Pathways for degradation of plastic polymers floating in the marine environment

Toxicological assessment of cigarette filter-derived microplastics in Daphnia magna

Cigarette filters are the most common form of litter worldwide and pose significant ecological risks because they degrade into microfibers and microplastics in aquatic environments. While previous studies have focused on the acute toxicity of cigarette leachate, the long-term ecological consequences of microplastic release from cigarette filters remain largely unexplored. This study evaluated the toxicity of cigarette filter-derived microplastics, including non-smoked cellulose acetate filters (CAF), smoked cigarette filters (GSF), on Daphnia magna, as well as leachate from smoked filter (LSF) for comparison. Imaging analysis confirmed that D. magna ingested cigarette filter-derived microplastics, which acted as carriers, gradually releasing harmful substances within organisms, a phenomenon consistent with the Trojan horse effect. Acute toxicity tests revealed similar 48-hour EC50 values (∼50 mg/L) for both GSF and LSF; however, GSF induced more pronounced long-term toxic effects. Chronic exposure to GSF significantly impairs reproduction, delays the timing of the first brood, reduces offspring size, and disrupts ecdysteroid-regulated genes. These findings indicate that cigarette filters are a persistent source of chemical pollution, threatening aquatic ecosystems. Specifically, microplastics from discarded cigarette filters act as Trojan horses, continuously releasing toxic chemicals and transporting hydrophobic contaminants, amplifying their environmental impact.

High levels of microplastics and microrubber pollution in a remote, protected Mediterranean Cladocora caespitosa coral bed

Coral reefs are increasingly threatened by anthropogenic stressors, including plastic pollution. This study investigates the abundance and possible ecological impact of microplastics (MPs) and microrubber pollution in sediments from a Cladocora caespitosa coral bed in the north-western Mediterranean. Despite being located in a remote marine protected area with no local plastic pollution sources, our results indicate exceptionally high MP concentrations (mean: 1514 particles/kg dry weight), attributed to long-distance transport of plastics by the Northern Current. Laser Directs Infrared (LDIR) Chemical Imaging and ATR-FTIR spectroscopy were used to characterize the MPs in terms of size, shape and polymer types. Most MPs are fragments (96 %), while fibers contribute only 4 %. The most abundant polymers were polyethylene (PE, 28 %), polyethylene terephthalate (PET, 25 %), and polystyrene (PS, 19 %), with significant contributions from polyurethane (PU) and microrubber. Particle size analysis showed that 92 % of MPs were smaller than 250 μm, with a median particle size varying by polymer type. Notably, polymers with heteroatoms in their main chain, such as PET and polyurethane, exhibited significantly smaller median sizes compared to polyolefins, possibly suggesting different degradation pathways. The high MP concentrations measured in sediments within coral colonies suggests that MPs could have adverse effects on heterotrophic feeding in C. caespitosa, a critical energy source during stress events. This study underscores the urgent need for targeted research on MP effects on the resilience of C. caespitosa and for increased global and regional efforts to curb plastic pollution mitigation in order to conserve coral populations in the Mediterranean.

Microplastics removal from stormwater runoff by bioretention cells: A review

Microplastics (MPs), as a new category of environmental pollutant, have been the hotspot of eco-friendly issues nowadays. Studies based on the aging process, the migration pattern of MPs in runoff rainwater, and the use of bioretention cells to remove MPs from runoff rainwater are beginning to attract widespread attention. This review analyses the migration patterns of MPs in rainwater runoff through their sources, structure and characteristics. The mechanism of removing MPs from runoff stormwater, the purification efficiency of different fillers and their influencing factors, and the accumulation, fate, and aging of MPs in bioretention cells are described. Furthermore, the hazards of MP accumulation on the performance of bioretention cells are summarised. Future directions for removing MPs in bioretention cells are proposed: (1) research on MPs smaller than 100 µm; (2) influence of MPs aging process on bioretention cells; (3) exploration of more effective fillers to enhance their removal efficiency; (4) research on synergistic removal mechanism of MPs and other pollution.

Effects of co-exposure to microplastics and perfluorooctanoic acid on the Caco-2 cells

As plastics are produced and used, humans are inevitably exposed to microplastics (MPs) on a daily basis. The pollution of MPs has aroused widespread human concern. Perfluorooctanoic acid (PFOA), a persistent organic pollutant (POP), can be adsorbed by microplastics and may exacerbate human health hazards. In this study, we investigated the effects of co-exposure of PET MPs and PFOA on the human intestinal tract in terms of both cytotoxicity and intestinal barrier through in vitro experiments. The results showed that PFOA induced cellular oxidative stress, mitochondrial dysfunction exerted cytotoxic effects, and inhibited tight junction (TJ) protein expression causing intestinal barrier damage. PET MPs can synergize with PFOA to exacerbate the deleterious effects on the intestinal tract by decreasing cell membrane permeability to increase PFOA accumulation in the cell and enhancing the ability of PFOA to inhibit zonula occludens-1 (ZO-1) proteins.

Microplastic abundance and characteristics in bivalves from Tam Giang-Cau Hai and O Loan Lagoons, coastal regions in Central Vietnam: Implication on human health

Four common bivalves, including white clam (Meretrix lusoria), lined clam (Paratapes undulatus), oysters (Crassostrea gigas), and green mussels (Perna viridi), which are commonly consumed in Central Vietnam, were collected from Tam Giang-Cau Hai and O Loan Coastal Lagoons. The samples were investigated for the presence of microplastics (MPs) in their tissues. The average number of MPs determined in white clams, lined clams, oysters, and green mussels in Central Vietnam varies from 0.3 to 0.9 per g-ww and from 0.9 to 5.6 per individual. Fibers, fragments, and pellets were found with various proportions concerning. Fibers were the most common shape, making up 36-74 % of the total microplastics, followed by fragments accounting for 16-47 %. The most prevalent colors were white-transparent and black-grey, comprising 49-81 % of the MPs. Regarding the microplastics found in the bivalve tissues, 78-80 % were <500 μm. Given chemical analysis, rayon accounted for 38 % of the microplastics discovered in bivalve tissues; closely PET (13 %), PA (10 %), and PP (10 %) were followed. This study offers valuable insights into the microplastic contamination concerned by bivalve consumption in Thua Thien Hue and Phu Yen, Central Vietnam; the results estimate the annual intakes are between 5000 and 10,000 particles per person. Unprecedentedly addressed in the literature, these findings contribute to a better understanding of microplastic pollution in Vietnam. The results altogether provide solid shreds of evidence for the MP contamination in Vietnam-based seafood, thus encouraging further attempts for plausible socio-economical regulations and raising public awareness on the issue.

Microbial degradation of polypropylene microplastics and concomitant polyhydroxybutyrate production: An integrated bioremediation approach with metagenomic insights

The persistence of plastics, particularly polypropylene (PP), and their conversion into microplastics (MPs), specifically PP-MPs, have emerged as serious ecological threats to soil and aquatic environments. In the present study, we aimed to isolate a microbial consortium capable of degrading PP-MPs. The results revealed that three microbial consortia (CPP-KKU1, CPP-KKU2, and CPP-KKU3) exhibited the ability to degrade PP-MPs, achieving weight losses ranging from 11.6 ± 0.2 % to 17.8 ± 0.5 % after 30 days. Fourier transform infrared (FTIR) spectroscopy analysis confirmed the degradation through oxidation, as evidenced by the presence of new functional groups (-OH and -C=O). In particular, CPP-KKU3 showed the highest degradation efficiency, with scanning electron microscopy (SEM) analysis revealing surface cracking after treatment. Additionally, gas chromatography-mass spectrometry (GC-MS) analysis identified various intermediate compounds, including heterocyclic aromatic compounds, phenyl groups, methylthio derivatives, and ethoxycarbonyl derivatives, indicating complex biochemical processes that were likely mediated by microbial enzymes. Furthermore, polyhydroxybutyrate (PHB) production by these consortia was also investigated. The result showed that both CPP-KKU2 and CPP-KKU3 successfully produced PHB, with CPP-KKU3 demonstrating superior performance in terms of PP-MP degradation and PHB production. Metagenomic analysis of CPP-KKU3 revealed abundant carbohydrate-active enzymes (CAZymes), particularly glycosyl transferases and glycoside hydrolases, which are associated with MP digestion. This study presents a promising bioremediation approach that addresses plastic waste degradation and sustainable bioplastic production, offering a potential solution for environmental plastic pollution.

