Impacts of polystyrene microplastics on the behavior and metabolism in a marine demersal teleost, black rockfish (Sebastes schlegelii)

Micro/nanoplastics impair the feeding of goldfish by disrupting the complicated peripheral and central regulation of appetite

The ubiquitous presence of plastic particles in water bodies poses a potential threat to aquatic species. Although numerous adverse effects of microplastics (MPs) and nanoplastics (NPs) have been documented, their effects on fish feeding, one of the most important behaviors of animals, are far from being fully understood. In this study, the effects of MPs and NPs (at environmentally realistic levels) on fish food consumption and feeding behavior were assessed using goldfish (Carassius auratus) and polystyrene (PS) particles as representatives. In addition, to reveal the potential mechanisms, the effects of MPs and NPs on peripheral and central regulation of appetite were evaluated by examining appetite-regulation related intestinal, serous, and hypothalamic parameters. The results obtained indicated that the 28-day MP- and NP-exposure significantly impaired goldfish feeding by disrupting peripheral and central appetite regulation. Based on differences observed in their effects on the abovementioned behavioral, histological, and physiological parameters, MPs and NPs may interfere with appetite regulation in a size-dependent manner. Blocking the gastrointestinal tract and causing histopathological and functional damage to inner organs may be the main routes through which MPs and NPs disrupt appetite regulation. Our findings suggested that plastic particles exposure may have far-reaching effects on fish species through impaired feeding, which warrants further attention.

Revealing the hidden threats: Genotoxic effects of microplastics on freshwater fish

New evidence regarding the risks that microplastics (MP) ingestion pose to human and wildlife health are being revealed with progress made in ecotoxicological research. However, comprehensive and realistic approaches that evaluate multiple physiological responses simultaneously are still scarce despite their relevance to understand whole-organism effects. To address this information gap, we performed an experiment to assess the effects of MP on freshwater fish physiology from the molecular to the organismal level. Using a model species of global commercial importance (Cyprinus carpio) and MP type (recycling industry fragments), size (range between 125-1000 µm), and two concentrations of environmental relevance (0.75 and 8.25 µg/L). Experimental design included 5 blocks containing 3 treatment levels each one: control, low, and high MP concentration, with 6 fish each aquarium (5 blocks x 3 treatments x 6 fish per aquarium = 90 fish). Our results suggest that, under the experimental conditions applied, MP exposure did not cause adverse effects at the morphological (variation in size of gut), metabolic (variation of standard metabolic rate), or ecological (growth performance) levels. Nonetheless, we observed an increased frequency of micronucleated cells with increasing MP concentration (df = 42, t-value = 3.68, p-value < 0.001), showing the potential genotoxicity of MP, which can clearly harm fish health in long-term. Thus, despite being a highly resistant species, exposure to MP may generate negative effects in juvenile C. carpio at cellular or subcellular levels. Our findings highlight that the manifestation of MP effects may vary over time, emphasizing the need for future studies to consider longer exposure durations in experimental designs.

Negligible additive effect of environmental concentrations of fragmented polyethylene terephthalate microplastics on the growth and reproductive performance of Java medaka exposed to 17β-estradiol and bisphenol A

To investigate whether environmental concentrations of fragmented polyethylene terephthalate (PET) microplastics (MPs) have additional or combined effects on endocrine-disrupting activity, Java medaka (Oryzias javanicus) were exposed to 17β-estradiol (E2; 5, 10, 50, and 100 ng L-1), bisphenol A (BPA; 5, 10, 50, and 100 µg L-1), and E2 and BPA combined with PET MPs (1 and 100 particles L-1) for 200 days. The growth parameters, such as body length and weight, were significantly decreased by the highest concentrations of E2 and BPA. A significant reduction in egg production was observed in female fish exposed to BPA, with an additive toxic effect of PET MPs. A female-biased sex ratio was observed in fish exposed to both chemicals. Exposure to E2 significantly increased the hepatosomatic index (HSI) in both sexes, while no significant effect was observed in the gonadosomatic index (GSI). Exposure to BPA significantly increased the HSI in female fish and decreased the GSI in both sexes of fish. An additive effect of PET MPs was observed on the GSI value of female exposed to BPA. Significant elevations in vitellogenin (VTG) levels were observed in both sexes due to exposure to E2 and BPA. Additive effects of PET MPs were observed on VTG levels in males exposed to E2 and BPA. Taken together, even long-term treatment with PET MPs induced only a negligible additive effect on the endocrine-disrupting activity in Java medaka at environmentally relevant concentrations.

