Sustainable struggling: decoding microplastic released from bioplastics-a critical review.

This comprehensive review delves into the complex issue of plastic pollution, focusing on the emergence of biodegradable plastics (BDPs) as a potential alternative to traditional plastics. While BDPs seem promising, recent findings reveal that a large number of BDPs do not fully degrade in certain natural conditions, and they often break down into microplastics (MPs) even faster than conventional plastics. Surprisingly, research suggests that biodegradable microplastics (BDMPs) could have more significant and long-lasting effects than petroleum-based MPs in certain environments. Thus, it is crucial to carefully assess the ecological consequences of BDPs before widely adopting them commercially. This review thoroughly examines the formation of MPs from prominent BDPs, their impacts on the environment, and adsorption capacities. Additionally, it explores how BDMPs affect different species, such as plants and animals within a particular ecosystem. Overall, these discussions highlight potential ecological threats posed by BDMPs and emphasize the need for further scientific investigation before considering BDPs as a perfect solution to plastic pollution.

Characteristics and adsorption behavior of typical microplastics in long-term accelerated weathering simulation.

Microplastics can function as carriers in the environment, absorbing various toxins and spreading to diverse ecosystems. Toxins accumulated in microplastics have the potential to be re-released, posing a threat. In this study, two typical plastics, namely polyethylene (PE) and polystyrene (PS), along with the degradable plastic poly(butylene adipate-co-terephthalate) (PBAT), were subjected to a long-term ultraviolet alternating weathering experiment. The study investigated the variations in the weathering process and pollutant adsorption of microplastics of different particle sizes. Furthermore, the adsorption capacity of microplastics for various pollutants was assessed. The findings indicate that particle size significantly influences weathering, leading to variations in adsorption capacity. The weathered PE displays a higher adsorption capacity for azo dyes. Additionally, the adsorption capacity of PBAT for neutral red is double that of antibiotics. Importantly, the maximum adsorption capacity of PBAT for pollutants after aging is approximately 10 times greater than that of PE. Consequently, degradable plastics undergoing weathering in the natural environment may pose a higher ecological risk than traditional plastics.

Traded Plastic, Traded Impacts? Designing Counterfactual Scenarios to Assess Environmental Impacts of Global Plastic Waste Trade.

The global trade of plastic waste has raised environmental concerns, especially regarding pollution in waste-importing countries. However, the overall environmental contribution remains unclear due to uncertain treatment shares between handling plastic waste abroad and domestically. Here, we conduct a life cycle assessment of global plastic waste trade in 2022 across 18 countries and six plastic waste types, alongside three "nontrade" counterfactual scenarios. By considering the required cycling rate, which balances importers' costs and recycling revenues, we find that the trade resulted in lower environmental impacts than treating domestically with the average treatment mix. The trade scenario alone reduced climate change impact by 2.85 million tonnes of CO2 equivalent and mitigated damages to ecosystem quality, human health, and resource availability by 12 species-years, 6200 disability-adjusted life years (DALYs), and 1.4 billion United States dollars (USD in 2013), respectively. These results underscore the significance of recognizing plastic waste trade as a pivotal factor in regulating global secondary plastic production when formulating a global plastics treaty.

Generation of Eroded Nanoplastics from Domestic Wastes and Their Impact on Macrophage Cell Viability and Gene Expression.

This study reports an innovative approach for producing nanoplastics (NP) from various types of domestic waste plastics without the use of chemicals. The plastic materials used included water bottles, styrofoam plates, milk bottles, centrifuge tubes, to-go food boxes, and plastic bags, comprising polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), high-density polyethylene (HDPE), and Poly (Ethylene-co-Methacrylic Acid) (PEMA). The chemical composition of these plastics was confirmed using Raman and FTIR spectroscopy, and they were found to have irregular shapes. The resulting NP particles ranged from 50 to 400 nm in size and demonstrated relative stability when suspended in water. To assess their impact, the study investigated the effects of these NP particulates on cell viability and the expression of genes involved in inflammation and oxidative stress using a macrophage cell line. The findings revealed that all types of NP reduced cell viability in a concentration-dependent manner. Notably, PS, HDPE, and PP induced significant reductions in cell viability at lower concentrations, compared to PEMA and PET. Moreover, exposure to NP led to differential alterations in the expression of inflammatory genes in the macrophage cell line. Overall, this study presents a viable method for producing NP from waste materials that closely resemble real-world NP. Furthermore, the toxicity studies demonstrated distinct cellular responses based on the composition of the NP, shedding light on the potential environmental and health impacts of these particles.

