Microplastic exposure and effects in aquatic organisms: A physiological perspective

Impacts of polyhydroxybutyrate (PHB) microplastic exposure on physiology and metabolic profiles of Litopenaeus vannamei

In light of increasing concerns about microplastic pollution, it is crucial to understand the biological impacts of biodegradable PHB microplastics on marine organisms. This study included a 96-h exposure experiment to assess acute toxicity at PHB concentrations of 0 mg/L, 100 mg/L, 500 mg/L and 1000 mg/L. Additionally, a 60-day feeding trial was conducted with PHB concentrations of 0, 0.5, 1.0 and 2.0 g/kg to evaluate the long-term effects on growth, physiological health and metabolic responses of Litopenaeus vannamei. Results from the exposure experiment indicated that PHB microplastics up to 100 mg/L were non-toxic to shrimp. However, the 60-day feeding trial revealed that higher concentrations led to slight reductions in survival rates and growth performance, indicating a concentration-dependent response. Analysis of antioxidant and immune enzymes showed minimal changes across most parameters. However, increases in malondialdehyde content and lysozyme activity at higher PHB levels suggested a stress response. Microbial analysis indicated higher species richness and greater community diversity in the PHB group compared to controls, as evidenced by Chao1, ACE, Shannon and Simpson indices. Linear discriminant analysis revealed that Enterobacteriales and related taxa were more prevalent in the PHB group, while Rhodobacteraceae and associated taxa dominated the control group. Pathway analysis highlighted enhanced signal transduction, cell mobility and metabolic resource reallocation in response to PHB-induced stress. Integrated transcriptomic and metabolomic analyses revealed significant regulatory changes, especially in lipid metabolism pathways. These findings suggest that while PHB microplastics trigger adaptive metabolic responses in shrimp, they do not cause acute toxicity. Significant variations in intestinal microbiome composition reflect potential shifts in gut health dynamics due to PHB ingestion. This study enhances our understanding of the ecological impacts of microplastics and underscores the necessity for further research into the environmental safety of biodegradable alternatives.

Quantification of additives in beached plastic debris from Aotearoa New Zealand

Plastics have become an essential part of modern society. Their properties can be easily manipulated by incorporating additives to impart desirable attributes, such as colour, flexibility, or stability. However, many additives are classified as hazardous substances. To better understand the risk of plastic pollution within marine ecosystems, the type and concentration of additives in plastic debris needs to be established. We report the quantification of thirty-one common plastic additives (including plasticisers, antioxidants, and UV stabilisers) in beached plastic debris collected across Aotearoa New Zealand. Additives were isolated from the plastic debris by solvent extraction and quantified using high-resolution liquid chromatography-mass spectrometry. Twenty-five of the target additives were detected across 200 items of debris, with plasticisers detected at the highest frequency (99 % detection frequency). Additives were detected in all samples, with a median of four additives per debris item. A significantly higher number of additives were detected per debris item for polyvinyl chloride (median = 7) than polyethylene or polypropylene (median = 4). The additives bis(2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and antioxidant 702 were detected at the highest concentrations (up to 196,930 μg/g). The sum concentration of additives per debris item (up to 320,325 μg/g) was significantly higher in polyvinyl chloride plastics (median 94,716 μg/g) compared to other plastic types, primarily due to the presence of phthalate plasticisers. Non-target analysis was consistent with the targeted analysis, indicating a higher number and concentration of additives in polyvinyl chloride debris items compared to all other polymer types. Feature identification indicated the presence of more additives than previously detected in the targeted analysis, including plasticisers (phthalate and non-phthalate), processing aids, and nucleating agents. This study highlights phthalates and polyvinyl chloride as key targets for consideration in ecotoxicology and risk assessments, and the development of policies to reduce the impacts of plastic pollution.

First Evidence of Microplastic Ingestion by Riverine Fish From the Freshwater of Northwest Peninsular Malaysia

In a baseline study, we investigated microplastic contamination in fish from the Pinang and Kerian Rivers in Northwest Peninsular Malaysia. In recognition of the growing concern over microplastic pollution in aquatic environments, we aimed to assess the abundance and characteristics of microplastics ingested by various fish species. Fish samples were collected from local fishermen, followed by a digestion process using 10% potassium hydroxide (KOH). Microplastics were isolated and analyzed through visual examination and attenuated total reflectance Fourier transform infrared spectroscopy. The results revealed a high prevalence of microplastics, with Johnius borneensis and Oreochromis sp. exhibiting the highest abundance, averaging 48.6 and 42.8 microplastics/g, respectively. The predominant shapes were fibers (55.6%) and fragments (25.9%), with colors primarily transparent (48.19%) and black (30.12%). Our results indicate significant contamination levels in freshwater fish, emphasizing the need for further research and effective mitigation strategies. These findings provide crucial baseline data on microplastics in Malaysian freshwater ecosystems. Environ Toxicol Chem 2024;43:2189-2198. © 2024 SETAC.

Effects of polyvinyl chloride and low-density polyethylene microplastics on oxidative stress and mitochondria function of earthworm (Eisenia fetida)

Plastics are widely used worldwide due to their convenience. However, microplastics (MPs) accumulation poses a serious threat to ecosystem health. Therefore, understanding the effects of MPs on living organisms within their native ecosystem is crucial. Previous studies have primarily focused on the impacts of MPs in aquatic environments, whereas the effects of MPs on terrestrial ecosystems have remained largely understudied. Therefore, our study assessed the impacts of MPs on soil ecosystems by characterizing their toxic effects on earthworms (Eisenia fetida). Here, we exposed earthworms to two representative plastics within soil environments: polyvinyl chloride (PVC) and low-density polyethylene (LDPE). Given the known link between MPs and oxidative stress, we next quantified oxidative stress markers and mitochondrial function to assess the effects of MPs on the redox metabolism of earthworms. Mitochondria are crucial metabolic organelles that generate reactive oxygen species via uncontrolled ATP production. Our findings demonstrated that MPs exert different effects depending on their type. Neither the PVC-exposed groups nor the LDPE-exposed groups exhibited changes in oxidative stress, as worked by the action of superoxide dismutase (SOD) and glutathione (GSH). While treatment of the two types of MP did not significantly affect the amount of reactive oxygen species/reactive nitrogen species (ROS/RNS) generated, PVC exhibited a more pronounced effect on antioxidant system compared to LDPE. However, mitochondrial function was markedly decreased in the group exposed to high LDPE concentrations, suggesting that the examined LDPE concentrations were too low to activate compensatory mechanisms. Collectively, our findings demonstrated that exposure of MPs not only influences the antioxidant defense mechanisms of earthworms but also alters their mitochondrial function depending on their types.

Critical review on unveiling the toxic and recalcitrant effects of microplastics in aquatic ecosystems and their degradation by microbes

Production of synthetic plastic obtained from fossil fuels are considered as a constantly growing problem and lack in the management of plastic waste has led to severe microplastic pollution in the aquatic ecosystem. Plastic particles less than 5mm are termed as microplastics (MPs), these are pervasive in water and soil, it can also withstand longer period of time with high durability. It can be broken down into smaller particles and can be adsorbed by various life-forms. Most marine organisms tend to consume plastic debris that can be accumulated easily into the vertebrates, invertebrates and planktonic entities. Often these plastic particles surpass the food chain, resulting in the damage of various organs and inhibiting the uptake of food due to the accumulation of microplastics. In this review, the physical and chemical properties of microplastics, as well as their effects on the environment and toxicity of their chemical constituents are discussed. In addition, the paper also sheds light on the potential of microorganisms such as bacteria, fungi, and algae which play a pivotal role in the process of microplastics degradation. The mechanism of microbial degradation, the factors that affect degradation, and the current advancements in genetic and metabolic engineering of microbes to promote degradation are also summarized. The paper also provides information on the bacterial, algal and fungal degradation mechanism including the possible enzymes involved in microplastic degradation. It also investigates the difficulties, limitations, and potential developments that may occur in the field of microbial microplastic degradation.

