Microplastics, Volume 1, Issue 3 (September 2022) – 16 articles

In order to identify how research contributes to the knowledge of marine litter as a pressure on beaches, we reviewed interactions of beach fauna with this pollutant. Entanglement of pinnipeds in fishing gear, negative correlations between macroinvertebrates abundance and sediment pollution, and the presence of plastic surrounding burrows were primary evidence of beach fauna interacting with stranded litter. Ingestion represents the main body of research; microplastic uptake by invertebrates has been studied by laboratory experiments and field collections to report the presence of polymers in tissues. In the natural context, the higher the urbanization surrounding beaches and sediment pollution, the higher the concentration of microplastics in organs of bivalves. This approach currently constitutes the main research direction, but ecotoxicological assays are emerging prospects to assess the effects of exposure to microplastics. Beached macroplastics entangle and entrap invertebrates and vertebrates, and studies have reported increasing negative interactions with seals and sea turtles. Changes in nesting and feeding behavior of resident and transient organisms have been shown as typical early warning indicators of marine litter impacts. The focus on fauna–litter interactions holds terrific potential for research and citizen science projects, which finally becomes a powerful driver towards environmental awareness on sandy beaches. Full article

Plastic pollution is one of the significant environmental concerns due to the threefold increase in global plastic waste. Marine microplastics, including petroleum-based plastic pieces and synthetic and artificial fibers smaller than 5 mm, are not only ubiquitous in natural water but also high in wastewater streams due to the direct discharge, transfer and breakdown of plastic items. This research aims to investigate the presence and dispersion of microplastics in the downtown area and coastal suburban area of Ho-Chi-Minh City by using Raman microscopy. As a result, the most common plastics (PE, PET, PA, PP, PVC, PS and PMMA) were detected, and most of them were fibrous shorter than 500 μm. The total microplastics decreased gradually from the urban waterborne (up to 220 MPs/L) via Can Gio UNESCO Mangrove Biosphere Reserve (10 MPs/L) and to the East Sea (3 MPs/L), which reveals the potential role of the mangrove in reducing marine contaminants including microplastics. This study provides important insights into microplastic pollution in the Western Pacific Region, especially the Saigon-Dong Nai river systems, supporting useful data for natural water resources management. Full article

A large amount of the globally produced plastics are not treated and are eventually released into landfills or natural environments, including surface waters. The plastics that enter the aquatic environment are very often microplastics, which are produced in households by the slow degradation or abrasion of plastic products, or as whole plastic products, which eventually degrade (abrasion, photodegradation). Together with microplastics, other pollutants such as pharmaceuticals of various kinds enter surface waters—both of these counterparts can interact with each other as well as with organic and inorganic molecules available in the natural environment. The aim of this study was to identify the interaction of microplastics with pharmaceuticals, especially under conditions that are common in inland waters as well as the seas and oceans that the rivers feed their water into. It was found that salinity has a great impact on the sorption capacity of microplastics and pharmaceuticals. The sorption of naturally occurring humic substances (humic and fulvic acids) can greatly increase when the microplastic–pharmaceutical complex is formed; however, the priority of the interaction happens with pharmaceuticals and humic substances. Such complexes can influence the organisms that feed on small organic-matter particles, as they can be mistaken for food and thus be transferred throughout the food chain. Full article

As there is still little knowledge of interactions between microplastics (MP) and hydrophilic compounds, we propose ways the toxicity of hydrophilic pesticides can be modulated by MP, when sorption can be excluded. Larvae of Chironomus riparius were exposed to thiacloprid (TH, 1 µg/L) and polystyrene microplastic particles (PS; <50 µm; 150,000 and 1,000,000 particles/L) for 96 h, solely or in co-exposure. Burrowing behavior and mortality were observed. Larvae in treatments containing PS established themselves quicker in the sediment and kept the ability to rebury for a longer time compared to control and TH, respectively. While TH elevated the mortality, exposure to PS alone did not affect the survival of the larvae. In co-exposure of TH and PS, a concentration of 150,000 particles/L significantly reduced the toxicity of 1 µg/L TH after 96 h, an effect that was not observed at 1,000,000 particles/L. Therefore, we hypothesize that this modulation of the toxicity of TH eventually may have resulted from a combination of a ‘protective MP layer’ in the gut and a higher retention time of particles in larvae exposed to 150,000 particles/L than in those exposed to 1,000,000 particles/L due to the lower number of ingestible particles in the former. Full article

