiments, the toxicity pattern showed a new trend: the toxicity of nano-TWP exceeded that of the leachate, while micro-TWP continued to maintain the lowest toxicity level. Continuous exposure to TWP exerted a significant negative impact on rotifer lifespan, and this effect increases cumulatively between generations. Notably, TWP was trans-generationally toxic to the lifespan of rotifers, and repeated exposure was more toxic than maternal exposure and continuous exposure. In addition, rotifers can ingest and accumulate TWP, and maternal transfer was another uptake pathway of TWP in rotifer offspring. This finding provided a new perspective for understanding the transmission mechanism of TWP in the marine food chain.

Marine Heatwaves Exacerbate the Toxic Effects of Tire Particle Leachate on Microalgae

Additives leached from tire particles (TPs) after entering the marine environment inevitably interact with marine life. Marine heatwaves (MHWs) would play a more destructive role than ocean warming during the interaction of pollutants and marine life. To evaluate the potential risks of TPs leachate under MHWs, the physiological and nutrient metabolic endpoints of microalgae Isochrysis galbana were observed for 7 days while being exposed to TPs leachate at current or predicted concentrations under MHWs. TPs leachate mainly contained Zn and 6-PPD, which could be absorbed by microalgae mostly, especially under MHWs. Additionally, TPs leachate increased the reactive oxygen species content, activated the antioxidant system, impaired photosynthesis and glycolysis, and decreased sugar and protein content. 10 mg/L TPs leachate increased the lipid content and saturation. Meanwhile, microalgae under such TPs leachate were biased toward the synthesis of long-chain fatty acids and Δ8 desaturation pathway. MHWs promoted the positive effects of TPs leachate on microalgae growth at the current concentration but exacerbated the negative effects at the predicted concentration. Our study emphasizes the potential risks of TPs leachate to marine primary production systems, especially if accompanied by the increasing intensity and frequency of extreme climate events.

Tire Wear Particles Exposure Enhances Denitrification in Soil by Enriching Labile DOM and Shaping the Microbial Community

Tire wear particles (TWP) are emerging contaminants in the soil environment due to their widespread occurrence and potential threat to soil health. However, their impacts on soil biogeochemical processes remain unclear. Here, we investigated the effects of TWP at various doses and their leachate on soil respiration and denitrification using a robotized continuous-flow incubation system in upland soil. Fourier transform ion cyclotron resonance mass spectrometry and high-throughput sequencing were employed to elucidate the mechanisms underpinning the TWP effects. We show that TWP increased soil CO2, N2, and N2O emissions, which were attributed to the changes in content and composition of soil dissolved organic matter (DOM) induced by TWP and their leachate. Specifically, the labile DOM components (H/C ≥ 1.5 and transformation >10), which were crucial in shaping the denitrifying community, were significantly enriched by TWP exposure. Furthermore, the abundances of denitrification genes (nirK/S and nosZ-I) and the specific denitrifying genera Pseudomonas were increased following TWP exposure. Our findings provide new insights into impacts of TWP on carbon and nitrogen cycling in soil, highlighting that TWP exposure may exacerbate greenhouse gas emissions and fertilizer N loss, posing adverse effects on soil fertility in peri-urban areas and climate change mitigation.

Plastic pollution and marine mussels: Unravelling disparities in research efforts, biological effects and influences of global warming

The ever-growing contamination of the environment by plastics is a major scientific and societal concern. Specifically, the study of microplastics (1 μm to 5 mm), nanoplastics (< 1 μm), and their leachates is a critical research area as they have the potential to cause detrimental effects, especially when they impact key ecological species. Marine mussels, as ecosystem engineers and filter feeders, are particularly vulnerable to this type of pollution. In this study, we reviewed the 106 articles that focus on the impacts of plastic pollution on marine mussels. First, we examined the research efforts in terms of plastic characteristics (size, polymer, shape, and leachates) and exposure conditions (concentration, duration, species, life stages, and internal factors), their disparities, and their environmental relevance. Then, we provided an overview of the effects of plastics on mussels at each organisational levels, from the smaller scales (molecular, cellular, tissue and organ impacts) to the organism level (functional, physiological, and behavioural impacts) as well as larger-scale implications (associated community impacts). We finally discussed the limited research available on multi-stressor studies involving plastics, particularly in relation to temperature stress. We identified temperature as an underestimated factor that could shape the impacts of plastics, and proposed a roadmap for future research to address their combined effects. This review also highlights the impact of plastic pollution on mussels at multiple levels and emphasises the strong disparities in research effort and the need for more holistic research, notably through the consideration of multiple stressors, with a specific focus on temperature which is likely to become an increasingly relevant forcing factor in an era of global warming. By identifying critical gaps in current knowledge, we advocate for more coordinated interdisciplinary and international collaborations and raise awareness of the need for environmental coherence in the choice and implementation of experimental protocols.

Temporal and spatial distribution of microplastics in the freshwater Atibaia river basin, Campinas-SP, Brazil

The contamination of surface waters by microplastics (MPs) is an emerging concern, due to their environmental impact and negative effects on biota. However, in recent years, although the occurrence of these pollutants has been widely reported in marine systems, studies on MPs in freshwater are still scarce in the literature, particularly in Southeastern Brazil. In this context, the current study aimed to provide unprecedented information on the abundance and spatial and temporal distribution of MPs in three sites located in the Atibaia river basin (Southeastern Brazil) - the main river, a tributary, and the discharge of effluent from a sewage treatment plant. Surface water was sampled in four sampling campaigns, two in wet season and two in dry season, between 2019 and 2020, at three sampling points. At each point, 200 L of water were collected with the aid of an aluminium bucket, followed by sieving in the field to isolate the particles between 100 μm and 5000 μm, using stainless steel sieves. Chemical identification of the polymer was performed by ATR-FTIR micro spectroscopy. The abundance of MPs in the water ranged from 188 to 533 items/m3. The water samples with the greatest MPs abundance corresponded to the sampling point that includes the receipt of domestic effluent treated by the local Sewage Treatment Station. The chemical identification of the polymers highlights polyester polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP) as the most frequent, respectively. This study emphasizes the importance of discharged domestic effluents and rivers as MPs transport systems. Therefore, further studies should be carried out to identify the main sources and contribute to the gathering of information, aiming to mitigate the emission of this pollutant in aquatic systems.

Priorities to inform research on tire particles and their chemical leachates: A collective perspective

Concerns over the ecological impacts of urban road runoff have increased, partly due to recent research into the harmful impacts of tire particles and their chemical leachates. This study aimed to help the community of researchers, regulators and policy advisers in scoping out the priority areas for further study. To improve our understanding of these issues an interdisciplinary, international network consisting of experts (United Kingdom, Norway, United States, Australia, South Korea, Finland, Austria, China and Canada) was formed. We synthesised the current state of the knowledge and highlighted priority research areas for tire particles (in their different forms) and their leachates. Ten priority research questions with high importance were identified under four themes (environmental presence and detection; chemicals of concern; biotic impacts; mitigation and regulation). The priority research questions include the importance of increasing the understanding of the fate and transport of these contaminants; better alignment of toxicity studies; obtaining the holistic understanding of the impacts; and risks they pose across different ecosystem services. These issues have to be addressed globally for a sustainable solution. We highlight how the establishment of the intergovernmental science-policy panel on chemicals, waste, and pollution prevention could further address these issues on a global level through coordinated knowledge transfer of car tire research and regulation. We hope that the outputs from this research paper will reduce scientific uncertainty in assessing and managing environmental risks from TP and their leachates and aid any potential future policy and regulatory development.

Tire and road wear particles in infiltration pond sediments: Occurrence, spatial distribution, size fractionation and correlation with metals

Stormwater systems, such as infiltration ponds or basins, play a critical role in managing runoff water and reducing particulate pollution loads in downstream environments through decantation. Road runoff carries several pollutants, including trace metals and tire and road wear particles (TRWP). To improve our understanding of infiltration ponds as regards TRWP and their capacity to reduce TRWP loads, we have studied the occurrence, spatial distribution and size distribution of TRWP, as well as their relationship with metals, in considering the input of metals as tire additives, in the sediments of an infiltration pond located along the Nantes urban ring road (Western France), which happens to be a high-traffic roadway site. The sediment was analyzed using pyrolysis coupled with gas chromatography-mass spectrometry to determine the polymeric content of tires, specifically in quantifying the styrene-butadiene rubber (SBR) and butadiene rubber (BR) pyrolytic markers. By applying an SBR + BR-to-TRWP conversion factor, the results showed significant TRWP contamination, up to 65 mg/g, with a spatial enrichment from the entrance to the overflow section of the pond. Size fractionation revealed a bimodal distribution, indicating two distinct types of TRWP. The first type is characterized by small diameters (63-160 μm), suggesting the presence of TRWP less integrated with mineral and organic particles. The second type, characterized by larger diameters (200-500 μm), suggests a more pronounced integration with these same mineral and organic particles. A significant positive correlation between TRWP and metals (As, Cd, Cr, Cu, Li, Mo, Ni, Sb, V, Zn) was found (r > 0.739, p < 0.05). This correlation implies that TRWP and/or their associated phases may act as an indicator of metal contamination in the pond sediments. Lastly, a mass balance between TRWP inputs and the amount retained in the sediments underscores the role of infiltration ponds as "sinks" for TRWP.