Microplastics and heavy metal contamination along a land-use gradient in a Himalayan foothill river: Prevalence and controlling factors

The co-occurrence of microplastics (MPs) and heavy metals in aquatic systems has raised significant concerns, yet their relationship in freshwater ecosystems remains poorly understood. This study aims to evaluate the prevalence of MPs and factors controlling their distribution in both water and sediment in the Markanda River, Northwest India. MPs were extracted from sediment and water samples using density separation and classified through fluorescence microscopy and Raman spectroscopy. Metal concentrations in river water samples were analyzed using ICP-MS, and their correlation with MP abundance was explored. The results indicated the widespread occurrence of MP pollution across the Markanda River basin, with particle concentrations ranging from 10 to 530 particles L-1 in surface water and 1330-4330 particles kg-1 dry weight (dw) in sediment samples. The variability in MP abundance at sampling sites along the Markanda River courses results from factors such as the proximity of industrial establishments and human habitation, while the influence of grain size on MP distribution appears to be limited. Pellets (88.5 %) and fragments (8.5 %) were the most abundant types of MPs, with polyethylene (45.45 %) and polystyrene (30.9 %) being the dominant forms in water samples. The ICP-MS analysis of heavy metals in water samples indicated elevated levels of As (1.67 to 32.31 ppb) in downstream areas of the river system, influenced by human activities. While metals exhibited correlation with each other, there was a weak association, except for As, with the levels of MPs in the Markanda River. The SEM-EDX analyses to characterize chemical elements absorbed onto the surface of MP showed distinct variations in upstream and downstream sites, with the presence of elements such as Mn, Ni, Cr, Zn, As, Se, and Cu found in downstream areas. We conclude that MPs contaminated with heavy metals potentially threaten the ecological security of freshwater aquatic systems and highlight the importance of management action to reduce plastic pollution worldwide.

Microplastic characterization in the stomachs of swordfish (Xiphias gladius) from the western Mediterranean Sea

In this study, we aimed to quantify the presence of microplastics (MPs) in the stomachs of large pelagic fish (swordfish, Xiphias gladius, Linnaeus, 1758) sampled in the western Mediterranean Sea, and assess temporal trends (2011-2012 vs. 2017-2019) in MP ingestion. MPs were extracted from stomachs and characterized by μ-Fourier transform infrared spectroscopy. Results highlighted the ingestion of MP in 39 out of 49 stomachs analysed. Ingested MPs consisted mostly of small (<1 mm) fibers (88.6 %, mean ± standard deviation = 2.5 ± 6.1 particles per stomach), with a greater frequency of occurrence (FO) in the second period (FO = 90 %, 3.3 ± 8.0 particles per stomach). The predominant colours were purple, black and blue, and polyethylene terephthalate was the most frequently detected polymer. These results are crucial for the development of management actions aimed at the conservation of swordfish in the Mediterranean Sea and the prevention of health risks to humans.

Effects of Microplastic Exposure against White Spot Syndrome Virus Infection in Pacific White Shrimp (Penaeus vannamei)

Plastic waste has emerged as a major environmental concern in recent years. As plastic waste discharged into the marine environment, it undergoes a breakdown process, eventually accumulating in aquatic organisms in the form of microplastics (MPs). To date, reduced food intake, nutritional absorption, and impaired immune system are known adverse effects of MPs-exposed aquatic organisms. This study aims to investigate whether MP exposure accelerated white spot syndrome virus (WSSV) infection in Pacific white shrimp (Penaeus vannamei) via laboratory tests. Briefly, experimental shrimp were divided into four groups; WSSV (group 1); MP (group 2); WSSV + MP (group 3); and Control (group 4). No mortality was observed in group 2, group 4, and even in group 1. However, group 3 showed a cumulative mortality of 50% during the experimental period. The PCR assay results showed no WSSV in the other three groups (groups 1, 2, and 4), but the dead and alive shrimp collected from group 3 were confirmed to be infected with the virus. Histopathological examination revealed normal structures in the hepatopancreas, gill, and muscle tissues of group 4, whereas numerous abnormally shaped nuclei were detected in the gill tissue of group 2. Moreover, group 1 showed minor WSSV-related lesions with few basophilic inclusion bodies in the gills, interestingly, group 3 exhibited severe lesions with numerous basophilic inclusion bodies in the gills. In conclusion, this study confirmed the correlation between the viral disease of shrimp and MPs, which can cause significant economic losses to the shrimp aquaculture industry.

Microplastics as a Threat to Aquatic Ecosystems and Human Health

The threat posed by microplastics has become one of the world's most serious problems. Recent reports indicate that the presence of microplastics has been documented not only in coastal areas and beaches, but also in water reservoirs, from which they enter the bodies of aquatic animals and humans. Microplastics can also bioaccumulate contaminants that lead to serious damage to aquatic ecosystems. The lack of comprehensive data makes it challenging to ascertain the potential consequences of acute and chronic exposure, particularly for future generations. It is crucial to acknowledge that there is still a substantial need for rapid and effective techniques to identify microplastic particles for precise evaluation. Additionally, implementing legal regulations, limiting plastic production, and developing biodegradation methods are promising solutions, the implementation of which could limit the spread of toxic microplastics.

Occurrence of specific pollutants in a mixture of sewage and rainwater from an urbanized area

Urban runoff appears to be a pathway for transferring new emerging pollutants from land-based sources to the aquatic environment. This paper aimed to identify and describe the groups of pollutants present in rainwater surface runoff as well as their mixture with wastewater in the combined sewer system from urbanized catchments and to determine the correlations between these pollutants. Four leading groups of new emerging pollutants have been identified that may be present in rainwater and municipal wastewater mixtures. The samples were tested for microplastics, phthalic acid esters, pesticides, and polycyclic aromatic hydrocarbons as well as basic parameters. The pilot site was Słupsk (northwestern Poland). We conducted nine sampling campaigns at three points. The results of the present study revealed that (i) polycyclic aromatic hydrocarbons were not present in the tested samples; (ii) the selected organochlorine pesticides were detected during one campaign in the dry season and therefore were not of critical importance; (iii) out of the 11 analyzed phthalic acid esters, five selected substances released from commonly used plastic products were present; and (iv) the number of microplastics contained in the tested samples ranged from 1,400 to 14,036 pcs/L and even occurred during pure rainfall.

Assessing genotoxic effects of plastic leachates in Drosophila melanogaster

Plastic polymers were largely added with chemical substances to be utilized in the items and product manufacturing. The leachability of these substances is a matter of concern given the wide amount of plastic waste, particularly in terrestrial environments, where soil represents a sink for these novel contaminants and a possible pathway of human health risk. In this study, we integrated genetic, molecular, and behavioral approaches to comparatively evaluate toxicological effects of plastic leachates, virgin and oxodegradable polypropylene (PP) and polyethylene (PE), in Drosophila melanogaster, a novel in vivo model organism for environmental monitoring studies and (eco)toxicological research. The results of this study revealed that while conventional toxicological endpoints such as developmental times and longevity remain largely unaffected, exposure to plastic leachates induces chromosomal abnormalities and transposable element (TE) activation in neural tissues. The combined effects of DNA damage and TE mobilization contribute to genome instability and increase the likelihood of LOH events, thus potentiating tumor growth and metastatic behavior ofRasV12 clones. Collectively, these findings indicate that plastic leachates exert genotoxic effects in Drosophila thus highlighting potential risks associated with leachate-related plastic pollution and their implications for ecosystems and human health.

Navigating the nexus: climate dynamics and microplastics pollution in coastal ecosystems

Microplastics (MPs) pollution is an emerging environmental health concern, impacting soil, plants, animals, and humans through their entry into the food chain via bioaccumulation. Human activities such as improper solid waste dumping are significant sources that ultimately transport MPs into the water bodies of the coastal areas. Moreover, there is a complex interplay between the coastal climate dynamics, environmental factors, the burgeoning issue of MPs pollution and the complex web of coastal pollution. We embark on a comprehensive journey, synthesizing the latest research across multiple disciplines to provide a holistic understanding of how these inter-connected factors shape and reshape the coastal ecosystems. The comprehensive review also explores the impact of the current climatic patterns on coastal regions, the intricate pathways through which MPs can infiltrate marine environments, and the cascading effects of coastal pollution on ecosystems and human societies in terms of health and socio-economic impacts in coastal regions. The novelty of this review concludes the changes in climate patterns have crucial effects on coastal regions, proceeding MPs as more prevalent, deteriorating coastal ecosystems, and hastening the transfer of MPs. The continuous rising sea levels, ocean acidification, and strong storms result in habitat loss, decline in biodiversity, and economic repercussion. Feedback mechanisms intensify pollution effects, underlying the urgent demand for environmental conservation contribution. In addition, the complex interaction between human, industry, and biodiversity demanding cutting edge strategies, innovative approaches such as remote sensing with artificial intelligence for monitoring, biobased remediation techniques, global cooperation in governance, policies to lessen the negative socioeconomic and environmental effects of coastal pollution.