An assessment of microplastic contamination in beach sediment of Maharashtra State, India, with special reference to anthropogenic activities.

The escalating issue of microplastic (MP) pollution poses a significant threat to the marine environment due to increasing plastic production and improper waste management. The current investigation was aimed at quantifying the MP concentration on 25 beaches on the Maharashtra coast, India. Beach sediments (1 kg) were collected from each site, with five replicates to evaluate the extent of MPs. The samples were homogenized, and three 20 g replicas were prepared for subsequent analysis. Later, the samples were sieved, and MPs were extracted using previously published protocols. The abundance of MPs found as 1.56 ± 0.79 MPs/g, ranges from 0.43 ± 0.07 to 3 ± 0.37 MPs/g. Fibers were found as the most abundant shape of MPs. Size-wise classification revealed dominance of <1 mm and 1-2 mm-sized MPs. Blue- and black-colored MPs were recorded dominantly. Polymer identification of MPs revealed polyurethane, polypropylene, polyvinyl chloride, acrylic or polymethyl methacrylate, and rubber. The findings revealed that MPs were found to be higher at highly impacted sites, followed by moderately impacted sites and low-impacted sites, possibly due to a different degree of anthropogenic pressure. The study recommended the urgent need for effective policy to prevent plastics accumulation in the coastal environment of Maharashtra State, India. PRACTITIONER POINTS: The study investigated the abundance and distribution of microplastics in the marine environment, specifically in sediments. The most common type of microplastic found was fibers, followed by fragments and films. Microplastics were found to pose a potential risk to the marine ecosystem, although further research is needed to fully understand their ecological impact. Future research should focus on expanding the sample size, assessing long-term effects, exploring sources and pathways, and considering size and shape of microplastics. The findings recommended urgent action to mitigate plastic pollution in Maharashtra coast.

Levels, Distribution and Ecological Risk Assessment of PBDEs in Soils and Plants Around the Engineering Plastics Factory.

This study systematically investigated the pollution levels and migration trends of PBDEs in soils and plants around engineering plastics factory, and identified the ecological risks of PBDEs in the environment around typical pollution sources.The results showed that 13 kinds of PBDEs were widely detected in the surrounding areas, and the concentration level was higher than the general environmental pollution level. The total PBDE concentrations (∑13PBDEs) in soils ranged from 14.6 to 278.4 ng/g dry weight (dw), and in plants ranged from 11.5 to 176 ng/g dw. Both soil and plant samples showed that BDE-209 was the most important congener, the pollution level in soil and plant was similar, and the composition of PBDEs congener was similar. In the soil column (50 cm), the radial migration of PBDEs was mainly concentrated in the 0-30 cm section. Except for BDE-66, which was mainly located in the 20-30 cm soil layer, the concentration of PBDEs was the highest in the 0-10 cm region. Furthermore, the environmental risks of PBDEs in soil and plants were evaluated by hazard quotient method, and the HQ values were all < 1, which did not exhibit any ecological risk. The evaluation results also showed that the ecological risk of PBDEs in soil was higher than that of plants, especially penta-BDE, which should be paid more attention.

Forecasting municipal solid plastic waste generation and management policy using system dynamics: a case study of Khulna City in Bangladesh.

