In Vitro Digestion of Tire Particles in a Fish Model (Oncorhynchus mykiss): Solubilization Kinetics of Heavy Metals and Effects of Food Coingestion

The chemical composition and sources of road dust, and of tire and road wear particles-A review

To gain better understanding of how the transition to electric vehicles affects road dust (RD) composition, and potential health and environmental risks, it is crucial to analyze the chemical composition of RD and identify its sources. Sources of RD include wear of tire tread (TT), brake wear (BW) and road wear (RW). A relevant component of RD are tire and road wear particles (TRWPs). This literature review compiles data on the chemical bulk composition of RD sources, RD in Asia, Europe and North America and TRWP as a RD component. The focus is on elements such as Cd, Co, Cr, Cu, Ni, Pb, V, and Zn. Although the comparability of global RD data is limited due to differences in sampling and analytical methods, no significant differences in the composition from Asia, Europe, and North America were found for most of the investigated elements studied, except for Cd, Co, and V. Sources of RD were analyzed using elemental markers. On average TT, BW, and RW contributed 3 %, 1 %, and 96 %, respectively. The highest concentrations of TT (9 %) and BW (2 %) were observed in the particle size fraction of RD ≤ 10 μm. It is recommended that these results be verified using additional marker compounds. The chemical composition of TRWPs from different sources revealed that (i) TRWPs isolated from a tunnel dust sample are composed of 31 % TT, 6 % BW, and 62 % RW, and (ii) test material from tire test stands show a similar TT content but different chemical bulk composition likely because e.g., of missing BW. Therefore, TRWPs from test stands need to be chemically characterized prior to their use in hazard testing to validate their representativeness.

Revealing chemical release from plastic debris in animals' digestive systems using nontarget and suspect screening and simulating digestive fluids

Plastic debris in the environment are not only pollutants but may also be important sources of a variety of contaminants. This work simulated kinetics and potential of chemical leaching from plastic debris in animals' digestive systems by incubating polyvinyl chloride (PVC) cord particles in artificial digestive fluids combined with nontarget and suspect screening based on UHPLC-Orbitrap HRMS. Impacts of particle size, aging, and digestive fluid were investigated to elucidate mechanisms of chemical leaching. Thousands of chemical features were screened in the leachates of PVC cord particles in the artificial digestive fluids, among which >60% were unknown. Bisphenol A (BPA) and bis(2-ethylhexyl) phthalate (DEHP) were the dominant identified CL1 compounds. Finer size and aging of the PVC particles and prolonged incubation time enhanced chemical release, resulting in greater numbers, higher levels, and more complexity in components of the released chemicals. The gastrointestinal fluid was more favorable for chemical leaching than the gastric fluid, with greater numbers and higher levels. Hundreds to thousands of chemical features were screened and filtered in the leachates of consumer plastic products, including food contact products (FCPs) in the artificial bird gastrointestinal fluid. In addition to BPA and DEHP, several novel bisphenol analogues were identified in the leachate of at least one FCP. The results revealed that once plastic debris are ingested by animals, hundreds to thousands of chemicals may be released into animals' digestive tracts in hours, posing potential synergistic risks of plastic debris and chemicals to plastic-ingesting animals. Future research should pay more attentions to identification, ecotoxicities, and environmental fate of vast amounts of unknown chemicals potentially released from plastics in order to gain full pictures of plastic pollution in the environment.

Ecotoxicity of tire wear particles to antioxidant enzyme system and metabolic functional activity of river biofilms: The strengthening role after incubation-aging in migrating water phases