Additives in bioplastics: Chemical characterization, migration in water and effects on photosynthetic organisms

The potential release in the environment and biological effects of chemicals like additives and non-intentionally added substances present in conventional plastics and bioplastics is an issue that could occur if these materials are not properly disposed of. Herein, seven leachates of biobased and biodegradable plastics made of polylactic acid (PLA), polybutylene succinate (PBS)/PLA blends, and starch-based blends (SB) were characterized and compared for the inorganic and organic additives present in the source materials. The main inorganic elements found in the leachates were Na, Mg, K, and Ca (0.1-100 mg L-1), corresponding to the main elements present in the bioplastics. Also trace elements such as Ba, Zn, Sr, B, Fe, Ti, Al, Mn, Cu, and Sn occurred in leachates with concentrations between 1 and 1000 μg L-1. In contrast, most of the organic additives found in the bioplastics did not migrate in water and the few organic compounds detected and identified were not of concern. The lowest tested concentration of PBS/PLA- and SB-leachates (0.5 % of the corresponding initial leachate) induced a significant algal growth inhibition (corresponding to bioplastic concentrations in water of 0.4 g L-1). Conversely, PLA-based materials were less toxic (LOEC corresponding to 10 % of the leachates or >75 %). No effect on seed germination nor the development of roots and shoots of cress was observed for any leachate prepared from PLA and PBS/PLA materials. Leachates prepared from SB bags inhibited the growth of roots and shoots at the concentrations of 25 and 50 %, while they induced hormesis at 10 % concentration promoting a growth higher than the control.

Tire wear particle leachate exhibits trophic and multi-generational amplification: Potential threat to population viability

The toxic additives leached from tire wear particles (TWPs) in road runoff can directly poison aquatic organism through high-dose exposure in sporadic hotspots. Given the ubiquity of road runoff carrying TWPs, it is necessary to assess whether there are lagging effects from low-dose exposure, as the toxicity of TWPs leachate can be transferred and amplified across multi-generations and different trophic levels: microalgae, zooplankton and larval fish. In this study, Chlorella pyrenoidesa exposed to different concentrations of TWPs leachate were fed to rotifer Brachionus calyciflorus, which were subsequently used as the initial feeding for fry of Cyprinus carpio. Below 1000 mg/L, the growth of microalgae was not influenced by TWPs leachate. Rotifer fed with contaminated microalgae for a single generation exhibited hormesis in their reproduction. After multigenerational feeding, the microalgae from 500 mg/L treatment were sufficient to suppress reproduction of rotifer since the third generation. For the secondary consumer carp fry, survival, growth, and feeding rate were significantly inhibited at first generation when consuming the rotifers fed with microalgae exposed to 250 mg/L TWPs leachate. So, evidence was presented for the generational and trophic amplification of toxicity in TWPs leachate within the food chain. A seemingly innocuous low dose can exhibit evident ecotoxicity after trophic and generational transfer, which could decline population viability of the aquatic organisms in the future.

Unveiling the environmental impact of tire wear particles and the associated contaminants: A comprehensive review of environmental and health risk

This review offers a novel perspective on the environmental fate and ecotoxicological effects of tire wear particles (TWPs), ubiquitous environmental contaminants ranging in size from micrometers to millimeters (averaging 10-100 micrometers). These particles pose a growing threat due to their complex chemical composition and potential toxicity. Human exposure primarily occurs through inhalation, ingesting contaminated food and water, and dermal contact. Our review delves into the dynamic interplay between TWP composition, transformation products (TPs), and ecological impacts, highlighting the importance of considering both individual chemical effects and potential synergistic interactions. Notably, our investigation reveals that degradation products of certain chemicals, such as diphenylguanidine (DPG) and diphenylamine (DPA), can be more toxic than the parent compounds, underscoring the need to fully understand these contaminants' environmental profile. Furthermore, we explore the potential human health implications of TWPs, emphasizing the need for further research on potential respiratory, cardiovascular, and endocrine disturbances. Addressing the challenges in characterizing TWPs, assessing their environmental fate, and understanding their potential health risks requires a multidisciplinary approach. Future research should prioritize standardized TWP characterization and leachate analysis methods, conduct field studies to enhance ecological realism, and utilize advanced analytical techniques to decipher complex mixture interactions and identify key toxicants. By addressing these challenges, we can better mitigate the environmental and health risks associated with TWPs and ensure a more sustainable future.

Evaluating physiological responses of microalgae towards environmentally coexisting microplastics: A meta-analysis

Microplastics (MPs) are abundantly present in aquatic environments, where the phytoplankton-microalgae, are now inevitably bound to a long-term coexistence with them. While numerous studies have focused on the toxicological effects of high-concentration MPs exposure, there remains controversy over whether and how MPs affect microalgae at environmentally relevant concentrations. This study aims to draw conclusions that narrow the gap from 52 studies with varying results. Overall, MPs can inhibit growth and photosynthesis, induce oxidative damage, from which microalgae can recover after an appropriate period. Cyanobacteria exhibit greater vulnerability than chlorophyta. The relative size of MPs to algal cells potentially governs their coexistence behavior, thereby altering the mechanisms of impact. Pristine MPs may increase the production of extracellular polymeric substances (EPS) and microcystins (MCs), while aged MPs have the opposite effect. Additionally, relevant factors are systematically discussed, offering insights for future research.

Towards realism in hazard assessment of plastic and rubber leachates - Methodological considerations

While plastic chemicals are key drivers of observed effects to aquatic species, there remains a lack of standardized and fit-for-purpose approaches for experimentally deconvoluting the effects of plastic chemicals from particle effects. This study investigated differences in chemical composition determined using two different organic solvents for extractions (dichloromethane-ethyl acetate, methanol) and by thermal desorption applied to 51 thermoplastic and elastomer products. The composition of natural water leachates of four select elastomers was also investigated. The number of chemical features in each material varied according to the extraction method, with solvent extracts exhibiting the most chemicals, and only 19 compounds commonly identified by all three methods. The number of chemical features in leachates was generally similar to the corresponding chemical extracts, but strong differences in relative composition were detected. While turbulence had minimal impact on leachate composition, particle loading strongly influenced leachate composition, temperature and salinity influenced the leachate concentration for some chemicals, and leaching time depended upon chemical mobility. Leachate composition cannot be readily predicted from particle characterization and multiple parameters are drivers of compositional variance in aquatic leachates. Recommendations for performing leaching studies that are relevant for hazard characterization in a realistic aquatic environment risk assessment scenario are suggested, with a particular focus on particle loading.

Effects of tire particles and associated-chemicals on the Pacific oyster (Magallana gigas) physiology, reproduction and next-generation

By 2040, tire particles (TP) are expected to dominate marine plastic contamination, raising concerns about their effects on marine animals. This study employed a multidisciplinary and multigenerational approach on the Pacific oyster Magallana gigas to investigate the effects of TP and their leachates (LEA). Effects were analyzed at the individual scale, from cellular, molecular, and microbiota changes to reproductive outputs and offspring performance. Microbiota characterization revealed potential dysbiosis in oysters treated with high concentration of both TP and LEA. RNA-seq analyses highlighted the activation of energy metabolism and stress responses in the LEA treatment. Additionally, transcriptional changes in oocytes and the reduction of motile spermatozoa suggested potential effects on gamete quality. Notably, possible oyster resilience was pointed out by the lack of significant ecophysiological modifications in adults and impacts on the growth and reproductive outputs of the offspring. Overall, the implications of the observed oyster resilience under our experimental setting are discussed in relation to available toxicity data and within a comprehensive view of coastal ecosystems, where a higher diversity of plastic/rubber materials and harsher environmental conditions occur.

Look before you leap: Are increased recycling efforts accelerating microplastic pollution?

