Characterisation of microplastics is key for reliable data interpretation

Toxic effects of fluoxetine-loaded onto virgin or aged polypropylene, polyamide and polyvinyl chloride microparticles on Daphnia magna

There is an increasing recognition that microplastics can act as a vector for micropollutants when co-occurring in the environment and that pollutant-loaded microplastics can become integral to food-webs. To evaluate whether fluoxetine-loaded microplastics can act as a vector for fluoxetine to enter the food chain, a toxicity assay with Daphnia magna neonates was performed. This study evaluated the fluoxetine availability when adsorbed onto virgin or aged polypropylene, polyamide, and polyvinyl chloride (PVC). Results demonstrated that fluoxetine-loaded microplastics displayed toxic effects for all microplastic types, with varying toxicity depending on plastic type and weathering. D. magna ingested microplastics in all experiments that microplastics were present, but survival rates were not significantly affected by microplastics alone. Neonate mortality did not correlate with the adsorption/desorption capacity of the microplastics. Fluoxetine showed the highest adsorption on virgin and aged polypropylene (83-98 %), followed by aged polyamide (25-68 %) and PVC (38-90 %). While negligible desorption occurred with polypropylene, polyamide and PVC exhibited up to 20 % desorption. However, higher mortality was observed with fluoxetine-loaded virgin polypropylene (30 %), polyamide (40 %), and PVC (35 %) compared to aged particles (0-10 %). The results indicate that microplastic can enter the food-chain and act as a vector for pollutants, exhibiting hazardous effects to wildlife.

A cost-effective and efficient fluorescence staining agent for the identification of microplastics in environmental samples and zebrafish (Danio rerio)

Microplastics (MPs) are recognized as a significant environmental hazardous material. Therefore, identifying and tracking microplastics are crucial to understand their harmfulness. Herein, we introduce (Z)-N'-(pyren-1-ylmethylene)pyrazine-2-carbohydrazide (PPC) as a cost-effective and efficient fluorescence staining agent. Unique properties of PPC, including aggregation-induced emission (AIE) and solvatochromism, were verified by spectroscopic studies and theoretical calculations. PPC selectively stained eight types of MPs with green fluorescence in water/tetrahydrofuran (THF) solution (97/3, v/v). Interestingly, only polyurethane (PU) was selectively stained both in green and blue channel using 50 % ethanol (EtOH) treatment. Moreover, with 30 % EtOH treatment, PU and polyethylene terephthalate (PET) were distinctly stained in the blue channel, highlighting their selective fluorescence. These results suggested that changes in solvent polarity induced by different EtOH amounts might alter the binding strength between PPC and MPs, resulting in varying fluorescence responses. In addition, the adsorption interaction of PPC to MPs was proposed, based on thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and non-covalent interaction (NCI) analysis. PPC could identify MPs without any influence in the size, aging and pH difference. Successfully, PPC could stain eight types of MPs and selectively PU and PET in artificial environmental samples like seawater, river water and soil. Moreover, PPC-labeled MPs could be tracked in biological system such as Danio rerio (zebrafish) to monitor the transit and accumulation of MPs. These results underscore the potential of PPC for efficient detection of MPs in environmental and biological systems.

Uptake, growth, and oxidative stress responses of Rhizophora mucronata (Poir. in Lam.) propagules exposed to high-density polyethylene microplastics

The plastic revolution's contribution to global pollution gives rise to microplastics (MPs), bearing a toll on the marine environment. Knowledge of mangrove exposure to MPs causing adverse effects has yet to be elucidated. Hence, the physiological responses of R. mucronata propagules exposed to ubiquitous High-Density Polyethylene Microplastics (HDPE-MPs) were investigated. The set-up consists of a control (0 mg/L) and an environmentally relevant treatment group (32.65 mg/L), acclimatized and exposed for three months. Scanning Electron Microscopy (SEM) shows agglomeration of HDPE-MPs on root surfaces and translocation to the shoot system of smaller MPs (< 50 μm). Attenuated Total Reflectance Fourier Transform-Infrared Spectroscopy (ATR FT-IR) confirmed uptake in the roots. Root length, count, plant height, foliar area, and oxidative stress biomarkers (carbonyl protein and total chlorophyll) all show significant differences (p < 0.05). Indeed, plastic pollution has detrimental effects on mangroves that may consequently affect mangrove forest diversity and productivity.