Emerging pollutant in surface water bodies: a review on monitoring, analysis, mitigation measures and removal technologies of micro-plastics

Water bodies play a crucial role in supporting life, maintaining the environment, and preserving the ecology for the people of India. However, in recent decades, human activities have led to various alterations in aquatic environments, resulting in environmental degradation through pollution. The safety of utilizing surface water sources for drinking and other purposes has come under intense scrutiny due to rapid population growth and industrial expansion. Surface water pollution due to micro-plastics (MPs) (plastics < 5 mm in size) is one of the emerging pollutants in metropolitan cities of developing countries because of its utmost resilience and synthetic nature. Recent studies on the surface water bodies (river, pond, Lake etc.) portrait the correlation between the MPs level with different parameters of pollution such as specific conductivity, total phosphate, and biological oxygen demand. Fibers represent the predominant form of MPs discovered in surface water bodies, exhibiting fluctuations across seasons. Consequently, present study prioritizes understanding the adaptation, prevalence, attributes, fluctuations, and spatial dispersion of MPs in both sediment and surface water environments. Furthermore, the study aims to identify existing gaps in the current understanding and underscore opportunities for future investigation. From the present study, it has been reported that, the concentration of MPs in the range of 0.2-45.2 items/L at the Xisha Islands in the south China sea, whereas in India it was found in the range of 96 items/L in water samples and 259 items/kg in sediment samples. This would certainly assist the urban planners in achieving sustainable development goals to mitigate the increasing amount of emergent pollutant load.

To spread or not to spread? Assessing the suitability of sewage sludge and other biogenic wastes for agriculture reuse

Sewage sludge (biosolids) management represents a worldwide issue. Due to its valuable properties, approximately one half of the EU production is recovered in agriculture. Nevertheless, growing attention is given to potential negative effects deriving from the presence of harmful pollutants. It is recognized that a (even very detailed) chemical characterization is not able to predict ecotoxicity of a mixture. However, this can be directly measured by bioassays. Actually, the choice of the most suitable tests is still under debate. This paper presents a multilevel characterization protocol of sewage sludge and other organic residues, based on bioassays and chemical-physical-microbiological analyses. The detailed description of the experimental procedure includes all the involved steps: the criteria for selecting the organic matrices to be tested and compared; the sample pre-treatment required before the analyses execution; the chemical, physical and microbiological characterisation; the bioassays, grouped in three classes (baseline toxicity; specific mode of action; reactive mode of action); data processing. The novelty of this paper lies in the integrated use of advanced tools, and is based on three pillars:•the direct ecosafety assessment of the matrices to be reused.•the adoption of innovative bioassays and analytical procedures.•the original criteria for data normalization and processing.

Toxicity effects and mechanism of micro/nanoplastics and loaded conventional pollutants on zooplankton: An overview

Micro/nanoplastics in aquatic environments is a noteworthy environmental problem. Zooplankton, an important biological group in aquatic ecosystems, readily absorb micro/nanoplastics and produce a range of toxic endpoints due to their small size. This review summarises relevant studies on the effects of micro/nanoplastics on zooplankton, including combined effects with conventional pollutants. Frequently reported adverse effects include acute/chronic lethal effects, oxidative stress, gene expression, energetic homeostasis, and growth and reproduction. Obstruction by plastic entanglement and blockage is the physical mechanism. Genotoxicity and cytotoxicity are molecular mechanisms. Properties of micro/nanoplastics, octanol/water partition coefficients of conventional pollutants, species and intestinal environments are important factors influencing single and combined toxicity. Selecting a wider range of micro/nanoplastics, focusing on the aging process and conducting field studies, adopting diversified zooplankton models, and further advancing the study of mechanisms are the outstanding prospects for deeper understanding of impacts of micro/nanoplastics on aquatic ecosystem.

Microplastics in a small river: Occurrence and influencing factors along the river Oker, Northern Germany

Much attention regarding the environmental pollution by plastics had focused on the Oceans. More recently, contamination of freshwater ecosystems has been addressed but information from smaller rivers in moderately populated catchments is still comparatively scarce. This study explored the microplastic (MP) occurrence in the small regional river Oker, Northern Germany (catchment area 1822 km2, population of ca. 500,000, discharge approx. 12 m3 s-1). MPs (fibers and fragments in the size range 0.3-5 mm, identification by microscopy) were found in all 10 in-stream samples collected along the course of the river, ranging between 28 and 134 particles m-3 with an overall average of 63 particles m-3. This MP concentration found in the small river Oker is similar to, or higher than, that reported for larger rivers in similar environments in Central Europe. On average, higher MP concentration was found at urban (71 particles m-3) compared to rural sampling sites (51 particles m-3). Within the Oker catchment, in-stream MP concentration showed no or low correlation to the catchment-scale factors of catchment size and population. Additional samples taken from three locations directly influenced by discharges of potential MP point sources confirmed wastewater treatment plants of different capacities and an urban rainwater sewer as sources. Our results support findings that MP concentrations in small rivers are crucially influenced by local sources, superimposing linear relationships to factors of catchment size and -population. They show that even small rivers draining moderately populated catchments may exhibit comparatively high concentrations of MPs, and thereby represent underestimated pathways of MP in the environment.

Unveiling the Tiny Invaders: A deep dive into microplastics in shrimp - Occurrence, detection and unraveling the ripple effects

Aquaculture is a rapidly expanding food sector worldwide; it is the farming of fish, shellfish, and other marine organisms. Microplastics (MPs) are small pieces of plastic with a diameter of less than 5 mm that end up in the marine environment. MPs are fragments of large plastics that take years to degrade but can frustrate into small pieces, and some commercially available MPs are used in the production of toothpaste, cosmetics, and aircraft. MPs are emerging contaminants; they are ingested by marine species. These MPs have effects on marine species such as growth retardation and particle translocation to other parts of the body. Recently, MPs accumulation has been observed in shrimps, as well as in a wide range of other scientific reports. So, in this study, we review the presence, accumulation, and causes of MPs in shrimp. These plastics can trophic transfer to other organisms, changes in plastic count, effects on the marine environment, and impacts of MPs on human health were also discussed. It also improves our understanding of the importance of efficient plastic waste management in the ocean, as well as the impact of MPs on marine biota and human health.

Effects of primary leachates of conventional and alternative plastics in Cyprinodon variegatus fish larvae: Endocrine disruption and toxicological responses

The inclusion of hazardous substances in the formulation of plastics raises significant concerns, particularly, if those substances are released as primary leachates during plastic degradation and/or fragmentation. In this sense, the production of degradable plastics holding deleterious additives can increase the release of harmful substances into the environment. Additionally, the effects of primary leachates of "eco-friendly" materials remain unexplored. To address this, we performed exposures to primary leachates of alternative polymers, and commercial bags to verify possible responses associated with endocrine disruption and/or activation of the detoxification pathway in larvae of the marine fish model Cyprinodon variegatus. The chemical characterization evidenced a great number of additives in the formulation of the materials analyzed in this study. Those include, except for the PLA sample, relevant levels of the hazardous phthalates DEHP and DiBP. Regarding the effects on marine fish larvae, exposure to leachates from alternative polymers (10 g/L) PHB and PHBV produced remarkable mortality (100%). While the exposure to bag leachates of all tested materials (1 and 10 g/L) produced alterations in biomarkers for steroidogenic and detoxification pathways. To a lesser extent (10 g/L), three materials produced significant alterations in estrogenic biomarkers (Home-compostable bag 1, LDPE and Recycled PE bags). Although the alterations in gene expression were not directly correlated to the amount of DEHP or DiBP, we can conclude that primary leachates of "eco-friendly" bags are harmful to marine vertebrates.