To fight plastic pollution and reach net-zero ambitions, policy and industry set goals to increase the recycling of plastics and the recycled content in products. While this ideally reduces demand for virgin material, it also increases pressure on recyclers to find suitable endmarkets for the recyclate. This may lead to two effects: a multiplication of recycled content in applications already made of plastic and a substitution of non-plastic materials with cheap, low-quality recyclate. Both areas of application may be sources of microplastic (MP) pollution. Combined with the inherent degradation of recyclate during its lifecycle, but also during recycling, we expect the increase in recycled content will subsequently lead to an increase in MP pollution. We propose a framework to investigate the risk of MP generation through plastic applications throughout their subsequent lifecycle of production, use phase, and end of life. We apply the framework to two prominent examples of recyclate endmarkets, that is, textiles and wood-plastic, and point out where the degradation effects can cause higher release. To conclude, we outline a research agenda to support policymakers in their decision making on specifying targets for recycling and recycled content.

Ecological linkages between top-down designed benzothiazole-degrading consortia and selection strength: From performance to community structure and functional genes

The inefficient biodegradation and incomplete mineralization of nitrogenous heterocyclic compounds (NHCs) have emerged as a pressing environmental concern. The top-down design offers potential solutions to this issue by targeting improvements in community function, but the ecological linkages between selection strength and the structure and function of desired microbiomes remain elusive. Herein, the integration of metagenomics, culture-based approach, non-targeted metabolite screening and enzymatic verification experiments revealed the effect of enrichment concentration on the top-down designed benzothiazole (BTH, a typical NHC)-degrading consortia. Significant differences were observed for the degradation efficiency and community structure under varying BTH selections. Notably, the enriched consortia at high concentrations of BTH were dominated by genus Rhodococcus, possessing higher degradation rates. Moreover, the isolate Rhodococcus pyridinivorans Rho48 displayed excellent efficiencies in BTH removal (98 %) and mineralization (∼ 60 %) through the hydroxylation and cleavage of thiazole and benzene rings, where cytochrome P450 enzyme was firstly reported to participate in BTH conversion. The functional annotation of 460 recovered genomes from the enriched consortia revealed diverse interspecific cooperation patterns that accounted for the BTH mineralization, particularly Nakamurella and Micropruina under low selection strength, and Rhodococcus and Marmoricola under high selection strength. This study highlights the significance of selection strength in top-down design of synthetic microbiomes for degrading refractory organic pollutants, providing valuable guidance for designing functionally optimized microbiomes used in environmental engineering.

Environmental occurrence and ecotoxicological risks of plastic leachates in aquatic and terrestrial environments

Plastic pollution poses a significant threat to environmental and human health, with microplastics widely distributed across various ecosystems. Although current ecotoxicological studies have primarily focused on the inherent toxicity of plastics in natural environments, the role of chemical additives leaching from plastics into the environment remains underexplored despite their significant contribution to the overall toxic potential of plastics. Existing systematic studies on plastic leachates have often examined isolated additive compounds, neglecting the ecotoxicological effects of multiple compounds present in plastic leachates. Additionally, most previous research has focused on aquatic environments, overlooking the leaching mechanisms and ecological risks to diverse species with various ecological roles in aquatic and terrestrial ecosystems. This oversight hinders comprehensive ecological risk assessments. This study addresses these research gaps by reviewing the environmental occurrence of plastic leachates and their ecotoxicological impacts on aquatic and terrestrial ecosystems. Key findings reveal the pervasive presence of plastic leachates in various environments, identifying common additives such as phthalates, polybrominated diphenyl ethers (PBDEs), bisphenol A (BPA), and nonylphenols (NPs). Ecotoxicologically, chemical additives leaching from plastics under specific environmental conditions can influence their bioavailability and subsequent uptake by organisms. This review proposes a novel ecotoxicity risk assessment framework that integrates chemical analysis, ecotoxicological testing, and exposure assessment, offering a comprehensive approach to evaluating the risks of plastic leachates. This underscores the importance of interdisciplinary research that combines advanced analytical techniques with ecotoxicological studies across diverse species and environmental conditions to enhance the understanding of the complex impacts of plastic leachates and inform future research and regulatory policies.

Beyond plastic pollution: Unveiling chemical release from plastic debris in river water and seawater using non-target screening

Oceans and rivers are predominant sinks, reservoirs, and carriers of plastic debris that are proposed to be long term sources of a variety of contaminants in the environments. This research unveiled kinetics of chemical releases from plastic debris in freshwater and marine environment via artificial river water (ARW) and seawater (ASW) in combination of nontarget screening. Chemical leaching from PVC cord particles in the ARW and ASW basically followed the first order kinetics, reaching pseudo-equilibrium in 30d and 14d, respectively, associated with both particle surface - water partitioning and inner-particle diffusion of chemicals. Dissolved organic carbon, finer size, and weathering of plastic particles might enhance whereas metal ions potentially hinder chemical releases from plastic debris in waters, respectively. Salinity and pH showed moderate effects on chemical leaching. In addition, chemicals' physiochemical properties might also affect their leaching behavior. Hundreds to thousands of chemicals would be released from plastic debris in days once entering waters, among which > 80% were unknown with rare or no information about eco-toxicity and environmental fate, posing unpredicted risks to the environment. Furthermore, new chemicals may keep being released with increasing weathering and extending retention time of plastics in waters, leading to increases in both numbers and complexities of released chemicals. Chemical leaching from plastics showed product-dependence and certain differences in freshwater and seawater. Large numbers of unknown chemicals potentially released from plastic debris in rivers, lakes, and oceans and subsequent environmental risks warrant in-depth research.

Investigating the sorption of Zinc-Oxide nanoparticles on Tire-wear particles and their toxic effects on Chlorella vulgaris: Insights from toxicological models and physiological analysis

This study investigated the interaction of Tire-wear particles (TWPs) with Zinc-Oxide nanoparticles (ZNPs) and studied their individual and combined toxic effects on Chlorella vulgaris in the co-presence of Humics. Physiological parameters, including growth, photosynthetic pigments, oxidative stress, and membrane damage, were analysed using Flow cytometry. Adsorption experiments exhibited that ZNPs were significantly absorbed by TWPs (qmax= 312.49 mg/g). A positive dose-response relation concerning inhibition in growth was observed in all treatment groups, and it was associated with reduced chlorophyll levels and damaged cell membranes. A negative impact of increased concentrations of TWPs and ZNPs was observed on anti-oxidant enzymes CAT and SOD; however, the impact was more severe when combined with exposure to both contaminants. Elevated concentrations of ZNPs and TWPs led to increased ROS production, lipid peroxidation and membrane damage, which could be contributing to the observed inhibition in growth. In the combined exposure groups, the Independent Action and the Abbott toxicity models revealed a synergistic effect on growth rates, which agreed with the Integrated Biomarker model results. The current study could enhance our understanding of the interaction between TWPs and metal nanoparticles in aquatic systems and offer novel understandings of the mechanisms underlying their combined toxic effects on microalgae.

Oxidative Stress in Mussel Mytilus trossulus Induced by Different-Sized Plastics

Polyethylene and polystyrene are massively used around the world in various applications and are the most abundant plastic waste. Once in the marine environment, under the influence of physical and chemical factors, plastic products degrade, changing from the size category of macroplastics to microplastics. In order to study the effect of plastic on marine organisms, we modeled the conditions of environmental pollution with different-sized plastic-polystyrene microparticles of 0.9 µm and macro-sized polyethylene fragments of 10 cm-and compared their effect on biochemical parameters in the tissues of the bivalve mollusk Mytilus trossulus. Using biomarkers, it was found that regardless of the size and type of polymer, polystyrene microparticles and polyethylene macrofragments induced the development of oxidative stress in mussels. A significant decrease in the level of lysosomal stability in mussel hemocytes was observed. Increases in the level of DNA damage and the concentration of malonic dialdehyde in the cells of gills and the digestive gland were also shown. The level of total antiradical activity in cells varied and had a tissue-specific character. It was shown that both ingested polystyrene particles and leachable chemical compounds from polyethylene are toxic for mussels.