Toxicity and absorption of polystyrene micro-nanoplastics in healthy and Crohn's disease human duodenum-chip models

Micro and nanoplastics (MNPs) are widespread environmental and food web contaminants that are absorbed by the intestine and distributed systemically, but the mechanisms of uptake are not well understood. In a triculture small intestinal epithelial model, we previously found that uptake of 26 nm polystyrene MNPs (PS26) occurred by both passive diffusion and active actin- and dynamin-dependent mechanisms. However, studies in a more physiologically relevant model are required to validate those results. Here, a microfluidic intestine-on-a-chip model was developed using primary human intestinal epithelial organoids from healthy and Crohn's disease donors, and used to evaluate the toxicity and mechanisms effectuating uptake of 25 nm polystyrene shell-gold core tracer MNPs (AuPS25). AuPS25 caused minimal toxicity after 24 h exposure in either healthy or Crohn's IOC models. RNAseq analysis of epithelial cells identified 9 genes dysregulated by AuPS25, including downregulation of IFI6 (interferon alpha-induced protein 6). Because IFI6 has important antiviral and immunosuppressive functions in the intestine, its downregulation suggests impairment of innate immune function, which could have important negative health consequences. Inhibitor studies revealed that AuPS25 uptake in the IOC occurred by both passive diffusion and active actin- and dynamin-dependent mechanisms, consistent with our previous findings in the triculture model.

Plastic additives alter the influence of photodegradation on biodegradation of polyethylene/polypropylene polymers in natural rivers

The biodegradation of microplastics in river sediments was subject to the prior photodegradation in surface water and can be greatly affected by polymers and additives. However, the understanding of the effects of additives on the cascade photo- and biodegradation processes remains limited. In this study, the characteristics of morphology, functional groups, and indictive degrading bacteria of polyethylene (PE) and polypropylene (PP) were detected to analyze the effects of Dioctyl phthalate (DOP), Bisphenol A (BPA) and Benzotriazole (BTA), on the single and cascade photo- and biodegradation processes of PP/PE films (PP/PEP, PP/PEB, PP/PEPB). The results showed that photodegradation enhanced the biodegradation, by creating smaller fractions which induced the proliferation of new PP/PE-degrading bacteria (P-bacteria). Compared to the general PP/PE-degrading bacteria, P-bacteria displayed higher standard betweenness centrality and carbon metabolism. Among the three additives, DOP most obviously promoted photo- and biodegradation processes, followed by BPA. BTA inhibited the photodegradation to biodegradation by absorbing UV light. Overall, these findings provide insights into the nonnegligible joint influence of photodegradation and additives on the biodegradation of PP/PE resins in natural rivers.

Charged polystyrene microplastics inhibit uptake and transformation of 14C-triclosan in hydroponics-cabbage system

INTRODUCTION

Since the outbreak of COVID-19, microplastics (MPs) and triclosan in pharmaceuticals and personal care products (PPCPs) are markedly rising. MPs and triclosan are co-present in the environment, but their interactions and subsequent implications on the fate of triclosan in plants are not well understood.

OBJECTIVE

This study aimed to investigate effects of charged polystyrene microplastics (PS-MPs) on the fate of triclosan in cabbage plants under a hydroponic system.

METHODS

14C-labeling method and liquid chromatography coupled with quadrupole/time-of-flight mass spectrometry (LC-QTOF-MS) analysis were applied to clarify the bioaccumulation, distribution, and metabolism of triclosan in hydroponics-cabbage system. The distribution of differentially charged PS-MPs in cabbage was investigated by confocal laser scanning microscopy and scanning electron microscopy.

RESULTS

The results showed that MPs had a significant impact on bioaccumulation and metabolism of triclosan in hydroponics-cabbage system. PS-COO-, PS, and PS-NH3+ MPs decreased the bioaccumulation of triclosan in cabbage by 69.1 %, 81.5 %, and 87.7 %, respectively, in comparison with the non-MP treatment (control). PS-MPs also reduced the translocation of triclosan from the roots to the shoots in cabbage, with a reduction rate of 15.6 %, 28.3 %, and 65.8 % for PS-COO-, PS, and PS-NH3+, respectively. In addition, PS-NH3+ profoundly inhibited the triclosan metabolism pathways such as sulfonation, nitration, and nitrosation in the hydroponics-cabbage system. The above findings might be linked to strong adsorption between PS-NH3+ and triclosan, and PS-NH3+ may also potentially inhibit the growth of cabbage. Specially, the amount of triclosan adsorbed on PS-NH3+ was significantly greater than that on PS and PS-COO-. The cabbage biomass was reduced by 76.9 % in PS-NH3+ groups, in comparison with the control.

CONCLUSION

The uptake and transformation of triclosan in hydroponics-cabbage system were significantly inhibited by charged PS-MPs, especially PS-NH3+. This provides new insights into the fate of triclosan and other PPCPs coexisted with microplastics for potential risk assessments.

Application and optimization of alkaline hydrolysis in recycling clear aligners

An increasing number of patients with malocclusion are choosing clear aligners for treatment, leading to a substantial rise in their production. Given the potential environmental impact of plastic products, recycling clear aligners is crucial. This study employed alkaline hydrolysis to recover the degradation products of clear aligners. The aligners were subjected to hydrolysis under various reaction conditions, including different concentrations of sodium hydroxide (NaOH), temperature, reaction time, ethanol-to-water mass ratio, and stirring rate. After the reaction, the organic components were isolated using thin-layer chromatography (TLC) plates, and their structure was characterized by 1H-NMR spectroscopy and mass spectrometry. The degradation product was identified as 4,4'-methylenedianiline (MDA). The optimal reaction conditions for achieving the maximum degradation yield of MDA were determined to be stirring at 300 rpm at 130°C in a solution containing 5 wt% NaOH and a 1:1 mass ratio of ethanol to water for 24 h. This method demonstrates that clear aligners can be effectively recycled through alkaline hydrolysis, supporting global efforts to reduce environmental emissions.

Polymer weathering under simulated solar radiation and comparison to stormwater and estuarine microplastics

Accurate spectral identification of weathered plastics and analyses that provide insight into environmental degradation and age are desirable for source tracking and understanding hazards. The objectives of this study were to (1) evaluate the kinetics of spectral changes for lab-weathered polymers and compare to spectra from environmental microplastics (MPs), and (2) assess the accuracy of spectral databases in identifying weathered polymers. For objective 1, polyethylene (PE) and polypropylene (PP) fragments were exposed to simulated solar radiation in water for 90 days. FTIR spectra were collected periodically and degradation was quantified using carbonyl and hydroxyl bond indices. Significant linear increases in carbonyl indices for PP, but not PE, were observed as a function of exposure time. Spectra (via principal component analysis) and bond indices from lab-weathered polymers were then compared to environmental MPs collected from urban stormwater and the Delaware Bay estuary. Estuarine PP carbonyl and hydroxyl indices varied as a function of spectral collection mode (i.e., ATR vs. transmission) and by sampling site, potentially indicating the bond indices provide insight into sources/fate/transport of PP and are worthy of further study. In contrast, no significant differences were observed for PP in stormwater samples, possibly due to the close proximity of collection locations. PE exhibited non-linear trends in bond indices in the laboratory study and showed no significant association with sampling location in environmental samples, suggesting these indices may be less useful for PE degradation analysis. For objective 2, 14 different polymers, eight of which were polymer blends, were exposed to simulated solar radiation for up to 90 days, in dry and wet conditions. FTIR spectra were collected periodically and analyzed with two spectral identification software. OpenSpecy achieved an 88 % true positive rate compared to siMPle's 57 % at a 70 % hit quality threshold. Expanding reference libraries, to include weathered polymers and polymer blends, could improve spectral identification accuracy, and manual interpretation of FTIR spectra is recommended for low-confidence matches.

Microplastic uptake with food increases risk-taking of a wide-spread decomposer, the common pill bug Armadillidium vulgare

Exposure to microplastics (MPs) i.e., plastic fragments between 1 μm and 1 mm in diameter causing growing concern for wildlife and humanity. It is now evident that MPs can accumulate in soil, freshwater, seawater and the atmosphere; thus, living organisms are directly or indirectly exposed to these significant ecological stressors globally. Studies on the physiological effects of MPs in wildlife are emerging, yet, to date, only a handful of studies with a special focus on how MPs affect animal behaviour are available, and there is even less research on how different components of among- and within-individual behavioural variation are affected by MPs. The main goal of this study was to investigate how prolonged exposure (6 weeks) to 10 μm spherical polystyrene microplastics in food (24.85 particles/mg) influences individual variation in risk-taking behaviour in a widespread decomposer, the common pill bug Armadillidium vulgare. Our results indicate a strong MP effect on different levels of behavioural variation: (i) individual mean risk-taking increased, while (ii) a correlation between mean risk-taking and residual within-individual risk-taking variation emerged (risk-takers became less predictable) in the MP treated group. These findings underscore the intricate effects of MPs on individual behavioural variation, with potentially far-reaching ecological and evolutionary consequences given their pervasive presence in both terrestrial and aquatic ecosystems. The negative impacts of these changes are widespread; in our study, MP exposure may increase the susceptibility of A. vulgare to predation, potentially contributing to population decline.