Monitoring of microplastic pollution in sediments along the Çoruh River Basin, NE Türkiye

Microplastic (MP) pollution has become a research issue on the world agenda. Monitoring studies are essential for MP content in aquatic environments since it is the final accumulation point. The present study focused on MP characterizations in sediment samples taken from 20 different stations on the Çoruh River, the major river in the North East of Türkiye. Accordingly, the potential anthropogenic pollution from settlements near the four stations (2, 15, 18, and 20) exceeding 400 MP kg-1 was estimated. On the other hand, stations (1, 3, 9, 11, and 13) far from settlements with quite low MP abundance were also observed. The polymer structures of the detected MPs are generally PE and PET, and their shapes are mostly fiber. This situation raises suspicion that MPs originate from primary use waste such as water bottles and packaging materials. In general, the fiber MPs are smaller than the fragments because of the river's high water flow rate and the low strength of the fiber MPs. In light of these results, the current monitoring data in the region will create awareness and guidance regarding MP pollution in settlements.

A Systematic Review on Microplastic Contamination in Fishes of Asia: Polymeric Risk Assessment and Future Prospectives

Microplastics (MPs) have attracted global concern because of their harmful effects on marine biota; their toxic properties can negatively impact aquatic ecosystems. Fish is an essential source of protein for humans, playing a crucial role in daily food intake. Until recently, MPs were addressed primarily as environmental pollutants, but they are now increasingly recognized as contaminants in the food supply. The present review has comprehended the current knowledge of MP contamination in freshwater and marine fishes of Asia, including 112 peer-reviewed sources from 2016 to 2023. The review recorded 422 Asian fishes (345 marine and 77 freshwater) to be contaminated with MPs. Clarias gariepinus and Selaroides leptolepi have shown maximum MP contamination in the freshwater and marine environments of Asia, respectively. Omnivorous and carnivorous fishes exhibited higher susceptibility to ingesting MPs. Benthopelagic, demersal, and reef-associated habitats were identified as more prone to MP accumulation. In both freshwater and marine environments, China has the highest number of contaminated species among all the countries. Pollution indices indicated high MP contamination in both freshwater and marine environments. A prevalence of fibers was recorded in all fishes. Black- and blue-colored MPs of <500 µm-1 mm size were found dominantly. Polyethylene terephthalate and polyethylene were recorded as the prevalent plastic polymers in freshwater and marine fish, respectively. Overall, the review served as a comprehensive understanding of MP concentrations and variations between species, between feeding habits, and between geographic locations, which can be pivotal for addressing pressing environmental challenges, protecting human health, and fostering global sustainability efforts in the face of escalating plastic pollution. Environ Toxicol Chem 2024;43:671-685. © 2024 SETAC.

Potentially Toxic Elements' Accumulation in Relation to Sediment Physicochemical Attributes and Microplastic Content in Zayandeh-Rood River, Iran

Microplastics (MPs) are an emerging pollutant whose ability to adsorb potentially toxic elements (PTEs) poses a serious threat to aquatic ecosystems, including rivers. In highly developed basins, the abundance of MPs in river sediment is expected to be high, elevating the sedimentary accumulation of PTEs. This hypothesis was tested in the Zayandeh-Rood River, Central Iran, with 21 sediment sampling stations distributed along the entire river stretch. Results of sediment analysis showed significant variations in the abundance and size of MPs, with concentrations ranked as Ba (270.71 mg/kg) > Li (21.29 mg/kg) > Cs (2.50 mg/kg) > Be (1.44 mg/kg) > Sn (1.17 mg/kg) > Mo (1.06 mg/kg) > Ag (0.76 mg/kg), along with sediment physicochemical attributes such as EC, TOC, pH and grain size. MPs were identified in all sediment samples with a mean of 588 items/kg dry weight. Except for Ag, all other PTEs were classified as uncontaminated but exhibited increased enrichment downstream. According to the results of the generalized additive model (maximum R-sq of 0.766), the sedimentary concentration of the majority of PTEs is nonlinearly and positively associated with smaller and more abundant MPs. This study acknowledges that MPs might influence sediment porosity, permeability and structure, thereby directly affecting the settling dynamics of other particles, especially PTEs.

Effects of different concentrations and particle sizes of nanoplastics on gut microbiology, metabolism, and immunity in Chiromantes dehaani

This study investigated the effects of nanoplastics (NPs) of varying particle sizes (75, 500, and 1000 nm) and concentrations (2.5 and 10 mg/L) on the gut health of Chiromantes dehaani. The experimental groups included a control (Cg0), and varying combinations of particle size and concentration. Our results showed that 75 nm NPs were more likely to enhance pathogenic bacterial growth than other sized NPs. Compared with CK, Low NPs concentrations (2.5 mg/L) raised total cholesterol (T-CHO) levels in the gut, while high concentrations significantly decreased both triglyceride (TG) and T-CHO levels (p < 0.05). The enzymatic activities of intestinal lipase and amylase were inhibited by NPs exposure, with greater inhibition at higher NPs concentrations. The 500 nm NPs exhibited a notably higher inhibitory effect than the 75 and 1000 nm NPs (P < 0.05). In terms of apoptosis, NPs exposure led to reduced mRNA expression of Bcl2 and increased expression of Caspase-3, Caspase-8, and Caspase-9, indicating an induction of apoptosis. This effect was more pronounced at higher NPs concentrations, with 75 nm NPs more likely to induce apoptosis in intestinal cells than 500 nm and 1000 nm NPs. Moreover, NPs triggered intestinal inflammatory responses, evidenced by the increased mRNA expression of TNF-β, TNF-α, IL1β, IL6, and IL8, and the decreased expression of IL10. High NPs concentrations were more likely to induce intestinal inflammation, with 500 nm NPs imparting the strongest effect. In summary, the study demonstrated that NPs, and particularly those at higher concentrations, disrupted the gut environment of C. dehaani by altering the microflora, reducing microbial diversity, inhibiting digestion and metabolism, inducing apoptosis, and triggering inflammation. Among the sizes of NPs tested, 500 nm NPs had the most significant adverse impact on digestion, metabolism, and inflammation, while 75 nm NPs most strongly induced apoptosis in C. dehaani's intestinal cells.

First register of microplastic contamination in oysters (Crassostrea gasar) farmed in Amazonian estuaries

The present study investigated the contamination of oysters farmed in Amazonian estuaries by microplastics (MPs). A total of 120 adult oysters (Crassostrea gasar) were collected from four sites along the Mangrove Coast of Pará/Brazil: S1, S2, S3 and S4, with 30 oyster for each. Overall, 58.33 % of the oyster samples contained microplastics, with mean concentrations of 0.23 MPs/g and 1.9 MPs/ind. The concentration of microplastics varied among the four sites, where S1 and S3 had the highest values while S4 had the lowest. PA fibers were the majority of particles (91 %), followed by PS fragments (9 %). The hepatopancreas and the gonad concentrated more microplastics than the rest of the body. As an important species for aquaculture in Amazon, we recommend additional regulation to reduce human exposure to microplastics, such as the installation of depuration facilities and constant monitoring of the contamination of oysters from farms in the region.

Toxicological impacts of microplastics on virulence, reproduction and physiological process of entomopathogenic nematodes

Microplastics have emerged as significant and concerning pollutants within soil ecosystems. Among the soil biota, entomopathogenic nematodes (EPNs) are lethal parasites of arthropods, and are considered among the most effective biological agents against pests. Infective juveniles (IJs) of EPNs, as they navigate the soil matrix scavenging for arthropod hosts to infect, they could potentially encounter microplastics. Howver, the impact of microplastics on EPNs has not been fully elucidated yet. We addressed this gap by subjecting Steinernema feltiae EPNs to polystyrene microplastics (PS-MPs) with various sizes, concentrations, and exposure durations. After confirming PS-MP ingestion by S. feltiae using fluorescent dyes, we found that the PS-MPs reduced the survival, reproduction, and pathogenicity of the tested EPNs, with effects intensifying for smaller PS-MPs (0.1-1 μm) at higher concentrations (105 μg/L). Furthermore, exposure to PS-MPs triggered oxidative stress in S. feltiae, leading to increased reactive oxygen species levels, compromised mitochondrial membrane potential, and increased antioxidative enzyme activity. Furthermore, transcriptome analyses revealed PS-MP-induced suppression of mitochondrial function and oxidative phosphorylation pathways. In conclusion, we show that ingestion of PS-MPs by EPNs can compromise their fitness, due to multple toxicity effects. Our results bear far-reaching consequences, as the presence of microplastics in soil ecosystems could undermine the ecological role of EPNs in regulating pest populations.