Mind your tyres: The ecotoxicological impact of urban sediments on an aquatic organism

The presence of tyre and road wear particles (TRWP) in the environment is an underestimated threat due to their potential impact on ecosystems and human health. However, their mode of action and potential impacts on aquatic ecosystems remain largely unknown. In the present study, we adopted a sediment exposure scenario to investigate the influence of sediment coming from an urban runoff sedimentation basin on the life cycle of Chironomus riparius. Targeted broad-spectrum chemical analysis helped to characterise the urban sediments and confirmed the significant contribution of contaminants from traffic (e.g. tyre wear contribution, Polycyclic Aromatic Hydrocarbons [PAHs], metals, tyre rubber additives). First-stage chironomid larvae were subjected to increasing concentrations of urban whole sediment. The results showed that exposure to this urban sediment influenced all measured endpoints. In vivo quantification of ROS showed that larvae exposed to the lowest concentration of contaminated sediment exhibited increased fluorescence. The contaminated sediment conditions increased mortality by almost 30 %, but this effect was surprisingly not concentration-dependent. Fertility decreased significantly and concentration-dependently. The results of the Mean Emergence Time (EmT50) and larval size showed an optimality curve. Furthermore, as a consequence of the effects on fitness, the Population Growth Rate (PGR) exhibited a significant decrease, which was concentration-dependent. Therefore, after a single generation, PGR calculation can be adopted as a sensitive tool to monitor pollution caused by complex matrices, i.e. composed of several contaminants. Our research highlights the importance of effective management of road runoff and underlines the need for further investigation to better understand the toxicity of TRWPs.

Zooming in the plastisphere: the ecological interface for phytoplankton-plastic interactions in aquatic ecosystems

Phytoplankton is an essential resource in aquatic ecosystems, situated at the base of aquatic food webs. Plastic pollution can impact these organisms, potentially affecting the functioning of aquatic ecosystems. The interaction between plastics and phytoplankton is multifaceted: while microplastics can exert toxic effects on phytoplankton, plastics can also act as a substrate for colonisation. By reviewing the existing literature, this study aims to address pivotal questions concerning the intricate interplay among plastics and phytoplankton/phytobenthos and analyse impacts on fundamental ecosystem processes (e.g. primary production, nutrient cycling). This investigation spans both marine and freshwater ecosystems, examining diverse organisational levels from subcellular processes to entire ecosystems. The diverse chemical composition of plastics, along with their variable properties and role in forming the "plastisphere", underscores the complexity of their influences on aquatic environments. Morphological changes, alterations in metabolic processes, defence and stress responses, including homoaggregation and extracellular polysaccharide biosynthesis, represent adaptive strategies employed by phytoplankton to cope with plastic-induced stress. Plastics also serve as potential habitats for harmful algae and invasive species, thereby influencing biodiversity and environmental conditions. Processes affected by phytoplankton-plastic interaction can have cascading effects throughout the aquatic food web via altered bottom-up and top-down processes. This review emphasises that our understanding of how these multiple interactions compare in impact on natural processes is far from complete, and uncertainty persists regarding whether they drive significant alterations in ecological variables. A lack of comprehensive investigation poses a risk of overlooking fundamental aspects in addressing the environmental challenges associated with widespread plastic pollution.

Location-dependent effect of microplastic leachates on the respiration rate of two engineering mussel species

Microplastics are ubiquitous in the world's oceans and pose serious environmental concerns, including their ingestion and the release of potentially toxic mixtures of intrinsic and extrinsic chemical compounds (i.e. leachates; MPLs). Mussels, as key intertidal bioengineers and filter-feeders are particularly susceptible to both exposure pathways. While the effects of microplastic ingestion have been widely investigated, research on the impacts of MPLs has only recently begun. This study examined the influence of MPLs derived from beached pellets collected in two separate regions, namely France and Portugal, on the respiration rates of two key ecosystem engineers, Mytilus edulis and Mytilus galloprovincialis. Possibly due to distinct mixtures of leached chemicals, unlike Portuguese-MPLs, exposure to French-MPLs significantly decreased the respiration rate of both mussel species. This research provides new insights into the physiological impacts of MPLs on bioengineer species, highlighting the importance of MP source and potential cascading effects at the ecosystem level. While we reported significant effects on mussel respiration after acute MPL exposure, future research should investigate long-term impacts and potential detoxification mechanisms to clarify the effects of MPs on mussel physiological performance and their potential consequences on specie fitness.

Photolysis of p-phenylenediamine rubber antioxidants in aqueous environment: Kinetics, pathways and their photo-induced toxicity

The widespread use of rubber antioxidants, especially p-phenylenediamines (PPDs), has raised increasing concerns about their risk assessment. However, there is a notable lack of research on their transformation products (TPs). Photolysis, influenced by active components, plays a significant role in the environmental fates of PPDs. This study investigated four emerging PPDs (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N, N'-diphenyl-p-phenylenediamine (DPPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N-cyclohexyl-N'-phenyl-p-phenylenediamine (CPPD)) through a combination of experiments (photolysis kinetics, quenching experiments, acute toxicity test to Vibrio Fischeri (V. fischeri) and identification of photolytic products) and theoretical calculations. The results revealed different pathways for indirect photolysis mediated by the hydroxyl radicals (•OH) and singlet oxygen (1O2) of DPPD and IPPD under simulated sunlight irradiation. The effects of dissolved organic matter (DOM) and fulvic acid (FA) on the rates of photolysis of PPDs highlighted the complex interactions among the molecular structure, light absorption properties, and environmental variables. Quenching for reactive oxygen species (ROS) reduced photo-induced toxicity, whereas the addition of DOM and FA increased it, suggesting the crucial role of ROS in the formation of more toxic photolytic products. The study of photolysis pathways and the evaluation of the health risks provide a comprehensive understanding of the environmental effects of these pollutants.

Chemical toxicity of leachates from synthetic and natural-based spat collectors on the embryo-larval development of the pearl oyster, Pinctada margaritifera

In French Polynesia, the pearl farming industry relies entirely on collecting natural spat using a shade-mesh collector, which is reported to contribute to both plastic pollution and the release of toxic chemicals. With the aim of identifying more environment-friendly collectors, this study investigates the chemical toxicity of shade-mesh (SM) and alternative materials, including reusable plates (P), a newly developed biomaterial (BioM) and Coconut coir geotextile (Coco), on the embryo-larval development of Pinctada margaritifera. Embryos were exposed during 48 h to four concentrations (0, 0.1, 10 and 100 g L-1) of leachates produced from materials. Chemical screening of raw materials and leachates was performed to assess potential relationships with the toxicity observed on D-larvae development. Compared to the other tested materials, results demonstrated lower levels of chemical pollutants in BioM and no toxic effects of its leachates at 10 g L-1. No toxicity was observed at the lowest tested concentration (0.1 g L-1). These findings offer valuable insights for promoting safer spat collector alternatives such as BioM and contribute to the sustainable development of pearl farming.

Granulated rubber in playgrounds and sports fields: A potential source of atmospheric plastic-related contaminants and plastic additives after runoff events

The use of "crumb rubber" coming from recycling materials in outdoor floors like playgrounds has been a frequent practice during the last years. However, these surfaces are object of abrasion and weathering being a potential source of micro and nanoplastics (MNPLs) to the atmosphere and a potential source of human exposure to them. Our main goal has been to expose different crumb rubber materials to summer weathering effects. The released inhalable fractions were sampled for two months with passive samplers and the composition of MNPLs and plastic additives (organic and inorganic) were evaluated. The ecotoxicological effects of leached materials emulating runoff events was evaluated in freshwater micro crustacean Daphnia magna and the green algae Chlorella vulgaris. The analysis of MNPLs showed the presence of polyethylene, polypropylene, polybutadiene, polysiloxanes and polybutylene at concentrations up to 30,426 ng/m3. In the same fraction, we also identified up to 56 plastic additives, including antioxidants, pigments, copolymers, flame retardants, fungicides, lubricants, plasticizers, UV filters and metal ions. Finally, runoff ecotoxicological effects on D. magna and C. vulgaris showed that leached compounds, either from virgin or aged material, would be toxicants for exposed organisms although at concentrations much higher than those expected to be released to the media.

Influences of bisphenol A on hydrogen production from food waste by thermophilic dark fermentation

The extensive use of plastic products in food packaging and daily life makes them inevitably enter the treatment process of food waste (FW). Plasticizer as a new pollutant is threatening the dark fermentation of FW. Our study showed that bisphenol A (BPA) at > 250 mg/L had a significant inhibition on hydrogen production from FW by thermophilic dark fermentation. The endogenous ATP content and lactate dehydrogenase (LDH) release showed that high level of BPA not only inhibited the growth of hydrogen-producing consortium, but also led to cell death. In addition, BPA mainly affects the hydrogen-producing consortium by reducing cell membrane fluidity, damaging cell membrane integrity and reducing cell membrane potential, resulting in cell death. This study provides some new insights into the mechanism of the effect of BPA on hydrogen production from FW by thermophilic dark fermentation, and lays the foundation on the utilization of FW.