Evaluating the environmental impact of cleaning the North Pacific Garbage Patch

Cleanup of existing plastic pollution is crucial to mitigate its impact on marine ecosystems, but such efforts must ensure benefits outweigh potential environmental damage caused by the cleanup. Here, we present an impact assessment framework and apply it to evaluate whether cleaning the North Pacific Garbage Patch (NPGP) benefits marine life and carbon cycling, using The Ocean Cleanup as a case study. Our findings indicate that marine life is more vulnerable to plastic pollution than to macroplastic cleanup, with average vulnerability scores (1 = low, 3 = high) of 2.3 for macroplastics, 1.9 for microplastics, and 1.8 for cleanup, suggesting a net positive impact. An 80% cleanup could reduce macroplastic concentrations to within reported safe levels for marine mammals and sea turtles. Estimated cleanup-related carbon emissions [0.4-2.9 million metric tons (Mt) in total] are significantly lower than potential long-term microplastics impacts on ocean carbon sequestration (15-30 Mt C per year). However, uncertainties remain regarding effects on air-sea carbon exchange. Our framework serves as a critical tool for assessing trade-offs between plastic pollution and remediation impacts. It demonstrates the environmental net benefits of the proposed NPGP cleanup and can be adapted to similarly evaluate other remediation plans.

Designing for degradation: the importance of considering biotic and abiotic polymer degradation

Considering the increasing global plastic demand, there is a critical need to gain insight into environmental processes that govern plastic degradation in order to inform novel design of sustainable polymers. Current biological degradation testing standards focus on formation of CO2 (i.e., mineralization) alone as a diagnostic, ultimately limiting identification of structure-degradation relationships in a timely fashion. This work developed a sequential abiotic (i.e., photodegradation and hydrolysis) and biotic degradation test and applied it to a suite of 18 polymers, including ten lab produced, novel polyhydroxyalkanoate polyesters, and eight commercially available, bio-based (i.e., polylactic acid and poly-3-hydroxybutyrate) and fossil-derived (i.e., polystyrene, polypropylene, low density polyethylene, poly(ethylene terephthalate) and tire rubber) polymers. Biomineralization alone following standard methods (i.e., ASTM 6691-17, ISO 23977-1 2020) underestimated polymer degradation up to two-fold over 28 days. Simulated sunlight enhanced the overall polymer degradation by mobilizing dissolved organic carbon (DOC). After photoirradiation, up to 100% of released dissolved organic carbon was bioavailable for marine microbes over 14 days. Photodegradation and hydrolysis could be explained by structural drivers in the commodity polymers, and the lab-synthesized polymers illustrated a limit to total degradation beyond which no enhancements in degradation were achieved. Taken together, this workflow allows for relatively fast experimental determination of environmentally relevant stimuli to help support eventual elucidation of structure-property relationships for enhanced a priori design of degradable polymers.

Volatile organic compounds as fingerprints for identifying marine plastics

The increase in global marine plastic pollution highlights the need for more advanced yet simplified methods of plastic analysis. This study investigated the potential of volatile organic compounds (VOCs) emitted from plastics as fingerprints for plastic identification. Selected ion flow tube-mass spectrometry was used to conduct real-time analysis of VOCs emitted from heated (20-80 °C) pellets of plastic types commonly encountered in marine environments, including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), expanded polystyrene (EPS), and poly(ethylene terephthalate) (PET). VOCs consistently reflected the compositional characteristics of each plastic type: alkanes, characterised by their monomer units, were dominant in LDPE, HDPE, and PP; aromatics were prevalent in EPS; and ethylene glycol was observed in PET. The concentrations of these components varied with temperature, reflecting their unique thermal properties. A tiered classification model employing partial least squares discriminant analysis based on key mass fragment ions of emitted VOCs successfully distinguished among polymer types, achieving 100 % accuracy in determination of plastic products. This novel approach offers a simplified plastic polymer identification method, demonstrating that the chemical signatures of VOCs emitted from plastics can serve as unique and reliable fingerprints.

Effects of micro- and nanoplastic exposure on macrophages: a review of molecular and cellular mechanisms

Micro- and nanoplastics (MNPs), pervasive environmental pollutants, contaminate water, soil, air, and the food chain and ultimately accumulate in living organisms. Macrophages are the main immune cells that gather around MNPs and engulf them through the process of phagocytosis. This internalization triggers M1 polarization and the secretion of inflammatory cytokines, including IL-1, IL-18, IL-12, TNF-α, and IFN-γ. Furthermore, MNPs damage mitochondria and lysosomes, causing overactivation of iNOS and excessive production of ROS. This results in cellular stress and induce apoptosis, necroptosis, and, in some cases, metosis in macrophages. The internalization of MNPs also increases the expression of receptors, involving CD36, SR-A, LOX-1, and the macrophage receptor with a collagenous structure (MARCO) while decreasing ABCA-1 and ABCG-1. MNPs in adipose tissue macrophages trigger proinflammatory cytokine secretion, causing adipogenesis, lipid accumulation, insulin resistance, and the secretion of inflammatory cytokines in adipocytes. Various factors influence the rate of MNP internalization by macrophages, including size, charge, and concentration, which affect internalization through passive diffusion. Receptor-mediated phagocytosis of MNPs occurs directly via receptors like T-cell immunoglobulin and mucin domain containing 4 (TIM-4) and MARCO. The attachment of biomolecules, including proteins, antibodies, opsonins, or microbes to MNPs (forming corona structures) promotes indirect receptor-mediated endocytosis, as macrophages possess receptors like TLRs and FcγRIII. MNPs also cause gut dysbiosis, a risk factor for proinflammatory microenvironment and M1 polarization. Here, we review the mechanisms and consequences of MNP macrophage exposure, which is linked to autoimmunity, inflammation, and cardiometabolic syndrome manifestations, including atherosclerosis and obesity, highlighting the immunotoxicity of MNPs.

Shock Wave-Induced Degradation of Polyethylene and Polystyrene: A Reactive Molecular Dynamics Study on Nanoplastic Transformation in Aqueous Environments

Degradation of polyethylene and polystyrene was studied theoretically using reactive molecular dynamics based on the ReaxFF force field. The degradation reactions were carried out on nanoparticles (approximately 2 nm in diameter) composed of ideal low-density polyethylene and polystyrene in the presence of water. The reactions leading to degradation were triggered by applying a shock wave through the simulation box. This approach allowed the energy to be transferred to the sample in a controllable manner and initiated the reactions. The state of the nanoparticles after the shock wave passage was investigated in detail, focusing on the type and quantities of new surface functional groups and new chemical connections in the bulk samples. It was found that polyethylene predominantly reveals surface hydroxyl groups (some of which can be protonated) and has the ability to release linear polyhydroxy alcohols. Other surface functional groups with significant presence are ether groups. The degradation of polystyrene proceeds through the addition of hydroxyl groups primarily to the benzene rings, causing their dearomatization. The number of hydroxyl groups in a single ring increases with the degree of degradation, and some hydroxyl groups are also protonated. Polystyrene is also susceptible to crosslink formation, mainly between aromatic rings, leading to branched and dearomatized forms that are chemically distinct from styrene.

Size-Dependent Interactions of Degraded PET Nanoparticles with Human Serum Albumin: Thermodynamic and Molecular Insights

This study examines the interaction between degraded polyethylene terephthalate (PET) nanoparticles and human serum albumin (HSA), focusing on the effects of nanoparticle size and surface modifications resulting from degradation. PET degradation, induced via shock compression in water, leads to significant chemical alterations, including the formation of hydroxyl, carboxyl, and carbonyl groups. These modifications influence the hydrophilicity of PET nanoparticles and their binding behavior with HSA. The production of degraded PET nanoparticles involves subjecting pristine PET to controlled shock compression in an aqueous environment, which initiates chemical reactions similar to those that may occur during degradation. The degradation process is characterized by a progressive breakdown of polymer chains, leading to an increase in functionalized surface groups that enhanced hydrophilicity. The performed analysis of surface chemistry reveals that the introduction of oxygen-containing groups alters the interaction properties of PET nanoparticles, making them more prone to hydrogen bonding with water molecules while simultaneously reducing their affinity for HSA binding. Molecular dynamics simulations, umbrella sampling, and weighted histogram analysis are employed to investigate the thermodynamic aspects of PET-HSA interactions. The study identifies preferred binding sites of PET nanoparticles on HSA, revealing that degraded PET nanoparticles preferentially bind to Domain I and Domain III of HSA. Interaction energy analysis demonstrates that larger PET nanoparticles exhibit stronger binding, whereas small degraded nanoparticles have significantly reduced interaction energies, indicating a higher likelihood of desorption. Further structural analysis using root-mean-squared deviation (RMSD) and root-mean-squared fluctuation (RMSF) confirms that PET binding does not significantly alter HSA's secondary structure. However, degradation significantly increases PET hydrophilicity, weakening their adsorption onto HSA. Large PET nanoparticles are strongly bound, whereas small degraded nanoparticles remain unbound, raising concerns regarding their potential toxicity due to free migration in the bloodstream. These findings provide crucial insights into the biological implications of PET degradation, the role of surface chemistry in determining nanoparticle interactions, and their potential contributions to nanoplastic toxicity.