Convergence zones of coastal waters as hotspots for floating microplastic accumulation

This study examines microplastic (MP, 1-5 mm) densities in convergence zones in a coastal sea, the Seto Inland Sea, comparing them to those of non-convergence zones and other areas. Notably, Seto convergence zones exhibit MP densities 40 to 300 times higher than non-convergence zones, with an extraordinary density of 3.7 ± 6.3 pieces m-3, similar to densities found in Tokyo Bay as known a MP hotspot. The predominant polymer found was expanded polystyrene, varying seasonally and peaking in summer. Juvenile fish associated with driftweed in these convergence zones face a risk of long-term MP exposure, potentially up to four months. This large number of MPs found in coastal convergence zones is similar to accumulation zones formed in the gyres of open oceans, with strong implications for detrimental effects on coastal marine life. However, these MPs are autochthonous, and may be manageable through local marine plastic waste management.

Effects of polystyrene microspheres on the swimming behavior and metabolism of grass carp (Ctenopharyngodon idella)

Microplastics (MPs) are a heterogeneous class of pollutants fouling aquatic environments and they are hazardous to aquatic organisms. This study investigated the size-dependent effects of polystyrene microspheres (PSMPs) on the swimming ability, metabolism, and oxidative stress of juvenile grass carp (Ctenopharyngodon idella). Test fish were exposed to four sizes of PSMPs (0.07, 0.5, 5, and 20-μm), and swimming ability was tested after different exposure times (2, 7, and 15 days). To measure the effect on swimming ability, critical swimming speed (Ucrit) was determined, and to assess metabolic effects, oxygen consumption (MO2), routine metabolic rate (RMR), maximum oxygen consumption (MMR), and excess post-exercise oxygen consumption (EPOC) were determined. To assess the effects on oxidative stress, the activities of two antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) were determined in the liver and gills of test fish. After exposure to 20 μm PSMPs, there was a significant drop in Ucrit compared to the control group (P<0.05), with decreases of 22 % on Day 2 and Day 7, and 21 % on Day 15. The RMR and MMR increased significantly (P<0.05), the RMR by 23.9 % on Day 2 and the MMR by 17.2 % on Day 2 and on Day 15, 44.7 % and 20.0 % respectively. The EPOC decreased with exposure time, by 31 % (0.07-μm), 45 %-(0.5-μm), 49 % (5-μm), and 57 % (20-μm) after 15 days. Exposure to the larger PSMPs increased CAT and SOD activity more than the smaller PSMPs and the increases began with SOD activity in the gills. The larger PSMPs were consistently more harmful to juvenile grass carp than the smaller PSMPs. Our results clearly show that PSMPs have detrimental effects on juvenile grass carp and provide additional scientific evidence that environmental monitoring and regulation of microplastic pollution is necessary.

Nanoplastic pollution changes the intestinal microbiome but not the morphology or behavior of a freshwater turtle

Humans produce 350 million metric tons of plastic waste per year, leading to microplastic pollution and widespread environmental contamination, particularly in aquatic environments. This subsequently impacts aquatic organisms in myriad ways, yet the vast majority of research is conducted in marine, rather than freshwater systems. In this study, we exposed eggs and hatchlings of the Chinese soft-shelled turtle (Pelodiscus sinensis) to 80-nm polystyrene nanoplastics (PS-NPs) and monitored the impacts on development, behavior and the gut microbiome. We demonstrate that 80-nm PS-NPs can penetrate the eggshell and move into developing embryos. This led to metabolic impairments, as evidenced by bradycardia (a decreased heart rate), which persisted until hatching. We found no evidence that nanoplastic exposure affected hatchling morphology, growth rates, or levels of boldness and exploration, yet we discuss some potential caveats here. Exposure to nanoplastics reduced the diversity and homogeneity of gut microbiota in P. sinensis, with the level of disruption correlating to the length of environmental exposure (during incubation only or post-hatching also). Thirteen core genera (with an initial abundance >1 %) shifted after nanoplastic treatment: pathogenic bacteria increased, beneficial probiotic bacteria decreased, and there was an increase in the proportion of negative correlations between bacterial genera. These changes could have profound impacts on the viability of turtles throughout their lives. Our study highlights the toxicity of environmental NPs to the embryonic development and survival of freshwater turtles. We provide insights about population trends of P. sinensis in the wild, and future directions for research.

Investigating the metabolic and oxidative stress induced by biofouled microplastics exposure in Seriola lalandi (yellowtail kingfish)

Microorganisms quickly colonise microplastics entering the ocean, forming a biofilm that, if ingested, is consumed with the microplastics. Past research often neglects to expose fish to biofouled microplastics, opting only for clean microplastics despite the low likelihood that fish will encounter clean microplastics. Here, we investigate the physiological impacts of biofouled polyethylene microplastic (300-335 μm) exposure in juvenile fish. Intermittent flow respirometry, antioxidant enzyme activity, and lipid peroxidation were investigated after fish were exposed to clean, biofouled, or no microplastic beads. Fish exposed to biofouled microplastics had a wider aerobic scope than those exposed to clean microplastics while antioxidant enzyme and lipid peroxidation levels were higher in clean microplastics. Clean microplastic exposure indicated higher fitness costs, potentially due to a nutritional advantage of the biofilm or varying bioavailability. These findings highlight the importance of replicating natural factors in exposure experiments when predicting the impacts of increasing pollutants in marine systems.