Occurrence of phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) in key species of anthozoans in Mediterranean Sea

The Mediterranean Sea's biodiversity is declining due to climate change and human activities, with plastics and emerging contaminants (ECs) posing significant threats. This study assessed phthalic acid esters (PAEs) and active pharmaceutical ingredients (APIs) occurrence in four anthozoan species (Cladocora caespitosa, Eunicella cavolini, Madracis pharensis, Parazoanthus axinellae) using solid phase microextraction (SPME) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). All specimens were contaminated with at least one contaminant, reaching maximum values of 57.3 ng/g for the ∑PAEs and 64.2 ng/g (wet weight) for ∑APIs, with dibutyl phthalate and Ketoprofen being the most abundant. P. axinellae was the most contaminated species, indicating higher susceptibility to bioaccumulation, while the other three species showed two-fold lower concentrations. Moreover, the potential adverse effects of these contaminants on anthozoans have been discussed. Investigating the impact of PAEs and APIs on these species is crucial, given their key role in the Mediterranean benthic communities.

Sediment-associated microplastics in Chilika lake, India: Highlighting their prevalence, polymer types, possible sources, and ecological risks

The primary objective of this research was to assess microplastics (MPs) in the sediments of Chilika lake. MPs were extracted from 22 sediment samples using the density separation method combined with vacuum pump filtration. A stereo-zoom microscope and Raman spectroscopy were employed to identify the sediment-associated MPs. The total MPs collected from all 22 sites was 440 ± 3.53 particles kg-1 wet sediments, with sizes ranging between 50 and 500 μm. In terms of morphology, fibers and fragments emerged as the dominant MP types, with counts of 210 ± 1.66 and 175 ± 1.76 particles kg-1 wet sediments, respectively. Raman spectroscopy verified the presence of various MP polymers in the sediments, predominantly HDPE (37 %), followed by PS (20 %), PET (18 %), PA (11 %), PP (7 %), and PC (7 %). A notable color variation was observed in MPs; black being the most prevalent (38.8 %), succeeded by blue (19.5 %), green (11.8 %), white (11.5 %), red (10.6 %), and transparent (7.5 %). ANOVA results indicated significant (p > 0.05) variations in MP abundance across the 22 sampling locations. However, principal component analysis (PCA) and multiple regression analysis indicated that water quality parameters did not significantly influence MP abundance, yet it was found that MP retention was higher in fine-grained sediments like clay and silt. The leading sources of MPs in Chilika lake were found to be aquafarming, trailed by river and sewage discharges, fishing activities, antifouling coatings and tourism. Additionally, the pollution load index (PLI) was employed to gauge the ecological risks, categorizing the lake under risk category 1, which implies a minimal level of MPs pollution. This research aims to serve as an early warning system for MPs pollution in productive brackish water habitats globally, including Chilika lake, guiding policymakers towards appropriate management strategies and preventive measures.

What do we know about plastic pollution in Brazilian aquatic ecosystems?

Due to the increasing use and inadequate disposal of plastic by humans, aquatic environments have become receptacles for pollutants such as plastic. This study aimed to perform an analysis of plastic particles pollution in Brazilian aquatic ecosystems with special attention to inland aquatic environments and fish in order to identify information gaps in this field. Manuscripts published in the last 21 years and indexed in the Web of Science database were consulted. A total of 185 met the proposed inclusion criteria, such as having empirical data, being conducted in Brazil, and dealing with plastic pollution. In general, the number of studies increases over the years, and this increasing number of publications is accompanied by declared financial support; the Southeast and Northeast regions are the regions that publish the most on the topic, with São Paulo, Rio de Janeiro, and Pernambuco being the main states; the main focus of the studies is the detection of plastic particles mainly in biota (51%) and sediment (34%), and the most frequent ecosystem is the marine (89%); regarding the taxa, the majority is about plastic detection in fish (75%). Only 18% of the papers studying fishes consider their bio-ecological data, and only 17% of the manuscripts carried out the chemical characterization of the particles. However, 99% of the papers considered the shape of the plastic particle. We emphasize the need for more research and grants for studies with Brazilian inland aquatic ecosystems on the effects of plastic particle pollution on freshwater fish. Regional and national research funding agencies are very important to encourage an increase in the number of grants and specific calls for studies on plastic pollution and its impact on freshwater biota, considering the different macro-regions in Brazil, especially in the northern region.

Potential Effects of Orally Ingesting Polyethylene Terephthalate Microplastics on the Mouse Heart

Polyethylene terephthalate microplastics (PET MPs) are widespread in natural environment, and can enter organisms and accumulate in the body, but its toxicity has not been well studied. Therefore, in order to investigate the toxic effects of PET microplastics on mammals, this study investigated the toxic effects of PET MPs on ICR mice and H9C2 cells by different treatment groups. The results indicated the cardiac tissue of mice in the PET-H (50 µg/mL) group showed significant capillary congestion, myocardial fiber breakage, and even significant fibrosis compared to the PET-C (control) group (P < 0.01). Results of the TUNEL assay demonstrated significant apoptosis in myocardial tissue in the PET-H and PET-M (5 µg/mL) groups (P < 0.01). Meanwhile, Western blotting showed increased expression of the apoptosis-related protein Bax and decreased expression of PARP, caspase-3, and Bcl-2 proteins in both myocardial tissues and H9C2 cells. In addition, flow cytometry confirmed that PET MPs decreased the mitochondrial membrane potential and apoptosis in H9C2 cells; however, this trend was reversed by N-acetylcysteamine application. Moreover, PET MP treatment induced the accumulation of reactive oxygen species (ROS) in H9C2 cells, while the MDA level in the myocardial tissue was elevated, and the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were decreased (P < 0.01), indicating a change in the redox environment. In conclusion, PET MPs promoted cardiomyocyte apoptosis by inducing oxidative stress and activating mitochondria-mediated apoptotic processes, ultimately leading to myocardial fibrosis. This study provides ideas for the prevention of PET MP toxicity and promotes thinking about enhancing plastic pollution control.

Effect of polystyrene nanoplastics exposure on gene expression and pathogenesis of zoonotic pathogen, Edwardsiella piscicida

A surge in the number of anthropogenic pollutants has been caused by increasing industrial activities. Nanoplastics are spotlighted as a new aquatic pollutant that are a threat to microbes and larger organisms. Our previous study showed that the subinhibitory concentrations of aquatic pollutants such as phenol and formalin act as signaling molecules and modulate global gene expression and metabolism. In this study, we aimed to investigate the impact of a new type of anthropogenic contaminant, polystyrene (PS) nanoplastics, on the expression of key virulence factors in zoonotic pathogen Edwardsiella piscicida and the assessment of potential changes in the susceptibility of zebrafish as a model host. The TEM data indicated a noticeable change in the cell membrane indicating that PS particles were possibly entering the bacterial cells. Transcriptome analyses performed to identify the differentially expressed genes upon PS exposure revealed that the genes involved in major virulence factor type VI secretion system (T6SS) were down-regulated. However, the expression of T6SS-related genes was recovered from the PS adapted E. piscicida when nanoplastics are free. This demonstrated the hypervirulence of pathogen in infection assays with both cell lines and in vivo zebrafish model. Therefore, this study provides experimental evidence elucidating the direct regulatory impact of nanoplastics influx into aquatic ecosystems on fish pathogenic bacteria, notably influencing the expression of virulence factors.

Similarity of Microplastic Characteristics between Amphibian Larvae and Their Aquatic Environment

Microplastics, pervasive environmental pollutants, are found across various ecosystems, including small inland water bodies. They are reported in different environmental media, yet little is known about the mutual relationships of microplastics' properties across components of small inland water bodies. Here, having extracted and analyzed these particles from water, sediment, and amphibian larvae from 23 sites, we test within-site similarities regarding shape (morphological type), color, and chemical composition (polymer type). We also provide a brief characterization of the microplastics extracted from water and sediment regarding these parameters. We observed a statistically significant similarity of microplastics' shapes and colors between those extracted from water and amphibian larvae. Such a similarity, though less pronounced, was also found between amphibian larvae and sediment. However, the chemical composition (polymer type) of the microplastics from water, sediment, and amphibian larvae did not exhibit any similarities beyond what would be expected by chance. The observed congruence in the colors and shapes of microplastics between amphibian larvae and their corresponding aquatic habitats underscores the profound interconnectedness among the constituents of freshwater ecosystems.