Ocean current modulation of the spatial distribution of microplastics in the surface sediments of the Beibu Gulf, China

Microplastic pollution, a major global environmental issue, is gaining heightened attention worldwide. Marginal seas are particularly susceptible to microplastic contamination, yet data on microplastics in marine sediments remain scarce, especially in the Beibu Gulf. This study presents a large-scale investigation of microplastics in the surface sediments of the Beibu Gulf to deciphering their distribution, sources and risk to marginal seas ecosystems. The results reveal widespread microplastic contamination, with an average abundance of 391 ± 27 items/kg in sediments. The spatial variability of microplastic abundance was significant, with lower levels in the western Beibu Gulf and higher concentrations in the northeastern and southeastern regions. The spatial distribution of microplastics was largely driven by geological features, hydrodynamic conditions, and human activity, with minimal influence from local environmental factors such as water depth, sediment grain size, organic carbon content, and sediment types. The pollution load index (PLI) suggests a low level of microplastic contamination, but the polymer hazard index (PHI) identified a high ecological risk, likely due to the presence of PVC, a polymer with higher chemical toxicity. Our findings highlight the significant role of hydrodynamic processes in determining microplastic distribution in the Beibu Gulf. These insights enhance our understanding of microplastic dispersal and its governing factors in semi-enclosed marginal seas, providing foundation for targeted pollution control strategies.

Biofilm colonization on non-degradable and degradable microplastics change the adsorption of Cu(II) and facilitate the dominance of pathogenic microbes

Microplastics (MPs) have become a global concern as they can accumulate pollutants in aquatic environments. In this research, Cu(II) and non-degradable (polyamide, PA), degradable (polylactic acid, PLA) MPs were employed to reveal the potential connection among different aged MPs and heavy metal pollutants. The aging processes of MPs induced alterations in the surface morphologies, led to an augmentation of the specific surface area, and formed more biofilm and oxygen-containing groups on the MPs surface. The Qe of PA and PLA MPs increased from 0.102 to 0.989 to 1.192 and 2.457 mg/g after aging, respectively. The analysis of site energy distribution further verified that the enhanced adsorption capacity resulted from more high-energy adsorption sites obtained during the aging processes of MPs. Moreover, pathogenic bacteria and resistant bacteria were accumulated on the surface of MPs regardless of the aging environment, and the abundance and diversity of pathogenic bacteria on the biofilm of the PA surface were greater than those on the PLA MPs. This research offers an insight into the mechanism underlying microbial colonization and adsorption in the relationship between MPs and Cu(II), which is beneficial for judging the enrichment of heavy metals on MPs within the aquatic environment.

The distribution of subsurface microplastics in the ocean

Marine plastic pollution is a global issue, with microplastics (1 µm-5 mm) dominating the measured plastic count1,2. Although microplastics can be found throughout the oceanic water column3,4, most studies collect microplastics from surface waters (less than about 50-cm depth) using net tows5. Consequently, our understanding of the microplastics distribution across ocean depths is more limited. Here we synthesize depth-profile data from 1,885 stations collected between 2014 and 2024 to provide insights into the distribution and potential transport mechanisms of subsurface (below about 50-cm depth, which is not usually sampled by traditional practices3,6) microplastics throughout the oceanic water column. We find that the abundances of microplastics range from 10-4 to 104 particles per cubic metre. Microplastic size affects their distribution; the abundance of small microplastics (1 µm to 100 µm) decreases gradually with depth, indicating a more even distribution and longer lifespan in the water column compared with larger microplastics (100 µm to 5,000 µm) that tend to concentrate at the stratified layers. Mid-gyre accumulation zones extend into the subsurface ocean but are concentrated in the top 100 m and predominantly consist of larger microplastics. Our analysis suggests that microplastics constitute a measurable fraction of the total particulate organic carbon, increasing from 0.1% at 30 m to 5% at 2,000 m. Although our study establishes a global benchmark, our findings underscore that the lack of standardization creates substantial uncertainties, making it challenging to advance our comprehension of the distribution of microplastics and its impact on the oceanic environment.

Effect of pH and salinity on the release of polystyrene microplastics derived dissolved organic matter as revealed by experimental studies and molecular dynamic simulations

Microplastics-derived dissolved organic matter (MPs-DOM) poses a significant risk to aquatic systems. This study characterized MPs-DOM from polystyrene microplastics (PSMPs) upon photoaging in freshwater and seawater. For pristine PSMPs, plastic additives are the predominant substances in MPs-DOM. As the degree of aging increases, intermediates emerge as the new predominant substances in MPs-DOM. Both higher pH and salinity accelerate the aging of PSMPs and MPs-DOM release. Molecular dynamics simulations align with experiments showing that increased pH and salinity levels enhance the release of MPs-DOM. Interaction energy calculations revealed a link between MPs-DOM release amount and the interaction intensity between PSMPs and MPs-DOM. Generally, MPs-DOM having lower interaction energy with PSMPs is more liable to release, and aging of PSMPs leads to a decrease in their interaction energy with MPs-DOM. For example, the interaction energies in the pH 10 seawater system were slightly lower than those in the pH 7 seawater system. In the pH 7 seawater system, the interaction energy between butyl acetate and PSMPs was -41.97 kJ/mol, while in the pH 10 seawater system, this value was -26.86 kJ/mol. These insights are crucial for assessing the environmental behavior of MPs and MPs-DOM in aqueous environments.

A study protocol for chemical analysis and toxicity testing of virgin and recycled microplastics and associated chemicals

Plastics can contain a variety of different chemicals, which are either intentionally (IAS) or non-intentionally (NIAS) added substances. Recycled plastics can contain especially NIAS, which might vary in amount and characteristics, possibly compromising the applicability of the plastics. As plastics can eventually degrade into microplastics, these substances can be released into their environment and upon human exposure, pose a threat to human health. Therefore, simple methods for the comprehensive monitoring of these chemicals are needed to guarantee the safe use of plastics. The purpose of this study was to set up methods for analyzing and toxicity testing of chemicals present in secondary microplastics of virgin and recycled origin. Accordingly, the chemical compounds of virgin and recycled polypropylene (PP), low-density polyethylene (LDPE), and high-density polyethylene (HDPE) microplastics were extracted using water, methanol, and chloroform as solvents, and the extracts were analyzed with nuclear magnetic resonance (NMR) and total reflection X-ray fluorescence (TXRF) methods. In addition, two cytotoxicity assays were applied to study the toxicity of the chloroform extracted virgin and recycled microplastics in human adenocarcinoma Caco-2 cells. The combination of NMR and TXRF methods allowed extensive analysis of the released chemicals showing that chloroform was the most efficient solvent for extraction. The results showed that microplastics milled from mechanically recycled plastics released more organic compounds and inorganic elements compared to microplastics milled from virgin plastics. In addition, the chloroform extracted microplastics decreased cell viability dose dependently and the observed effect was more prominent with the recycled microplastics compared to their virgin counterparts. In conclusion, these results suggest that chemicals tend to accumulate in recycled plastics, and therefore, these chemicals need to be monitored to guarantee the safe use of recycled plastics. This study showed that chloroform extraction is efficient in releasing substances accumulated in plastics for chemical analysis and toxicity testing.

An Atmospheric Chemistry Perspective on Airborne Micro- and Nanoplastic Particles

Micro- and nanoplastic particles (MNPPs) are emerging pollutants with significant environmental impacts due to their persistence, increasing concentrations, and potential health risks. Most MNPP studies have focused on identifying, quantifying, and assessing their ecotoxicological impacts in water or soil. However, the atmosphere is crucial in transporting and chemically transforming MNPPs. Further, well-established aerosol particle characterization techniques are underutilized and inconsistently applied in existing atmospheric MNPP studies. This perspective synthesizes the existing literature and addresses future research needs unique to atmospheric MNPPs, highlighting the need to bridge the microplastics and atmospheric aerosol communities to better understand their sources, chemical transformations, transport mechanisms, as well as their health effects and ecological impacts, which differ from those in soil and water. Advancing research in these areas requires standardized methods and a multidisciplinary approach to comprehensively assess MNPP interactions across environmental compartments, providing essential insights into their environmental fate and risks.

