Effects of nanopolystyrene on the feeding behavior of the blue mussel (Mytilus edulis L.)

Microplastics distribution, ecological risk and outflows of rivers in the Bohai Rim region of China - A flux model considering small and medium-sized rivers

Microplastics (MPs) pollution and its ecological risks have attracted increasing global attention. The Bohai Rim region (BRR), as the economic and population center of the entire northern China, still lacks a precise assessment of MPs pollution. Although current attention on MPs pollution mainly focuses on large rivers, small and medium-sized rivers are more numerous and more closely connected to human activities. In this study, measurement data of MPs from 11 estuaries in the BRR was collected to understand MPs distribution and ecological risk. The results indicate that the overall MPs pollution in these estuaries is still at a low level, with an average abundance of 1254.3 particles m-3. While the pollution load index (1.85) is relatively low, the potential ecological risk of PVC in some area (S8, EPVC = 1433.78, III) warrants further attention. Then we integrated data from 22 relevant rivers (covering all size rivers) in this region from the literature to fit a MPs flux model and assessed the MPs outflow from the four provinces and cities in the region. A strong correlation is achieved between modeled estimates and field measurements (r2 = 0.74), which can well estimate the river MPs outflows in northern China such as the Nanfei River. The MPs outflow from the four provinces (cities) is calculated to be 123.235 (range 44.415-242.314) T year-1, of which Shandong accounted for >80 % (104.066 T year-1). The small and medium-sized rivers accounted for 47 % (58.08 T year-1), whose contribution to MPs outflows should not be underestimated. This study can help us to accurately assess MPs pollution in different coastal areas in northern China, benefiting the formulation of precise control measures and policies for marine MPs pollution.

Polyamide microplastics can mitigate the effects of pathogenic bacterium on the health of marine mussels

Vibrio parahaemolyticus and microplastics are prevalent in the ocean. Bacteria attach onto plastic particles, forming harmful biofilms that collectively threaten bivalve health. This study investigates the interaction between polyamide microplastics (PA: particle size 38 ± 12 µm) and V. parahaemolyticus, as well as their combined impact on thick-shelled mussels (Mytilus coruscus). We introduced 1011 CFU/L of V. parahaemolyticus into varying PA concentrations (0, 5, 50, and 500 particles/L) to observe growth over 14 h and biofilm formation after 48 h. Our findings indicate that microplastics suppress biofilm formation and virulence gene expression. Four treatments were established to monitor mussel responses: a control group without PA or V. parahaemolyticus; a group with 50 particles/L PA; a group with 1011 CFU/L V. parahaemolyticus; and a co-exposure group with both 50 particles/L PA and 1011 CFU/L V. parahaemolyticus, over a 14-day experiment. However, combined stress from microplastics and Vibrio led to immune dysregulation in mussels, resulting in intestinal damage and microbiome disruption. Notably, V. parahaemolyticus had a more severe impact on mussels than microplastics alone, yet their coexistence reduced some harmful effects. This study is the first to explore the interaction between microplastics and V. parahaemolyticus, providing important insights for ecological risk assessments.

Diving into the metabolic interactions of titanium dioxide nanoparticles in "Sparus aurata" and "Ruditapes philippinarum"

The biological response to nanomaterials exposure depends on their properties, route of exposure, or model organism. Titanium dioxide nanoparticles (TiO2 NPs) are among the most used nanomaterials; however, concerns related to oxidative stress and metabolic effects resulting from their ingestion are rising. Therefore, in the present work, we addressed the metabolic effects of citrate-coated 45 nm TiO2 NPs combining bioaccumulation, tissue ultrastructure, and proteomics approaches on gilthead seabream, Sparus aurata and Japanese carpet shell, Ruditapes philippinarum. Sparus aurata was exposed through artificially contaminated feeds, while R. philippinarum was exposed using TiO2 NPs-doped microalgae solutions. The accumulation of titanium and TiO2 NPs in fish liver is associated with alterations in hepatic tissue structure, and alteration to the expression of proteins related to lipid and fatty acid metabolism, lipid breakdown for energy, lipid transport, and homeostasis. While cellular structure alterations and the expression of proteins were less affected than in gilthead seabream, atypical gill cilia and microvilli and alterations in metabolic-related proteins were also observed in the bivalve. Overall, the effects of TiO2 NPs exposure through feeding appear to stem from various interactions with cells, involving alterations in key metabolic proteins, and changes in cell membranes, their structures, and organelles. The possible appearance of metabolic disorders and the environmental risks to aquatic organisms posed by TiO2 NPs deserve further study.

Microplastic pollution in commercially important edible marine bivalves: A comprehensive review

Microplastics have become major pollutants in the marine environment and can accumulate in high concentrations, especially in the gut of marine organisms. Unlike other seafood, bivalves are consumed whole, along with their digestive systems, resulting in the transfer of microplastics to humans. Therefore, there is an urgent need to review the status of microplastic pollution in marine bivalves. In this context, this article provides a comprehensive review of the status of microplastic pollution in marine bivalves and the impact of microplastics on the physiology and immunology of marine bivalves. In general, marine bivalves can accumulate high levels of microplastics in a tissue-specific manner. Although microplastic pollution does not cause mortality in bivalves, it can adversely affects bivalves' immunity, byssus production, and reproduction, potentially affecting bivalve populations. This article provides important information that will aid establishing management measures and determining the direction of future research.

Bio-based microplastic polylactic acid exerts the similar toxic effects to traditional petroleum-based microplastic polystyrene in mussels

Microplastics (MPs) have accumulated in the oceans, causing adverse effects on marine organisms and the environment. Biodegradable polylactic acid (PLA) is considered as an excellent substitute for traditional petroleum-based plastics, but it is difficult to degrade completely and easily become MPs in the marine environment. To test the ecological risk of bio-based PLA, we exposed thick-shelled mussels (Mytilus coruscus) to bio-based PLA and petroleum-based polystyrene (PS) (at 102, 104, and 106 particles/L) for 14 days. The significant increase in enzyme activities related to oxidative stress and immune response showed that mussels were under physiological stress after MP ingestion. While enzyme activities of nerve conduction and energy metabolism were significantly disturbed after exposure. Meanwhile, normal physiological activities in respiration, ingestion and assimilation were also suppressed in association with enzyme changes. The negative effects of PS and PLA in mussels were not differentiated, and further integration analysis of integrated biomarker response (IBR) and principal component analysis (PCA) also showed that PLA would induce adverse effects in mussels and ecological risks as PS, especially at environmental concentrations. Therefore, it is necessary to pay more attention to the environmental and ecological risk of bio-based MP PLA accumulating in the marine environment.

Impacts of elevated temperature, decreased salinity and microfibers on the bioenergetics and oxidative stress in eastern oyster, Crassostrea virginica

Projected increases in temperature and decreases in salinity associated with global climate change will likely have detrimental impacts on eastern oyster, Crassostrea virginica, as these variables can influence physiological processes in these keystone species. We set out to determine how the interactive effects of temperature (20 °C or 27 °C) and/or salinity (27‰ or 17‰) impacted the energetic reserves, aerobic and anaerobic metabolism, and changes to oxidative stress or total antioxidant potential as a consequence of an altered environment over a 21-day exposure. Gill and adductor muscle were used to quantify changes in total glycogen and lipid content, Electron Transport System and Citrate Synthase activities, Malate Dehydrogenase activity, Protein Carbonyl formation, lipid peroxidation, and total antioxidant potential. A second exposure was performed to determine if these environmental factors influenced the ingestion of microfibers, which are now one of the leading forms of marine debris. Elevated temperature and the combination of elevated temperature and decreased salinity led to an overall decline in oyster mass, which was exacerbated by the presence of microfibers. Changes in metabolism and oxidative stress were largely influenced by time, but exposure to elevated temperature, decreased salinity, the combination of these stressors or exposure to microfibers had small impacts on oyster physiology and survival. Overall these studies demonstrate that oyster are fairly resilient to changes in salinity in short-term exposures, and elevations in temperature or temperature combined with salinity result in changes to the oyster energetic response, which can be further impacted by the presence of microfibers.