Comparison of adsorption capacity of 4-Nonylphenol on conventional and biodegradable microplastics aged under natural water

This study investigated the adsorption of 4-Nonylphenol (4-NP) on aged microplastics (MPs) composed of polyethylene terephthalate (PET) and poly(butylene-adipate-co-terephthalate)/polylactic acid (PBAT/PLA). Morphological analysis revealed wear, wrinkles, and increased surface roughness in both aged MPs, with X-ray diffraction showing slight increases in crystallinity. Infrared spectroscopy showed an increase in the carbonyl index from 2.78 to 4.37 for PBAT/PLA and 0.51 to 2.32 for PET after aging. The natural water from the San Pedro River in Chile Atacama region (5.91 mS·cm-1 conductivity, 3.25 PSU salinity, 2955 mg·L-1 total dissolved solids, 435 mg·L-1 CaCO3 hardness) was used as the environmental medium and compared with a 0.01 mol·L-1 CaCl2 as a model solution. Kinetic modeling showed a decrease in 4-NP percentage removal from 90.0 % (2277 μg∙g-1 adsorption capacity) to 50.2 % (1268 μg∙g-1) for PET and from 86.8 % (2087 μg∙g-1) to 70.3 % (1955 μg∙g-1) for PBAT/PLA when comparing the model solution to natural water, with 30 and 84 h equilibrium times, respectively. Isotherm data showed that 4-NP/PET fits BET n-layer and Temkin models, while 4-NP-PBAT/PLA fits the Toth and Hill models The ionic composition of natural water induces cation attraction to polarized MPs surfaces, intensifying competition for adsorption sites. This involves ion and molecular cooperation, 4-NP reorientation, external diffusion effects, and surface oxidation variations, which are attributed to explaining the bilayer (PET) and monolayer (PBAT/PLA) formation. This work contributes to understanding MP pollution and the importance of considering the bioplastics life cycle, since their waste presents significant potential to resist external factors for transporting contaminants.

The unseen perils of oral-care products generated micro/nanoplastics on human health

The extensive use of plastics in modern dentistry, including oral care products and dental materials, has raised significant concerns due to the increasing evidence of potential harm to human health and the environment caused by the unintentional release of microplastics (MPs) and nanoplastics (NPs). Particles from sources like toothpaste, toothbrushes, orthodontic implants, and denture materials are generated through mechanical friction, pH changes, and thermal fluctuations. These processes cause surface stress, weaken material integrity, and induce wear, posing health risks such as exposure to harmful monomers and additives, while contributing to environmental contamination. MPs/NPs released during dental procedures can be ingested, leading to immune suppression, tissue fibrosis, and systemic toxicities. The gut epithelium absorbs some particles, while others are excreted, entering ecosystems, accumulating through the food chain, and causing ecological damage. Although analytical techniques have advanced in detecting MPs/NPs in oral care products, more robust methods are needed to understand their release mechanisms. This review explores the prevalence of MPs/NPs in dentistry, the mechanisms by which MPs/NPs are released into the oral environment, and their implications for human and ecological health. It underscores the urgency of public awareness and sustainable dental practices to mitigate these risks and promote environmental well-being.

Single-use commercial bio-based plastics under environmental degradation conditions: Is their biodegradability and compostability a fact?

Evaluating compostability is increasingly essential for proving commercial bio-based cutlery or packaging since these materials must biodegrade under controlled conditions quickly. Utensils for eating represent Mexico's most popular consumer single-use materials, and Mexican regulations based on biodegradation or compostability are still vague and lack scientific evaluations. This study analyzed three bio-based polymeric materials (bags, dishes, and forks) from commercial brands following Mexican regulations and using various analytical techniques to verify their biodegradability and compostability. First, weight loss measurements, stress-strain tests, and topographic imaging were applied for preliminary observations at the macro scale up to 90 days of compostability. Besides, spectroscopy, microscopy, and thermal techniques indicate changes and behavior of the bio-based materials depending on the composition. The results suggest that bags exhibited the highest decomposition rate (80 %) compared to dishes and forks. Similarly, mechanical resistance indicates a reduction of 62 % for bags, 30 % for dishes, and almost none for forks. Texture image analysis revealed that the complexity and roughness of the materials increased over time, correlating with the physical changes observed. These results indicate minimal surface topography changes and higher stiffness for dishes and forks, indicating low biodegradability. SEM images supported these findings, showing surface degradation in bags and dishes but not in forks. FTIR and XRD analyses confirmed the presence of polyamide (bags) and polypropylene (dishes and forks). These results reduce biodegradation and differ from the claims made by manufacturers. The thermal analysis found similar results, indicating that the materials' thermal stability decreased after degradation, which is related to lower biodegradability and compostability. Overall, the study concluded only bags meet the criteria for compostability in national regulations. However, dishes and forks made of petroleum-derived polymers have higher resistance to natural and microbial degradation.