A comprehensive analysis of municipal solid plastic waste (MSPW) management while emphasizing plastic pollution severity in coastal cities around the world is mandatory to alleviate the augmenting plastic waste footprint in nature. Thus, decision-makers' persuasion for numerous management solutions of MSPW flow-control can be met through meditative systematic strategies at the regional level. To forecast solutions focused on systematic policies, an agent-based system dynamics (ASD) model has been developed and simulated from 2023 to 2040 while considering significant knit parameters for MSPW management of Khulna City in Bangladesh. Baseline simulation results show that per-capita plastic waste generation will increase to 11.6 kg by 2040 from 8.92 kg in 2023. Eventually, the landfilled quantity of plastic waste has accumulated to 70,000 tons within 18 years. Moreover, the riverine discharge has increased to 834 tons in 2040 from a baseline quantity of 512 tons in 2023. So the plastic waste footprint index (PWFI) value rises to 24 by 2040. Furthermore, the absence of technological initiatives is responsible for the logarithmic rise of non-recyclable plastic waste to 1.35*1000=1350 tons. Finally, two consecutive policy scenarios with baseline factors such as controlled riverine discharge, increased collection and separation of plastic waste, expansion of recycle business, and locally achievable plastic conversion technologies have been simulated. Therefore, policy 2, with 69% conversion, 80% source separation, and 50% riverine discharge reduction of MSPW, has been found adequate from a sustainability perspective with the lowest PWFI ranges of 3.97 to 1.07 alongside a per-capita MSPW generation of 7.63 to 10 kg from 2023 till 2040.

Evaluating the performance of thermoplastic 3D bolus used in radiation therapy.

A 3D-printed bolus is being developed to deliver accurate doses to superficial cancers. In this study, flexible thermoplastic filaments, specifically PLA, TPU, PETG, and HIPS, were fabricated into boluses and then compared to commercial bolus for the variation of the dose elevation region of photon beams. The experimental results indicate that the maximum dose depth is similar, and the consistent trend of the percentage depth dose confirms the potential usage as a build-up bolus.

Microplastic Pollution in High Population Density Zones of Selected Rivers from Southeast Asia.

Southeast Asia (SEA) faces significant environmental challenges due to rapid population growth and economic activity. Rivers in the region are major sources of plastic waste in oceans. Concerns about their contribution have grown, but knowledge of microplastics in the area is still limited. This article compares microplastic levels in sediment and water from urban zones of three major rivers in SEA: Chao Phraya River (Thailand), Saigon River (Vietnam), and Citarum River (Indonesia). The study reveals that in all three rivers, microplastics were found, with the highest concentrations in Chao Phraya's water (80 ± 60 items/m3) and Saigon's sediment (9167 ± 4559 items/kg). The variations in microplastic sizes and concentrations among these rivers may be attributed to environmental factors and the exposure duration of plastic to the environment. Since these rivers are important water supply sources, rigorous land-use regulations and raising public awareness are crucial to mitigate plastic and microplastic pollution.

Breaking the plastic habit: Drivers of single-use plastic reduction among Thai university students.

This study investigated the decision-making dynamics for pro-environmental behavior among Thai university students, focusing on reducing the consumption of single-use plastics (SUP). By adopting a dynamic approach to the Theory of Planned Behavior (TPB), the research examined the influence of psychosocial factors, including attitudes, perceived behavioral control, and subjective norms, on SUP reduction intention at different phases of behavior change. Using structural equation modelling, we analyzed quantitative data (n = 317) from the selected universities. The results revealed that attitudes predicted behavioral intentions only among individuals in the contemplation phase of reducing SUP. Attitudes had a small but limited influence on the behavioral intentions of students who had not yet acted. Perceived behavioral control, on the other hand, significantly impacted behavioral intentions across all phases of behavior change, highlighting its importance in SUP reduction. The study also confirmed subjective norms' positive influence on students' behavioral intentions in the pre-contemplation phase. Practical implications suggested segmenting residents based on their behavior change phase so that public policymakers can allocate resources more efficiently and effectively by tailoring campaigns to specific behavior change phases, ultimately promoting sustainable behavior among university students.

Nile red staining for rapid screening of plastic-suspect particles in edible seafood tissues.