A comprehensive review on the adverse effect of microplastics in the gastrointestinal system of Artemia sp

Microplastic waste in aquatic environments can lead to the mortality of large marine creatures, as it increases the risk of entanglement, strangulation, and starvation. Even though micro- and nano-plastics pose a hidden threat, researchers still know little about them. The food source is an essential factor in gut microbial diversity. A well-balanced intestinal microbiome impacts animal development and health. According to research, microplastics (MPs) like polyethylene (PE) and polystyrene (PS) affected the gut microbiota of Artemia sp., increasing their genetic diversity. Therefore, the present study examined the negative impacts of MPs within the gastrointestinal tract of Artemia sp., the primary protein source of fish. A comprehensive literature review showed that microplastic contamination and its additives impair environmental and aquatic health. The findings of this research show that MPs alter the gut microbiota of Artemia, which in turn affects fish and, ultimately, human health via a cascade of impacts.

Microplastics and copper impacts on feeding, oxidative stress, antioxidant enzyme activity, and dimethylated sulfur compounds production in Manila clam Ruditapes philippinarum

Microplastics (MPs) are widespread ocean pollutants and many studies have explored their effects. However, research on MPs combined impact with copper (Cu) on dimethylated sulfur compound production is limited. Dimethyl sulfide (DMS) is an important biogenic sulfur compound related to global temperatures. This study examined the ecotoxicological effects of polyamide 6 MPs and Cu on dimethylsulfoniopropionate (DMSP), DMS, and dimethyl sulfoxide (DMSO) production in Manila clams (Ruditapes philippinarum). Our findings showed that MPs and Cu increased oxidative stress, indicated by higher superoxide anion radical production and malondialdehyde levels while decreasing glutathione contents and increasing superoxide dismutase activities. Additionally, MPs and Cu exposure reduced DMS and dissolved DMSO (DMSOd) concentrations due to decreased grazing. These results contribute to a better understanding of the ecotoxicological effects of MPs/Cu on bivalves and their roles in the organic sulfur cycle, suggesting a need for further research on long-term impacts on them.

Occurrence, characteristics and distribution of microplastics in commercial marine fishes of the Bay of Bengal

The study aimed to assess and characterize microplastics (MPs) in muscles, guts, and gills of six commercially important marine fish from the Bay of Bengal. FTIR was utilized to identify MP's polymer compositions. A total 7085 MPs identified, where tuna exhibited the highest count and Bombay duck had the lowest. MPs abundance (MPs/g) was ranged from 1.56 ± 0.39 to 7.16 ± 1.36 in muscles, 1.91 ± 0.32 to 4.46 ± 0.75 in guts, and 2.36 ± 0.24 to 6.53 ± 1.58 in gills. The predominant MPs were 1-5 mm size (33.33-62.78 %), white/transparent color (18.45-54.63 %), filament shapes (75.00-94.71), and fiber types (73.21-94.71 %). FTIR revealed MPs 58.89 % polyethylene, 21.67 % polypropylene, 17.22 % polyester, and 2.22 % non-plastic compositions. Cluster analysis grouped two species with 50 % similarity, while PCA indicated significant variations among principal components (14-69.4 %) highlighting the dominance of fiber, particles, and 0.5-1.0 mm MPs in the fish tissues. The prevalence of MPs in seafood underscores measures to safeguard both the marine ecosystem and human health.

Size, shape, and elemental composition as predictors of microplastic surface erosion

The degradation of surfaces and its possible dependence on shape, size, and elemental composition of plastic particles were subjected. The surfaces of 146 microplastics were classified from smooth to fully eroded (%) by SEM/EDS. Structural elements and various additives were found on microplastics depending on their shapes. The surface of plastic items > 100 µm in length showed a relatively more eroded area than smaller ones, regardless of their shapes. Depending on shape, the percentage of surface erosion of irregularly shaped fragments < 100 µm was significantly enhanced compared to microbeads of the same size. These results may provide insights into assessing potential risks posed by microplastics and improve our understanding of the role of these parameters concerning possible adverse health effects on the environment.

Quantification and characterization of microplastics ingested by mangrove oysters across West Africa

Microplastic ingestion by marine organisms presents a challenge to both ecosystem functioning and human health. We characterized microplastic abundance, shape, size, and polymer types ingested by the West African mangrove oyster, Crassostrea tulipa (Lamarck, 1819) sampled from estuaries and lagoons from the Gambia, Sierra Leone, Ghana, Benin, and Nigeria using optical microscopy and Fourier transform infrared (FTIR) techniques. A total of 780 microplastics were isolated in the whole tissues of the 250 oysters (n = 50 oysters per country). The abundance and distribution of microplastics in the oysters followed the pattern: the Gambia > Ghana > Sierra Leone > Nigeria > Benin. The Tanbi wetlands in the Gambia recorded the highest average of 10.50 ± 6.69 per oyster while the Ouidah lagoon in Benin recorded the lowest average of 1.80 ± 1.90 per oyster. Overall, microplastic numbers varied significantly (p < 0.05) among the five countries. Microfibers, particularly those within 1001-5000 μm size, dominated the total microplastic count with a few fragments and films. No spherical microplastics were isolated in the oysters. In the Sierra Leone and Benin oysters, fragments and films were absent in the samples. Microplastic between the 1001 and 5000 μm size class dominated the counts, followed by 501-1000 μm, 101-500 μm, and 51-100 μm. Five polymer groups namely polyethylene, polyester, nylon, polypropylene, and polyamide were identified across the five countries, with polyethylene occurring in oysters from all five countries and polyester occurring in all but the oysters from Nigeria. This diversity of polymers suggests varied sources of microplastics ingested by the studied oysters. The absence of microspheres across the five supports findings from other studies that they are the least ingested and highly egested by the oysters.

Assessment of microplastics in coastal ecosystem of Bangladesh

Microplastics (MPs) pose one of the major environmental threats to marine organisms and ecosystems on a global scale. The present study investigated MPs in surface water, beach sediments, and fish in two coastal areas of Bangladesh namely Cox's Bazar and Kuakata. The MPs were identified and characterized using three different techniques, including the binocular microscope, the ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy), and SEM-EDS (Scanning Electron Microscopy- Energy Dispersive Spectroscopy). The number of MPs in seawater was 10.1 ± 3.10 and 8.52 ± 3.92 items/100 L and in beach sediment, 13.2 ± 3.68 and 9.48 ± 3.63 items/100 g in Cox's Bazar and Kuakata, respectively. In fish samples, the abundance of MPs was 7.82 ± 1.28 and 6.82 ± 1.87 items/individual species of Cox's Bazar and Kuakata, respectively, where the highest quantities of MP were found in Euthynnus affinisand Sillago sihama and the lowest in Terapon jarbua and Pampus chinensisin Cox's Bazar and Kuakata, respectively. The number of MPs in GITs (Gastrointestinal tracts) was 1.63 ± 0.991 and 1.25 ± 0.546 items/g GIT and in BW (Body Weight) were 0.042 ± 0.014 and 0.037 ± 0.014 items/g BW in Cox's Bazar and Kuakata, respectively. There revealed a positive correlation between MP abundance and GIT weight and body weight in fish species. MPs were predominantly fiber-shaped, white/transparent, and small size. The most common MP polymers were polyethylene and polypropylene. SEM images of MPs demonstrate surface roughness, cracks, mechanical weathering and oxidative weathering, demonstrating their ongoing environmental exposure. The EDS spectrum unearthed that the MPs contained several elements (C, N, O, Na, Al, Fe, and Si). Findings from this study might be useful in coastal plastic particle management and to mitigate the potential risks associated with them.

Transitioning to Microplastic-Free Seed Coatings: Challenges and Solutions

This review addresses the issue of replacing manufactured microplastics in seed coatings used in agriculture. Firstly, it focuses on the policy and regulatory actions taken on microplastics at a global level. There is no consensus within the scientific community on the definition of a microplastic and, more generally, on the classification of plastic debris. Nevertheless, several decision schemes have been proposed in an attempt to define the notion of microplastics. The different criteria relevant to this definition, such as the size, physical state, chemical structure, origin, and persistence of microplastics, are discussed, with a comparison being made between the REACH regulation and the scientific literature. Seed production and processing are also discussed, with the functions of seed coatings being explained in order to gain a better understanding of the properties to be considered in a substitution strategy for currently used microplastics. The main challenges are multiple; substitutes must provide the same performance as microplastics: (i) improving the adherence of the treatment to the seed, (ii) distributing the treatment more evenly over the seed, (iii) reducing the amount of dust-off when handling treated seed, and (iv) improving the seed flowability, which is particularly important during the sowing stage, all while preserving the physiological properties of the seed. Substitute polymers are proposed according to the desired performance and functional properties: two main chemical families of biopolymers were identified in the literature: polysaccharides and proteins. Among them, 13 and 6 polymers, respectively, complied with REACH regulation, demonstrating adhesion, dust reduction performances, and preservation of seed physiological quality in particular. This work aims to guide future studies on microplastic substitution in seed coatings, and to highlight research needs in this area. It is based on an analysis and discussion of the literature, identifying and listing potential substitutes.