Tire wear particles (TWPs) are commonly studied for their exudation toxicity, yet a critical knowledge gap exists regarding the source nature and migration of these particulate pollutants, hindering comprehensive environmental risk assessments. This study explores the pristine properties of three typical TWPs (rolling friction (R-TWPs), sliding friction (S-TWPs), and cryogenically milled tire treads (C-TWPs)) and their aging characteristics after incubation in runoff (primary aging) and sewage (further aging). Our investigation aims to unveil the intrinsic mechanisms of TWPs ecotoxicity towards freshwater biofilms. Results reveal that the generation modes significantly impact pristine physicochemical properties, including surface structure, particle size, and EPFR abundance. These factors, in turn, influence acute ecotoxicity, as evidenced by cell mortality, antioxidant enzyme activity responses, and metabolic changes in freshwater biofilms. The ecological toxicity ranking of pristine exposure groups is S-TWPs, R-TWPs, and C-TWPs, attributed to variations in surface properties and particle size. Following incubation and aging, especially in sewage, differences in physicochemical properties among TWPs types diminish. Alarmingly, ecotoxicity intensifies and becomes consistent across TWPs types, driven by the screening of small particles during water incubation aging and the formation of EPFRs on TWPs surfaces stimulated by photosensitive organic matter or groups. This study underscores the aquatic ecological risks associated with TWP surface properties, highlighting the significant influence of environmental aging conditions on these risks.

Adsorption of copper by naturally and artificially aged polystyrene microplastics and subsequent release in simulated gastrointestinal fluid

Microplastics, especially aged microplastics can become vectors of metals from environment to organisms with potential negative effects on food chain. However, a few studies focused on the bioavailability of adsorbed metals and most studies related to aged microplastics used artificial method that cannot entirely reflect actual aging processes. In this study, virgin polystyrene was aged by ozone (PS-O3), solar simulator (PS-SS) and lake (PS-lake) to investigate adsorption of Cu by virgin, artificially and naturally aged microplastics and subsequent release in simulated gastrointestinal fluids (SGF). Characterization results show carbonyl was formed in PS-O3 and PS-SS, and the oxidation degree was PS-O3 > PS-SS > PS-lake. However, Cu adsorption capacity followed this order PS-lake (158 μg g-1) > PS-SS (117 μg g-1) > PS-O3 (65 μg g-1) > PS-virgin (0). PS-O3 showed highest Cu adsorption capacity at 0.5 h (71 μg g-1), but it dropped dramatically later (10 μg g-1, 120 h), because PS-O3 could break up and the adsorbed Cu released in solutions subsequently. For PS-lake, precipitation of metallic oxides contributes to the accumulation of Cu. The addition of dissolved organic matter (DOM) could occupy adsorption sites on PS and compete with Cu, but also can attach PS and adsorb Cu due to its rich functional groups. The simultaneous ingestion of microplastics with food suggested that adsorbed Cu is solubilized mostly from aged PS to SGF.

Evaluation of tire tread particle toxicity to fish using rainbow trout cell lines

Tire and road wear particles (TRWP) resulting from tire abrasion while driving raise concerns due to their potential contribution to aquatic toxicity. Our study aimed to assess cryogenically milled tire tread (CMTT) particle toxicity, used as a proxy for TRWP, and associated chemicals to fish using two Rainbow Trout (Oncorhynchus mykiss) cell lines representing the gill (RTgill-W1) and the intestinal (RTgutGC) epithelium. CMTT toxicity was evaluated through several exposure pathways, including direct contact, leaching, and digestion, while also assessing the impact of particle aging. Following OECD TG249, cell viability was assessed after 24 h acute exposure using a multiple-endpoint assay indicative of cell metabolic activity, membrane integrity and lysosome integrity. In vitro EC50 values for the fish cell lines exceeded river TRWP concentrations (2.02 g/L and 4.65 g/L for RTgill-W1 and RTgutGC cell lines, respectively), and were similar to in vivo LC50 values estimated at 6 g/L. Although toxicity was mainly driven by the leaching of tire-associated chemicals, the presence of the particles contributed to the overall toxicity by inducing a continuous leaching, highlighting the importance of considering combined exposure scenarios. Aging and digestion conditions were also found to mediate CMTT toxicity. Thermooxidation resulted in a decreased chemical leaching and toxicity, while in vitro digestion under mimicked gastrointestinal conditions increased leaching and toxicity. Specific chemicals, especially Zn, 2-mercaptobenzothiazole, 1,3-diphenylguanidine, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) were identified as contributors to the overall toxicity. Although 6PPD-quinone was detected in CMTT digestate, cytotoxicity assays with RTgill-W1 and RTgutGC cell lines showed no toxicity up to 6 mg/L, supporting the notion of a specific mode of action of this chemical. This study provides insights into the toxicological mechanisms induced by tire particles and their associated chemicals and can help in the evaluation of potential risks to aquatic life associated with TRWP.