Microplastics pollution in the marine environment: A review of sources, impacts and mitigation

Over the past few years, microplastics (MPs) pollution in the marine environment has emerged as a significant environmental concern. Poor management practices lead to millions of tons of plastic waste entering oceans annually, primarily from land-based sources like mismanaged waste, urban runoff, and industrial activities. MPs pollution in marine environments poses a significant threat to ecosystems and human health, as it adsorbs pollutants, heavy metals, and leaches additives such as plasticizers and flame retardants, thus contributing to chemical pollution. The review article provides a comprehensive overview of MPs pollution, its sources, and impacts on marine environments, including human health, detection techniques, and strategies for mitigating microplastic contamination in marine environments. The paper provides current information on microplastic pollution in marine environments, offering insights for researchers, policymakers, and the public, as well as promoting sustainable practices to protect the environment.

Deciphering the role of nonylphenol adsorption in soil by microplastics with different polarities and ageing processes

In the soil environment, microplastics (MPs) commonly coexist with organic pollutants such as nonylphenol (NP), affecting the migration of NP through adsorption/desorption. However, few studies have focused on the interaction between NP and MPs in soil, especially for MPs of different types and ageing characteristics. In this study, non-polar polypropylene (PP) and polar polyamide (PA) MPs were aged either photochemically (144 h) or within soil (60 days), then used to determine the effect of 5 % MPs on the adsorption behaviour of NP (0.1-4.0 mg/L) in soil. Results showed that both ageing processes significantly promoted the conversion of -CH3 groups to C-O and CO on the surface of PPMPs, while PAMPs exhibited amide groups changes and a reduction in average particle size due to ageing. Additionally, both ageing processes promoted the adsorption of NP by soil containing PPMPs, due to an increase in oxygen-containing functional groups and specific surface area. In contrast, the NP adsorption capacity of soil containing PAMPs decreased by 15.4 % following photochemical ageing due to hydrolysis of amide groups, but increased by 21.15 % after soil ageing due to reorganization of amide groups, respectively. The soil-PAMPs systems exhibited a stronger affinity for NP compared to the soil-PPMPs systems, which was primarily attributed to the dominant role of hydrogen bonding. NP was found to be distributed mainly on soil particles in the soil-PPMPs systems, while it tended to be adsorbed by MPs in the soil-PAMPs systems, especially in the soil aged MPs system. This study provides a comprehensive analysis of the complex effects of MPs on coexisting pollutants in soil environments, highlighting the effect of MP characteristics on the adsorption of organic pollutants, which is essential for understanding the transport behaviour of organic pollutants.

Evaluation of microplastic pollution using bee colonies: An exploration of various sampling methodologies

Recent research has highlighted the potential of honeybees and bee products as biological samplers for monitoring xenobiotic pollutants. However, the effectiveness of these biological samplers in tracking microplastics (MPs) has not yet been explored. This study evaluates several methods of sampling MPs, using honeybees, pollen, and a novel in-hive passive sampler named the APITrap. The collected samples were characterized using a stereomicroscopy to count and categorise MPs by morphology, colour, and type. To chemical identification, a micro-Fourier transform-infrared (FTIR) spectroscopy was employed to determine the polymer types. The study was conducted across four consecutive surveillance programmes, in five different apiaries in Denmark. Our findings indicated that APITrap demonstrated better reproducibility, with a lower variation in results of 39%, compared to 111% for honeybee samples and 97% for pollen samples. Furthermore, the use of APITrap has no negative impact on bees and can be easily applied in successive samplings. The average number of MPs detected in the four monitoring studies ranged from 39 to 67 in the APITrap, 6 to 9 in honeybee samples, and 6 to 11 in pollen samples. Fibres were the most frequently found, accounting for an average of 91% of the total MPs detected in the APITrap, and similar values for fragments (5%) and films (4%). The MPs were predominantly coloured black, blue, green and red. Spectroscopy analysis confirmed the presence of up to five different synthetic polymers. Polyethylene terephthalate (PET) was the most common in case of fibres and similarly to polypropylene (PP), polyethylene (PE), polyacrylonitrile (PAN) and polyamide (PA) in non fibrous MPs. This study, based on citizen science and supported by beekeepers, highlights the potential of MPs to accumulate in beehives. It also shows that the APITrap provides a highly reliable and comprehensive approach for sampling in large-scale monitoring studies.