Physiological and transcriptomic analysis reveals the toxicological mechanisms of polystyrene micro- and nano-plastics in Chlamydomonas reinhardtii

With the accumulation of plastic waste in the environment, the toxicity of micro- and nano-plastics (MNPs) to microalgae has attracted increasing attention. However, the underlying toxic mechanisms of MNPs remain to be elucidated. In this study, we synthesized micro- and nano-scale of polystyrene MNPs (PS MNPs) to investigate their toxicity and toxic mechanisms in Chlamydomonas reinhardtii. We found that PS MNPs significantly inhibit the production of photosynthetic pigments and increase soluble protein content. The detailed analysis of results shows that both materials affect photosynthetic efficiency by damaging the donor side, reaction center, and electron transfer of photosystem II. Moreover, compared to PS MPs, PS NPs have a greater negative impact on algal cells. Analyzing the transcriptome of cells suggests that the most sensitive metabolic pathways in response to PS MNPs involve oxidative phosphorylation, biosynthesis of secondary metabolites, and photosynthesis. Especially, genes related to photosynthesis and oxidative phosphorylation showed significant changes in expression after exposure to PS MNPs. This study provided molecular-level insights into the toxic mechanisms of PS MNPs on microalgae.

Decoding the molecular concerto: Toxicotranscriptomic evaluation of microplastic and nanoplastic impacts on aquatic organisms

The pervasive and steadily increasing presence of microplastics/nanoplastics (MPs/NPs) in aquatic environments has raised significant concerns regarding their potential adverse effects on aquatic organisms and their integration into trophic dynamics. This emerging issue has garnered the attention of (eco)toxicologists, promoting the utilization of toxicotranscriptomics to unravel the responses of aquatic organisms not only to MPs/NPs but also to a wide spectrum of environmental pollutants. This review aims to systematically explore the broad repertoire of predicted molecular responses by aquatic organisms, providing valuable intuitions into complex interactions between plastic pollutants and aquatic biota. By synthesizing the latest literature, present analysis sheds light on transcriptomic signatures like gene expression, interconnected pathways and overall molecular mechanisms influenced by various plasticizers. Harmful effects of these contaminants on key genes/protein transcripts associated with crucial pathways lead to abnormal immune response, metabolic response, neural response, apoptosis and DNA damage, growth, development, reproductive abnormalities, detoxification, and oxidative stress in aquatic organisms. However, unique challenge lies in enhancing the fingerprint of MPs/NPs, presenting complicated enigma that requires decoding their specific impact at molecular levels. The exploration endeavors, not only to consolidate existing knowledge, but also to identify critical gaps in understanding, push forward the frontiers of knowledge about transcriptomic signatures of plastic contaminants. Moreover, this appraisal emphasizes the imperative to monitor and mitigate the contamination of commercially important aquatic species by MPs/NPs, highlighting the pivotal role that regulatory frameworks must play in protecting all aquatic ecosystems. This commitment aligns with the broader goal of ensuring the sustainability of aquatic resources and the resilience of ecosystems facing the growing threat of plastic pollutants.

Toxicological review of micro- and nano-plastics in aquatic environments: Risks to ecosystems, food web dynamics and human health

The increase of micro- and nano-plastics (MNPs) in aquatic environments has become a significant concern due to their potential toxicological effects on ecosystems, food web dynamics, and human health. These plastic particles emerge from a range of sources, such as the breakdown of larger plastic waste, consumer products, and industrial outputs. This review provides a detailed report of the transmission and dangers of MNPs in aquatic ecosystems, environmental behavior, and interactions within aquatic food webs, emphasizing their toxic impact on marine life. It explores the relationship between particle size and toxicity, their distribution in different tissues, and the process of trophic transfer through the food web. MNPs, once consumed, can be found in various organs, including the digestive system, gills, and liver. Their consumption by lower trophic level organisms facilitates their progression up the food chain, potentially leading to bioaccumulation and biomagnification, thereby posing substantial risks to the health, reproduction, and behavior of aquatic species. This work also explores how MNPs, through their persistence and bioaccumulation, pose risks to aquatic biodiversity and disrupt trophic relationships. The review also addresses the implications of MNPs for human health, particularly through the consumption of contaminated seafood, highlighting the direct and indirect pathways through which humans are exposed to these pollutants. Furthermore, the review highlights the recommendations for future research directions, emphasizing the integration of ecological, toxicological, and human health studies to inform risk assessments and develop mitigation strategies to address the global challenge of plastic pollution in aquatic environments.

UV-aged polystyrene nanoplastics aggravate intestinal barrier damage by overproduction of ROS

UV irradiation significantly alters nanoplastics (NPs) physicochemical properties, thus affecting their biological toxicity. This study is the first to assess the influence of virgin and UV-aged polystyrene NPs (v-PS NPs, a-PS NPs) on the intestinal barrier of ICR mice. We found that a-PS NPs can cause more severe intestinal barrier damage compared with v-PS NPs. The reason may be attributed to that a-PS NPs produced more ROS in intestinal tissue. Moreover, the strong oxidizing property of hydroxyl radicals (·OH) generated from the a-PS NPs can damage cell membranes through lipid peroxidation, thereby leading to a low clearance rate of ·OH due to the impaired intestinal tissue function, in turn, causing more ROS to accumulate and inducing severe oxidative damage. This research underscores the crucial role of ·OH in mediating oxidative damage from UV-aged nanoparticles, emphasizing the need to consider environmental factors in assessing NPs toxicity.

Using marine mussels to assess the potential ecotoxicological effects of two different commercial microplastics

Microplastics (MPs) in the aquatic environment pose a serious threat to biota, by being confounded with food. These effects occur in mussels which are filter-feeding organisms. Mussels from the genus Mytilus sp. were used to evaluate the ecotoxicological effects of two MPs, polypropylene (PP) and polyethylene terephthalate (PET), after 4 and 28-days. Measured individual endpoints were condition index and feeding rate; and sub-individual parameters, metabolism of phase I (CYP1A1, CYP1A2 and CYP3A4) and II (glutathione S-transferases - GSTs), and antioxidant defense (catalase - CAT). MPs decreased both condition index (CI) and feeding rate (FR). No alterations occurred in metabolic enzymes, suggesting that these MPs are not metabolized by these pathways. Furthermore, lack of alterations in GSTs and CAT activities suggests the absence of conjugation and oxidative stress. Overall, biochemical markers were not responsive, but non-enzymatic responses showed deleterious effects caused by these MPs, which may be of high ecological importance.

Development of a New Aggregation Method to Remove Nanoplastics from the Ocean: Proof of Concept Using Mussel Exposure Tests

The overproduction and mismanagement of plastics has led to the accumulation of these materials in the environment, particularly in the marine ecosystem. Once in the environment, plastics break down and can acquire microscopic or even nanoscopic sizes. Given their sizes, microplastics (MPs) and nanoplastics (NPs) are hard to detect and remove from the aquatic environment, eventually interacting with marine organisms. This research mainly aimed to achieve the aggregation of micro- and nanoplastics (MNPs) to ease their removal from the marine environment. To this end, the size and stability of polystyrene (PS) MNPs were measured in synthetic seawater with the different components of the technology (ionic liquid and chitosan). The MPs were purchased in their plain form, while the NPs displayed amines on their surface (PS NP-NH2). The results showed that this technology promoted a significant aggregation of the PS NP-NH2, whereas, for the PS MPs, no conclusive results were found, indicating that the surface charge plays an essential role in the MNP aggregation process. Moreover, to investigate the toxicological potential of MNPs, a mussel species (M. galloprovincialis) was exposed to different concentrations of MPs and NPs, separately, with and without the technology. In this context, mussels were sampled after 7, 14, and 21 days of exposure, and the gills and digestive glands were collected for analysis of oxidative stress biomarkers and histological observations. In general, the results indicate that MNPs trigger the production of reactive oxygen species (ROS) in mussels and induce oxidative stress, making gills the most affected organ. Yet, when the technology was applied in moderate concentrations, NPs showed adverse effects in mussels. The histological analysis showed no evidence of MNPs in the gill's tissues.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