Textile materials from polyester fibres are sensitive to washing, especially at higher temperatures, due to their thermoplastic properties, hydrophobic nature and sensitivity to the alkaline medium. The issue of microplastic fibres’ (MFs’) release from polyester textiles is a topic that attracts the attention of researchers from different scientific fields, since microplastics are now among the serious environmental risks. In this study, two washing protocols, a standard and an innovative procedure, were presented, aiming to preserve the properties of polyester fabrics and reduce the pollution of washing effluents. The standard procedure followed HRN EN ISO 6330, while the innovative procedure was a modification of the standard that involved gradually cooling the bath before rinsing. The effects of these washing protocols were studied based on the physicochemical properties of the fabrics compared to the unwashed material, the composition of the effluents, and the filtrates after 10 cycles. The characterisation parameters of the fabrics, effluents and filtrates according to the standard and the innovative washing protocols showed differences in the observed parameters during the 10 washing cycles. The obtained results show the usefulness of the proposed concept of cooling the bath before rinsing in order to preserve the properties of polyester fabrics and reduce the load of washing effluents. Hierarchical cluster analysis (HCA) also confirmed differences in pH, conductivity and turbidity for effluents and filtrates from standard and innovative washing protocols. Full article

This study aims to determine whether differences exist between the presence of microplastics and mesoplastics in fishes of coral reef and mangrove ecosystems, in Isla Grande, Colombian Caribbean. The collection of three species of coral reef (Centropomus undecimalis, Caranx hippos, and Lutjanus synagris) and three species of mangrove from coral reef (Centropomus undecimalis, Eugerres plumieri, and Archosargus rhomboidalis) were found to have ingested microplastics and mesoplastics, with a significantly higher in the mangrove species than in the coral reef species (1.9 vs. 1.6 items/individual). Furthermore, the average abundance and weight of microplastics and mesoplastics were significantly higher in females than in males (p < 0.05) and the abundance of microplastics and mesoplastics in the intestines was significantly higher than in the stomach (p < 0.05). PE, polyester, PVC, and PET were the most abundant polymers among common plastics found in species of the two habitats. Our findings highlight the importance of more rigorous plastic waste management strategies in areas nearby the coast and mangrove habitats. Full article

A wide range of weathering processes contributes to the degradation of plastic litter items which leads to the formation of microplastics that may be detrimental to marine ecosystems and the organisms inhabiting them. In this study, the impact of UV exposure on the degradation of clear polypropylene (CPP), black polypropylene (BPP), and polyethylene terephthalate (PET) packaging materials was investigated over a period of 6 weeks under dry air conditions representing the terrestrial environment. The exposure was conducted using differently sized and shaped samples at irradiation intensities of 65 W/m² and 130 W/m². Results indicated that UV irradiation led to changes in the properties of PET, BPP, and CPP that were proportional to the intensity delivered, leading to a higher level of mass loss, carbonyl indices, crystallinities, and microhardness in all polymer types at 130 W/m² relative to 65 W/m². However, material shape and size did not have a significant influence on any property for any of the test materials. Increased mass loss over time was accompanied by considerable increases in carbonyl index (CI) for both PPs. Clear PP (CPP) underwent the most severe degradation, resulting in the highest mass loss, increase in crystallinity, and CI. BPP was less degraded and modified by the UV irradiation than the CPP, indicating that the colorant, carbon black, provided some degree of protection to the bulk polymer material. PET was the least degraded of the three materials, suggesting this polymer type is more resistant to UV degradation. The differences in the degradation behaviours of the three test materials under dry environmental conditions indicate that the UV exposure history of plastic litter might play an important role in its potential for further degradation once it reaches the marine environment. Furthermore, analysis of samples exposed to UV in aqueous media reveals a more irregular set of trends for most material properties measured. Overall, the degree of degradation resulting from UV irradiation in dry environments was more pronounced than in aqueous environments, although the most significant property changes were observed for materials without previous UV exposure histories. Samples with previous UV histories showed higher resistance to further crystallinity changes, which appeared to be due to crosslinking in the pretreatment exposures inhibiting chain alignment into crystalline structures. The effect of solution medium was insignificant, although the presence of water allowed hydrolytic degradation to proceed simultaneously with UV degradation for PET. The reduction of CI in pretreated materials in the aqueous exposures, combined with the mass loss, suggest that the degraded surface layer erodes or products dissolve into surrounding solution medium, leaving a fresh surface of plastic exposed. Full article