Investigation of the effects of nanoplastic polyethylene terephthalate on environmental toxicology using model Drosophila melanogaster

Plastic pollution has become a major environmental concern, and various plastic polymers are used daily. A study was conducted to examine the toxic effects of polyethylene terephthalate (PET) nanoplastics (NPLs) on Drosophila melanogaster. We have successfully synthesized PET NPLs and characterized using DLS, Zeta potential, TEM, HRTEM, SAED, XRD, FTIR, and Raman spectroscopy to gain crucial insights into the structure and properties. We fed PET NPLs to Drosophila to assess toxicity. ROS was quantified using DCFH-DA and NBT, and the nuclear degradation was checked by DAPI staining. Quantification of protein and activity of antioxidant enzymes like SOD, catalase depicted the adverse consequences of PET NPLs exposure. The dorsal side of the abdomens, eyes, and wings were also defective when phenotypically analyzed. These results substantiate the genotoxic and cytotoxic impact of nanoplastics. Notably, behavioral observations encompassing larval crawling and climbing of adults exhibit normal patterns, excluding the presence of neurotoxicity. Adult Drosophila showed decreased survivability, and fat accumulation enhanced body weight. These findings contribute to unraveling the intricate mechanisms underlying nanoplastic toxicity and emphasize its potential repercussions for organismal health and ecological equilibrium.

Polyoxometalate nanocluster-infused triple IPN hydrogels for excellent microplastic removal from contaminated water: detection, photodegradation, and upcycling

Microplastic (MP) pollution pervades global ecosystems, originating from improper plastic disposal and fragmentation due to factors like hydrolysis and biodegradation. These minute particles, less than 5 mm in size, have become omnipresent, impacting terrestrial, freshwater, and marine environments worldwide. Their ubiquity poses severe threats to marine life by causing physical harm and potentially transferring toxins through the food chain. Addressing this environmental crisis necessitates a sustainable strategy. Our proposed solution involves a highly efficient copper substitute polyoxometalate (Cu-POM) nanocluster infused triple interpenetrating polymer network (IPN) hydrogel, comprising chitosan (CS), polyvinyl alcohol (PVA), and polyaniline (PANI) (referred to as pGel@IPN) for mitigating MP contamination from water. This 3D IPN architecture, incorporating nanoclusters, also enhances the hydrogel's photodegradation capabilities. Our scalable approach offers a sustainable strategy to combat MPs in water bodies, as demostrated by the adsorption behaviors on the hydrogel matrix under varying conditions, simulating real-world scenarios. Evaluations of physicochemical properties, mechanical strength, and thermal behavior underscore the hydrogel's robustness and stability. Detecting minute MP particles remains challenging, prompting us to label MPs with Nile red for fluorescence microscopic analysis of their concentration and adsorption on the hydrogel. The catalytic properties of POM within the hydrogel facilitate UV-induced MP degradation, highlighting a sustainable solution. Our detailed kinetics and isotherm studies revealed pseudo-first-order and Langmuir models as fitting descriptors for MP adsorption, exhibiting a high maximum adsorption capacity (Qm). Notably, pGel@IPN achieved ∼95% and ∼93% removal efficiencies for polyvinyl chloride (PVC) and polypropylene (PP) MPs at pH ∼ 6.5, respectively, also demonstrating reusability for up to 5 cycles. Post-end-of-life, the spent adsorbent was efficiently upcycled into carbon nanomaterials, effectively removing the heavy metal Cr(VI), exemplifying circular economy principles. Our prepared hydrogel emerges as a potent solution for MP removal from water, promising effective mitigation of the emerging pollutants of MPs while ensuring sustainable environmental practices.