Sulfate radical-based advanced oxidation process effects on tire wear particles aging and ecotoxicity

Tire wear particles (TWPs) are widely distributed in natural water and pose as major pollutants in aquatic environments. In this study, heat-activated persulfate (HPT) and ultraviolet-activated persulfate treatments (UPT) were employed to investigate the influence of sulfate radical (SO4-•)-based advanced oxidation process (SAOPs) on TWP physicochemical properties and to clarify their ecotoxic effects in laboratory-level studies. Results showed that the specific surface areas of TWPs increased after UPT but decreased after HPT. In terms of chemical properties, the increase of oxygen-containing functional groups on the surfaces of TWPs was more evident in UPT than that in HPT. The atrazine (ATZ) adsorption capacity of TWPs after HPT and UPT was increased compared with the untreated TWPs. Atrazine adsorbed by TWPs was easily resolved and released in artificial intestinal fluid (1.89-2.08 mg/g) and artificial gastric fluid (1.60-2.04 mg/g) conditions. Acute toxicity experiments of Photobacterium phosphoreum and SEM-EDS detection results suggested that various heavy metals (e.g., Zn2+, Cu2+) in the TWPs would be released into the water system in SAOPs. ATZ released from TWPs that adsorbed ATZ herbicide, rather than TWPs themselves, had a negative effect on aquatic plant growth (e.g., C. vulgaris). The leaching solution of oxidized TWPs (after HPT and UPT) showed a more significant inhibition effect on the zebrafish survival compared with that of untreated TWPs, which was possibly caused by the generation of oxidation byproducts such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone.

Differential cytotoxicity to human cells in vitro of tire wear particles emitted from typical road friction patterns: The dominant role of environmental persistent free radicals

Tire wear particles (TWPs) have been recognized as one of the major sources of microplastics (MPs), however, effects of initial properties and photochemical behavior of TWPs on cytotoxicity to human cells in vitro have not been reported. Therefore, here, three TWPs generated from typical wear of tires and pavements (i.e., rolling friction (R-TWPs) and sliding friction (S-TWPs)) and cryogenically milled tire tread (C-TWPs), respectively, and their photoaging counterparts were used to study the reasons for their differential cytotoxicity to 16HBE cells in vitro. Results showed in addition to changes of surface structure and morphology, different preparation methods could also induce formation of different concentration levels of environmental persistent free radicals (EPFRs) (from 1.24 to 3.06 × 1017 spins/g with g-factors ranging 2.00307-2.00310) on surfaces of TWPs, which contained 7.3%-65.8% of reactive EPFRs (r-EPFRs). Meanwhile, photoaging for 90 d could strengthen formation of EPFRs (from 4.03 to 4.61 × 1017 spins/g) with containing 74.7%-78.1% r-EPFRs on surfaces of TWPs and improve their g-factor indexes (ranging 2.00309-2.00313). At 100 μg mL-1 level, compared to C-TWPs, both R-TWPs and S-TWPs (whether photoaging or not) carried higher intensity EPFRs could significantly inhibit 16HBE cells proliferation activity, cause more cells oxidative stress and induce more cell apoptosis/necrosis and secretion of inflammatory factor (P < 0.05). However, regardless of how TWPs were prepared, photoaged or not, exposure at a concentration of 1 μg mL-1 appeared to be non-acute cytotoxic. Correlation analysis suggested dominant toxicity of TWPs was attributed to the formation of r-EPFRs on their surfaces, which could promote accumulation of excess reactive oxygen species in cells and the massive deposition of intracellular particles. This study provides direct evidence of TWPs cytotoxicity, and underlining the need for a better understanding of the influences of initial properties and photochemical characteristics on risk assessment of TWPs released into the environment.