Microplastic contamination in different shell length in Tivela mactroides (Born, 1778)

Microplastic identification and distribution throughout oceans has become a great concern due to its substantial uprising and its consequent interactions with marine biota. Microplastics can be absorbed and adsorbed by several marine species owing to their very small size. Among these organisms are bivalves, including ones used as food for humans. In this context, this research aims to understand the absorption scale of microplastics by Tivela mactroides according to their size and consequently life stage. Thus, T. mactroides mussels were collected at Camburi Beach (Brazil) and grouped into 30 different size classes from 06 to 35 mm. Later, 20 specimens from each size class (N = 600) had the soft tissues removed and a pool was performed through digestion with 10 % KOH solution. Results showed the presence of microplastics in all size classes of T. mactroides, evidencing that organisms from 06 mm can already be contaminated by microplastics and a tendency of the number of microplastics particles to increase as shell size increases. Furthermore, the amount of blue filament-type MPs was significantly higher than the other types and colors. Additionally, analyzes performed by Raman spectroscopy showed that the blue filaments have a PET composition. Finally, larger individuals presented larger quantities of MPs, as well as larger filaments. This might suggest that there are differences between the assimilation of the size of MPs in the different size classes, i.e. that size makes a difference.

Mussels (Mytilus spp.) in Svalbard contain microplastic particles in tissues: Implications for monitoring

We examined the presence of microplastics in blue mussels Mytilus spp. from the intertidal zone of western Spitsbergen in Arctic Svalbard. The optical microscopy technique detected a total of 148 microplastics, with the highest concentration per mussel being 24 particles. Microplastics were found in 84% of the examined mussels. The microplastics ranged in size from <0.5 mm to 5 mm and consisted of fibers (83%), fragments (13%), plates (3%), and spherules (1%). The micro-Raman spectroscopy technique revealed four different types of polymers: polyethylene (67%), nylon-12 (17%), low-density polyethylene (11%), and polypropylene (5%). Our research shows that Arctic coastal waters are polluted with microplastics notwithstanding their remoteness. These findings suggest that microplastic contamination may harm marine life and coastal ecosystems and require further research into long-term environmental effects. We also indicate that intertidal mussels may be beneficial for monitoring microplastics because they can be collected without involving diving.

Tire particles and their leachates reduce the filtration rate of the mussel Mytilus edulis

Microplastics (MPs) are found in aquatic environments all over the world. Among MPs, tire wear particles (TWPs) are a major contributor to microplastic pollution, and their effects on marine ecosystems are of emerging concern. The blue mussel (Mytilus edulis) is a keystone species in coastal ecosystems with a high risk of exposure to microplastic pollution as the microplastics often overlap in size with the plankton consumed by mussels. In the present study, we investigated the effect of tire particles and their leachates on the filtration rates of M. edulis after short (72 h) and long-term (3 weeks) exposure. Acute exposure to leachates alone causes a significant decrease in the filtration rates of M. edulis with a low observed effect concentration (LOEC) of 1.25 g L-1 and a median effect concentration (EC50) = 3 g L-1. At a concentration of 1.25 g L-1, the filtration rate was reduced compared to the control on average by 38% when mussels were exposed to either TWP or leachates for 72 h. Similarly, mussels exposed to tire particles or their leachates for 3 weeks showed a 46% reduction in filtration rates, compared to the control group. A non-significant difference in filtration rate decrease was found between leachates alone or TWP, which indicates that leachates are the main responsible for the observed toxicity. Our findings indicate that elevated levels of TWP pollution can cause an adverse impact on M. edulis. This could disrupt the natural grazing pressure exerted by M. edulis on phytoplankton, potentially leading to an increased likelihood of algal blooms and hypoxia occurrence in coastal ecosystems.

The physiological response of the clam Ruditapes philippinarum and scallop Chlamys farreri to varied concentrations of microplastics exposure

Microplastics (MPs) pollution's impact on the marine ecosystem is widely recognized. This study compared the effects of polyethylene (PE) and polyethylene terephthalate (PET) on two bivalve species, Ruditapes philippinarum (clam) and Chlamys farreri (scallop), at two particle concentrations (10 and 1000 μg/L). MPs were found in the digestive glands and gills of both species. Although clearance rates showed no significant changes, exposure to different MPs caused oxidative stress, energy disruption, and lipid metabolism disorders in both clam and scallop. Histopathological damage was observed in gills and digestive glands. IBR values indicated increasing toxicity with concentration, with PET being more toxic than PE. WOE model suggested increasing hazard with concentration, highlighting higher PET toxicity on clam digestive glands. In contrast, PE hazard increased in gills, showing different species responses. R. philippinarum exhibited higher sensitivity to MPs than C. farreri, providing insights for assessing ecological risk under realistic conditions and stress conditions.

Polystyrene nanoplastics induce developmental impairments and vasotoxicity in zebrafish (Danio rerio)

The exponential use of plastics has significantly increased environmental pollution by nanoplastics (NPs). In the aquatic environment, NPs interact and bioaccumulate in the biota, posing a potential ecotoxicological risk. The present study investigated the developmental toxicity, vasotoxicity, cytotoxicity, ROS induction, and behavioral impairments in zebrafish (Danio rerio) exposed to environmentally relevant polystyrene NPs (PS-NPs) concentrations (0.04, 34 ng L-1, and 34 μg L-1) for 144 h through multiple biomarkers response (mortality, frequency of spontaneous contractions, heart rate, and morphological changes). Furthermore, vasotoxicity (head, yolk sac, tail, and branchial vessels) was evaluated using the transgenic zebrafish tg(Fli1:eGFP). Results showed that PS-NPs interacted mainly with zebrafish chorion, gills, tail, and larvae head. PS-NPs at 34 ng L-1 and 34 μg L-1 induced neurotoxicity (decreased frequency of spontaneous contractions), cardiotoxicity (bradycardia), and morphological changes in the eyes and head, indicating that PS-NPs induce developmental impairments in zebrafish. In addition, cytotoxicity in the caudal region (34 ng L-1), ROS production, decreased mean swimming speed, and distance covered were observed in all tested concentrations. PS-NPs also induced vasotoxicity (yolk sac region) in transgenic zebrafish. Overall, the present study demonstrates the harmful effects of PS-NPs on the early developmental stages of freshwater fish, indicating their environmental risk.

Polystyrene nanoplastics affected the nutritional quality of Chlamys farreri through disturbing the function of gills and physiological metabolism: Comparison with microplastics

Although microplastics (MPs) and nanoplastics (NPs) have become a global concern because of their possible hazards to marine organisms, few studies have investigated the effects of MPs/NPs on the nutritional quality of marine economic species, and the toxicity mechanisms remain unclear. We therefore investigated the effects of polystyrene MPs (PS-MPs, 5 μm) and NPs (PS-NPs, 100 nm) at an environmentally relevant concentration on adult scallops Chlamys farreri through the determination of nutritional composition, physiological metabolism, enzymatic response, and histopathology. Results showed that plastic particles significantly decreased the plumpness (by 33.32 % for PS-MPs and 36.69 % for PS-NPs) and protein content of the adductor muscle (by 4.88 % for PS-MPs and 8.77 % for PS-NPs) in scallops, with PS-NPs causing more notable impacts than PS-MPs. Based on the integrated biomarker response analysis, PS-NPs exhibited greater toxicity than PS-MPs, suggesting a size-dependent effect for plastic particle. Furthermore, PS-NPs significantly affected the physiological metabolism (e.g., filtration and ammonia excretion) than PS-MPs. Using gill transcriptomics analysis, the key toxicological mechanisms caused by NPs exposure included enrichment of the mitophagy pathway, responses to oxidative stress, and changes related to genes associated with nerves. This study provides new insights into the potential negative effects of MPs/NPs on the mariculture industry.