Exposure to plastic debris alters expression of biomineralization, immune, and stress-related genes in the eastern oyster (Crassostrea virginica)

The degradation of marine plastic debris poses a threat to organisms by fragmenting into micro- and nano-scale pieces and releasing a complex chemical leachate into the water. Numerous studies have investigated harms from plastic pollution such as microplastic ingestion and exposure to single chemicals. However, few studies have examined the holistic threat of plastic exposure and the synergistic impacts of chemical mixtures. The objective of this study was to measure changes in gene expression of gill and gonadal tissue of the eastern oyster (Crassostrea virginica) in response to plastic debris exposure during their first year, using RNA-seq to explore multiple types of physiological responses. Shell and polyethylene terephthalate plastic were used as substrate for the metamorphosis of larval oysters in a settlement tank. Substrate pieces were then transferred to metal cages and outplanted in pairs - shell cage and plastic cage - onto restoration reefs in the St. Mary's River, Maryland, USA. After 10 months of growth, the oysters were collected, gill and gonadal tissue removed, and sex identified. The tissues of six oysters from each sex and substrate type were then analyzed in RNA-seq. Both gill and gonadal tissue samples had altered expression of immune and stress-response genes in response to plastic exposure. Genes upregulated in response to plastic were enriched for gene ontology functions of proteolysis and fibrinolysis. Downregulated genes were involved in shell biomineralization and growth. One male oyster exposed to plastic had "feminized" gene expression patterns despite developing mature sperm, suggesting plastic leachate can alter gene expression and shift protandric individuals to develop as females. Plastic pollution may therefore reduce shell growth, initiate immune and stress responses, alter sex differentiation, and impact reproductive output of eastern oysters through changes in transcription.

Weathering Process and Characteristics of Microplastics in Coastal Wetlands: A 24-Month In Situ Study

Coastal wetlands function as critical retention zones for environmental microplastics, potentially accelerating their degradation through unique hydrological conditions. This study conducted a comprehensive 24-month in situ experiment at the Chongming Dongtan National Nature Reserve, examining the weathering processes of five morphologically distinct polyethylene (PE), polypropylene (PP), and polystyrene (PS) microplastics. Quarterly analyses revealed progressive surface deterioration in all microplastics after initial exposure, followed by polymer-specific fragmentation patterns and environmental pollutant adherence. Surface elemental analysis showed rising O/C ratios, with intertidal zones exhibiting higher variance (0.0014-0.0096 vs 0.0006-0.0028 supratidal). Carbonyl index (CI) displayed fluctuating increases, with PS showing the highest CI rise (75.75%/year intertidal vs 61.77%/year supratidal). Systematic comparisons identified three weathering determinants: enhanced intertidal degradation from mechanical-photochemical synergy; spherical particles degrading faster than films via larger surface area; and polymer vulnerabilities dictating PS > PP > PE degradation rates. These findings demonstrate that microplastic weathering in coastal wetlands is collectively governed by hydrological conditions, particle morphology, and polymer composition, providing crucial quantitative parameters for assessing environmental persistence and ecological risks in these sensitive transition ecosystems.

Biodegradable Gel Blends with Enhanced Sensing Capabilities: SIO₂-Based Innovations for Sustainable and Eco-Friendly Packaging

Biopolymer blends (GGs) derived from renewable plant or animal-based raw materials, hold significant potential for competing in the packaging industry by offering environmentally biodegradable and bioresorbable alternatives. One of the main challenges lies in optimizing the mechanical properties to enhance stress transfer between active additives and the gelatin matrices reinforced with modified SiO₂ compounds. In this study, a 5 °C increase in the glass transition temperature and a fourfold improvement in tensile strength (reaching 12 MPa) were achieved by incorporating hydrophilic SiO₂ nanoclay. Ion distribution maps visualized the interactions between silicon derivatives and polypeptide domains within the gel matrix, revealing increased stability attributed to ions such as Si+, SiO+, SiH+, and SiHO+. The absence of heavy metals in the blends underscores their potential as environmentally friendly and sustainable packaging solutions, with promising applications in sectors such as medical packaging.

Photothermal radiometric image identification of microplastics through near-infrared excitation

Near-infrared excitation photothermal radiometric image identification is demonstrated as a rapid analysis tool for visualizing different types of microplastics (MPs). The excitation wavelengths used for four types of plastic materials, polyethylene terephthalate, polystyrene, polyvinyl chloride, and polypropylene, were 1662 nm, 1681 nm, 1716 nm, and 1725 nm, respectively, in the near-infrared region. After irradiating for 20 s with a specified wavelength, a photothermal radiometric image was recorded with a commercially available thermal camera. Each of the four types of MPs in a 2 mm square and with a 1 mm thickness was successfully visualized. A simple thermal diffusion analysis predicts a time-dependent increase in the temperature rise of each of the plastic materials having their own specific physical properties.

Review of Techniques for the Detection, Removal, and Transformation of Environmental Microplastics and Nanoplastics

Plastic residues have emerged as a significant challenge in the environmental sector. Microplastics, which are plastic fragments smaller than 5 mm, have the ability to disperse through the atmosphere, oceans, and land, posing a serious threat to human health by accumulating in the food chain. However, their minuscule size makes it difficult to effectively remove them from the environment using the current technologies. This work provides a comprehensive overview of recent advancements in microplastic detection and removal technologies. For detection methods, we discuss commonly used techniques such as microscopic analysis, thermal analysis, mass spectrometry, spectroscopic analysis, and energy spectrometry. We also emphasize the importance of integrating various analytical and data-processing techniques to achieve efficient and nondestructive detection of microplastics. In terms of removal strategies, we explored innovative methods and technologies for extracting microplastics from the environment. These include physical techniques like filtration, adsorption, and magnetic separation; chemical techniques such as coagulation-flocculation-sedimentation and photocatalytic conversion; and bioseparation methods such as activated sludge and biodegradation. We also highlight the promising potential for converting microplastic contaminants into high-value chemicals. Additionally, we identify current technical challenges and suggest future research directions for the detection and removal of microplastics. We advocate for the development of unified and standardized analytical methods to guide further research on the removal and transformation of microplastics.

Distinguishing between extractable and leachable contents of styrene oligomers in various polystyrene consumer products: Towards environmentally realistic scenarios

Plastic additives' environmental impacts remain insufficiently understood due to knowledge gaps in their bioavailability, despite growing concerns from increased plastic use and waste. Additives that are non-covalently bound but strongly interact with polymers can be extractable but not leachable, thus non-bioavailable. Nevertheless, most studies have not distinguished between extractable (EC) and leachable content (LC) in plastic additives. We quantified the EC and LC of styrene oligomers (SOs) in polystyrene (PS) by applying the selective solvent compatibility of PS-dissolution in dichloromethane for EC and swelling in n-hexane for LC. Significant differences were found between EC and LC of SOs in 28 widely consumed PS products and across three PS types-expanded PS (EPS), extruded PS (XPS), and solid PS. EPS showed lower EC and LC values and fewer SO isomers. LCs were only 32 % (EPS), 84 % (XPS), and 72 % (solid PS) of ECs, suggesting bioavailable fractions may be overestimated if only EC is considered. We estimate that 3.3 MT of PS-incorporated SOs, with 76 % in leachable forms, have entered the environment, but much may still remain in PS debris. Distinct isomer ratios and high non-leachable fractions in EPS suggest that SOs could serve as effective tracers for distinguishing and quantifying invisible EPS-origin particles in beach sediments. This study underscores the need to differentiate EC from LC for environmentally realistic risk assessment and source identification.

Effects of Nanoplastics on Lipid Membranes and Vice Versa: Insights from All-Atom Molecular Dynamics Simulations

We compute the potential of mean force (PMF) between semicrystalline polyethylene (PE) nanoplastics (NPLs) and model POPC and DPPC bilayers, which approximate in vivo membranes, using atomistic simulations. Our work shows that atomistic resolution is required to characterize the NPL and lipid interactions. By analyzing the PMF, we demonstrate that the mechanical properties of membranes, rather than NPL semicrystalline morphologies, govern NPL-membrane interactions. Resistance to NPL penetration arises from the elastic energy of the membrane deformation. The flexible POPC membranes resist NPL translocation, and the brittle DPPC membranes fracture under stress. Using an elastic free energy model, we approximate effective repulsions between lipid membranes and NPLs of various sizes. Our mean first-passage time analysis shows that even small, bare NPLs cannot easily penetrate brittle lipid membranes via passive diffusion, even at high concentrations. However, eco-coronas or other mechanisms, such as endocytosis, may still facilitate the cellular uptake of NPLs and MPLs. While semicrystalline morphologies do not directly impact NPL translocation, they do influence NPL behavior within lipid membranes upon translocation. Semicrystalline NPLs remain intact within lipid membranes, whereas amorphous NPLs can dissolve into the hydrophobic core and alter the elastic properties of the membrane.