Investigation of 6PPD-Quinone in Rubberized Asphalt Concrete Mixtures

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)-quinone (6PPD-Q), a transformation byproduct of 6PPD used in tires as an antiozonant and antioxidant, was recently discovered as the chemical primarily responsible for the acute lethal toxicity of urban storm runoff to coho salmon. The asphalt concrete (AC) surface layer is the primary medium to contact 6PPD-Q immediately upon its release from tires, and the addition of recycled tire rubber (RTR) to the asphalt binder and mixture is a widely accepted practice in asphalt production. Therefore, it is urgent to understand the fate of 6PPD-Q at the asphalt concrete surface layer-water interface. This study analyzed the sorption and desorption of 6PPD-Q by compacted and crushed loose (loose particles, ∼5 mm) rubberized asphalt mixtures and their mobilization from compacted asphalt mixtures during simulated rainfall events. It should be noted that the crushed loose asphalt mixtures demonstrated the physicochemical properties of the asphalt materials, while the compacted asphalt mixtures represent in-service AC layers. Sorption of 6PPD-Q by crushed loose and compacted asphalt mixtures reached equilibrium within 12 days, with a sorption coefficient of 151.57-257.51 L/kg for compacted asphalt mixtures. Within 12 days, desorption of 6PPD-Q from crushed loose and compacted rubberized asphalt mixtures (20 g particles/L) to the double deionized (DDI) water and synthetic stormwater was 0.01-0.09 and 0.025-0.05 μg/L, respectively. Through the rainfall simulation experiments, 0.0015-0.0049 μg/L 6PPD-Q was detected in the runoff water, much lower than the lethal concentration (LC50) of 6PPD-Q of 0.095 μg/L and 308.67 μg/L for coho salmon and zebrafish larvae. Our results indicate that, while the release of 6PPD-Q from compacted rubberized asphalt mixtures is minor, the mixtures can serve as sorbents for tire-derived 6PPD-Q and retain this emerging contaminant.

Differential developmental and proinflammatory responses of zebrafish embryo to repetitive exposure of biodigested polyamide and polystyrene microplastics

Microplastics (MPs) have attracted global concern and are at the forefront of current research on environmental pollution, whereas, little is known about the degradation of ingested MPs in the gastrointestinal environment and repetitive exposure-associated risk of egested MPs to organisms. The present study revealed that polyamide (PA) and polystyrene (PS) MPs exhibited remarkably differential biodegradations in the gastric and intestinal fluids of a model fish (Siniperca chuatsi). Significant disintegration of the skeleton structure, size reduction (from 27.62 to 9.17 µm), benzene ring scission, and subsequent biogenic corona coating and surface oxidation occurred during in vitro digestion, thus increasing the hydrophilicity and agglomeration of PS. Conversely, PA MPs exhibited high resistance to enzymolysis with slight surface erosions and protein adsorption. Relative to the pristine form, the bioaccumulation of digested PS elevated and the musculoskeletal deformity and mortality of juvenile zebrafish were obviously enhanced, but these changes were unobservable for PA. Lipopolysaccharide-triggered inflammation and apoptosis via Toll-like receptor signaling pathways and reduction of extracellular matrix secretions driven by oxidative stress contributed to the aggravated inhibitory effects of digested PS on larval development. These findings emphasize the necessity of concerning the biota digestion in MP risk assessments in natural waters.

Identifying potential toxic organic substances in leachates from tire wear particles and their mechanisms of toxicity to Scenedesmus obliquus

Tire wear particles (TWPs) are increasingly being found in the aquatic environment. However, there is limited information available on the environmental consequences of TWP constituents that may be release into water. In this study, TWP leachate samples were obtained by immersing TWPs in ultrapure water. Using high-resolution mass spectrometry and toxicity identification, we identified potentially toxic organic substances in the TWP leachates. Additionally, we investigated their toxicity and underlying mechanisms. Through our established workflow, we structurally identified 13 substances using reference standards. The median effective concentration (EC₅₀) of TWP leachates on Scenedesmus obliquus growth was comparable to that of simulated TWP leachates prepared with consistent concentrations of the 13 identified substances, indicating their dominance in the toxicity of TWP leachates. Among these substances, cyclic amines (EC₅₀: 1.04-3.65 mg/L) were found to be toxic to S. obliquus. We observed significant differential metabolites in TWP leachate-exposed S. obliquus, primarily associated with linoleic acid metabolism and purine metabolism. Oxidative stress was identified as a crucial factor in algal growth inhibition. Our findings shed light on the risk posed by TWP leachable substances to aquatic organisms.