Two plant-growth-promoting Bacillus species can utilize nanoplastics

Plastics in agricultural soils pose a potential risk to humans because environmental plastics can enter our foods. Here, we present a first step toward developing bacteria that can both flourish in agricultural settings and bioremediate nanoplastics. We exposed two species known to promote plant growth in agricultural settings, Bacillus inaquosorum and B. velezensis, to polystyrene nanoplastic beads at various dosages. When grown in a medium with a low dosage of plastic as the only carbon source, the bacteria could oxidize the plastic, indicating the possibility of utilizing the plastic in their growth. When plastic was added to a rich medium, low and high dosages brought immediate death or inhibition to about a third of B. inaquosorum cells during 1 h. Despite the immediate harm, over the course of 24 h, the bacteria from one strain each of B. inaquosorum and B. velezensis reached higher densities at low plastic doses than with no plastic, although they reached lower densities at high plastic doses (a toxicological phenomenon known as hormesis). Microscopic studies demonstrated that the bacteria are shielded from excessive accumulation of nanoplastic particles. Because these plant-growth-promoting species can utilize polystyrene nanoplastics, strains of these species might be developed to bioremediate environmental plastic in agricultural settings. SYNOPSIS: Plastic fragments on farmlands accumulate on produce, creating a need for bioremediation. We identify bacteria that can flourish on agricultural land and utilize nanoplastics, a first step toward developing agricultural bioremediators.

Microcosm study of the effects of polyester microfibers on the indigenous marine amphipod (Cyphocaris challengeri) in the Strait of Georgia (BC, Canada)

Microplastics (MP) remain contaminants of great concern in the ocean because of their abundance, prevalence, and threat to marine organisms. Still, there is a great need for studies on the impact of MP on marine zooplankton. Here, we investigated the effects of polyethylene terephthalate (PET) microfibers (Mf) on the survival, Mf ingestion and retention, predation, and fecal pellets (FP) of the marine amphipod (Cyphocaris challengeri) at environmentally relevant concentrations (0, 10, 100, 1000, 10,000 and 50,000 Mf·L-1) and varied exposure time (24, 48 and 72 h). Our study demonstrated that exposure of C. challengeri to PET Mf did not affect their survival. The average number of ingested Mf and the Mf ingestion rate increased significantly with Mf concentrations. Nonetheless, the Mf ingestion rates by C. challengeri decreased significantly between 24 and 72 h in the two highest Mf treatments (10,000 and 50,000 Mf·L-1), suggesting careful rejection of the Mf or reduced feeding activity. Indeed, PET Mf significantly reduced the copepod feeding rate of the amphipods at Mf concentrations ≥1000 Mf·L-1 after 24 and 48 h of exposure duration. Over time, prey intake reduction in amphipods due to Mf ingestion could affect their reproductive outcome, growth, development, and cellular and ecosystem function. The encapsulation of PET Mf into the FP of C. challengeri significantly increased the FP density and sinking velocities, ultimately doubling the transfer rate of the FP from the surface waters to the sediments in SoG. Conversely, ingesting PET microfibers and their incorporation in FP will potentially enhance the role of C. challengeri in the biological C pump and sequestration in SoG. Our study showed that changes in Mf concentration had a more significant effect on C. challengeri Mf ingestion and ingestion rate, prey consumption, FP density and sinking velocity than the exposure time.

Application of advanced oxidation processes for the removal of micro/nanoplastics from water: A review

Micro/nanoplastics (MNPs) have been increasingly found in environments, food, and organisms, arousing wide public concerns. MNPs may enter food chains through water, posing a threat to human health. Therefore, efficient and environmentally friendly technologies are needed to remove MNPs from contaminated aqueous environments. Advanced oxidation processes (AOPs) produce a vast amount of active species, such as hydroxyl radicals (·OH), known for their strong oxidation capacity. As a result, an increasing number of researchers have focused on using AOPs to decompose and remove MNPs from water. This review summarizes the progress in researches on the removal of MNPs from water by AOPs, including ultraviolet photolysis, ozone oxidation, photocatalysis, Fenton oxidation, electrocatalysis, persulfate oxidation, and plasma oxidation, etc. The removal efficiencies of these AOPs for MNPs in water and the influencing factors are comprehensively analyzed, meanwhile, the oxidation mechanisms and reaction pathways are also discussed in detail. Most AOPs can achieve the degradation of MNPs, mainly manifest as the decrease of particle size and the increase of mass loss, but the mineralization rate is low, thus requiring further optimization for improved performance. Investigating various AOPs is crucial for achieving the complete decomposition of MNPs in water. AOPs will undoubtedly play a vital role in the future for the removal of MNPs from water.

Effects of polymethylmethacrylate nanoplastics on the polychaete Hediste diversicolor: Behavioural, regenerative, and biochemical responses

Plastics, particularly microplastics (MPs) and nanoplastics (NPs), have been regarded as pollutants of emerging concern due to their effects on organisms and ecosystems, especially considering marine environments. However, in terms of NPs, there is still a knowledge gap regarding the effects of size and polymer on marine invertebrates, such as benthic organisms. Therefore, this study aimed to understand, regarding behavioural, physiological, and biochemical endpoints (neurotransmission, energy metabolism, antioxidant status, and oxidative damage), the effects of 50 nm waterborne polymethylmethacrylate (PMMA) NPs (0.5 to 500 µg/L) on the marine benthic polychaete Hediste diversicolor, a key species in estuarine and coastal ecosystems. Results demonstrated that worms exposed to PMMA NPs had a shorter burrowing time than control organisms. Nevertheless, worms exposed to PMMA NPs (0.5 and 500 µg/L) decreased cholinesterase activity. Energy metabolism was decreased at 50 and 500 µg/L, and glycogen content decreased at all concentrations of PMMA NPs. Enzymes related to the antioxidant defence system (superoxide dismutase and glutathione peroxidase) displayed increased activities in H. diversicolor specimens exposed to concentrations between 0.5 and 500 µg/L, which led to no damage at the cell membrane and protein levels. In this study, polychaetes also displayed a lower regenerative capacity when exposed to PMMA NPs. Overall, the data obtained in this study emphasize the potential consequences of PMMA NPs to benthic worms, particularly between 0.5 and 50 µg/L, with polychaetes exposed to 50 µg/L being the most impacted by the analysed NPs. However, since sediments are considered to be sinks and sources of plastics, further studies are needed to better understand the impacts of different sizes and polymers on marine organisms, particularly benthic species.

Ecotoxicological effects of antibiotic adsorption behavior of microplastics and its management measures

Microplastics adsorb heavy metals and organic pollutants to produce combined pollution. Recently, the adsorption behavior of antibiotics on microplastics has received increasing attention. Exploring the sorption behavior of pollutants on microplastics is an important reference in understanding their ecological and environmental risk studies. In this paper, by reviewing the academic literature in recent years, we clarified the current status of research on the adsorption behavior of antibiotics on microplastics, discussed its potential hazards to ecological environment and human health, and summarized the influence of factors on the adsorption mechanisms. The results show that the adsorption behavior of antibiotics on microplastics is controlled by the physical and chemical properties of antibiotics, microplastics, and water environment. Antibiotics are adsorbed on microplastics through physical and chemical interactions, which include hydrophobic interaction, partitioning, electrostatic interaction, and other non-covalent interactions. Intensity of adsorption between them is mainly determined by their physicochemical properties. The basic physicochemical properties of the aqueous environment (e.g., pH, salinity, ionic strength, soluble organic matter content, and temperature) will affect the physicochemical properties of microplastics and antibiotics (e.g., particle size, state of dispersibility, and morphology), leading to differences in the type and strength of their interactions. This paper work is expected to provide a meaningful perspective for better understanding the potential impacts of antibiotic adsorption behavior of microplastics on aquatic ecology and human health. In the meantime, some indications for future related research are provided.

Factors affecting the leaching of micro and nanoplastics in the water distribution system

The role of the water distribution system (WDS) requires that it supply water of sufficient quality to households. Unregulated leaching of micro and nanoplastics from plastic pipes of the distribution system is therefore a cause for concern, particularly with the rise in research associating these plastic particles to adverse health impacts in living organisms. Within this study, four parameters (pH, free chlorine concentration, pipe material, and time) were varied in a pipe loop network to observe their effect on microplastic (MP) and nanoplastic (NP) leaching into the simulated distribution network. Results indicated an abundance of MPs/NPs in different shapes and sizes throughout the samples. Graphical trends illustrated that basic pH values contributed to a higher number of particles. Statistical analysis via analysis of variance (ANOVA) confirmed this observation and further showed interaction of chlorine dose and pH concentration (p-value = 0.000), and chlorine dose and pipe material (p-value = 0.038) was also significant to leaching. Numerically, polyethylene (PE) particles were the most abundant with a total of 15194 particles, followed by 12920 polypropylene random copolymer (PPR) particles and 12317 polyvinyl chloride (PVC) particles. It was also noticed that the number of particles decreased with time.© 2023 Elsevier Inc. All rights reserved.