An intra-laboratory calibration to quantify microplastic in fine-grained marine sediments was performed with two objectives: (a) to determine the recovery rate of self-produced microplastics characterized by a size ranging from 220 µm to 5 mm and differing in color (pink, orange, gray, yellow, silver), shape (fragments, filaments, spheres, films), and chemical composition (polystyrene, polyethylene, polyvinyl chloride, acrylonitrile-butadiene-styrene, polypropylene, poly(methyl methacrylate)) artificially introduced into real samples; and (b) to analyze whether operator experience can be a key factor in the quality of the results. To answer this question, the same protocol was assigned to an experienced and an inexperienced operator. The results of this comparison are detailed in terms of root mean square and percent error. Possible strategies to increase the recovery rate are presented, and an ad hoc category, namely “glitter”, was created to adjust the results with respect to this unique type of microplastic usually ignored and excluded from the analysis. Full article

Food packaging has been demonstrated as a crucial issue for the migration of microplastics (MPs) into foodstuffs, concerning human health risk factors. Polymeric materials called plastics are continuously utilized in food packaging. Polyethylene (PE) is commonly used as a food packaging material, because it offers easy handling during transportation and optimal storage conditions for food preservation. In this work, three types of cured meat products of different fat compositions and meat processing methods—bacon, mortadella, and salami—were studied using spectroscopic methods (Raman and FT–IR/ATR) to determine the migration of low-density polyethylene (LDPE) from plastic packaging to the surface of the meat samples. The experimental duration of this study was set to be 28 days owing to the selected meat samples’ degradation, which started to become visible to the human eye after 10 days of storage in vacuum LDPE packaging, under refrigerated conditions at 4 °C. Spectroscopic measurements were performed at 0, 3, 9, 12, 15, and 28 days of storage to obtain comparative results. We demonstrated that the Raman spectral peaks of LDPE firstly appeared as a result of polymeric migration on day 9 in Bacon, on day 15 in Salami, and finally on day 28 in Mortadella. On day 28, all meat samples were tainted, with a layer of bacterial outgrowth developed, as proven by bright–field microscopic observation. Food packaging migration to the surface of cured meat samples was validated using Raman vibrational spectroscopy. To ensure minimal consumption of MPs in cured meat products stored in plastic packaging, while at the same time maintaining good food quality, they should be kept in refrigerated conditions and consumed within a short period of time. In this work, the migration of MPs from food packaging to the surface of cured meat samples was observed using micro-Raman spectroscopy. Full article

In ancient Greece, people said that “honey is the Food of the Gods”, and they were right. They believed that honey fell from the sky, with the morning dew, on the flowers and leaves, and from this point, the bees collected it. Honey is one of the most nutritious food products, which can be found in most homes. A lot of honey products are stored in different types of packaging materials, including plastics. Plastic packaging has been studied for the migration of plasticizers, chemical compounds, and MPs and NPs in foodstuffs. Most of them have been achieved through food simulations, while some studies managed to detect and isolate MPs/NPs. Recent studies presented evidence for the presence of MPs/NPs in honey products but not directly connected to food packaging or to the different types of honey and their properties (viscosity, pH value, and moisture content) or their storing conditions (temperature, humidity, light, and time). Spectroscopic and analytical techniques like Raman, FTIR, HPLC, and GC-MS are in the foreground for MP/NP detection and identification, but a universal way of isolation, detection, characterization, and quantification has not yet been found. This leaves an open field for more work to be done to clarify the factors affecting the migration of plastic packaging material in honey. Full article

Microplastic (MP) contamination is an urgent environmental issue to address. Fibrous microplastics (FMPs) are the principal MP type in the air and have already been found in human stool and lung tissues. FMPs are generated from the lifecycle of synthetic and blended textiles and are expected to increase due to fast fashion. Among textile processes, the finishing of fabrics is estimated to generate 5000 t/year of textile waste fibers in Italy, including FMPs. To limit FMPs spread, this paper suggests, for the first time, the direct collection of blended finishing textile waste microfibers and reuse in designing thermal-insulating and mechanical-performing fiber-reinforced cementitious composites (FRCs). The microfibers were thoroughly characterized (size, morphology, composition, and density), and their use in FRCs was additionally evaluated by considering water absorption and release capacity. Untreated, water-saturated, and NaOH-treated microfibers were considered in FRCs up to 4 wt%. Up to a +320% maximum bending load, +715% toughness, −80% linear shrinkage, and double-insulating power of Portland cement were observed by increasing microfiber contents. NaOH-treated and water-saturated microfibers better enhanced toughness and linear shrinkage reduction. Therefore, green and performant composite construction materials were obtained, allowing for the mitigation of more than 4 kg FMPs per ton of cement paste. This is a great result considering the FMP contamination (i.e., 2–8 kg/day fallout in Paris), and that FRCs are promising and shortly-widely used construction materials. Full article