A combined method for human health risk area identification of heavy metals in urban environments

Multi-medium heavy metals pollution is a crucial pathway to destroy the urban environmental resources cycle. In this study, Nanjing of China, a typical mega city, was taken as the study area. Compared with other cities or countries, Cr, Cu and Zn in human nails and hair in the study area have higher concentration characteristics, while Cd and Pb have lower concentration characteristics. By combining the health risk status of heavy metals in soil and dustfall, the spatial clustering characteristics of heavy metals in soil dustfall and the concentration information of heavy metals in humans in the study area, a potential toxic risk area identification method based on soil-dustfall-human (SDB-HR) was established. Through Monte Carlo analysis, it's found that the risk of Zn and Cr in soil-dustfall to human health is relatively high, with the probability of carcinogenesis reaching 51.2 % and 50.2 %, respectively. By the proposed method, different levels of heavy metal risk areas in urban environments can be more reasonably and effectively identified, which will provide important technical and theoretical support for the precise management of heavy metals in urban environments.

The potential effects of in vitro digestion on the physicochemical and biological characteristics of polystyrene nanoplastics

The presence of plastic waste in our environment has continued growing and become an important environmental concern. Because of its degradation into micro- and nanoplastics (MNPLs), MNPLs are becoming environmental pollutants of special environmental/health concern. Since ingestion is one of the main exposure routes to MNPLs, the potential effects of digestion on the physicochemical/biological characteristics of polystyrene nanoplastics (PSNPLs) were determined. The results indicated a high tendency of digested PSNPLs to agglomerate and a differential presence of proteins on their surface. Interestingly, digested PSNPLs showed greater cell uptake than undigested PSNPLs in all three tested cell lines (TK6, Raji-B, and THP-1). Despite these differences in cell uptake, no differences in toxicity were observed except for high and assumed unrealistic exposures. When oxidative stress and genotoxicity induction were determined, the low effects observed after exposure to undigested PDNPLs were not observed in the digested ones. This indicated that the greater ability of digested PSNPLs to internalize was not accompanied by a greater hazard. This type of analysis should be performed with other MNPLs of varying sizes and chemical compositions.

Exploring the Potential Hormonal Effects of Tire Polymers (TPs) on Different Species Based on a Theoretical Computational Approach

Tire polymers (TPs) are the most prevalent type of microplastics and are of great concern due to their potential environmental risks. This study aims to determine the toxicity of TPs with the help of molecular-dynamics simulations of their interactions with receptors and to highlight the differences in the toxicity characteristics of TPs in different environmental media (marine environment, freshwater environment, soil environment). For this purpose, five TPs—natural rubber, styrene–butadiene rubber (SBR), butadiene rubber, nitrile–butadiene rubber, and isobutylene–isoprene rubber—were analyzed. Molecular-dynamics calculations were conducted on their binding energies to neurotoxic, developmental, and reproductive receptors of various organisms to characterize the toxic effects of the five TPs. The organisms included freshwater species (freshwater nematodes, snails, shrimp, and freshwater fish), marine species (marine nematodes, mussels, crab, and marine fish), and soil species (soil nematodes, springtails, earthworms, and spiders). A multilevel empowerment method was used to determine the bio-toxicity of the TPs in various environmental media. A coupled-normalization method–principal-component analysis–factor-analysis weighting method—was used to calculate the weights of the TP toxicity (first level) categories. The results revealed that the TPs were the most biologically neurotoxic to three environmental media (20.79% and 10.57% higher compared with developmental and reproductive toxicity, respectively). Regarding the effects of TPs on organisms in various environmental media (second level), using a subjective empowerment approach, a gradual increase in toxicity was observed with increasing trophic levels due to the enrichment of TPs and the feeding behavior of organisms. TPs had the greatest influence in the freshwater-environment organisms according to the subjective empowerment approach employed to weight the three environmental media (third level). Therefore, using the minimum-value method coupled with the feature-aggregation method, the interval-deflation method coupled with the entropy-weighting method, and the standard-deviation normalization method, the three toxicity characteristics of SBR in three environmental media and four organisms were determined. SBR was found to have the greatest impact on the overall toxicity of the freshwater environment (12.38% and 9.33% higher than the marine and soil environments, respectively). The greatest contribution to neurotoxicity (26.01% and 15.95% higher than developmental and reproductive toxicity, respectively) and the greatest impact on snails and shrimp among organisms in the freshwater environment were observed. The causes of the heterogeneity of SBR’s toxicity were elucidated using amino-acid-residue analysis. SBR primarily interacted with toxic receptors through van der Waals, hydrophobic, π-π, and π-sigma interactions, and the more stable the binding, the more toxic the effect. The toxicity characteristics of TMPs to various organisms in different environments identified in this paper provide a theoretical basis for subsequent studies on the prevention and control of TMPs in the environment.