Deposition characteristics of microplastics in coral reef fish with different feeding habits from the Xisha Islands Waters, South China Sea

Over the past decade, awareness of plastic pollution has significantly increased, leading to a focus on its potential adverse effects on biota, including the ingestion of microplastics by fish. This study investigates the abundance, composition, and characteristics of microplastics in the gills and gastrointestinal tracts (GITs) of 96 coral reef fish with different feeding habits (herbivorous fish: Scarus rivulatus, Naso lituratus, and Acanthurus triostegus; omnivorous fish: Abudefduf vaigensis; carnivorous fish: Epinephelus merra) from the Xisha Islands Waters, South China Sea. The relationships between microplastic abundance and fish length, weight, and feeding habits were also analyzed. Results show that 97.92% of the sampled coral reef fish contained microplastics. The average abundance of microplastics in the gills and GITs was 1.09 ± 0.25 items individual-1 and 1.74 ± 0.26 items individual-1, respectively. The predominant shapes of microplastics were fibers, with black and blue being the most common colors. Most microplastics (90%) were smaller than 1 mm, and the main polymer types were PET, CP, PE, and PP. Additionally, the GITs contained more microplastics than the gills. Unlike the scope of previous studies, this study newly found the following two points: 1.Herbivorous fish had higher microplastic content than omnivorous fish, while carnivorous fish had the lowest, likely due to herbivorous fish feeding primarily on microplastic-polluted coral reefs. 2.The abundance of microplastics in the gills and GITs was not related to gill weight or GITs weight, however, the abundance of microplastics was significantly correlated with fish body length and body weight.

Construction of a Real-Time Detection for Floating Plastics in a Stream Using Video Cameras and Deep Learning

Rivers act as natural conduits for the transport of plastic debris from terrestrial sources to marine environments. Accurately quantifying plastic debris in surface waters is essential for comprehensive environmental impact assessments. However, research on the detection of plastic debris in surface waters remains limited, particularly regarding real-time monitoring in natural environments following heavy rainfall events. This study aims to develop a real-time visual recognition model for floating plastic debris detection using deep learning with multi-class classification. A YOLOv8 algorithm was trained using field video data to automatically detect and count four types of floating plastic debris such as common plastics, plastic bottles, plastic film and vinyl, and fragmented plastics. Among the various YOLOv8 algorithms, YOLOv8-nano was selected to evaluate its practical applicability in real-time detection and portability. The results showed that the trained YOLOv8 model achieved an overall F1-score of 0.982 in the validation step and 0.980 in the testing step. Detection performance yielded mAP scores of 0.992 (IoU = 0.5) and 0.714 (IoU = 0.5:0.05:0.95). These findings demonstrate the model's robust classification and detection capabilities, underscoring its potential for assessing plastic debris discharge and informing effective management strategies. Tracking and counting performance in an unknown video was limited, with only 6 of 32 observed debris items detected at the counting line. Improving tracking labels and refining data collection are recommended to enhance precision for applications in freshwater pollution monitoring.

Comparison of macrolitter and meso- and microplastic pollution on French riverbanks and coastal beaches using citizen science with schoolchildren

Rivers are the major source of anthropogenic litter entering the ocean, especially plastic debris that accumulates in all ecosystems around the world and poses a risk to the biota. Reliable data on distribution, abundance, and types of stranded plastics are needed, especially on riverbanks that have received less attention than coastal beaches. Here, we present the citizen science initiative Plastique à la loupe (Plastic under the magnifier), which compares for the first time the distribution of different litter sizes (macrolitter and meso- and microplastics) over 81 riverbanks and 66 coastal beaches sampled in France between 2019 and 2021. A total of 147 school classes (3113 schoolchildren) from middle to high school collected, sorted, and enumerated 55,986 pieces of plastic to provide a baseline of the current pollution by stranded debris at the national level. Single-use plastics (mainly food-related items) were very abundant on riverbanks (43%), whereas fragmented debris dominated the macrolitter on coastal beaches (28%). Microplastics were always higher in number compared to mesoplastics and macrolitter, with polystyrene and polyethylene found in equivalent proportions on riverbanks while polyethylene dominated microplastics on coastal beaches. Tracing the source of plastic items was possible only for a small proportion of the numerous collected items, mainly for identifiable macrolitter and microplastic pellets. This study lays out the foundations for further works using the Plastique à la loupe citizen science initiative in France and additional comparisons to other studied habitats worldwide, which can be used by scientists and policy-makers for future litter monitoring, prevention and clean-up strategies.

Mechanism of quiescent nanoplastic formation from semicrystalline polymers

Polymers are known to spontaneously produce microplastics (sizes 1 μm - 3 mm) and nanoplastics (10 nm - 1 μm). Still, the mechanisms by which environmentally-triggered Å-level random bond breaking events lead to the formation of these relatively large fragments are unclear. Significantly, ≈ 70% of commercial polymers are semicrystalline, with a morphology comprised of alternating crystalline and amorphous layers, each tens of nanometers thick. It is well-accepted that chain scission events accumulate in the amorphous phase. We show that this leads to mechanical failure and the concurrent release of particulate nanoplastics comprised of polydisperse stacks of lamellae even under quiescent conditions. Noncrystalline analogs, which do not have a well-defined microstructure, do not form nanoplastics. While the amorphous phase of the semicrystalline nanoplastics continues to degrade, crystal fragments do not, and hence, they temporally persist in the environment. These results stress the critical role of polymer microstructure and fracture mechanics on particulate nanoplastic creation.

Application of Computational Studies Using Density Functional Theory (DFT) to Evaluate the Catalytic Degradation of Polystyrene

The degradation of polystyrene (PS) represents a significant challenge in plastic waste management due to its chemical stability and low biodegradability. In this study, the catalytic degradation mechanisms of PS were investigated by density functional theory (DFT)-based calculations using the hybrid functional B3LYP and the 6-311G++(d,p) basis in Gaussian 16. The influence of acidic (AlCl3, Fe2(SO4)3) and basic (CaO) catalysts was evaluated in terms of activation energy, reaction mechanisms, and degradation products. The results revealed that acid catalysts induce PS fragmentation through the formation of carbocationic intermediates, promoting the selective cleavage of C-C bonds in branched chains with bond dissociation energies (BDE) of 176.8 kJ/mol (C1-C7) and 175.2 kJ/mol (C3-C8). In contrast, basic catalysts favor β-scission by stabilizing carbanions, reducing the BDE to 151.6 kJ/mol (C2-C3) and 143.9 kJ/mol (C3-C4), which facilitates the formation of aromatic products such as styrene and benzene. Fe2(SO4)3 was found to significantly decrease the activation barriers to 328.12 kJ/mol, while the basic catalysts reduce the energy barriers to 136.9 kJ/mol. Gibbs free energy (ΔG) calculations confirmed the most favorable routes, providing key information for the design of optimized catalysts in PS valorization. This study highlights the usefulness of computational modeling in the optimization of plastic recycling strategies, contributing to the development of more efficient and sustainable methods.

Mesoplastics: A Review of Contamination Status, Analytical Methods, Pollution Sources, Potential Risks, and Future Perspectives of an Emerging Global Environmental Pollutant

Mesoplastics are emerging environmental pollutants that can pose a threat to the environment. Researching mesoplastics is crucial as they bridge the gap between macroplastics and microplastics by determining their role in plastic fragmentation and pathways, as well as their ecological impact. Investigating mesoplastic sources will help develop targeted policies and mitigation strategies to address plastic pollution. These pollutants are found across aquatic, terrestrial, and agricultural ecosystems. Unlike microplastics, mesoplastics are reviewed in the scientific literature. This paper focuses on existing published research on mesoplastics, determining the trends and synthesizing key findings related to mesoplastic pollution. Research primarily focused on marine and freshwater ecosystems, with surface water and beach sediments being the most studied compartments. Mesoplastics research often offers baseline data, with increased publications from 2014 to 2024, particularly in East Asia. However, certain ecosystems and regions remain underrepresented. Also, mesoplastics can disrupt ecosystems by degrading biodiversity, contaminating soils and waters, and affecting food chains. Mesoplastics can also become vectors for additives and pathogenic microorganisms, highlighting their environmental risks. Various factors influence mesoplastics' prevalence, including anthropogenic and non-anthropogenic activities. With this, future research should expand into less-studied ecosystems and regions, explore mesoplastic interactions with pollutants and organisms, and promote public awareness, education, and policy measures to reduce plastic use and mitigate pollution globally.