Concerns regarding microplastic (MP) contamination in aquatic ecosystems and its impact on seafood require a better understanding of human dietary MP exposure including extensive monitoring. While conventional techniques for MP analysis like infrared or Raman microspectroscopy provide detailed particle information, they are limited by low sample throughput, particularly when dealing with high particle numbers in seafood due to matrix-related residues. Consequently, more rapid techniques need to be developed to meet the requirements of large-scale monitoring. This study focused on semi-automated fluorescence imaging analysis after Nile red staining for rapid MP screening in seafood. By implementing RGB-based fluorescence threshold values, the need for high operator expertise to prevent misclassification was addressed. Food-relevant MP was identified with over 95% probability and differentiated from natural polymers with a 1% error rate. Comparison with laser direct infrared imaging (LDIR), a state-of-the-art method for rapid MP analysis, showed similar particle counts, indicating plausible results. However, highly variable recovery rates attributed to inhomogeneous particle spiking experiments highlight the need for future development of certified reference material including sample preparation. The proposed method demonstrated suitability of high throughput analysis for seafood samples, requiring 0.02-0.06 h/cm2 filter surface compared to 4.5-14.7 h/cm with LDIR analysis. Overall, the method holds promise as a screening tool for more accurate yet resource-intensive MP analysis methods such as spectroscopic or thermoanalytical techniques.

Plastic Pandemic after COVID-19: A Global Health Concern.

Abstract: COVID-19 pandemic has increased the amount of plastic burden to environment and complexities of plastic waste management. Change in behavioral pattern with advent of this pandemic led to increased practice of hygiene and increased use of different types of personal protective equipment. Unfortunately, rapid rise in production of the PPEs (like Hazmat suit, gloves, etc.) and single-use plastics used in RT-PCR and other testing are the biggest source for increased non-biodegradable plastic waste leading to amplified burden on plastic waste management. A number of measures like prioritizing the policies directed towards changes at behavioral, social and institutional level need to be started. Also, reduction in plastic waste along with proper plastic waste management policies should be implemented. To prevent the transition from one pandemic to other; improvement in government policies with public private partnership are the need of the hour.

Environmental taxation of plastic bags and substitutes: Balancing marine pollution and climate change.

Several countries have imposed either a ban or a tax on single-use plastic packaging, motivated by their contribution to marine plastic pollution. This may lead consumers to opt for similar unregulated substitutes, potentially undermining or even counteracting the intended effect of the policy instrument. The purpose of this study is to theoretically and empirically compare the environmental and welfare effects of the first-best Pigouvian taxes on both plastic bags and a substitute (paper bags), with two alternative second-best policy instruments: a tax on plastic products alone, and a common uniform tax on all packaging materials. The empirical analysis accounts for two different types of environmental externalities from the use of both bag types: marine pollution and greenhouse gas emissions. It also compares results for two countries, Denmark and the USA, which differ in the demand for plastic and paper bags. The theoretical analysis shows that a unilateral tax on plastic bags should equal the marginal environmental damage of plastic bags minus a fraction of the marginal environmental cost of paper bags, hence being lower than the Pigouvian tax. The optimal common tax should equal a weighted average of the marginal environmental damage of the two bag types and would be lower than the Pigouvian tax on plastics if the marginal external cost of plastic bags exceeds that for paper bags. The empirical analysis shows that for default parameters, the variation in tax level across the studied scenarios is small. It also shows that if Pigouvian taxes cannot be implemented, a common uniform tax on both bag types would result in a higher welfare gain than a tax on plastic bags alone. Sensitivity analysis reveals that the level of the second-best taxes and their associated environmental and welfare impacts are sensitive to assumptions regarding the littering rate and decay rate of plastic bags in the marine environment.

Innovative methods for microplastic characterization and detection: Deep learning supported by photoacoustic imaging and automated pre-processing data.

Plastic products' widespread applications and their non-biodegradable nature have resulted in the continuous accumulation of microplastic waste, emerging as a significant component of ecological environmental issues. In the field of microplastic detection, the intricate morphology poses challenges in achieving rapid visual characterization of microplastics. In this study, photoacoustic imaging technology is initially employed to capture high-resolution images of diverse microplastic samples. To address the limited dataset issue, an automated data processing pipeline is designed to obtain sample masks while effectively expanding the dataset size. Additionally, we propose Vqdp2, a generative deep learning model with multiple proxy tasks, for predicting six forms of microplastics data. By simultaneously constraining model parameters through two training modes, outstanding morphological category representations are achieved. The results demonstrate Vqdp2's excellent performance in classification accuracy and feature extraction by leveraging the advantages of multi-task training. This research is expected to be attractive for the detection classification and visual characterization of microplastics.

Plastic waste management through liquefaction in hydrogen donating solvents: A review.