Various additive release from microplastics and their toxicity in aquatic environments

Additives may be present in amounts higher than 50% within plastic objects. Additives in plastics can be gradually released from microplastics (MPs) into the aquatic environment during their aging and fragmentation because most of them do not chemically react with the polymers. Some are known to be hazardous substances, which can cause toxicity effects on organisms and pose ecological risks. In this paper, the application of functional additives in MPs and their leaching in the environment are first summarized followed by their release mechanisms including photooxidation, chemical oxidation, biochemical degradation, and physical abrasion. Important factors affecting the additive release from MPs are also reviewed. Generally, smaller particle size, light irradiation, high temperature, dissolved organic matter (DOM) existence and alkaline conditions can promote the release of chemicals from MPs. In addition, the release of additives is also influenced by the polymer's structure, electrolyte types, as well as salinity. These additives may transfer into the organisms after ingestion and disrupt various biological processes, leading to developmental malformations and toxicity in offspring. Nonetheless, challenges on the toxicity of chemicals in MPs remain hindering the risk assessment on human health from MPs in the environment. Future research is suggested to strengthen research on the leaching experiment in the actual environment, develop more techniques and analysis methods to identify leaching products, and evaluate the toxicity effects of additives from MPs based on more model organisms. The work gives a comprehensive overview of current process for MP additive release in natural waters, summarizes their toxicity effects on organisms, and provides recommendations for future research.

Mitigating microplastic pollution: A critical review on the effects, remediation, and utilization strategies of microplastics

Microplastics are found ubiquitous in the natural environment and are an increasing source of worry for global health. Rapid industrialization and inappropriate plastic waste management in our daily lives have resulted in an increase in the amount of microplastics in the ecosystem. Microplastics that are <150 μm in size could be easily ingested by living beings and cause considerable toxicity. Microplastics can aggregate in living organisms and cause acute, chronic, carcinogenic, developmental, and genotoxic damage. As a result, a sustainable approach to reducing, reusing, and recycling plastic waste is required to manage microplastic pollution in the environment. However, there is still a significant lack of effective methods for managing these pollutants. As a result, the purpose of this review is to convey information on microplastic toxicity and management practices that may aid in the reduction of microplastic pollution. This review further insights on how plastic trash could be converted as value-added products, reducing the load of accumulating plastic wastes in the environment, and leading to a beneficial endeavor for humanity.

Bioaccumulation of polystyrene nanoplastics and BDE-209 induced oxidative stress, photosynthesis and growth impairments in floating fern Salvinia natans

Aquatic ecosystems are facing increasing exposure to pollutants, posing potential threats to the stability and wellness of aquatic species. This study focused on evaluating the impacts of single and combined exposure to 80 nm polystyrene nanoplastics (PS-NPs, 0.1, 1, 10, 20 mg/L) and decabromodiphenyl ether (BDE-209, 300 ng/L) for 14 days on the bioaccumulation, growth, photosynthesis and oxidative stress in the free-floating fern Salvinia natans. PS-NPs primarily accumulated in the epidermis and trichomes of S. natans. Meanwhile, the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were significantly increased, while those for peroxidase (POD), catalase (CAT), total antioxidant capacity (T-AOC), and relative growth rate (RGR) decreased. Furthermore, the chlorophyll contents in submerged leaves were decreased, while those in floating leaves were increased at PS-NPs concentrations of 0.1 and 1 mg/L. However, the chlorophyll contents in both submerged and floating leaves displayed a decreasing trend with increasing concentrations of PS-NPs. Under the co-exposure of PS-NPs and BDE-209, the contents of MDA were significantly elevated, whereas CAT, POD, SOD, T-AOC and RGR were significantly decreased (p < 0.05). Our results revealed that, compared to single exposure, more pronounced ecotoxic effects are observed in S. natans under co-exposure to PS-NPs and BDE-209. These findings offer valuable perspectives into the possible environmental risks of BDE-209 and PS-NPs in freshwater ecosystems, contributing to the development of effective management strategies for protecting aquatic organisms and ecosystems. This research highlights the urgent need to understand the toxic effects of emerging contaminants on different aquatic organisms, emphasizing the importance of protecting and preserving aquatic ecosystems.

Toxic effects of polystyrene microbeads and benzo[α]pyrene on bioaccumulation, antioxidant response, and cell damage in goldfish Carassius auratus

Microplastics (MP) are harmful, causing stress in aquatic species and acting as carriers of hydrophobicity. In aquatic environments, benzo[α]pyrene (BaP) is an endocrine-disrupting chemical that accumulates in the body and causes toxic reactions in living organisms. We investigated the effects of single and combined microbead (MB) and BaP environments on goldfish antioxidant response and apoptosis. For 120 h, goldfish were exposed to single (MB10, MB100, and BaP5) and combined (MB10+BaP5 and MB100+BaP5) environments of 10 and 100 beads/L of 0.2 µm polystyrene MB and 5 µg/L BaP. We measured MB and BaP bioaccumulation as well as plasma parameters including ALT, AST, and glucose. The level of oxidative stress was determined by evaluating lipid peroxidation (LPO) and total antioxidant capacity (TAC) in plasma, as well as antioxidant-related genes for superoxide dismutase and catalase (SOD and CAT) and caspase-3 (Casp3) mRNA expression in liver tissue. The TUNEL assay was used to examine SOD in situ hybridization and apoptosis in goldfish livers. Except for the control group, plasma LPO levels increased at the end of the exposure period in all experimental groups. TAC increased up to 24 h of exposure and then maintained a similar level until the trial ended. SOD, CAT, and Casp3 mRNA expression increased substantially up to 120 h as the exposure concentration and time increased. The TUNEL assay revealed more signals and apoptotic signals in the combined exposure environments as a consequence of SOD in situ hybridization than in single exposure environments. These results suggest that combined exposure to toxic substances causes oxidative stress in organisms, which leads to apoptosis.

Assessment of machine learning-based methods predictive suitability for migration pollutants from microplastics degradation

The aim of the work was to assess the usefulness of machine learning in predicting the migration of pollutants from microplastics. The search for methods to reduce unnecessary laboratory analyzes is a necessary action both to protect the environment and from an economic perspective. Multiple regression, artificial neural networks, support vector method and random forest regression were used in the study to predict leaching of plasticizers and other contaminants from microplastics. The development of the methods were based on the results of laboratory tests obtained by the GC-MS method. The results obtained confirm the potential of artificial neural networks and the support vector method for effective modelling and prediction of chemical compounds leached from microplastics. Correlation results were obtained for the analyzed parameters between the data obtained in the model and laboratory data in the range of 0.96-0.98 and 0.93-0.99 for artificial neural networks and the support vector method, respectively. Multiple regression showed the lowest performance in all cases in predicting plastic phthalic acid esters (coefficient of determination (R2) in the range of 0.03-0.24). ENVIRONMENTAL IMPLICATION: The results presented in this paper will provide new insight into the influence of different parameters and factors on the leaching of plastic additives. This information is necessary to assess the harmfulness of these materials. The collected data is unique on a global scale. For the first time, machine learning were used to predict the leaching rate of plasticizers from different polymers under different environmental conditions. The use of machine learning allows to reduce unnecessary laboratory tests and reduce costs and protect the environment. Currently, there are no research results in this field in the scientific literature.

Leaching and transformation of chemical additives from weathered plastic deployed in the marine environment

Plastic pollution causes detrimental environmental impacts, which are increasingly attributed to chemical additives. However, the behaviour of plastic additives in the marine environment is poorly understood. We used a marine deployment experiment to examine the impact of weathering on the extractables profile, analysed by liquid chromatography-mass spectrometry, of four plastics at two locations over nine months in Aotearoa/New Zealand. The concentration of additives in polyethylene and oxo-degradable polyethylene were strongly influenced by artificial weathering, with deployment location and time less influential. By comparison, polyamide 6 and polyethylene terephthalate were comparatively inert with minimal change in response to artificial weathering or deployment time. Non-target analysis revealed extensive differentiation between non-aged and aged polyethylene after deployment, concordant with the targeted analysis. These observations highlight the need to consider the impact of leaching and weathering on plastic composition when quantifying the potential impact and risk of plastic pollution within receiving environments.