Photodegradation Controls of Potential Toxicity of Secondary Sunscreen-Derived Microplastics and Associated Leachates

The escalating environmental concern over secondary microplastics (SMPs) stems from their physicochemical evolution from primary microplastics (PMPs), yet the contribution of varying physicochemical transformations to the ultimate environmental risks remains unknown. In this study, a photomechanical degradation process was employed to convert the primary sunscreen-derived microplastics (SDMPs) into secondary SDMPs. While mechanical degradation caused physical fragmentation, photodegradation induced both physical and chemical alterations, introducing surface oxidation, chemical bond scission, and cross-linking to the secondary SDMPs. Employing a combination of alkaline digestion and pyrolysis GC-MS techniques, it was observed that both physical fragmentation and photooxidation led to heightened intracellular sequestration of MPs. Although the bioaccumulated SDMPs could be indicated by the enlarged lysosomes and fragmented mitochondria, toxicity of secondary SDMPs at the cellular level was primarily driven by chemical transformations post-photodegradation. A nontargeted analysis employing high-resolution mass spectrometry identified 46 plastic-associated compounds in the leachate, with photodegradation-induced chemical transformations playing a crucial role in the dissociation of hydrophobic additives and oxidative conversion of leached compounds. The toxicity of the leachate was exacerbated by photodegradation, with mitochondrial fragmentation serving as the primary subcellular biomarker, indicative of leachate toxicity. This study elucidates the pivotal role of photodegradation in augmenting the cytotoxicity of secondary SDMPs, shedding light on the intricate interplay between physicochemical transformations and environmental risks.

Can the insects Galleria mellonella and Tenebrio molitor be the future of plastic biodegradation?

Plastics have been an integral part of human lives, enhancing the functionality and safety of many everyday products, contributing significantly to our overall well-being. However, petroleum-based plastics can take hundreds or even thousands of years to decompose, resulting in an unprecedented plastic waste accumulation in the environment. Widely used conventional plastic disposal methods as landfilling and incineration are also environmentally harmful, frequently leading to soil/water contamination and the release of microplastics. To overcome these limitations, researchers have been investigating novel sustainable alternatives for plastic waste management, such as the use of microorganisms, microbial-based enzymes, and, more recently, some insect larvae, being Galleria mellonella and Tenebrio molitor the most promising ones. In this review, we explore different methods of plastic waste disposal focusing on recent discoveries regarding biological plastic degradation using insects as alternative methods. We also discuss the plastic degradation mechanisms employed by G. mellonella and T. molitor larvae known so far, as salivary enzymes and the pool of microorganisms in their gut. Finally, this review highlights key challenges in plastic biodegradation, such as standardization and experimental comparability, while proposing innovative perspectives like using insects as bioreactors and exploring unexplored research directions.

Two sides of the same coin: Weathering differences of plastic fragments in coastal environments around the globe

Plastic debris in coastal environments usually undergoes weathering due to various environmental conditions. However, the weathering effects on exposed and shaded sides of the same plastics are underexplored. In this study, 1573 plastic fragments were collected from 15 coastal sites worldwide between December 2021 and December 2022, and weathering experiments were conducted outdoors. The field investigation showed significant two-sided weathering differences of plastic fragments. The weathering morphology included biota, cracks, delamination, discoloration, etc. The weathering degree was assessed with three metrics, i.e., line density (0-58 mm/mm2), surface loss (0-92 %), and texture index (0-2). The 3D magnitudes of these three metrics revealed the two-sided weathering differences of plastic fragments. Specifically, 43 % of the samples had magnitudes > 5, indicating significant differences. Outdoor simulations suggested that sun-exposed sides developed more cracks, pores, and bubbles, while shaded sides remained smoother. After 12 months, the line density increased from 2.85 to 9.23 mm/mm² for polyethylene (PE) and 4.16-8.47 mm/mm² for polypropylene (PP) (p < 0.05). The carbonyl index increased from 0.50 to 1.70 (PE), from 0.18 to 1.10 (PP), and from 0.45 to 1.57 (polyvinyl chloride). This increase indicated oxidative degradation on sun-exposed sides. Our results highlighted the uneven degree of weathering on both sides of the same plastic fragment due to different environmental factors. The study provided critical insights for creating more accurate models to predict plastic degradation, which will help inform global strategies to reduce plastic pollution.

Bringing to light vinyl chloride oligomers, a class of polychlorinated alkanes differing from chlorinated paraffins

Polyvinyl chloride (PVC) is one of the most widely used polymers, which contrasts with the low amount of literature on the leaching of associated additives and in particular unintended oligomers, a class of non-intentionally added substances (NIAS). This study sheds light on the occurrence of vinyl chloride oligomers (VCOs) in a variety of PVC analytical standards (n = 4), PVC items employed for construction, medical or food contact applications (n = 14), as well as in foodstuffs and environmental matrices (n = 10). Samples were analysed by liquid chromatography coupled to high-resolution mass spectrometry hyphenated with chloride-enhanced electrospray ionisation. Series of saturated (0VCO), monounsaturated (1VCO), diunsaturated (2VCO) and triunsaturated (3VCO) VCOs were revealed. The dominant series remained 1VCOs of the general formula C2nH3nCln, accounting for ∼80 % of VCOs in PVC standards. A risk of signal overlap was found between 0VCOs of the general formula C2nH3n+1Cln+1 (accounting for ∼8 % in PVC standards) and polychlorinated alkanes making up chlorinated paraffins, given that they share the same chemical formulas. A methodology for discriminating between signals arising from VCOs and chlorinated paraffins has been proposed. VCOs were detected in 88 % of the samples analysed (other than standards), and in particular in some foodstuffs and environmental matrices, suggesting that VCOs have the capacity to leach out of PVC materials, and thus contaminate food and the environment. Overall, these results call for greater attention to be paid to vinyl chloride oligomers and raise the question of whether they pose a risk to living organisms.

How does alkaline-thermal pretreatment followed by anaerobic digestion affect the content of polyethylene terephthalate and polyamide 66 microplastics?

Microplastics (MPs) are ubiquitous and increasing in quantity, causing raising concern. Wastewater treatment plants (WWTPs) are a point source for both aquatic environments and soil, through the use of sludge in agriculture. Understanding the fate of MPs within the wastewater and sludge lines of a treatment plant and, possibly, enhancing their removal will improve the safe reuse of sludge and water effluent and the wastewater biorefinery concept application. This study investigates the effects of alkaline-thermal pretreatment of sludge, followed by anaerobic digestion, on the physical and chemical characteristics of polyethylene terephthalate (PET) and polyamide 66 (PA(66)) contained. Experiments were conducted to evaluate the influence of different NaOH concentrations, temperatures, and reaction times on the degradation of the MPs in anaerobic digestion. PET MPs exhibited relevant mass reduction and structural changes in relation to the NaOH concentration and temperature. PA(66) MPs showed limited chemical alterations, indicating higher resistance to degradation. Batch anaerobic digestion tests of pretreated samples did not modify them further. Chemical characterization of MPs was performed using both Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) and Focal Plane Array-Fourier Transform-Imaging-Micro-Spectroscopy (FPA-μFTIR-Imaging), revealing distinct trends between surface-level and bulk material changes in the MPs. The results highlighted that ATR-FTIR recorded lower carbonyl index values compared to FPA-μFTIR-Imaging. These findings emphasized the importance of using complementary analytical techniques to thoroughly understand MPs degradation. The outcomes suggest that tailored pretreatment strategies are essential to enhance MPs removal in WWTPs, ensuring safer sludge reuse within a circular economy framework.

The wheel of time: The environmental dance of aged micro- and nanoplastics and their biological resonance

The aging of micro- and nanoplastics (MNPs) significantly affects their environmental behavior and ecological impacts in both aquatic and terrestrial ecosystems. This review explored the known effects of aging on MNPs and identified several key perspectives. Firstly, aging can alter the environmental fate and transport of MNPs due to changes in their surface properties. This alteration accelerates their accumulation in specific habitats like oceans and soils, resulting in increased bioaccumulation by organisms. In addition, aged MNPs interact differently with living organisms than their pristine counterparts by influencing the attachment of biofilms and other microorganisms in aquatic ecosystems. Moreover, the aging processes of MNPs exhibit adverse effects on aquatic and terrestrial organisms via increasing the bioavailability and potential toxicity of MNPs as degradation products are released. Last but not least, the biodegradation potential of MNPs can be altered by the aging process, thus affecting their degradation rates and pathways in the environment. However, there are still knowledge gaps regarding the natural aging behaviors of MNPs, such as the aging mechanisms of different types of plastic, the influence of environmental factors, the release of pollutants, and even the effects of aging on their transformation in different ecosystems. Therefore, a great contribution can be made to sustainable plastic use and environmental preservation by studying the natural aging of common MNPs and their subsequent biological effects.