First record of microplastic in the Brazilian sea hare Aplysia brasiliana Rang, 1828 (Mollusca: Aplysiidae)

The presence of plastic debris in the marine environment has reached massive levels in the past decades. In marine environments, microplastics can exist for hundreds of years and the presence of microplastics in this environment has been reported since 1970 and since then has been considered ubiquitous. Mollusks are being used as microplastic pollution indicators, especially in coastal areas and bivalves are more often used in microplastic-monitoring studies. On the other hand, gastropods are poorly used as indicators for microplastic pollution, even though they are the most diverse group of mollusks. The sea hares of the genus Aplysia are herbivorous gastropods, important model organisms commonly used in neuroscience studies, isolating the compounds in their defensive ink. Until today, there is no previous record of the presence of MPs in Aplysia gastropods. Therefore, this study aims to investigate the presence of microplastics in tissues of A. brasiliana found in southeastern Brazil. We collected seven individuals of A. brasiliana from a beach in southeastern Brazil, dissected them to isolate the digestive tract and the gills, and digested the tissues with a solution of 10 % NaOH. In the end, 1021 microplastic particles were found, 940 in the digestive tissue, and 81 in the gills. These results represent the first record of the presence of microplastics in the Brazilian sea hare A. brasiliana.

Bioaccumulation of polystyrene microplastics and changes in antioxidant and AChE pattern in a freshwater snail (Filopaludina bengalensis) from river Ganga

Microplastic pollution is a leading global problem affecting terrestrial and marine aquatic ecosystems. Due to the stagnant nature of microplastics, the toxic effect of microplastics is more pronounced to benthic organisms than the surface feeder. Hence, the present study effort was to study the microplastic bioaccumulation pattern and changes in the enzymatic and nonenzymatic antioxidant and AChE pattern of freshwater snail Filopaludina bengalensis, which were subjected to 0.5 ppm to 5 ppm levels of polystyrene microsphere (∼ 30 µm) for 27 days. The study showed that microplastics were easily accumulated in the test organism in a dose and time-dependent manner, amounting to 82 ± 6.02 particles /individuals at a 5 ppm dose on the 27th day. However, no mortality was observed at the test microplastic dosages. The enzymatic antioxidant profile (SOD and catalase) showed limited variability and remained stable with increased duration and microplastic dose. However, the nonenzymatic antioxidant profile showed distinct variability with the complete seizing of the DPPH activity on the 27th day at 5 ppm microplastic dose and a gradual decrease of ABTS and FRAP activity at all the dose ranges. Even the AChE activity decreased with higher exposure concentrations. The present study for the first time shows the direct impact of microplastics on a freshwater snail widely available in the Indian subcontinent, indicating the role of microplastic pollution will create havoc in the Ganga river eco-biosystem in the long run.

Polystyrene nanoplastics in the marine mussel Mytilus galloprovincialis

Concerns about plastic pollution and its toxicity towards animals and people are growing. Polystyrene (PS) is a plastic polymer highly produced in Europe for packaging purposes and building insulation amongst others. Whatever their source-illegal dumping, improper waste management, or a lack of treatment for the removal of plastic debris from wastewater treatment plants-PS products ultimately end up in the marine environment. Nanoplastics (<1000 nm) are the new focus for plastic pollution, gaining broad interest. Whether primary or secondary, their small size permits nanoparticles to cross cellular boundaries, consequently leading to adverse toxic effects. An in vitro assay of Mytilus galloprovincialis haemocytes exposed to 10 μg/L of polystyrene nanoplastics (PS-NPs; 50 nm) for 24 h was used to test cellular viability along with the luminescence inhibition (LC50) of Aliivibrio fischeri bacteria to evaluate acute toxicity. Cellular viability of mussel haemocytes decreased significantly after a 24 h exposure and PS-NPs LC50 range from 180 to 217, μg/L. In addition, a 28-day exposure of the marine bivalve M. galloprovincialis to PS-NPs (10 μg/L; 50 nm) was performed to evaluate the neurotoxic effects and the uptake of these plastic particles in three bivalve tissues (gills, digestive gland, and gonads). The ingestion of PS-NPs was time- and tissue-specific, suggesting that PS-NPs are ingested through the gills and then translocated through the mussel bloodstream, to the digestive gland and gonads where the highest amount of ingested PS-NPs was reported. Ingested PS-NPs may compromise the digestive glands' key metabolic function and impair mussels' gametogenic and reproductive success. Data on acetylcholinesterase inhibition and those previously obtained on a wide range of cellular biomarkers were elaborated through weighted criteria providing a synthetic assessment of cellular hazard from PS-NPs.

Modelling marine microplastics accumulation zones through freshwater discharge sources: Simulated release from the Onkaparinga River and Torrens River, South Australia

Plastic pollution is fast becoming one of the most prominent contamination issues facing the marine environment. Microplastics are a major subset of plastic waste now present in all global oceans, with their numbers standing only to increase. This study applies a coupled hydrodynamic model and Lagrangian particle-tracking model to predict and simulate microplastic transport in South Australian waters. Virtual particles representing microplastics were released daily for 365 days from two major freshwater input sources along the coastline of Adelaide, Australia. These particles entered the Gulf St Vincent and were tracked over two model years using LTRANS software. The model identified general gulf circulation as circular, clockwise, with net southward particle transport from particle release sites. A potential accumulation zone associated with a local eddy was identified. Concentrations of particles that passed through local marine parks were also calculated in response to the potential concerns they pose in vulnerable protected areas.

Plastic nanoparticles cause proteome stress and aggregation by compromising cellular protein homeostasis ex vivo and in vivo

Decomposition of plastic materials into minuscule particles and their long-term uptake pose increasing concerns on environmental sustainability and biosafety. Besides common cell viability and cytotoxicity evaluations, how plastic nanoparticles interfere with different stress response pathways and affect cellular fitness has been less explored. Here, we provided the first piece of evidence to demonstrate plastic nanoparticles potentially can deteriorate proteome stability, compromise cellular protein homeostasis, and consequently cause global proteome misfolding and aggregation. Polystyrene (PS) nanoparticles of different sizes and surface charges were exploited as model plastic materials. In cell lysate and human blood plasma, naked PS nanoparticles with hydrophobic surface deteriorated proteome thermodynamic stability and exaggerated its aggregation propensity. While no cell viability ablation was observed in cells treated with PS nanoparticles up to 200 μg·mL-1, global proteome aggregation and stress was detected by a selective proteome aggregation sensor. Further proteomics analysis revealed how protein homeostasis network was remodeled by positively charged PS nanoparticles via differential expression of key proteins to counteract proteome stress. In mice model, size-dependent liver accumulation of positively charged PS nanoparticles induced hepatocellular proteome aggregation and compromised protein homeostasis network capacity that were invisible to standard alanine transaminase and aspartate transaminase (ALT/AST) liver function as-say and histology. Meanwhile, long-term liver accumulation of plastic nanoparticles deteriorated liver metabolism and saturated liver detoxification capacity of overdosed acetaminophen. This work highlighted the impact of nanoplastics on cellular proteome integrity and cellular fitness that are invisible to current biochemical assays and clinical tests.

A framework for systematic microplastic ecological risk assessment at a national scale

Microplastic pollution is widespread in terrestrial and aquatic environments; however, a systematic assessment of the ecological risks of microplastics is lacking. This study collected research studies on microplastics in soil, aquatic and sediment environments, and screened 128 articles including 3459 sites to assess the ecological risks posed by microplastics in China following a literature quality assessment. We developed a systematic ecological risk assessment framework for microplastics in terms of spatial characterization, biotoxicity and anthropogenic impacts. The results of the pollution load index indicated that 74% and 47% of the soil and aquatic environments studied, respectively, faced a medium or higher level of pollution. Comparing predicted no effect concentrations (PNEC) and measured environmental concentrations (MECs), revealed that soil (97.70%) and aquatic (50.77%) environmental studies were at serious ecological risk from microplastics. The results of the pressure-state-response model showed that the microplastic pollution in Pearl River Delta was in a high-risk state. In addition, we found that ultraviolet radiation and rainfall exacerbate soil microplastic pollution, and higher river runoff may carry large amounts of microplastic from the source. The framework developed in this study will help assess the ecological risks of microplastics in the region to promote the mitigation of plastic pollution.