Effects of tire wear particle on growth, extracellular polymeric substance production and oxidation stress of algae Chlorella vulgaris: Performance and mechanism

Tire wear particles (TWP) represent a distinctive form of microplastics (MPs) that are widely distributed in aquatic ecosystems. However, the toxicity of various types of TWP on phytoplankton remain to be further explored. Thus, three different TWPs originating from replaced bicycle, car, and electro-mobile tire (marked as BTWP, CTWP, and ETWP) were selected and their long-term biological influences on Chlorella vulgaris were investigated. Results demonstrated TWPs showed a concentration-dependent growth promotion of Chlorella vulgaris, with a maximum promotion rate reached to 40.51 % (10 mg/L, 10 d), 23.5 % (80 mg/L, 12 d), and 28.7 % (20 mg/L, 12 d) in the presence of BTWP, CTWP and ETWP, respectively. Meanwhile, TWPs could stimulate the secretion of EPS and induce oxidative stress. EPS analysis revealed the increase of polysaccharides could protect the cell from the direct contact with TWP particles. Moreover, the increased concentration of EPS also helps to induce the settlement of TWP and reduce the leachate release. The release of TWP into the environment could act as an accelerator for the growth of Chlorella vulgaris, which might further change the normal physicochemical behaviors of algae colony in aquatic system. Our findings provide new insights into the toxicity mechanism of TWPs on freshwater algae and valuable data on environmental risk assessment of TWPs.

Occurrence of plastic additives in coral-reef invertebrates on natural and plastic substrates

Numerous studies have investigated the occurrence of plastic additives in marine biota. Yet, their main vector of transfer into organisms tissues remains unknown. We explored seven common additives in benthic coral reef invertebrates residing on natural/plastic substrates in a protected marine reserve versus an unprotected reef to ascertain whether additives transfer by substrate leaching. Samples of three coral-reef species were extracted and analyzed by GCMS and HPLC. Of the seven chemical additives investigated, dibenzylamine and bis(2-ethylhexyl) phthalate were detected. No significant association was found between additives and substrate type, possibly because these plastics have been submerged for years, and the majority of additives within them have leached. The marine reserve had fewer samples with additives, highlighting the importance of active management. Understanding the transfer vectors of plastic additives into biota is essential for assessing the risk they pose and devising effective management tools for protecting coral reefs.

Differential sensitivity of hemocyte subpopulations (Mytilus edulis) to aged polyethylene terephthalate micro- and nanoplastic particles

Bivalve hemocytes, particularly granulocytes and hyalinocytes, play a crucial role in cell-mediated immunity. However, their interactions with aged plastic particles, exhibiting altered properties that more closely resemble those in natural environments, remain largely underexplored. This study assesses the differential responses of hemocyte subpopulations (Mytilus edulis) to chemically aged polyethylene terephthalate (PET) microplastic (MPs) and nanoplastic (NPs) particles across multiple cellular effect endpoints. Particle characteristics were analyzed using Single Particle Extinction and Scattering, Raman Spectroscopy, Scanning Electron Microscopy, and Dynamic Light Scattering. In vitro experiments with aged PET MPs (1.9 µm) and NPs (0.68 µm) were conducted at three internally relevant concentrations: 10 (C1), 10³ (C2), and 10⁵ particles/mL (C3). Cellular responses were assessed by measuring lysosomal content stability, reactive oxygen species (ROS) production, cellular mortality, and morphological parameters using flow cytometry at 6, 12, 24, and 48 hours. Our findings provide mechanistic insights into the differential sensitivities of granulocytes and hyalinocytes to aged PET, influenced by particle size and concentration. Specifically, aged PET MPs and NPs induce distinct size and concentration-dependent patterns of lysosomal destabilization, coinciding with the loss of functional integrity. Elevated ROS levels were observed only in granulocytes and hyalinocytes exposed to high concentrations of aged PET NPs, underscoring the effects on oxidative stress. Both aged PET MPs and NPs induce significant increases in cellular mortality, particularly after 24 h of exposure at high concentrations. These findings reveal the complex cellular mechanisms underlying hemocyte functional impairment following exposure to aged PET particles under environmentally and biologically relevant conditions.

The time for ambitious action is now: Science-based recommendations for plastic chemicals to inform an effective global plastic treaty

The ubiquitous and global ecological footprint arising from the rapidly increasing rates of plastic production, use, and release into the environment is an important modern environmental issue. Of increasing concern are the risks associated with at least 16,000 chemicals present in plastics, some of which are known to be toxic, and which may leach out both during use and once exposed to environmental conditions, leading to environmental and human exposure. In response, the United Nations member states agreed to establish an international legally binding instrument on plastic pollution, the global plastics treaty. The resolution acknowledges that the treaty should prevent plastic pollution and its related impacts, that effective prevention requires consideration of the transboundary nature of plastic production, use and pollution, and that the full life cycle of plastics must be addressed. As a group of scientific experts and members of the Scientists' Coalition for an Effective Plastics Treaty, we concur that there are six essential "pillars" necessary to truly reduce plastic pollution and allow for chemical detoxification across the full life cycle of plastics. These include a plastic chemical reduction and simplification, safe and sustainable design of plastic chemicals, incentives for change, holistic approaches for alternatives, just transition and equitable interventions, and centering human rights. There is a critical need for scientifically informed and globally harmonized information, transparency, and traceability criteria to protect the environment and public health. The right to a clean, healthy, and sustainable environment must be upheld, and thus it is crucial that scientists, industry, and policy makers work in concert to create a future free from hazardous plastic contamination.

Impacts of microplastics on ecosystem services and their microbial degradation: a systematic review of the recent state of the art and future prospects

Microplastics are tiny plastic particles with a usual diameter ranging from ~ 1 μ to 5 µm. Recently, microplastic pollution has raised the attention of the worldwide environmental and human concerns. In human beings, digestive system illness, respiratory system disorders, sleep disturbances, obesity, diabetes, and even cancer have been reported after microplastic exposure either through food, air, or skin. Similarly, microplastics are also having negative impacts on the plant health, soil microorganisms, aquatic lives, and other animals. Policies and initiatives have already been in the pipeline to address this problem to deal with microplastic pollution. However, many obstacles are also being observed such as lack of knowledge, lack of research, and also absence of regulatory frameworks. This article has covered the distribution of microplastics in water, soil, food and air. Application of multimodel strategies including fewer plastic item consumption, developing low-cost novel technologies using microorganisms, biofilm, and genetic modified microorganisms has been used to reduce microplastics from the environment. Researchers, academician, policy-makers, and environmentalists should work jointly to cope up with microplastic contamination and their effect on the ecosystem as a whole which can be reduced in the coming years and also to make earth clean.

Comparative assessment of the acute toxicity of commercial bio-based polymer leachates on marine plankton

Conventional plastics have become a major environmental concern due to their persistence and accumulation in marine ecosystems. The development of potential degradable polymers (PBP), such as polyhydroxyalkanoates (PHAs) and polylactic acid (PLA), has gained attention as an alternative to mitigate plastic pollution, since they have the potential to biodegrade under certain conditions, and their production is increasing as replacement of conventional polyolefins. This study aimed to assess and compare the toxicity of leachates of pre-compounding PBP (PLA and the PHA, polyhydroxybutyrate-covalerate (PHBv)) and polypropylene (PP) on five marine planktonic species. A battery of standard bioassays using bacteria, microalgae, sea urchin embryos, mussel embryos and copepod nauplii was conducted to assess the toxicity of leachates from those polymers. Additionally, the presence of chemical additives in the leachates was also verified through GC-MS and LC-HRMS analysis. Results showed that PHBv leachates exhibited higher toxicity compared to other polymers, with the microalgae Rhodomonas salina, being the most sensitive species to the tested leachates. On the other hand, PP and PLA generally displayed minimal to no toxicity in the studied species. Estimated species sensitivity distribution curves (SSD) show that PHBv leachates can be 10 times more hazardous to marine plankton than PP or PLA leachates, as demonstrated by the calculated Hazardous Concentration for 5 % of species (HC5). Qualitative chemical analysis supports the toxicological results, with 80 % of compounds being identified in PHBv leachates of which 2,4,6-trichlorophenol is worth mentioning due to the deleterious effects to aquatic biota described in literature. These findings underscore the fact that whereas environmental persistence can be targeted using PBP, the issue of chemical safety remains unsolved by some alternatives, such as PHBv. Gaining a comprehensive understanding of the toxicity profiles of PBP materials through a priori toxicological risk assessment is vital for their responsible application as alternatives to conventional plastics.