Cytotoxicity of amine-modified polystyrene MPs and NPs on neural stem cells cultured from mouse subventricular zone

Microplastics (MPs) and nanoplastics (NPs) are found in various environments such as aquatic, terrestrial, and aerial areas. Once ingested and inhaled, these tiny plastic debris damaged the digestive and respiratory organ systems in animals. In humans, the possible connection between MPs and various diseases such as lung diseases has been raised. Yet, the impact of MPs on the human nervous system has been unclear. Previous research using animals and cultured cells showed possible neurotoxicity of MPs and NPs. In this study, we used neural stem cells cultured from mouse subventricular zone to examine the effects of polystyrene (PS) NPs and MPs with sizes of 0.1 μm, 1 μm, and 2 μm on the cell proliferation and differentiation. We observed that only positively charged NPs and MPs, but not negatively charged ones, decreased cell viability and proliferation. These amine-modified NPs and MPs decreased both neurogenesis and oligodendrogenesis. Finally, fully differentiated neurons and oligodendrocytes were damaged and removed by the application of NPs and MPs. All these effects varied among different sizes of NPs and MPs, with the greatest effects from 1 μm and the least effects from 2 μm. These results clearly demonstrate the cytotoxicity and neurotoxicity of PS-NPs and MPs.

Effect of microplastics on oxytetracycline trophic transfer: Immune, gut microbiota and antibiotic resistance gene responses

Microplastics and antibiotics are prevalent and emerging pollutants in aquatic ecosystems, but their interactions in aquatic food chains remain largely unexplored. This study investigated the impact of polypropylene microplastics (PP-MPs) on oxytetracycline (OTC) trophic transfer from the shrimp (Neocaridina denticulate) to crucian carp (Carassius auratus) by metagenomic sequencing. The carrier effects of PP-MPs promoted OTC bioaccumulation and trophic transfer, which exacerbated enterocyte vacuolation and hepatocyte eosinophilic necrosis. PP-MPs enhanced the inhibitory effect of OTC on intestinal lysozyme activities and complement C3 levels in shrimp and fish, and hepatic immunoglobulin M levels in fish (p < 0.05). Co-exposure of MPs and OTC markedly increased the abundance of Actinobacteria in shrimp and Firmicutes in fish, which caused disturbances in carbohydrate, amino acid, and energy metabolism. Moreover, OTC exacerbated the enrichment of antibiotic resistance genes (ARGs) in aquatic animals, and PP-MPs significantly increased the diversity and abundance of ARGs and facilitated the trophic transfer of teta and tetm. Our findings disclosed the impacts of PP-MPs on the mechanism of antibiotic toxicity in aquatic food chains and emphasized the importance of gut microbiota for ARGs trophic transfer, which contributed to a deeper understanding of potential risks posed by complex pollutants on aquatic ecosystems.

Vertebrate response to microplastics, nanoplastics and co-exposed contaminants: Assessing accumulation, toxicity, behaviour, physiology, and molecular changes

Pollution from microplastics (MPs) and nanoplastics (NPs) has gained significant public attention and has become a serious environmental problem worldwide. This review critically investigates MPs/NPs' ability to pass through biological barriers in vertebrate models and accumulate in various organs, including the brain. After accumulation, these particles can alter individuals' behaviour and exhibit toxic effects by inducing oxidative stress or eliciting an inflammatory response. One major concern is the possibility of transgenerational harm, in which toxic consequences are displayed in offspring who are not directly exposed to MPs/NPs. Due to their large and marked surface hydrophobicity, these particles can easily absorb and concentrate various environmental pollutants, which may increase their toxicity to individuals and subsequent generations. This review systematically provides an analysis of recent studies related to the toxic effects of MPs/NPs, highlighting the intricate interplay between co-contaminants in vitro and in vivo. We further delve into mechanisms of MPs/NPs-induced toxicity and provide an overview of potential therapeutic approaches to lessen the negative effects of these MPs/NPs. The review also emphasizes the urgency of future studies to examine the long-term effects of chronic exposure to MPs/NPs and their size- and type-specific hazardous dynamics, and devising approaches to safeguard the affected organisms.