Assessment of the bioaccessibility of PAHs and other hazardous compounds present in recycled tire rubber employed in synthetic football fields

Recycled tire crumb rubber (RTCR) surfaces contain harmful and carcinogenic substances, which can be ingested by the users of these facilities, mainly athletes and children. In this work, the potential in-vitro oral bioaccessibility of eighteen polycyclic aromatic hydrocarbons (PAHs) from RTCR employed as infill in synthetic football fields was studied in human synthetic body fluids (saliva, gastric, duodenal and bile), prepared according the Unified Bioaccessibility Method. Solid-phase extraction (SPE) using commercial sorbents and a new green material based on cork (cork industry by-product) were used to isolate the bioaccessible PAHs before gas chromatography-tandem mass spectrometry analysis. The method was optimized and validated attending the analytical figures of merit. The feasibility of cork biosorbent for the extraction of the compounds was demonstrated, as well as the suitability of the UBM method to perform the digestion with good precision. The application to real samples collected from football fields demonstrated the presence of 17 of the 18 target PAHs in the biofluids. Most volatile PAHs such as NAP, ACY, ACE, FLU, PHN and ANC, achieved the highest bioaccessibility percentage levels. The carcinogenic B[a]P was detected in 75 % of the samples at concentrations up to 2.5 ng g^-1 (bioaccessible fraction). Children exposure assessment was carried out to identify potential risk. Other hazardous and environmentally problematic compounds such as N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-quinone), recently related with the dead of coho salmon, and hexamethoxymethylmelamine (HMMM), among others, were also detected. This is the first study in which the bioaccesibility from real crumb rubber samples of 15 out of the 16 PAHs considered as priority pollutants by the United States Environmental Protection Agency (EPA) and the presence of 6PPD-quinone and HMMM in the bioaccessible fractions is reported.

Tyre particle exposure affects the health of two key estuarine invertebrates

Tyre wear particles may be the largest source of microplastic to the natural environment, yet information on their biological impacts is inadequate. Two key estuarine invertebrates; the clam Scrobicularia plana and the ragworm Hediste diversicolor were exposed to 10% tyre particles in sediment for three days. Both species consumed the particles, although S. plana consumed 25x more than H. diversicolor (967 compared with 35 particles.g^-1 wet weight, respectively). We then investigated the impact of 21 days exposure to different concentrations of tyre particles in estuarine sediments (0.2, 1, and 5% dry weight sediment) on aspects of the health of S. plana and H. diversicolor. Reductions in feeding and burial rates were observed for S. plana but not H. diversicolor, whilst both species showed a decrease in protein content in response to the greatest tyre particle concentration (5%), linked to an 18% decrease in energy reserves for H. diversicolor. Five percent tyre particle exposure led to an increase in total glutathione in the tissues of H. diversicolor, whilst lipid peroxidation decreased in the digestive glands of S. plana, possibly due to an increase in cell turnover. This study found that S. plana's health was impacted at lower concentrations than H. diversicolor, likely due to its consumption of large quantities of sediment. At the high exposure concentration (5%), the health of both invertebrates was impacted. This study did not separate the effects caused by the microplastic particles versus the effects of the chemical additives leaching from these particles, but our results do indicate that future studies should investigate effects in isolation and in combination, to determine the main drivers of toxicity.