Plastic pollution poses a significant environmental threat, particularly to marine ecosystems, as conventional plastics persist without degradation, accumulating plastic waste in landfills and natural environments. A promising alternative to address this issue involves the use of hydrogen donor solvents in plastic liquefaction, offering a dual benefit of waste reduction and the generation of valuable liquid products with diverse industrial applications. This review delves into plastic recycling methods with a specific focus on liquefaction using hydrogen donating solvents as an innovative approach to waste management. Liquefaction, conducted at moderate to high temperatures (280-450 °C) and pressures (7-30 MPa), yields high oil conversion using various solvents. This study examined the performance of hydrogen-donating solvents, including water, alcohols, decalin, and cyclohexane, in enhancing the oil yield while minimising the oxygen content. Supercritical water, recognised for its effective plastic degradation and chemical production capabilities, and alcohols, with their alkylating and hydrogen-donating properties, have emerged as key solvents in plastic liquefaction. The use of hydrogen donor solvents stabilizes the free radicals, enhancing the conversion of plastic waste into valuable products. In addition, this review addresses the economic efficiency of the liquefaction process.

Interactions between methyl octabromo ether flame retardant and expanded polystyrene microplastics in the photoaging process.

Expanded polystyrene (EPS) plastic is widely used because of its low density and lightweight properties, enabling it to float on water and increase its exposure to sunlight. In this study, we simulated the photoaging process of flame retardant-added EPS (FR-EPS) and common original EPS (OR-EPS) microplastic (MP) particles with and without methyl octabromoether flame retardant (MOBE) in the laboratory to explore the effect of MOBE on the photodegradation of EPS. Results showed that MOBE accelerated size reduction and surface hole formation on the particles, hastening the shedding and replacement of particle surfaces. FR-EPS particles exhibited a weight loss exceeding that of OR-EPS, reaching 40.85 ± 3.72% after 36 days of irradiation. Moreover, rapid physical peeling of the FR-EPS surface was accompanied by continuous chemical oxidation and fluctuations of the carbonyl index and O/C ratio. A diffusion model based on Fick's second law fitted well for the concentration of MOBE remaining in FR-EPS particles. MOBE's sensitivity to direct photochemical reactions inhibited the early-stage photoaging of EPS MP particles by competing for photons. However, MOBE as chromophores could absorb photons and produce •OH to promote the aging of EPS. Moreover, the capacity of EPS to absorb light energy also accelerated MOBE degradation. These findings suggested that the photoaging behavior of commercial EPS products containing flame retardants in the environment is quite different from that of pure EPS, indicating that additive-plastic interactions significantly alter MP fate and environmental risks.

Unveiling the molecular mechanisms of size-dependent effect of polystyrene micro/nano-plastics on Chlamydomonas reinhardtii through proteomic profiling.

Microplastics have become a prevalent environmental pollutant due to widespread release and production. Algae, as primary producers, play a crucial role in maintaining the ecological balance of freshwater environments. Despite reports on the inhibition of microalgae by microplastics, the size-dependent effects on microalgae and associated molecular mechanism remain poorly understood. This study investigates the impacts of three polystyrene micro/nano-plastics (PS-MNPs) with different sizes (100 nm, 350 nm, and 6 µm) and concentrations (25-200 mg/L) on Chlamydomonas reinhardtii (C. reinhardtii) throughout its growth period. Results reveal size- and concentration-dependent growth inhibition and induction of oxidative stress by PS-MNPs, with microalgae exhibiting increased vulnerability to smaller-sized and higher-concentration PS-MNPs. Proteomics analysis elucidates the size-dependent suppression of proteins involved in the photosynthesis process by PS-MNPs. Photosynthetic activity assays demonstrate that smaller PS-MNPs more significantly reduce chlorophyll content and the maximal photochemical efficiency of photosystem II. Finally, electron microscope and Western blot assays collectively confirm the size effect of PS-MNPs on microalgae growth is attributable to suppressed protein expression rather than shading effects. This study contributes to advancing our understanding of the intricate interactions between micro/nano-plastics and algae at the molecular level, emphasizing the efficacy of proteomics in dissecting the mechanistic aspects of microplastics-induced biological effects on environmental indicator organisms.