Alteration of shoaling behavior and dysbiosis in the gut of medaka (Oryzias latipes) exposed to 2-μm polystyrene microplastics

There is global concern that microplastics may harm aquatic life. Here, we examined the effects of fine polystyrene microplastics (PS-MPs, 2-μm diameter, 0.1 mg/L, 2.5 × 107 particles/L) on the behavior and the microbiome (linked to brain-gut interaction) of a fish model using medaka, Oryzias latipes. We found that shoaling behavior was reduced in PS-MP-exposed medaka compared with control fish during the exposure period, but it recovered during a depuration period. There was no difference in swimming speed between the PS-MP-exposed and control groups during the exposure period. Analysis of the dominant bacterial population (those comprising ≥1% of the total bacterial population) in the gut of fish showed that exposure to PS-MPs tended to increase the relative abundance of the phylum Fusobacteria and the genus Vibrio. Furthermore, structural-equation modeling of gut bacteria on the basis of machine-learning data estimated strong relationship involved in the reduction of the functional bacterial species of minority (<1% of the total bacterial population) such as the genera Muribaculum (an undefined role), Aquaspirillum (a candidate for nitrate metabolism and magnetotactics), and Clostridium and Phascolarctobacterium (potential producers of short-chain fatty acids, influencing behavior by affecting levels of neurotransmitters) as a group of gut bacteria in association with PS-MP exposure. Our results suggest that fish exposure to fine microplastics may cause dysbiosis and ultimately cause social behavior disorders linked to brain-gut interactions. This effect could be connected to reduction of fish fitness in the ecosystem and reduced fish survival.

Hepatotoxic of polystyrene microplastics in aged mice: Focus on the role of gastrointestinal transformation and AMPK/FoxO pathway

Microplastic (MP) toxicity has attracted widespread attention, whereas before triggering hepatotoxicity, ingested MPs first undergo transportation and digestion processes in the gastrointestinal tract, possibly interacting with the gastrointestinal contents (GIC). More alarming is the need for more understanding of how this process may impact the liver health of aged animals. This study selected old mice. Firstly, we incubated polystyrene microplastics (PS-MPs, 1 μm) with GIC extract. The results of SEM/EDS indicated a structural alteration in PS-MPs. Additionally, impurities resembling corona, rich in heteroatoms (O, N, and S), were observed. This resulted in an enhanced aggregating phenomenon of MPs. We conducted a 10-day experiment exposing aged mice to four concentrations of PS-MPs, ranging from 1 × 103 to 1 × 1012 particles/L. Subsequent measurements of tissue pathology and body and organ weights were conducted, revealing alterations in liver structure. In the liver, 12 crucial metabolites were found by LC-MS technology, including purines, lipids, and amino acids. The AMPK/FoxO pathway was enriched, activated, and validated in western blotting results. We also comprehensively examined the innate immune system, inflammatory factors, and oxidative stress indicators. The results indicated decreased C3 levels, stable C4 levels, inflammatory factors (IL-6 and IL-8), and antioxidant enzymes were increased to varying degrees. PS-MPs also caused DNA oxidative damage. These toxic effects exhibited a specific dose dependence. Overall, after the formation of the gastrointestinal corona, PS-MPs subsequently impact various cellular processes, such as cycle arrest (p21), leading to hepatic and health crises in the elderly. The presence of gastrointestinal coronas also underscores the MPs' morphology and characteristics, which should be distinguished after ingestion.

Assessment of dietary polyvinylchloride, polypropylene and polyethylene terephthalate exposure in Nile tilapia, Oreochromis niloticus: Bioaccumulation, and effects on behaviour, growth, hematology and histology

Microplastics (MPs) have been recognized as emerging aquatic pollutants receiving major concern due to their detrimental effects on aquatic life. Nile Tilapia, Oreochromis niloticus is a model species considered in toxicological studies to address the effects of pollutants in freshwater animals. However, comprehensive knowledge comparing the impacts on fish across various MPs polymers is scarce. Therefore, the overarching aim of the current study was to examine the bioconcentration of MPs polymers: polyvinylchloride (PVC), polypropylene (PP), and polyethylene terephthalate (PET), and their toxic effects on growth, and behavioral responses, hematology, and histology of gills, liver, and intestine in O. niloticus. Fishes were subjected to a 21-day dietary exposure to MPs by assigning them into six treatment groups: T1 (4% of PVC), T2 (4% of PP), T3 (4% of PET), T4 (8% of PVC), T5 (8% of PP), T6 (8% of PET), and control (0% of MPs), to assess the effects on fish across the polymers and dosage. Results showed several abnormalities in anatomical and behavioral parameters, lower growth, and high mortality in MPs-exposed fish, indicating a dose-dependent relationship. The elevated dosage of polymers raised the bioavailability of PVC, PP, and PET in gills and gut tissues. Noteworthy erythrocyte degeneration referred to cytotoxicity and stress imposed by MPs, whereas the alterations in hematological parameters were possibly due to blood cell damage, also indicating mechanisms of defense against MPs toxicity. Histopathological changes in the gills, liver, and intestine confirmed the degree of toxicity and associated dysfunctions in fish. A higher sensitivity of O. niloticus to PET-MPs compared to other polymers is likely due to its chemical properties and species-specific morphological and physiological characteristics. Overall, the present study reveals valuable insights into the emerging threat of MPs toxicity in freshwater species, which could be supportive of future toxicological research.