Carryover effects of tire wear particle leachate threaten the reproduction of a model zooplankton across multiple generations

The toxic additives that leach from tire wear particles (TWPs) cause mass die-offs in fish and impact zooplankton as secondary consumers in the aquatic food web. In addition to the direct impacts of TWP leachate on a single generation, there may be potential delayed carryover effects across multiple generations from parental exposure, which may amplify the adverse effects of the leachate on individual reproduction and, consequently, on the entire population. In this study, the single, multiple, and transgenerational effects of TWP leachate at various concentrations on the reproduction and lifespan of the rotifer Brachionus calyciflorus were investigated. The results indicated that the lifespan and reproductive output of rotifers exposed to TWP leachate (0-1500 mg/L) decreased as the concentration increased above 250 mg/L. There was a clear multigenerational effect of TWP leachate on rotifer reproduction. The inhibition rates were consistently greater at 500 mg/L than at 250 mg/L leachate. Although the reproduction of rotifers exposed to 250 mg/L TWP leachate increased in the first two generations (P and F1), it was inhibited in subsequent generations. The inhibitory effect of 500 mg/L TWP leachate persisted across all generations, leading to population extinction by the F4 generation. A significant transgenerational effect of TWP leachate was found on reproduction. The adverse impact of exposure to 250 mg/L leachate for fewer than three generations could be reversed when offspring were transferred to clean media. However, this recovery was not observed after continuous exposure for more than four generations. Exposure to high-dose TWP leachate also caused irreversible damage to reproduction. Therefore, TWP leachate can result in cascading toxicity on zooplankton populations through carryover and cumulative effects on reproduction.

New Insights into the Mechanisms of Toxicity of Aging Microplastics

Nowadays, synthetic polymer (plastic) particles are ubiquitous in the environment. It is known that for several decades microplastics (MPs) have been accumulating in the World Ocean, becoming available to a large variety of marine organisms. Particularly alarming is the accumulation of aging plastic particles, as the degradation processes of such particles increase their toxicity. The diverse display of negative properties of aging MPs and its effect on biota are still poorly understood. In this study, in vitro experiments modeling the interaction of pristine and UV-irradiated aging polypropylene (PP) fragments with hemocytes and mitochondria of bivalve mollusks Mytilus sp. were performed. The appearance of free radicals in the environment was recorded by spectral characteristics of indicator dyes-methylene blue (MB) and nitroblue tetrazolium (NBT). It was found that due to photooxidation, aging PP fragments sorbed more than threefold MB on their modified surface compared to pristine samples of this polymer. Using NBT, the formation of reactive oxygen species in seawater in the presence of pristine and photoactivated PP was recorded. It was also found that photodegraded PP fragments largely stimulated the development of lipid peroxidation processes in mitochondrial membranes and reduced the stability of hemocyte lysosome membranes compared to pristine PP fragments. In general, the results obtained concretize and supplement with experimental data the previously stated hypothesis of toxicity of aging MPs.

Tire Rubber Based Microplastic Particles Cause Adverse on Quality Parameters of Rainbow Trout Sperm Cells

In the present study, we aimed to determine the parameters of oxidative stress markers, motility and kinematics of rainbow trout (Oncorhynchus mykiss) sperm cells exposed to different doses (0.001, 0.01, 0.1, 1.0, and 10 mg/L, in vitro 4 h) of tire rubber based microplastic particles (TRMP-Ps) the leachates procedure of rubber pieces. First of all, TRMP-Ps were prepared by abrasion method in accordance with the literature. Structural and morphological features of TRMP-Ps were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) methods, respectively. Energy dispersive X-ray (EDX) analysis technique was used to characterize the elemental composition of TRMP-Ps. Particle size of microplastic structures was measured hydrodynamically with dynamic light scattering analysis (DLS). After exposure, the effect of TRMP-Ps was defined by the observations of kinematics and antioxidant activities in sperm cells. Our findings showed that the straight line velocity, the curvilinear velocity, the angular path velocity, and the amplitude of lateral displacement of sperm cells decreased. Moreover, while the level of superoxide dismutase decreased dose-dependently against the toxicity of TRMP-Ps, no significant change was observed in the levels of malondialdehyde and total glutathione. The 4-h median effective concentrations (EC50) of TRMP-Ps based on mobility parameters of sperm ranged from 0.31 mg/L for reduced straight line velocity of sperm cells to 0.51 mg/L for reduced amplitude of lateral displacement of the spermatozoa head. Therefore, we concluded that TRMP-Ps can be a risk for the reproduction cycle of fish in aquatic environments.

A review of tire wear particles: Occurrence, adverse effects, and control strategies

Tire wear particles (TWPs), common mixed particulate emerging contaminants in the environment, have global per capita emissions accounting for 0.23-1.9 kg/year, attracting global attention recently due to their wide detection, small size, mobility, and high toxicity. This review focuses on the occurrence characteristics of TWPs in multiple environmental media, adverse effects on organisms, potential toxicity mechanisms, and environmental risk prevention and control strategies of TWPs. The environmental fate of TWPs throughout the entire process is systematically investigated by the bibliometric analysis function of CiteSpace. This review supplements the gap in the joint toxicity and related toxicity mechanisms of TWPs with other environmental pollutants. Based on the risks review of TWPs and their additives, adverse impacts have been found in organisms from aquatic environments, soil, and humans, such as the growth inhibition effect on Chironomus dilutes. A multi-faceted and rationalized prevention and control treatment of "source-process-end" for the whole process can be achieved by regulating the use of studded tires, improving the tire additive formula, growing plants roadside, encouraging micro-degradation, and other methods, which are first reviewed. By addressing the current knowledge gaps and exploring prospects, this study contributes to developing strategies for reducing risks and assessing the fate of TWPs in multiple environmental media.

Oxidative damage and cardiotoxicity induced by 2-aminobenzothiazole in zebrafish (Danio rerio)

There is limited information available on cardiovascular toxicity of 2-Aminobenzothiazole (NTH), a derivative of benzothiazole (BTH) commonly used in tire production, in aquatic organisms. In the present study, the zebrafish embryos were exposed to varying concentrations of NTH (0, 0.05, 0.5, and 5 mg/L) until adulthood and the potential cardiovascular toxicity was assessed. NTH exposure resulted in striking aberrations in cardiac development, including heart looping failure and interference with atrioventricular canal differentiation. RNA-sequencing analysis indicated that NTH causes oxidative damage to the heart via ferroptosis, leading to oxygen supply disruption, cardiac malformation, and ultimately, zebrafish death. Quantitative real-time polymerase chain reaction (qPCR) analysis demonstrated the dysregulation of genes associated with early heart development, contraction, and oxidative stress. Additionally, reactive oxygen species accumulation and glutathione/malondialdehyde levels changes suggested a potential link between cardiac developmental toxicity and oxidative stress. In adult zebrafish, NTH exposure led to ventricular enlargement, decreased heart rate, reduced blood flow, and prolonged RR, QRS, and QTc intervals. To the best of our knowledge, this study is the first to provide evidence of cardiac toxicity and the adverse effects of ontogenetic NTH exposure in zebrafish, revealing the underlying toxic mechanisms connected with oxidative stress damage. These findings may provide crucial insights into the environmental risks associated with NTH and other BTHs.

Combined toxicity of pristine or artificially aged tire wear particles and bisphenols to Tigriopus japonicus

Tire wear particles (TWPs) are considered an important component of microplastic pollution in the marine environment and occur together with a variety of aquatic pollutants, including frequently detected bisphenols. The adverse effects of TWPs or bisphenols on aquatic organisms have been widely reported. However, the combined toxicity of TWPs and bisphenols is still unknown. In this study, the combined toxicity of both pristine (p-) and aged TWPs (a-TWPs) and four bisphenols ((bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF)) to Tigriopus japonicus was evaluated. TWPs increased the toxicity of BPA and BPF but decreased the toxicity of BPAF. For BPS, there was synergistic toxic effect in the presence of p-TWPs, but slightly antagonistic effect was observed in the presence of a-TWPs. This adsorption of BPAF by TWPs resulted in a reduction of its toxicity to the copepod. A-TWPs could release more Zn than p-TWPs, and the released Zn contributed to the synergistic effect of TWPs and BPA or BPF. The aggregation formed by TWPs in certain sizes (e.g., 90-110 μm) could cause intestinal damage and lipid peroxidation in T. japonicus. The synergistic effect of p-TWPs and BPS might be due to the aggregation size of the binary mixture. The results of the current study will be important to understand the combined toxic effect of TWPs and bisphenols and the potential toxic mechanisms of the binary mixture.