Bisphenol A decreases the developmental toxicity and histopathological alterations caused by polystyrene nanoplastics in developing marine medaka Oryzias melastigma

Nanoplastics (NPs) are emerging pollutants posing risks to marine biota and human health due to their small size and high bioavailability. However, there are still knowledge gaps regarding effects of co-existing pollutants on NPs toxicity to marine organisms at their respective environmentally relevant concentrations. Herein we investigated developmental toxicity and histopathological alterations caused by co-exposure of polystyrene nanoplastics (PS-NPs) and bisphenol A (BPA) to marine medaka, Oryzias melastigma. Embryos at 6 h post-fertilization were exposed to 50-nm PS-NPs (55 μg/L) or BPA (100 μg/L) or co-exposed to a combination of both. Results showed that PS-NPs exhibited decreased embryonic heart rate, larval body length, and embryonic survival as well as larval deformities such as hemorrhaging and craniofacial abnormality. When co-exposed, BPA mitigated all the adverse developmental effects caused by PS-NPs. PS-NPs also led to an increase in histopathological condition index of liver with early inflammatory responses, while co-exposure of BPA with PS-NPs did not. Our data suggest that the toxicity reduction of PS-NPs in the presence of BPA might result from the decreased bioaccumulation of PS-NPs caused by the interaction between BPA and PS-NPs. This study unveiled the impact of BPA on the toxicity of nanoplastics in marine fish during early developmental stages and highlight the need of more research on the long-term effects of complex mixtures in the marine environment by applying omics approaches to better understand the toxicity mechanism.

Microplastic pollution in riverine ecosystems: threats posed on macroinvertebrates

Microplastics (MPs) are pollutants of emerging concern that have been reported in terrestrial and aquatic ecosystems as well as in food items. The increasing production and use of plastic materials have led to a rise in MP pollution in aquatic ecosystems. This review aimed at providing an overview of the abundance and distribution of MPs in riverine ecosystems and the potential effects posed on macroinvertebrates. Microplastics in riverine ecosystems are reported in all regions, with less research in Africa, South America, and Oceania. The abundance and distribution of MPs in riverine ecosystems are mainly affected by population density, economic activities, seasons, and hydraulic regimes. Ingestion of MPs has also been reported in riverine macroinvertebrates and has been incorporated in caddisflies cases. Further, bivalves and chironomids have been reported as potential indicators of MPs in aquatic ecosystems due to their ability to ingest MPs relative to environmental concentration. Fiber and fragments are the most common types reported. Meanwhile, polyethylene, polypropylene, polystyrene, polyethylene terephthalate (polyester), polyamide, and polyvinyl chloride are the most common polymers. These MPs are from materials/polymers commonly used for packaging, shopping/carrier bags, fabrics/textiles, and construction. Ingestion of MPs by macroinvertebrates can physically harm and inhibit growth, reproduction, feeding, and moulting, thus threatening their survival. In addition, MP ingestion can trigger enzymatic changes and cause oxidative stress in the organisms. There is a need to regulate the production and use of plastic materials, as well as disposal of the wastes to reduce MP pollution in riverine ecosystems.

Mapping of heavy metal contamination associated to microplastics marine debris - A case study: Dubai, UAE

Microplastics (MPs) are ubiquitously detected in the environment. The adverse impact of microplastics on marine life is well documented. Previous research has shown that MPs can adsorb heavy metals, however, this fact has not been investigated along the coast of Dubai, UAE. Elemental composition of MPs debris was determined using X-ray fluorescence spectroscopic (XRF) analysis. The analyzed MPs were extracted from 80 sediment samples collected from the wrack lines of 16 Dubai, UAE beaches. A total of 480 MPs pieces extracted from the samples were analyzed in order to detect heavy metals. The polymer composition was previously confirmed by FTIR spectroscopy, showing that polyethylene (PE) and polypropylene (PP) were the most abundant MPs. 14 heavy metals were identified in the samples: Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Ce, Pr, Nd, Pd, and Co with different concentrations. Five of them (Cr, Ni, Cu, Zn, and Pb) are priority pollutants according to EPA. Their average concentrations in oxide form were Cr₂O₃ (2.96 %), NiO (0.32 %), CuO (0.45 %), ZnO (0.56 %), and PbO (1.49 %).

Uptake and Effects of Nanoplastics on the Dinoflagellate Gymnodinium corollarium

Plastic nanoparticles (NPs) are the final state of plastic degradation in the environment before they disintegrate into low-molecular-weight organic compounds. Unicellular organisms are highly sensitive to the toxic effects of nanoplastics, because they are often capable of phagotrophy but are unable to consume a foreign material such as synthetic plastic. We studied the effect of polystyrene, poly(vinyl chloride), poly(methyl acrylate), and poly(methyl methacrylate) NPs on the photosynthetic dinoflagellate Gymnodinium corollarium Sundström, Kremp et Daugbjerg. Fluorescent tagged particles were used to visualize plastic capture by dinoflagellate cells. We found that these dinoflagellates are capable of phagotrophic nutrition and thus should be regarded as mixotrophic species. This causes their susceptibility to the toxic effects of plastic NPs. Living cells ingest plastic NPs and accumulate in the cytoplasm as micrometer-level aggregates, probably in food vacuoles. The action of nanoplastics leads to a dose-dependent increase in the level of reactive oxygen species in dinoflagellate cells, indicating plastic degradation in the cells. The introduction of a methyl group into the main chain in the α-position in the case of poly(methyl methacrylate) causes a drastic reduction in toxicity. We expect that such NPs can be a tool for testing unicellular organisms in terms of heterotrophic feeding ability. We suggest a dual role of dinoflagellates in the ecological fate of plastic waste: the involvement of nanoplastics in the food chain and its biochemical destruction. Environ Toxicol Chem 2023;42:1124-1133. © 2023 SETAC.

Tissue accumulation of polystyrene microplastics causes oxidative stress, hepatopancreatic injury and metabolome alterations in Litopenaeus vannamei

Microplastics (MPs) pose one of the major environmental threats to marine organisms and ecosystems on a global scale. Although many marine crustaceans are highly susceptible to MPs pollution, the toxicological effects and mechanisms of MPs on crustaceans are poorly understood. The current study focused on the impacts of MPs accumulation in shrimp Litopenaeus vannamei at the behavioral, histological and biochemical levels. The results demonstrated the accumulation of polystyrene MPs in various organs of L. vannamei, with highest MPs abundance in the hepatopancreas. The MPs accumulated in shrimp caused growth inhibition, abnormal swimming behavior and reduced swimming performance of L. vannamei. Following MPs exposure, oxidative stress and lipid peroxidation were also observed, which were strongly linked to attenuated swimming activity of L. vannamei. The above MPs-induced disruption in balance of antioxidant system triggered the hepatopancreatic damage in L. vannamei, which was exacerbated with increasing MPs concentrations (from 0.02 to 1 mg L^-1). Furthermore, metabolomics revealed that MPs exposure resulted in alterations of metabolic profiles and disturbed glycolysis, lipolysis and amino acid metabolism pathways in hepatopancreas of L. vannamei. This work confirms and expands the knowledge on the sublethal impacts and toxic modes of action of MPs in L. vannamei.

Understanding the aggregation, consumption, distribution and accumulation of nanoparticles of polyvinyl chloride and polymethyl methacrylate in Ruditapes philippinarum

Plastic products have become an integral part of our life. A widespread usage, high stability, uncontrolled disposal and slow degradation of plastics in the environment led to the generation and accumulation of nanoparticles of polymers (NPs) in the marine environment. However, little is known about the aggregation, consumption and distribution of NPs from common polymers such as polyvinyl chloride (NP-PVC) and polymethyl methacrylate (NP-PMMA) inside marine animal physiologies. In the current study, two types of polymers (PVC and PMMA) × four exposure concentrations (1, 5, 15 and 25 mg/L) × four times (4, 8, 12 and 24 h) exposure studies were conducted to understand the consumption and distribution of luminescent NP-PVC (98.6 ± 17.6 nm) and NP-PMMA (111.9 ± 37.1 nm) in R. philippinarum. Under laboratory conditions, NP-PVC showed a higher aggregation rate than NP-PMMA in seawater within a period of 24 h. Aggregations of NPs increased with an increase in initial NP concentrations, leading to significant settling of nanoparticles within 24 h exposure. Such aggregation and settling of particles enhanced the consumption of NPs by benthic filter-feeding R. philippinarum at all exposure concentrations during 4 h exposure. More interestingly, NP-PVC and NP-PMMA were observed in large amounts in both liver and gills (22.6 % - 29.1 %) of the clams. Furthermore, NP-PVC was detected in most organs of R. philippinarum as compared to NP-PMMA. This study demonstrates that different polymers distribute and accumulate differently in the same biological model under laboratory exposure conditions based on their chemical nature.