Microplastics and nanoplastics induced differential respiratory damages in tilapia fish Oreochromis niloticus

With the increasing micro(nano)plastics (MNPs) pollution in aquatic environments, fish respiration is encountering a huge threat. Herein, polystyrene (PS) MNPs with three sizes (80 nm, 2 µm, and 20 µm) were exposed to tilapia Oreochromis niloticus at an environmentally relevant concentration of 100 μg/L for 28 days and their impacts on respiratory function were investigated. Based on the results of oxygen consumption and histological analysis, all the three treatments could induce respiratory damages and such impacts were more severe for the 2 µm and 20 µm treatments than for the 80 nm treatment. These results were explained by the more significant upregulation of egln3 and nadk, and the downregulation of isocitrate. Transcriptomics and metabolomics further revealed that TCA cycle played a key role in respiratory dysfunction induced by micro-sized PS particles, and cytokine and chemokine related functions were simultaneously enriched. Although nano-sized PS particles had the potential to penetrate the respiratory epithelium and reached the internal structure of the O. niloticus gills, they were easily expelled through the blood circulation. Our results highlighted the serious threat of MNPs to fish respiration and provided insights into the differential toxicological mechanisms between micro-sized and nano-sized particles, thus assisting in ecological risk assessments.

Size-dependent toxicity of polystyrene microplastics on the gastrointestinal tract: Oxidative stress related-DNA damage and potential carcinogenicity

Microplastics (MPs) and nanoplastics (NPs) have been generally regarded as emerging pollutants and received worldwide attention in recent years. Water and food consumption are the primary pathways for human exposure to MPs/NPs, thus gastrointestinal tracts may be susceptible to their toxicity. Although the recent report has indicated the presence of MPs/NPs in multiple human organs, little is known about their gastric effects. Therefore, this study focused on the adverse effects of polystyrene microplastics (PS-MPs) on gastric epithelium in vivo and in vitro. Surface-enhanced Raman spectroscopy (SERS) revealed the distribution of PS-MPs was associated with their particle sizes, and predominantly concentrated in gastric tissues. Gastric barrier injury and mitochondrial damage were observed in rats after exposure to PS-MPs. Compared with the larger ones, polystyrene nanoplastics (PS-NPs) more significantly reduced the activity of antioxidant enzymes while enhancing the level of MDA, 8-OhdG and γ-H2AX. Meanwhile, PS-MPs caused upregulation of β-catenin/YAP through redox-dependent regulation of nucleoredoxin (NXN) and dishevelled (Dvl). These findings supported the size-dependent effects of PS-MPs on oxidative stress and DNA damage. Moreover, the redox-dependent activation of the β-catenin/YAP cascade suggested a novel toxic mechanism for PS-MPs and implied the potential carcinogenic effects.

A biodegradable oxidized starch/carboxymethyl chitosan film coated with pesticide-loaded ZIF-8 for tomato fusarium wilt control

Film mulching is one of the most important methods to control soil-borne diseases. However, the traditional mulch may cause microplastic pollution and soil ecological damage. Herein, a biodegradable film was developed using oxidized starch and carboxymethyl chitosan and incorporated ZIF-8 carrying fludioxonil to sustainably control soil-borne disease. The microstructure, mechanical properties, optical properties, and water barrier properties of the composite films (Flu@ZIF-8-OS/CMCS) were investigated. The results show that Flu@ZIF-8-OS/CMCS had a smooth and uniform surface and excellent light transmittance. The excellent mechanical properties of the films were verified by tensile strength, elongation at break and Young's modulus. Higher contact angle and lower water vapor permeability indicate water retention capacity of the soil was improved through using Flu@ZIF-8-OS/CMCS. Furthermore, the release properties, biological activity, degradability and safety to soil organisms of Flu@ZIF-8-OS/CMCS was determined. The addition of ZIF-8 significantly improved the film's ability to retard the release of Flu, while the Flu@ZIF-8-OS/CMCS has good soil degradability. In vitro antifungal assays and pot experiments demonstrated excellent inhibitory activity against Fusarium oxysporum f. sp. Lycopersici. Flu@ZIF-8-OS/CMCS caused only 13.33 % mortality of earthworms within 7 d. This research provides a new approach to reducing microplastic pollution and effectively managing soil-borne diseases.

Polyethylene microplastic can adsorb phosphate but is unlikely to limit its availability in soil