Dose Effect of Polyethylene Microplastics Derived from Commercial Resins on Soil Properties, Bacterial Communities, and Enzymatic Activity

Soils are the largest reservoir of microplastics (MPs) on earth. Since MPs can remain in soils for a very long time, their effects are magnified. In this study, different concentrations of polyethylene (PE) MPs derived from commercial resins (0%, 1%, 7%, and 14%, represented as MP_0, MP_1, MP_7, and MP_14) were added to soils to assess the changes in the soils' chemical properties, enzyme activities, and bacterial communities during a 70-day incubation period. The results show that PE MP treatments with low concentrations differed from other treatments in terms of exchangeable Ca and Mg, whereas at high concentrations, the pH and availability of phosphate ions differed. Fluorescein diacetate (FDA), acid phosphatase (ACP), and N-acetyl-β-d-glucosaminidase (NAG) enzyme activities exhibited a dose-related trend with the addition of the PE MPs; however, the average FDA and ACP activities were significantly affected only by MP_14. Changes in the microbial communities were observed at both the phylum and family levels with all PE MP treatments. It was revealed that even a low dosage of PE MPs in soils can affect the functional microbes, and a greater impact is observed on those that can survive in polluted environments with limited resources.

Overview of the environmental risks of microplastics and their controlled degradation from the perspective of free radicals

Owing to the significant environmental threat posed by microplastics (MPs) of varying properties, MPs research has garnered considerable attention in current academic discourse. Addressing MPs in river-lake water systems, existing studies have seldom systematically revealed the role of free radicals in the aging/degradation process of MPs. Hence, this review aims to first analyze the pollution distribution and environmental risks of MPs in river-lake water systems and to elaborate the crucial role of free radicals in them. After that, the study delves into the advancements in free radical-mediated degradation techniques for MPs, emphasizing the significance of both the generation and elimination of free radicals. Furthermore, a novel approach is proposed to precisely govern the controlled generation of free radicals for MPs' degradation by interfacial modification of the material structure. Hopefully, it will shed valuable insights for the effective control and reduction of MPs in river-lake water systems.

New insights into the impact of leachates from in-field collected plastics on aquatic invertebrates and vertebrates

The impact of leachates from micronized beached plastics of the Mediterranean Sea and Atlantic Ocean on coastal marine ecosystems was investigated by using a multidisciplinary approach. Chemical analysis and ecotoxicological tests on phylogenetically distant species were performed on leachates from the following plastic categories: bottles, pellets, hard plastic (HP) containers, fishing nets (FN) and rapido trawling rubber (RTR). The bacteria Alivibrio fischeri, the nauplii of the crustaceans Amphibalanus amphitrite and Acartia tonsa, the rotifer Brachionus plicatilis, the embryos of the sea urchin Paracentrotus lividus, the ephyrae of the jellyfish Aurelia sp. and the larvae of the medaka Oryzias latipes were exposed to different concentrations of leachates to evaluate lethal and sub-lethal effects. Thirty-one additives were identified in the plastic leachates; benzophenone, benzyl butyl phthalate and ethylparaben were present in all leachates. Ecotoxicity of leachates varied among plastic categories and areas, being RTR, HP and FN more toxic than plastic bottles and pellets to several marine invertebrates. The ecotoxicological results based on 13 endpoints were elaborated within a quantitative weight of evidence (WOE) model, providing a synthetic hazard index for each data typology, before their integrations in an environmental risk index. The WOE assigned a moderate and slight hazard to organisms exposed to leachates of FN and HP collected in the Mediterranean Sea respectively, and a moderate hazard to leachates of HP from the Atlantic Ocean. No hazard was found for pellet, bottles and RTR. These findings suggest that an integrated approach based on WOE on a large set of bioassays is recommended to get a more reliable assessment of the ecotoxicity of beached-plastic leachates. In addition, the additives leached from FN and HP should be further investigated to reduce high concentrations and additive types that could impact marine ecosystem health.

Tire and road wear particles in the aquatic organisms - A review of source, properties, exposure routes, and biological effects

With the continuous development of the modern social economy, rubber has been widely used in our daily life. Tire and road wear particles (TRWPs) are generated by friction between tires and the road surface during the processes of driving, acceleration, and braking. TRWPs can be divided into three main components according to their source: tire tread, brake wear, and road wear. Due to urban runoff, TRWPs flow with rainwater into the aquatic environment and influence the surrounding aquatic organisms. As an emerging contaminant, TRWPs with the characteristics of small particles and strong toxicity have been given more attention recently. Here, we summarized the existing knowledge of the physical and chemical properties of TRWPs, the pathways of TRWPs into the water body, and the exposure routes of TRWPs. Furthermore, we introduced the biological effects of TRWPs involved in size, concentration, and shape, as well as key toxic compounds involved in heavy metals, polycyclic aromatic hydrocarbons (PAHs), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), and benzothiazole on aquatic organisms, and attempted to find the relevant factors influencing the toxic effects of TRWPs. In the context of existing policies that ignore pollution from TRWPs emissions in the aquatic environment, we also proposed measures to mitigate the impact of TRWPs in the future, as well as an outlook for TRWPs research.

Behind conventional (micro)plastics: An ecotoxicological characterization of aqueous suspensions from End-of-Life Tire particles

Million tons of tires become waste every year, and the so-called End-of-Life Tires (ELTs) are ground into powder (ELT-dp; size < 0.8 mm) and granules (ELT-dg; 0.8 < size < 2.5 mm) for recycling. The aim of this study was to evaluate the sub-lethal effects of three different concentrations (0.1, 1, and 10 mg/L) of aqueous suspensions from ELT-dp and ELT-dg on Danio rerio (zebrafish) larvae exposed from 0 to 120 h post-fertilization (hpf). Chronic effects were assessed through biomarkers, real-time PCR, and proteomics. We observed a significant increase in swimming behavior and heart rate only in specimens exposed to ELT-dp suspensions at 1 and 10 mg/L, respectively. Conversely, the activities of detoxifying enzymes ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) showed significant modulation only in specimens exposed to ELT-dg groups. Although no effects were observed through real-time PCR, proteomics highlighted alterations induced by the three ELT-dp concentrations in over 100 proteins involved in metabolic pathways of aromatic and nitrogen compounds. The results obtained suggest that the toxic mechanism of action (MoA) of ELT suspensions is mainly associated with the induction of effects by released chemicals in water, with a higher toxicity of ELT-dp compared to ELT-dg.

Looking beyond the obvious: The ecotoxicological impact of the leachate from fishing nets and cables in the marine mussel Mytilus galloprovincialis

Once in the marine environment, fishing nets and cables undergo weathering, breaking down into micro and nano-size particles and leaching plastic additives, which negatively affect marine biota. This study aims to unravel the ecotoxicological impact of different concentrations of leachate obtained from abandoned or lost fishing nets and cables in the mussel Mytilus galloprovincialis under long-term exposure (28 days). Biochemical biomarkers linked to antioxidant defense system, xenobiotic biotransformation, oxidative damage, genotoxicity, and neurotoxicity were evaluated in different mussel tissues. The chemical nature of the fishing nets and cables and the chemical composition of the leachate were assessed and metals, plasticizers, UV stabilizers, flame retardants, antioxidants, dyes, flavoring agents, preservatives, intermediates and photo initiators were detected. The leachate severely affected the antioxidant and biotransformation systems in mussels' tissues. Following exposure to 1 mg·L-1 of leachate, mussels' defense system was enhanced to prevent oxidative damage. In contrast, in mussels exposed to 10 and 100 mg·L-1 of leachate, defenses failed to overcome pro-oxidant molecules, resulting in genotoxicity and oxidative damage. Principal component analysis (PCA) and Weight of Evidence (WOE) evaluation confirmed that mussels were significantly affected by the leachate being the hazard of the leachate concentrations of 10 mg·L-1 ranked as major, while 1 and 100 mg·L-1 was moderate. These results highlighted that the leachate from fishing nets and cables can be a threat to the heath of the mussel M. galloprovincialis.