Untangling the Interactions between Anionic Polystyrene Nanoparticles and Lipid Membranes Using Laurdan Fluorescence Spectroscopy and Molecular Simulations

Several classes of synthetic nanoparticles (NPs) induce rearrangements of cell membranes that can affect membrane function. This paper describes the investigation of the interactions between polystyrene nanoparticles and liposomes, which serve as model cell membranes, using a combination of laurdan fluorescence spectroscopy and coarse-grained molecular dynamics (MD) simulations. The relative intensities of the gel-like and fluid fluorescent peaks of laurdan, which is embedded in the liposome membranes, are quantified from the areas of deconvoluted lognormal laurdan fluorescence peaks. This provides significant advantages in understanding polymer-membrane interactions. Our study reveals that anionic polystyrene NPs, which are not cross-linked, induce significant membrane rearrangement compared to other cationic or anionic NPs. Coarse-grained MD simulations demonstrate that polymer chains from the anionic polystyrene NP penetrate the liposome membrane. The inner leaflet remains intact throughout this process, though both leaflets show a decrease in lipid packing that is indicative of significant local rearrangement of the liposome membrane. These results are attributed to the formation of a hybrid gel made up of a combination of polystyrene (PS) and lipids that forces water molecules away from laurdan. Our study concludes that a combination of negative surface charge to interact electrostatically with positive charges on the membrane, a hydrophobic core to provide a thermodynamic preference for membrane association, and the ability to extend non-cross linked polymer chains into the liposome membrane are necessary for NPs to cause a significant rearrangement in the liposomes.

Habitual feeding patterns impact polystyrene microplastic abundance and potential toxicity in edible benthic mollusks

That increasing microplastics (MPs, <5 mm) eventually end up in the sediment which may become a growing menace to diverse benthic lives is worthy of attention. In this experiment, three edible mollusks including one deposit-feeding gastropod (Bullacta exarate) and two filter-feeding bivalves (Cyclina sinensis and Mactra veneriformis) were exposed to polystyrene microplastic (PS-MP) for 7 days and depurated for 3 days. PS-MP numbers in the digestive system and non-digestive system, digestive enzymes, oxidative stress indexes, and a neurotoxicity index of three mollusks were determined at day 0, 3, 7, 8 and 10. After seven-day exposure, the PS-MP were found in all three mollusks' digestive and non-digestive systems. And PS-MP in M. veneriformis (9.57 ± 2.19 items/individual) was significantly higher than those in C. sinensis (3.00 ± 2.16 items/individual) and B. exarate (0.83 ± 1.07 items/individual) at day 7. Three-day depuration could remove most of the PS-MP in the mollusks, and higher PS-MP clearance rates were found in filter-feeding C. sinensis (77.78 %) and M. veneriformis (82.59 %) compared to surface deposit-feeding B. exarate (50.00 %). The digestive enzymes of B. exarate significantly reacted to PS-MP exposure, while oxidative responses were found in C. sinensis. After three-day depuration, the changes of digestive enzymes and the oxidative states were fixed, but neurotoxicity induced by PS-MP was not recoverable. Besides, it is noteworthy that changes of digestive enzymes and acetylcholinesterase are related to feeding patterns.

How plastic debris and associated chemicals impact the marine food web: A review

Contamination from plastic debris is omnipresent in marine environments, posing a substantial risk to marine organisms, food webs and the ecosystem. The overlap between the size range of marine plastic pollution with prey means that plastics are readily available for consumption by organisms at all trophic levels. Large plastic debris can directly result in the death of larger marine organisms, through entanglement, strangulation, choking and starvation through a false sense of satiation. Whereas smaller plastic debris, such as micro- and nano-plastics can have adverse impact to marine organisms due to their large surface area to volume ratio and their ability to translocate within an organism. Various physiological processes are reported to be impacted by these small contaminants, such as feeding behaviour, reproductive outputs, developmental anomalies, changes in gene expression, tissue inflammation and the inhibition of growth and development to both adults and their offspring. Micro- and nano-plastics are still relatively poorly understood and are considered a hidden threat. Plastic is a complex contaminant due to the diversity in sizes, shapes, polymer compositions, and chemical additives. These factors can each have unique and species-specific impacts. Consumption of plastics can occur directly, through ingestion and indirectly, through trophic transfer, entanglement of prey, adherence of plastics to external surfaces, and adherence of organisms to the external surfaces of plastics. This review investigated the intrusion of plastics into the marine food web and the subsequent consequences of plastic pollution to marine biota.The objective of this review was to identify the complexity of impacts to marine organisms through the food web from plastic contamination. Through a concise analysis of the available literature the review has shown that plastic pollution and their associated additives can adversely impact environmental and biological health.

The risks of marine micro/nano-plastics on seafood safety and human health

A considerable mass of plastics has been released into the marine environment annually through different human activities, including industrial, agriculture, medical, pharmaceutical and daily care products. These materials are decomposed into smaller particles such as microplastic (MP) and nanoplastic (NP). Hence, these particles can be transported and distributed in coastal and aquatic areas and are ingested by the majority of marine biotas, including seafood products, thus causing the contamination of the different parts of aquatic ecosystems. In fact, seafood involves a wide diversity of edible marine organisms, such as fish, crustaceans, molluscs, and echinoderms, which can ingest the micro/nanoplastics particles, and then transmit them to humans through dietary consumption. Consequently, these pollutants can cause several toxic and adverse impacts on human health and the marine ecosystem. Therefore, this chapter provides information on the potential risks of marine micro/nanoplastics on seafood safety and human health.

Toxicity of nanoplastics to aquatic organisms: Genotoxicity, cytotoxicity, individual level and beyond individual level

Due to the small size, high mobility and large surface area, nanoplastics (NPs) showed high potential risks to aquatic organisms. This paper reviews the toxicity of NPs to aquatic organism at various trophic levels including bacteria, plankton (algae), zooplankton, benthos, and nekton (fish). The effects at individual level caused by NPs were explained and proved by cytotoxicity and genotoxicity, and the toxicity of NPs beyond individual level was also illustrated. The toxicity of NPs is determined by the size, dosage, and surface property of NPs, as well as environmental factors, the presence of co-contaminants and the sensitivity of tested organisms. Furthermore, the joint effects of NPs with other commonly detected pollutants such as organic pollutants, metals, and nanoparticles etc. were summarized. In order to reflect the toxicity of NPs in the real natural environment, studies on toxicity assessment of NPs with the coexistence of various environmental factors and contaminants, particularly under the concentrations in natural environment are suggested.

Efficient removal of microplastics from aqueous solution by a novel magnetic biochar: performance, mechanism, and reusability

Microplastics' (MPs) pollution removal from water bodies has become an urgent task to ensure water quality safety and water ecological security on a global scale. In this work, coprecipitation was employed to investigate the adsorption of MPs by magnetic biochar (MRB) prepared from agricultural waste rice husks in an aquatic system. The results showed that MRB can adsorb up to 99.96% of MPs in water; acidic conditions were favorable for the effective MPs' adsorption reaction, and competing anions had a greater effect on adsorption. The adsorption mechanism results revealed that the adsorption of MPs by MRB was a spontaneous process, and electrostatic attraction, surface complexation, hydrogen bonding and π-π interactions were present in the adsorption process. Furthermore, after the adsorption of MPs, MRB can be recovered by thermal treatment (500 °C) and still exhibits up to 90% MPs adsorption (after four uses). This work reveals that MRB is an inexpensive, efficient, and reusable nanoscale adsorbent for MPs pollution removal in water, which may provide new ideas for microplastic pollution control in the aqueous environment.