Effects of polyethylene terephthalate microplastics on cell growth, intracellular products and oxidative stress of Scenedesmus sp

Polyethylene terephthalate (PET) has been widely utilized in the synthesis of textile materials and packaging of foods and beverages. In recent years, it has been commonly detected in the form of microplastics (MPs) in wastewater. However, the effects of PET MPs on microalgal intracellular products and their interrelationships have been poorly investigated. In this study, the microalgae Scenedesmus sp. Strain H-1 was exposed to PET MPs to explore their effects on the growth, intracellular products (such as lipids, carbohydrates, and proteins), and antioxidative defense systems of Scenedesmus sp. The results demonstrated that PET MPs significantly reduced Scenedesmus sp. cell growth, with a maximum inhibition rate of 38.25% in the 500 mg L-1 treatment group. PET MPs had negative effects on glucose and nitrate utilization rates and reduced intracellular carbohydrates, intracellular proteins, and photosynthetic pigments. Surprisingly, PET MPs reduced acetyl-CoA carboxylase activity but induced lipid accumulation in microalgae. In addition, PET MPs significantly decreased the essential linoleic acid concentration and increased the palmitic acid content, resulting in reduced biodiesel quality. PET MPs induced the production of reactive oxygen species and malondialdehyde as well as the activities of superoxide dismutase and catalase. The results of the PCA indicated that the response mechanism of Scenedesmus sp. to PET MPs exposure was synergistic. This study provides fundamental data on the impact of MPs on the intracellular products of microalgae.

Characteristics and potential human health risks of microplastics identified in typical clams from South Yellow Sea Mudflat

The ingestion of clams (Meretrix) with microplastics (MP) contamination could pose potential risk to human health. The characteristics and potential risks of MP identified in wild-clam and farm-clam from South Yellow Sea Mudflat were studied comprehensively in this paper. The results indicated that MP were identified in both wild-clam (3.4-21.3 items/individual, 2.11-10.65 items/g) and farm-clam (1.3-20.8 items/individual, 0.62-8.67 items/g) among 21 sampling sites along South Yellow Sea Mudflat. The MP abundance of clams from marine estuarine or coast ports were significantly higher than those from purely marine coast mudflat, implying that environmental habitats played an important role on MP characteristics. MP abundance were significantly and positively related to shell length, shell height, shell width and soft tissue wet weight by Pearson test, suggesting the bigger the shell, there existed more MP abundance. Among MP in wild-clams and farm-clams, fragment, fiber were most abundant MP shapes, most MP's sizes were lower than 0.25 mm, the predominant colors were black, red, blue and transparent, chlorinated polyethylene (CPE) was the major polymer. Additionally, estimated dietary intake (EDI) of MP for adults via consumption of wild-clam and farm-clam were 1123.33 ± 399.97 and 795.07 ± 326.72 items/kg/year, respectively, suggesting EDI values of wild-clams were higher than those of farm-clams, and MP intake via wild-clam consumption were more than that via farm-clam consumption. The polymer risk indexes (PRI) of MP in total tissue and digestive system for wild-clam were 1297.8 ± 92.15 (hazard level: IV ~ V), 1038 ± 69.55 (IV ~ V), respectively, while PRI of MP in total tissue and digestive system for farm-clam were 979.92 ± 75.45 (III ~ IV), 735 ± 47.78 (III ~ IV), respectively, implying that PRI and hazard level of MP from wild-clam were higher than those from farm-clam, and the potential risks would decrease greatly when digestive systems of clams are removed during ingestion.

Freshwater Lacustrine Zooplankton and Microplastic: An Issue to Be Still Explored

Lakes are essentially interlinked to humans as they provide water for drinking, agriculture, industrial and domestic purposes. The upsurge of plastic usage, its persistence, and potential detrimental effects on organisms cause impacts on the trophic food web of freshwater ecosystems; this issue, however, still needs to be explored. Zooplankton worldwide is commonly studied as an indicator of environmental risk in aquatic ecosystems for several pollutants. The aim of the review is to link the existing knowledge of microplastic pollution in zooplankton to assess the potential risks linked to these organisms which are at the first level of the lacustrine trophic web. A database search was conducted through the main databases to gather the relevant literature over the course of time. The sensitivity of zooplankton organisms is evident from laboratory studies, whereas several knowledge gaps exist in the understanding of mechanisms causing toxicity. This review also highlights insufficient data on field studies hampering the understanding of the pollution extent in lakes, as well as unclear trends on ecosystem-level cascading effects of microplastics (MPs) and mechanisms of toxicity (especially in combination with other pollutants). Therefore, this review provides insight into understanding the overlooked issues of microplastic in lake ecosystems to gain an accurate ecological risk assessment.

Occurrence of microplastics in Antarctic fishes: Abundance, size, shape, and polymer composition

Presence of microplastics (MPs) in Antarctic ecosystems has attracted global attention, due to the potential threat to the Antarctic marine organisms. However, data on the occurrence of MPs in Antarctic fishes remains very limited. This study investigated the abundance and characteristics of MPs in four species of Antarctic fish (n = 114). The highest mean abundance of MPs was detected in Trematomus eulepidotus (1.7 ± 0.61 items/individual), followed by that in Chionodraco rastrospinosus (1.4 ± 0.26 items/individual), Notolepis coatsi (1.1 ± 0.57 items/individual), and Electrona carlsbergi (0.72 ± 0.19 items/individual). MPs in Notolepis coatsi (mean 747 μm) had the highest mean size, followed by that in Trematomus eulepidotus (653 μm), Chionodraco rastrospinosus (629 μm), and Electrona carlsbergi (473 μm). This is possibly attributed to the feeding habits and egestion behaviors of different Antarctic fishes. Fiber was consistently the predominant shape of MPs in Trematomus eulepidotus, Chionodraco rastrospinosus, and Electrona carlsbergi, accounting for 82 %, 76 %, and 60 % of total items of MPs, respectively. Polypropylene, polyamide, and polyethylene were the predominant polymer composition of MPs in Antarctic fishes, collectively contributed 63-86 % of total items of MPs. This may be because these types of MPs have been widely used in global household materials. To our knowledge, this is the most comprehensive study examining the occurrence of MPs in Antarctic fishes. This study provides fundamental data for evaluating the risks of MP exposure for Antarctic fishes.

Microplastics in the River Ganga and its fishes: Study of a Himalayan River

The River Ganga has been explored for microplastics (MPs) majorly in the lower or middle course, while the upper course from where the river starts its journey remains untouched. This study investigates the occurrence and distribution of MPs in the river environment (water and sediment) and common fishes inhabiting the upper stretch of River Ganga in the Uttarakhand state of India. A volume-reduce method by using sieve filtration was used to take water and sediment samples from the study area while fish samples were collected using net method. The samples underwent alkali digestion, microscopic examination, and chemical analysis using Fourier Transformed Infrared Spectroscopy (FTIR). An average of 118.5 ± 49.65 particles per 1000 L and 131.5 ± 53.60 particles/kg dry weight were found in water and sediment respectively. While in the fishes, Tor tor, Schizothorax richardsonii, Labeo dero and Gara gotyla gotyla MPs were 53.13 ± 63.77, 36.33 ± 22.34, 15.42 ± 9.33 and 12.63 ± 5.93 particles/individual respectively. A positive correlation was observed between the number of MPs in fish and their body length, weight, and gut weight, while no correlation was found between feeding habit and MP accumulation. The majority of MPs detected were fibers ranging from 100 μm to 1 mm in size. Polymer types varied among water, sediment, and fish samples, with polyethylene (PE) predominant in water, polypropylene (PP) dominant in sediment, and polyethylene terephthalate (PET) and polystyrene (PS) most abundant in fish samples.

The potential of Lecane rotifers in microplastics removal

Dealing with hard-to-degrade plastics pollution of terrestrial and aquatic environments is one of the most urgent problems of the modern world. The smallest fraction (<5 mm) called micro-plastics (MP) has been found everywhere from ice in Greenland, streams, rivers, soil and even in the human placenta. The goal of our research was to assess the ability of rotifers Lecane inermis to remove micro-plastics suspended in the water column. In the experiments we investigated specific interactions between MP, biofilm and rotifers specialized in feeding on biofilm. We hypothesized that MP adhere to the biofilm and after ingestion by rotifers could be extracted from the water in the form of compact conglomerates excreted with fecal pellets. In these experiments, we demonstrated that: (i) the rotifers preferentially ingest microplastics embedded in biofilm, (ii) the presence of microplastics does not affect growth and fecundity of rotifers, and (iii) that MP aggregation is significantly improved by the presence of biofilm, additionally enhanced in the presence of rotifers. Our findings will help to understand the role of micro-grazers, such as L. inermis feeding on biofilm, in the fate of MP in nature. In the longer term, our results could help to develop biotechnological tools for MP removal from the aquatic environment.