Immunotoxicity of microplastics in fish

Plastic waste degrades slowly in aquatic environments, transforming into microplastics (MPs) and nanoplastics (NPs), which are subsequently ingested by fish and other aquatic organisms, causing both physical blockages and chemical toxicity. The fish immune system serves as a crucial defense against viruses and pollutants present in water. It is imperative to comprehend the detrimental effects of MPs on the fish immune system and conduct further research on immunological assessments. In this paper, the immune response and immunotoxicity of MPs and its combination with environmental pollutants on fish were reviewed. MPs not only inflict physical harm on the natural defense barriers like fish gills and vital immune organs such as the liver and intestinal tract but also penetrate cells, disrupting intracellular signaling pathways, altering the levels of immune cytokines and gene expression, perturbing immune homeostasis, and ultimately compromising specific immunity. Initially, fish exposed to MPs recruit a significant number of macrophages and T cells while activating lysosomes. Over time, this exposure leads to apoptosis of immune cells, a decline in lysosomal degradation capacity, lysosomal activity, and complement levels. MPs possess a small specific surface area and can efficiently bind with heavy metals, organic pollutants, and viruses, enhancing immune responses. Hence, there is a need for comprehensive studies on the shape, size, additives released from MPs, along with their immunotoxic effects and mechanisms in conjunction with other pollutants and viruses. These studies aim to solidify existing knowledge and delineate future research directions concerning the immunotoxicity of MPs on fish, which has implications for human health.

Leaching hazards of tire wear particles in hydrothermal treatment of sludge: Exploring molecular composition, transformation mechanism, and ecological effects of tire wear particle-derived compounds

Tire wear particles (TWPs) are considered a significant contributor of microplastics (MPs) in the sludge during heavy rainfall events. Numerous studies have shown that hydrothermal treatment (HT) of sludge can accelerate the leaching of MP-derived compound into hydrothermal liquid, thus impairing the performance of subsequent anaerobic digestion and the quality of the hydrothermal liquid fertilizer. However, the leaching behavior of TWPs in the HT of sludge remains inadequately explored. This study examined the molecular composition of TWP-derived compounds and transformation pathways of representative tire-related additives under different hydrothermal temperatures using liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with mass difference analysis. The acute toxicity and phytotoxicity of TWP leachates were assessed using Vibrio qinghaiensis Q67 and rice hydroponics experiments. The results indicated that elevating the hydrothermal temperature not only amplified the leaching behavior of TWPs but also enhanced the chemical complexity of the TWP leachate. Utilizing both suspect and non-target screenings, a total of 144 compounds were identified as additives, including N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PDD), hexa(methoxymethyl)melamine (HMMM), dibutyl phthalate (DBP). These additives underwent various reactions, such as desaturation, acetylation, and other reactions, leading to the formation of different transformation products (TPs). Moreover, certain additives, including caprolactam and 2,2,6,6-tetramethyl-4-piperidinol, demonstrated the potential to form conjugate products with amino acids or Maillard products. Meanwhile, TWP-derived compounds showed significant acute toxicity and detrimental effects on plant growth. This study systematically investigated the environmental fate of TWPs and their derived compounds during the HT of sludge, offering novel insights into the intricate interactions between the micropollutants and dissolved organic matter (DOM) in sludge.

Microplastics and PAHs mixed contamination: An in-depth review on the sources, co-occurrence, and fate in marine ecosystems

Microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) are toxic contaminants that have been found in marine ecosystems. This review aims to explore the sources and mechanisms of PAHs and MPs mixed contamination in marine environments. Understanding the released sources of PAHs and MPs is crucial for proposing appropriate regulations on the release of these contaminants. Additionally, the mechanisms of co-occurrence and the role of MPs in distributing PAHs in marine ecosystems were investigated in detail. Moreover, the chemical affinity between PAHs and MPs was proposed, highlighting the potential mechanisms that lead to their persistence in marine ecosystems. Moreover, we delve into the various factors influencing the co-occurrence, chemical affinity, and distribution of mixed contaminants in marine ecosystems. These factors, including environmental characteristics, MPs properties, PAHs molecular weight and hydrophobicity, and microbial interactions, were critically examined. The co-contamination raises concerns about the potential synergistic effects on their degradation and toxicity. Interesting, few studies have reported the enhanced photodegradation and biodegradation of contaminants under mixed contamination compared to their individual remediation. However, currently, the remediation strategies reported for PAHs and MPs mixed contamination are scarce and limited. While there have been some initiatives to remove PAHs and MPs individually, there is a lack of research specifically targeting the removal of mixed contaminants. This deficiency highlights the need for further investigation and the development of effective remediation approaches for the efficient remediation of PAHs and MPs from marine ecosystems.

Cocktail effects of tire wear particles leachates on diverse biological models: A multilevel analysis

Tire wear particles (TWP) stand out as a major contributor to microplastic pollution, yet their environmental impact remains inadequately understood. This study delves into the cocktail effects of TWP leachates, employing molecular, cellular, and organismal assessments on diverse biological models. Extracted in artificial seawater and analyzed for metals and organic compounds, TWP leachates revealed the presence of polyaromatic hydrocarbons and 4-tert-octylphenol. Exposure to TWP leachates (1.5 to 1000 mg peq L-1) inhibited algae growth and induced zebrafish embryotoxicity, pigment alterations, and behavioral changes. Cell painting uncovered pro-apoptotic changes, while mechanism-specific gene-reporter assays highlighted endocrine-disrupting potential, particularly antiandrogenic effects. Although heavy metals like zinc have been suggested as major players in TWP leachate toxicity, this study emphasizes water-leachable organic compounds as the primary causative agents of observed acute toxicity. The findings underscore the need to reduce TWP pollution in aquatic systems and enhance regulations governing highly toxic tire additives.

Aging increases the particulate- and leachate-induced toxicity of tire wear particles to microalgae

The toxic effects of tire wear particles (TWPs) on organisms have attracted widespread concerns over the past decade. However, the underlying toxicity mechanism of TWPs, especially aged TWPs to marine microalgae remains poorly understood. This study investigated the physiological and metabolic responses of Phaeodactylum tricornutum to different concentrations of TWPs (Experiment 1), virgin and differently aged TWPs (Experiment 2) as well as their leachates and leached particles (Experiment 3). Results demonstrated that TWPs promoted the growth of microalgae at low concentrations (0.6 and 3 mg L-1) and inhibited their growth at high concentrations (15 and 75 mg L-1). Moreover, aged TWPs induced more profound physiological effects on microalgae than virgin TWPs, including inhibiting microalgae growth, decreasing the content of Chla, promoting photosynthetic efficiency, and causing oxidative damage to algal cells. Untargeted metabolomics analysis confirmed that aged TWPs induced more pronounced metabolic changes than virgin TWPs. This study represented the first to demonstrate that both particulate- and leachate-induced toxicity of TWPs was increased after aging processes, which was confirmed by the changes in the surface morphology of TWPs and enhanced release of additives. Through the significant correlations between the additives and the microalgal metabolites, key additives responsible for the shift of microalgal metabolites were identified. These results broaden the understanding of the toxicity mechanism of aged TWPs to microalgae at the physiological and metabolic levels and appeal for considering the effects of long-term aging on TWP toxicity in risk assessment of TWPs.

Where the rubber meets the road: Emerging environmental impacts of tire wear particles and their chemical cocktails

About 3 billion new tires are produced each year and about 800 million tires become waste annually. Global dependence upon tires produced from natural rubber and petroleum-based compounds represents a persistent and complex environmental problem with only partial and often-times, ineffective solutions. Tire emissions may be in the form of whole tires, tire particles, and chemical compounds, each of which is transported through various atmospheric, terrestrial, and aquatic routes in the natural and built environments. Production and use of tires generates multiple heavy metals, plastics, PAH's, and other compounds that can be toxic alone or as chemical cocktails. Used tires require storage space, are energy intensive to recycle, and generally have few post-wear uses that are not also potential sources of pollutants (e.g., crumb rubber, pavements, burning). Tire particles emitted during use are a major component of microplastics in urban runoff and a source of unique and highly potent toxic substances. Thus, tires represent a ubiquitous and complex pollutant that requires a comprehensive examination to develop effective management and remediation. We approach the issue of tire pollution holistically by examining the life cycle of tires across production, emissions, recycling, and disposal. In this paper, we synthesize recent research and data about the environmental and human health risks associated with the production, use, and disposal of tires and discuss gaps in our knowledge about fate and transport, as well as the toxicology of tire particles and chemical leachates. We examine potential management and remediation approaches for addressing exposure risks across the life cycle of tires. We consider tires as pollutants across three levels: tires in their whole state, as particulates, and as a mixture of chemical cocktails. Finally, we discuss information gaps in our understanding of tires as a pollutant and outline key questions to improve our knowledge and ability to manage and remediate tire pollution.