In plant growth experiments, the presence of microplastics (MPs) often reduces plant growth. We conducted laboratory experiments to investigate the potential of microplastics to adsorb the major soil nutrient phosphate; adsorption to MPs was then compared to adsorption to soil. Adsorption experiments used two contrasting soils, pristine high density polyethylene and artificially weathered material (the same material but exposed to 185 nm UV light for 420 h over 105 days), phosphate solutions (dissolved KH2PO4) ranging from 0.2 to 200 mg L-1 and a solid (g) to liquid (mL) ratio of 1: 150 at different values of pH (2-12) and different concentrations of background electrolyte (0.00-0.10 M NaNO3). The adsorption data were best fitted to linear and Freundlich isotherms. In initial experiments where pH was not fixed and with a background electrolyte of 0.10 M NaNO3, Kd values ranged from 3.37 to 27.65 L kg-1, log Kf from 1.21 to 1.96 and 1/n from 0.36 to 0.84. Exposure of the MP to 185 nm UV radiation led to the appearance of a C=O functional group in the MP; the partition coefficient Kd, calculated from the linear isotherm did not increase but the logKf value derived from fits to the Freundlich isotherm increased by a factor of 1.5. Kd values for soils were 3-7.5 times greater than those for MPs and log Kf values 1.1-1.7 greater. In the experiments in which initial pH and ionic strength were varied, adsorption was similar across all treatments with adsorption parameters for the higher organic content soil sometimes having the highest values and the pristine microplastic the lowest. In the desorption experiments most of the adsorbed phosphate desorbed. Overall our findings indicate that despite their ability to adsorb phosphate, MPs are unlikely to control the fate and behaviour of phosphate in soil.

Polystyrene microplastics induce size-dependent multi-organ damage in mice: Insights into gut microbiota and fecal metabolites

Particle size is one of the most important factors in determining the biological toxicity of microplastics (MPs). In this study, we attempted to examine the systemic toxicity of polystyrene MPs of different sizes (0.5 µm MP1 and 5 µm MP2) in C57BL/6 J mice. After the mice were given oral gavage of MPs for 8 consecutive weeks, histopathology and molecular biology assays, 16 S rRNA sequencing of the gut microbiota, and untargeted metabolomics were performed. The results showed that MPs were distributed in the organs in a size-dependent manner, with smaller particles demonstrating greater biodistribution. Further analysis indicated that exposure to MPs caused multi-organ damage through distinct toxicity pathways. Specifically, exposure to 0.5 µm MP1 led to excessive accumulation and induced more serious inflammation and mechanical damage in the spleen, kidney, heart, lung, and liver. However, 5 µm MP2 led to more severe intestinal barrier dysfunction, as well as gut dysbiosis and metabolic disorder in association with neuroinflammation. These results are helpful in expanding our knowledge of the toxicity of MPs of different sizes in mammalian models.

Exposure to petroleum-derived and biopolymer microplastics affect fast start escape performance and aerobic metabolism in a marine fish

Evidence suggests that petroleum-derived polymers can impact marine organisms however, little is understood about whether biopolymers affect the behaviour and physiology of marine teleost fish. The aim of this research was to examine the potential effects of microplastics from a petroleum-derived polymer, (polyethylene, PE), and a biopolymer, (edible food coating EFC) on the escape performance, routine swimming, and aerobic metabolism of Forsterygion capito (the mottled triplefin). PE exposure negatively affected fish through longer latencies (∼25 % slower to respond), slower maximum speeds and higher responsiveness in escape performance compared to control fish. Furthermore, fish exposed to PE displayed slower mean speeds and reduced the distance travelled by ∼25 %. After an exhaustive challenge, PE-exposed fish showed higher excess post-exercise oxygen consumption during recovery, compared to control fish. By contrast, EFC exposure only negatively affected maximum speed during an escape. Directionality and mean speed in escape performance, metabolic rate and recovery time were unaffected by biopolymer exposure. With the ever-increasing number of microplastics in the ocean, a shift to biodegradable polymers may be beneficial to marine organisms due to the smaller effect found when compared to petroleum-derived polymers in this study. As a central tool for conservation, this study represents a significant advance to predict the impact of microplastics on wild fish populations.

"Microplastic seasoning": A study on microplastic contamination of sea salts in Bangladesh

This study investigated microplastics (MPs) in commercial sea salts from Bangladesh. The presence of MPs in the 18 sea salt bands was 100 %, where the mean MPs abundance was 471.67 MPs/kg, ranging between 300 and 670 MPs/kg. The maximum number of MPs in the 300-1500 μm size class was significantly higher than the 1500-3000 μm and 3000-5000 μm size class. The most dominant color was black. Fibers and foams were the dominant shapes. The highest number of MPs was 41 %, obtained from coarse salt grains. Four types of polymers were mainly identified from the analyzed samples: PP, PE, PET, and PA. The mean polymer risk index value among these sea salts was 539 to 1257. The findings of this study can be helpful for consumers, salt industries, and policymakers to be aware of or reduce MP contamination levels in sea salts during production and consumption.