Composite materials constitute an appealing choice in many industrial sectors, due to their unique composition and characteristics, such as low maintenance requirements, light weight, corrosion resistance, and durability. However, the sustainable management of end-of-life composite materials remains a challenge. Recovery strategies, design aspects, and their interconnection are currently largely unexplored, while technologies involved in the circular economy (reuse, reduce, recycle, refurbish, etc.) could be improved. The current paper provides an overview of the existing methods of composite material waste management, while presenting new circular economy prospects for end-of-life strategies and providing a brief roadmap towards circularity for industries. Finally, existing circular economy practices in regard to composites are presented in different European countries to present the applicability of composite material end-of-life waste management. Full article

Assessing data analysis routines (DARs) for microplastics (MP) identification in Fourier-transform infrared (FTIR) images left the question ‘Do we overlook any MP particles in our sample?’ widely unanswered. Here, a reference image of microplastics, RefIMP, is presented to answer this question. RefIMP contains over 1200 MP and non-MP particles that serve as a ground truth that a DAR’s result can be compared to. Together with our MatLab^® script for MP validation, MPVal, DARs can be evaluated on a particle level instead of isolated spectra. This prevents over-optimistic performance expectations, as testing of three hypotheses illustrates: (I) excessive background masking can cause overlooking of particles, (II) random decision forest models benefit from high-diversity training data, (III) among the model hyperparameters, the classification threshold influences the performance most. A minimum of 7.99% overlooked particles was achieved, most of which were polyethylene and varnish-like. Cellulose was the class most susceptible to over-segmentation. Most false assignments were attributed to confusion of polylactic acid for polymethyl methacrylate and of polypropylene for polyethylene. Moreover, a set of over 9000 transmission FTIR spectra is provided with this work, that can be used to set up DARs or as standard test set. Full article

The presence of microplastics (MPs) in the environment, and the effects that the ingestion of these materials can have on organisms, can be aggravated by the adsorption of harmful substances on the surface or inside the MPs. Of special relevance are the studies that have been carried out on the adsorption and transport of polycyclic aromatic hydrocarbons (PAHs) as well as persistent organic pollutants (POPs) such as dioxins and furans (PCDD/Fs). This review will delve into the research carried out to date regarding the adsorption by conventional and biodegradable MPs of dangerous organic compounds such as those mentioned. In general, the presence of MPs is considered a vector for the entry of these contaminants into living beings, since their capacity to adsorb contaminants is very high and they are ingested by different organisms that introduce these contaminants into the trophic chain. Full article

Microplastics-induced histopathological changes in gastrointestinal tracts of fish have been widely reported. However, the translation of adverse effects in the gut to impacts on growth are understudied. This study investigated the effect of MP-induced small intestinal histomorphological changes on growth performance of Oreochromis urolepis juveniles. Sixty larvae were exposed in control (0), 1, 10, and 100 polyethylene microplastic particles (PE MPs)/mL treatment groups. On day 65, juveniles were euthanized, dissected, and biometric data were taken. Small intestine histomorphological lesion index (HLI) was calculated following histological preparation using routine hematoxylin and eosin procedure. Results showed increase in HLI proportional to PE MPs exposure dose. These deteriorations equally reduced growth in final weight, weight gain and total length (One-Way ANOVA, p > 0.05), and Specific Growth Rate (SGR) (Kruskal–Wallis Test, p > 0.05), though there were insignificant differences between treatment groups. Condition factors of fishes in control and 1 PE MPs differed significantly and with other treatment groups (Tukey HSD, p < 0.05). Small intestines HLI correlated significantly with growth pattern (Spearman, r = 1.00, p = 0.01), condition factors (Pearson, r = −0.995, p < 0.05), final weight, weight gain, and total length (Spearman, r = −1.00, p = 0.01) but not with SGR. The allometric growth pattern changed towards isometric corresponding to increasing HLI. These findings suggest that MPs damaged small intestine structure and thus impaired digestion and nutrients absorption functions which disrupted growth. Such effects may impair juveniles’ ability to escape enemies, find food, and eventually reproduce, and therefore require further study. Full article

In recent years, microfibers released from synthetic fabrics have been identified as the main contributor to primary microplastic pollution. These pollutants have been detected in several products for human consumption. This work aims to evaluate the efficiency of a specific device used with the purpose to monitor and reduce this anthropogenic pollution in potable water. The device was tested using potable water from several cities in Slovenia by mounting the device containing the porous membrane directly to the faucet in private and public buildings. The results highlight the effectiveness of the applied device in removing natural and synthetic microfibers from tap water and confirm the abundance of microfibers as a contaminant of potable water. Full article