Exposure protocol for ecotoxicity testing of microplastics and nanoplastics

Despite the increasing concern about the harmful effects of micro- and nanoplastics (MNPs), there are no harmonized guidelines or protocols yet available for MNP ecotoxicity testing. Current ecotoxicity studies often use commercial spherical particles as models for MNPs, but in nature, MNPs occur in variable shapes, sizes and chemical compositions. Moreover, protocols developed for chemicals that dissolve or form stable dispersions are currently used for assessing the ecotoxicity of MNPs. Plastic particles, however, do not dissolve and also show dynamic behavior in the exposure medium, depending on, for example, MNP physicochemical properties and the medium's conditions such as pH and ionic strength. Here we describe an exposure protocol that considers the particle-specific properties of MNPs and their dynamic behavior in exposure systems. Procedure 1 describes the top-down production of more realistic MNPs as representative of MNPs in nature and particle characterization (e.g., using thermal extraction desorption-gas chromatography/mass spectrometry). Then, we describe exposure system development for short- and long-term toxicity tests for soil (Procedure 2) and aquatic (Procedure 3) organisms. Procedures 2 and 3 explain how to modify existing ecotoxicity guidelines for chemicals to target testing MNPs in selected exposure systems. We show some examples that were used to develop the protocol to test, for example, MNP toxicity in marine rotifers, freshwater mussels, daphnids and earthworms. The present protocol takes between 24 h and 2 months, depending on the test of interest and can be applied by students, academics, environmental risk assessors and industries.

Microparticles in marine mussels at regional and localized scales across the Salish Sea, Washington

Microparticles (MP; particles <5 mm) are ubiquitous in marine environments. Understanding MP concentrations at different spatial scales in the Salish Sea, Washington, USA, can provide insight into how ecologically and economically important species may be affected. We collected mussels across the Salish Sea at regional and localized scales, chemically processed tissue to assess MP contamination, and used visual and chemical analyses for particle identification. Throughout the Salish Sea, mussel MP concentrations averaged 0.75 ± 0.09 MP g-1 wet tissue. At a regional scale, we identified slight differences in concentrations and morphotypes of MP while at a localized scale these metrics were not significant and did not differ from controls. In a subset of particles, 20 % were identified as synthetic materials, which include polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and nylon. Differences in MP sources, heterogeneous transport of MP, and distinct shellfish feeding mechanisms may contribute to plastic contamination patterns in the Salish Sea.

Microplastics and their environmental effects

Microplastics (MPs) are acknowledged as emerging contaminants that pose a substantial threat to the environment. The adverse impacts of MP pollution extend across marine, freshwater, and terrestrial ecosystems, covering regions from the Tropics to the Poles. Although our comprehension of MP behavior has progressed in recent years, it is still difficult to predict exposure hotspots or exposure scenarios. Despite a noteworthy increase in data concerning MP occurrence in different environmental compartments and species, there is a noticeable scarcity of experimental data on MP uptake, accumulation, and effects. This Virtual Special Issue (VSI) received a total of 19 contributions from 11 countries, with a significant majority originating from Italy, India, Spain, and China. These contributions were categorized into three main themes: the occurrence and effects of MPs on aquatic and terrestrial organisms, the presence of chemical additives in plastics, and review articles summarizing previously published research on MPs.

Impact of accelerated weathering on the leaching kinetics of stabiliser additives from microplastics

The release of additives from microplastics is known to harm organisms. In the environment, microplastics are exposed to weathering processes which are suspected to influence additive leaching kinetics, the extent and mechanism of which remain poorly understood. We examined the impact of weathering on stabiliser additive leaching kinetics using environmentally relevant accelerated weathering and leaching procedures. Nine binary polymer-additive formulations were specifically prepared, weathered, analysed, and evaluated for their leaching characteristics. Cumulative additive release (Ce) varied widely between formulations, ranging from 0.009 to 1162 µg/g. Values of Ce generally increased by polymer type in the order polyethylene terephthalate < polyamide 6 < polyethylene. The change in leaching kinetics after accelerated weathering was incongruous across the nine formulations, with a significant change in Ce only observed for three out of nine formulations. Physicochemical characterisation of the microplastics demonstrated that additive blooming was the primary mechanism influencing the leaching response to weathering. These findings highlight the dependency of additive fate on the polymer type, additive chemistry, and the extent of weathering exposure. This has significant implications for risk assessment and mitigation, where the general assumption that polymer weathering increases additive leaching may be too simplistic.

Interaction between microplastic biofilm formation and antibiotics: Effect of microplastic biofilm and its driving mechanisms on antibiotic resistance gene

As two pollutants with similar transport pathways, microplastics (MPs) and antibiotics (ATs) inevitably co-exist in water environments, and their interaction has become a topic of intense research interest for scholars over the past few years. This paper comprehensively and systematically reviews the current interaction between MPs and ATs, in particular, the role played by biofilm developed MPs (microplastic biofilm). A summary of the formation process of microplastic biofilm and its unique microbial community structure is presented in the paper. The formation of microplastic biofilm can enhance the adsorption mechanisms of ATs on primary MPs. Moreover, microplastic biofilm system is a diverse and vast reservoir of genetic material, and this paper reviews the mechanisms by which microplastics with biofilm drive the production of antibiotic resistance genes (ARGs) and the processes that selectively enrich for more ARGs. Meanwhile, the enrichment of ARGs may lead to the development of microbial resistance and the gradual loss of the antimicrobial effect of ATs. The transfer pathways of ARGs affected by microplastic biofilm are outlined, and ARGs dependent transfer of antibiotic resistance bacteria (ARB) is mainly through horizontal gene transfer (HGT). Furthermore, the ecological implications of the interaction between microplastic biofilm and ATs and perspectives for future research are reviewed. This review contributes to a new insight into the aquatic ecological environmental risks and the fate of contaminants (MPs, ATs), and is of great significance for controlling the combined pollution of these two pollutants.

A critical review on the removal of toxic pollutants from contaminated water using magnetic hybrids

The persistence of organic/inorganic pollutants in the water has become a serious environmental issue. Among the different pollutants, dyes and heavy metal pollution in waterways are viewed as a global ecological problem that can have an impact on humans, plants, and animals. The necessity to develop a sustainable and environmentally acceptable approach to remove these toxic contaminants from the ecosystem has been raised. In the past two decades, rapid industrialization and anthropogenic activities in developed countries have aggravated environmental pollution. Industrial effluents that are discharged directly into the natural environment taint the water, which has a consequence for the water resources. Magnetic nanohybrids are broadly investigated materials used in the adsorption and photocatalytic degradation of poisonous pollutants present across water effluents. In the present review, the toxic health effects of heavy metals and dyes from the water environment have been discussed. This paper reviews the role of magnetic nanohybrids in the removal of pollutants from the water environment, providing an adequate point of view on their new advances regarding their qualities, connection methodologies, execution, and their scale-up difficulties.

Microplastic ingestion by invasive Prussian carp (Carassius gibelio) used in fishmeal production in Türkiye

MP contamination in the gastrointestinal tract (GIT) of Prussian carp (Carassius gibelio) used in fishmeal production was examined. The samples were collected from Balık Lake, Karaboğaz Lake, and Liman Lake located in Kızılırmak Delta, Türkiye. The overall average abundance was 3.20±0.18 MP per fish and 0.036±0.002 MP per g. No significant correlation was determined between the MP abundance in the fish, fish length, and fish weight. The polymers were composed of 56.91% PET, 25.20% PP, 9.76% PE, and 8.13% PA. The determined shapes were fiber (78.0%), fragment (13.46%), and film (8.54%). The size ranged between 112 and 4775 μm with an average of 1341.41±66.07 μm. Depending on the occurrence frequency and abundance, it can be concluded that Carassius gibelio can be considered a MP vector in fishmeal. The results provide an essential baseline for future MP studies on the potential effects of MPs on aquatic organisms, fate, and impact on the fishmeal production process, aquaculture practices, and human health.