Microplastic migration and transformation pathways and exposure health risks

Plastics play a crucial role in modern life, but improper use and disposal have resulted in microplastics becoming widespread in the environment, raising significant concerns about both the environment and human health. Extensive research has explored the transformation mechanisms, bioaccumulation, ecological impacts, and health risks associated with microplastics. The present review first analyzes the migration, transformation, and degradation pathways of microplastics on a global scale, and then synthesizes current knowledge on the types, sources, and migration pathways of microplastics in soil, atmosphere, and aquatic environments, emphasizing transformation mechanisms like photo-aging and microbial degradation, and detailing their ecological and human health impacts. Additionally, this review examines gaps in current research and identifies critical areas needing further study, such as key control points in microplastic degradation processes and the mechanisms underlying health risks to populations. The aim is to provide a comprehensive reference for advancing microplastic pollution control, ecological protection efforts, and health risk assessment frameworks.

Biodegradable fishing gears: A potential solution to ghost fishing and marine plastic pollution

Fishing gears are conventionally made from non-biodegradable materials including polyamide (PA). When lost in the ocean, these gears have long-lasting impacts, including marine littering, microplastics production, leaching of chemicals, and an extended period of ghost fishing due to its durability. The use of biodegradable co-polyester material such as polybutylene succinate co-adipate-co-terephthalate (PBSAT) and polybutylene succinate-co-butylene adipate (PBSA) as fishing gear materials have been considered as a potential solution to reduce the associated impact. Ocean is a complex environment in which multiple degradation paths can occur for plastic materials, and decoupling of factors could aid in understanding the impact of each potential factor. In this study, the focus is on the impact of pure water hydrolysis phenomena on biodegradable co-polyester PBSAT and PBSA in comparison to PA monofilaments through accelerated aging at 40 °C, 60 °C, 70 °C and 80 °C. As a single factor accelerated aging process, the prediction of loss of mechanical strength over time was possible at other temperatures namely 2 °C, 10 °C, 15 °C, 20 °C and 30 °C. Different end-of-life criteria were used. This study concluded that solely through pure hydrolysis, a drastic reduction of the time to reach end-of-life criteria was observed by using biodegradable monofilaments instead of PA, but still longer than the expected service time. For example, at 2 °C, it would take approximately 10 years, 20 years and 1000 years for PBSAT, PBSA and PA to have lost 50 % of their initial stress at break respectively.

Molecular modeling to elucidate the dynamic interaction process and aggregation mechanism between natural organic matters and nanoplastics

The interactions of nanoplastics (NPs) with natural organic matters (NOMs) dominate the environmental fate of both substances and the organic carbon cycle. Their binding and aggregation mechanisms at the molecular level remain elusive due to the high structural complexity of NOMs and aged NPs. Molecular modeling was used to understand the detailed dynamic interaction mechanism between NOMs and NPs. Advanced humic acid models were used, and three types of NPs, i.e., polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS), were investigated. Molecular dynamics (MD) simulations revealed the geometrical change of the spontaneous formation of NOMs-NPs supramolecular assemblies. The results showed that pristine NPs initially tend to aggregate homogeneously due to their hydrophobic nature, and then NOM fragments are bound to the formed NP aggregates mainly by vdW interaction. Homo- and hetero-aggregation between NOMs and aged NPs occur simultaneously through various mechanisms, including intermolecular forces and Ca2+ bridging effect, eventually resulting in a mixture of supramolecular structures. Density functional theory calculations were employed to characterize the surface properties and reactivity of the NP monomers. The molecular polarity indices for unaged PE, PS, and PVC were 3.1, 8.5, and 22.2 kcal/mol, respectively, which increased to 43.2, 51.6, and 42.2 kcal/mol for aged NPs, respectively, indicating the increase in polarity after aging. The vdW and electrostatic potentials of NP monomers were visualized. These results clarified the fundamental aggregation processes, and mechanisms between NPs and NOMs, providing a complete molecular picture of the interactions of nanoparticles in the natural aquatic environment.

High Carbon Recovery in Photocatalytic Degradation of High-Density Polyethylene (HDPE): Blend with Stearic Acid as a Radical Source

A blend of high-density polyethylene (HDPE, Mw = 59.4 kDa) and stearic acid was efficiently degraded under cerium catalyzed photodecarboxylation conditions, and the molecular weight decreased to Mw = ∼5 kDa. The reaction proceeds at 100 °C in tert-butylnitrile (tBuCN) in air, where HDPE does not dissolve or swell. The products are solid material with >90% weight recovery of the starting HDPE + stearic acid. Control experiments supported that carbon radicals generated by cerium-catalyzed photodecarboxylation of stearic acid transferred to the main chain of the HDPE, which undergoes oxidative degradation to lower the molecular weight.

Metagenomic insights into the functional potential of non-sanitary landfill microbiomes in the Indian Himalayan region, highlighting key plastic degrading genes

Solid waste management in the Indian Himalayan Region (IHR) is a growing challenge, intensified by increasing population and tourism, which strain non-sanitary landfills. This study investigates microbial diversity and functional capabilities within these landfills using a high-throughput shotgun metagenomic approach. Physicochemical analysis revealed that the Manali and Mandi landfill sites were under heavy metal contamination and thermal stress. Taxonomic annotation identified a dominance of bacterial phyla, including Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, with genera like Pseudomonas and Bacillus prevalent. Squeezemeta analysis generated 9,216,983 open reading frames (ORFs) across the sampling sites, highlighting diverse metabolic potentials for heavy metal resistance and degrading organic, xenobiotics and plastic wastes. Hierarchical clustering and principal component analysis (PCA) identified distinct gene clusters in Manali and Mandi landfill sites, reflecting differences in pollution profiles. Functional redundancy of landfill microbiome was observed with notable xenobiotic and plastic degradation pathways. This is the first comprehensive metagenomic assessment of non-sanitary landfills in the IHR, providing valuable insights into the microbial roles in degrading persistent pollutants, plastic waste, and other contaminants in these stressed environments.

Polyethylene terephthalate nanoplastics-induced neurotoxicity in adult male Swiss albino mice with amelioration of betaine: a histopathological, neurochemical, and molecular investigation

Medicines, food packaging, personal care products, and cosmetics extensively use polyethylene terephthalate nanoplastics (PET-NaPs). However, they also have harmful impacts on several organs. Betaine demonstrates potent antioxidant and anti-inflammatory characteristics. Our goal was to investigate the detrimental impact of PET-NaPs on the mouse brain and evaluate the neuroprotective properties of betaine. We allocated 40 completely mature male Swiss albino mice into four distinct groups: control group, betaine group, PET-NaPs group, and betaine-co-treated group. Following a 30-day duration, euthanasia was performed on the mice, and analyzed tissue samples were obtained from the cerebrum, cerebellum, and hippocampus. PET-NaPs resulted in an elevated level of malondialdehyde and upregulated cyclooxygenase-2 and interleukin-1 beta (IL-1β) expression while significantly reducing the levels of glutathione and downregulating acetylcholinesterase. The PET-NPs also caused significant changes in the histopathology of the brain tissue, and there was a demonstrable rise in the immunostaining of IL-1β and glial fibrillary acidic proteins. Consequently, betaine effectively alleviated the negative consequences of PET-NaPs. Therefore, betaine possesses the capacity to mitigate the neurotoxic consequences induced by PET-NaPs.

Multiphase photochemical reactions as sinks of nanoplastic photodissolution products in aqueous environments: a model study for benzene

Carcinogenic benzene is the most concerning product of the irradiation of polystyrene nanoplastics in aqueous suspension. Interestingly, benzene formed in water from polystyrene can volatilise to the gas phase or react with aqueous-phase hydroxyl radicals (•OH(w)) to produce toxic phenol. The persistence of benzene in water would range from some weeks to some months, and the branching ratio between the •OH(w) reaction and volatilisation mainly depends on water depth and the DOC (dissolved organic carbon) concentration. Actually, benzene volatilisation is particularly important in shallow waters (1-2 m depth), or even in relatively deep waters (> 5 m) if the DOC value is high enough (> 5 mgC L-1). Aqueous phenol formed from benzene + •OH(w) reacts in turn with •OH(w), the carbonate radical (CO3•-(w)), and the triplet states of chromophoric dissolved organic matter (3CDOM*(w)) in different proportions, depending on water chemistry. In the gas phase, benzene reacts with •OH(g) to produce phenol, which in turn reacts with •OH(g) and especially with the nitrate radical (•NO3 (g)). The overall degradation is fast enough for phenol to reach an extremely low steady-state concentration in the atmosphere. However, up to 50% of the initial water-dissolved benzene would produce gas-phase phenol as intermediate compound and, eventually, yield phytotoxic nitrophenols. Among the latter, 4-nitrophenol has strong potential to partition into atmospheric waters and reach back aqueous environments (or soil) via wet depositions. To a lesser extent, similar phenomena would involve the highly phytotoxic 2,4-dinitrophenol.