Bioaccessibility of Organic Compounds Associated with Tire Particles Using a Fish In Vitro Digestive Model: Solubilization Kinetics and Effects of Food Coingestion

Tire and road wear particles (TRWP) account for an important part of the polymer particles released into the environment. There are scientific knowledge gaps as to the potential bioaccessibility of chemicals associated with TRWP to aquatic organisms. This study investigated the solubilization and bioaccessibility of seven of the most widely used tire-associated organic chemicals and four of their degradation products from cryogenically milled tire tread (CMTT) into fish digestive fluids using an in vitro digestion model based on Oncorhynchus mykiss. Our results showed that 0.06-44.1% of the selected compounds were rapidly solubilized into simulated gastric and intestinal fluids within a typical gut transit time for fish (3 h in gastric and 24 h in intestinal fluids). The environmentally realistic scenario of coingestion of CMTT and fish prey was explored using ground Gammarus pulex. Coingestion caused compound-specific changes in solubilization, either increasing or decreasing the compounds' bioaccessibility in simulated gut fluids compared to CMTT alone. Our results emphasize that tire-associated compounds become accessible in a digestive milieu and should be studied further with respect to their bioaccumulation and toxicological effects upon passage of intestinal epithelial cells.

Amidoxime functionalized PVDF-based chelating membranes enable synchronous elimination of heavy metals and organic contaminants from wastewater

Aiming at the synchronous elimination of heavy metals and organic contaminants from wastewater, the amidoxime functionalized PVDF-based chelating membrane was fabricated in this study. The structure and morphology of the chelating membrane were characterized using infrared spectroscopy (FT-IR), nuclear magnetic resonance spectrometer (NMR) and scanning electron microscopy (SEM). The SEM results show that the chemical modification with amidoxime groups did not damage the structure of the PVDF-based membrane. The chelating membrane has a high removal efficiency for Cu²⁺ (77.33%) and Pb²⁺ (79.23%) owing to the chemisorption through coordination bonds. However, the chelating membrane exhibits a low removal efficiency for Cd²⁺ (29.88%) due to the physical adsorption. The chelating membrane has a high rejection efficiency of BSA (95.17%) and lysozyme (70.09%), which is attributed to the sieving effect and increased hydrophobicity. Furthermore, the membrane performance for simultaneously removing metals and proteins from simulated wastewater was examined. The interaction of metal ions with proteins (BSA and lysozyme) can enhance the ion removal efficiency of the chelated membrane, but decrease the protein rejection efficiency due to the destructive effect. The amidoxime functionalized PVDF-based chelating membrane has a high potential for application in wastewater treatment.

Aging relieves the promotion effects of polyamide microplastics on parental transfer and developmental toxicity of TDCIPP to zebrafish offspring

Understanding the role of microplastics (MPs) in the biological fate and toxicity of organic pollutants in food webs is vital for its risk assessment. However, contradictory results and the neglect of MP aging as a factor have led to a research gap, which needs to be filled. Our study discovered that polyamide (PA, a ubiquitous MP in water) MPs clearly facilitated bioaccumulation of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) in the F0 zebrafish gonads and parental transfer of TDCIPP to the F1 offspring. Rapid TDCIPP desorption in the gut and intestine barrier dysfunction triggered by MPs were the causes for the phenomenon. In contrast to the pristine forms, aged PA with higher hydrophilcity exhibited stronger binding and polar interactions with TDCIPP, and the intestine damage was neglectable, resulting in increased intestinal immobilization and prevented parental transfer of TDCIPP. Additionally, the aggravated body weight loss and decreased length of TDCIPP offspring were relieved after PA aging. The recovery of subintestinal venous plexus angiogenesis, yolk lipid utilization, and ATP synthesis were responsible for the mitigated transgenerational toxicity. Our results highlight the significance of aging on the role of MPs with respect to coexisting pollutants and have great implications for understanding MP-associated risks.