Vitamin D modulates disordered lipid metabolism in zebrafish (Danio rerio) liver caused by exposure to polystyrene nanoplastics

In this study, zebrafish (Danio rerio) were exposed to polystyrene nanoplastics (PS-NPs, 80 nm) at 0, 15, or 150 μg/L for 21 days and supplied with a low or high vitamin D (VD) diet (280 or 2800 IU/kg, respectively, indicated by - or +) to determine whether and how VD can regulate lipid metabolism disorder induced by PS-NPs. Six groups were created according to the PS-NP concentration and VD diet status: 0-, 0+, 15-, 15+,150-, and 150 +. Transmission electron microscopy showed that PS-NPs accumulated in the livers of zebrafish, which led to large numbers of vacuoles and lipid droplets in liver cell matrices; this accumulation was most prominent in the 150- group, wherein the number of lipid droplets increased significantly by 136.36%. However, the number of lipid droplets decreased significantly by 76.92% in the 150+ group compared with the 150- group. An examination of additional biochemical indicators showed that the high VD diet partially reversed the increases in the triglyceride and total cholesterol contents induced by PS-NPs (e.g., triglycerides decreased by 58.52% in the 150+ group, and total cholesterol decreased by 44.64% in the 15+ group), and regulated lipid metabolism disorder mainly by inhibiting lipid biosynthesis. Untargeted lipidomics analysis showed that exposure to PS-NPs was associated mainly with changes in the lipid molecular content related to cell membrane function and lipid biosynthesis and that the high VD diet reduced the content of lipid molecules related to lipid biosynthesis, effectively alleviating cell membrane damage and lipid accumulation. These findings highlight the potential of VD to alleviate lipid metabolism disorder caused by PS-NP exposure, thereby providing new insights into how the toxic effects of NPs on aquatic organisms could be reduced.

Comprehensive analysis of nanoplastic effects on growth phenotype, nanoplastic accumulation, oxidative stress response, gene expression, and metabolite accumulation in multiple strawberry cultivars

Nanoplastics (NPs) have emerged as a novel environmental threat due to their potential impacts on both animals and plants. Currently, research on the ecotoxicity of NPs has mainly focused on marine aquatic organisms and freshwater algae, with very limited investigations conducted on horticultural plants. This study examined the effects of varying concentrations (0, 1, 10, 50 mg·L-1) of polystyrene NPs (PS-NPs) on strawberry growth. The findings revealed that low concentrations of PS-NPs stimulated strawberry growth, whereas high concentrations impeded it. Notably, diverse strawberry cultivars displayed considerable differences in their sensitivity to PS-NP exposure. Laser scanning confocal microscopy confirmed the absorption of PS-NPs by strawberry roots, with variations in PS-NP accumulation observed across different cultivars. Comparative transcriptomics analysis suggested that the differential expression of genes responsible for calcium ion transport played a significant role in the observed intervarietal differences in PS-NP accumulation among strawberry cultivars. Furthermore, distinct variations in endogenous oxidative responses were observed in different strawberry cultivars under PS-NP treatment. Further analysis indicated that the down-regulation of peroxidase (POD) gene expression and terpenoid compounds accumulation were responsible for heightened endogenous oxidative stress observed in certain strawberry cultivars under PS-NP treatment. Transcriptomic and metabolomic analyses were performed on six strawberry cultivars to investigate their response to PS-NPs in terms of endogenous gene expression and metabolite accumulation. The results identified one commonly up-regulated gene (wall-associated receptor kinase-like) and sixteen commonly down-regulated genes associated with lipid metabolism and carbohydrate metabolism. In addition, a significant reduction in fatty acid metabolite accumulation was observed in the six strawberry cultivars under PS-NP treatment. These findings have significant implications for understanding the effects of NPs on strawberry growth, metabolism, and antioxidant responses, as well as identifying marker genes for monitoring and evaluating the impact of NP pollution on strawberry.

Microplastic polyamide toxicity: Neurotoxicity, stress indicators and immune responses in crucian carp, Carassius carassius

This study aimed to determine the toxicity standard and potential risks and effects of polyamide (PA) exposure on neurotoxicity, stress indicators, and immune responses in juvenile crucian carp Carassius carassius. Numerous microplastics (MPs) exists within aquatic environments, leading to diverse detrimental impacts on aquatic organisms. The C. carassius (mean weight, 23.7 ± 1.6 g; mean length, 13.9 ± 1.4 cm) were exposed to PA concentrations of 0, 4, 8, 16, 32 and 64 mg/L for 2 weeks. Among the neurotransmitters, the acetylcholinesterase (AChE) activity in the liver, gill, and intestine of C. carassius was significantly inhibited by PA exposure. Stress indicators such as cortisol and heat shock protein 70 (HSP70) in the liver, gill, and intestine of C. carassius were significantly increased, while immune responses to lysozyme and immunoglobulin M (IgM) were significantly decreased. Our study demonstrates the toxic effects of MP exposure on crucian carp's neurotoxicity, stress indicators, and immune responses.

Response of moulting genes and gut microbiome to nano-plastics and copper in juvenile horseshoe crab Tachypleus tridentatus

Nanoplastics (NPs) and heavy metals are typical marine pollutants, affecting the gut microbiota composition and molting rate of marine organisms. Currently, there is a lack of research on the toxicological effects of combined exposure to horseshoe crabs. In this study, we investigated the effects of NPs and copper on the expression of molt-related genes and gut microbiome in juvenile tri-spine horseshoe crabs Tachypleus tridentatus by exposing them to NPs (100 nm, 104 particles L-1) and/or Cu2+ (10 μgL-1) in seawater for 21 days. Compared with the control group, the relative mRNA expression of ecdysone receptor (EcR), retinoid x receptor (RXR), calmodulin-A-like isoform X1 (CaM X1), and heat shock 70 kDa protein (Hsp70) were significantly increased under the combined stress of NPs and Cu2+. There were no significant differences in the diversity and abundance indices of the gut microbial population of horseshoe crabs between the NPs and/or Cu2+ groups and the control group. According to linear discriminant analysis, Oleobacillus was the most abundant microorganism in the NPs and Cu2+ stress groups. These results indicate that exposure to either NPs stress alone or combined NPs and Cu2+ stress can promote the expression levels of juvenile molting genes. NPs exposure has a greater impact on the gut microbial community structure of juvenile horseshoe crabs compared to Cu2+ exposure. This study is helpful for predicting the growth and development of horseshoe crabs under complex environmental pollution.

Toxicological Profile of Polyethylene Terephthalate (PET) Microplastic in Ingested Drosophila melanogaster (Oregon R+) and Its Adverse Effect on Behavior and Development

Microplastics are readily available in the natural environment. Due to the pervasiveness of microplastic pollution, its effects on living organisms necessitate further investigation. The size, time of exposure, and amount of microplastic particles appear to be the most essential factor in determining their toxicological effects, either organismal or sub-organismal. For our research work, we preferred to work on a terrestrial model organism Drosophila melanogaster (Oregon R+). Therefore, in the present study, we characterized 2-100 µm size PET microplastic and confirmed its accumulation in Drosophila, which allowed us to proceed further in our research work. At larger dosages, research on locomotory activities such as climbing, jumping, and crawling indicated a decline in physiological and neuromuscular functions. Our studies also determined retarded development in flies and decreased survival rate in female flies after exposure to the highest concentration of microplastics. These experimental findings provide insight into the possible potential neurotoxic effects of microplastics and their detrimental effects on the development and growth of flies.

Combined effect of anthracene and polyethylene microplastics on swimming speed and cytochrome P4501A monooxygenase expression of Java medaka (Oryzias javanicus)

Microplastics have been detected in a variety of aquatic ecosystems, and the combined effect of microplastics and chemical pollutants has become a matter of increasing concern. We conducted a 12-d co-exposure test of anthracene and spherical or fragmented polyethylene microplastics (size 200 µm) on Java medaka (Oryzias javanicus). The accumulation of anthracene in Java medaka muscle reached a plateau on day 5 in all anthracene exposure groups, and no significant differences were detected among the groups (ANT, 20.4 ± 5.5; ANT + SPPE-MP, 24.7 ± 2.7; ANT + FRPE-MP, 24.6 ± 4.7 µg/g). However, co-exposure to anthracene and spherical or fragmented polyethylene microplastics increased the duration of slow swimming in a swimming behavior test (control, 4.1 ± 1.4; ANT, 5.2 ± 2.8; ANT + SPPE-MP, 12.4 ± 3.7; ANT + FRPE-MP, 17.4 ± 5.1 min/30 min), and co-exposure to anthracene and fragmented polyethylene microplastics induced higher cytochrome P4501A monooxygenase (CYP1A) expression in Java medaka livers than the other anthracene exposure groups (ANT, 189 ± 74; ANT + SPPE-MP, 203 ± 75; ANT + FRPE-MP 272 ± 36% of control). Polyethylene microplastics appear to be weak vectors of anthracene at the size tested (200 µm), and the effect of shape (spherical or fragmented) on the vector effect was small. However, the presence of polyethylene microplastics could affect the swimming behavior and CYP1A expression in Java medaka.

Nano- and Microplastics Migration from Plastic Food Packaging into Dairy Products: Impact on Nutrient Digestion, Absorption, and Metabolism

The ongoing use of plastic polymers to manufacture food packaging has raised concerns about the presence of nano- and microplastics (NMPs) in a variety of foods. This review provides the most recent data on NMPs' migration from plastic packaging into dairy products. Also discussed are the possible effects of NMPs on nutrient digestion, absorption, and metabolism. Different kinds of dairy products, including skimmed milk, whole liquid milk, powder milk, and infant formula milk, have been found to contain NMPs of various sizes, shapes, and concentrations. NMPs may interact with proteins, carbohydrates, and fats and have a detrimental impact on how well these nutrients are digested and absorbed by the body. The presence of NMPs in the gastrointestinal tract may impact how lipids, proteins, glucose, iron, and energy are metabolized, increasing the risk of developing various health conditions. In addition to NMPs, plastic oligomers released from food packaging material have been found to migrate to various foods and food simulants, though information regarding their effect on human health is limited. Viewpoints on potential directions for future studies on NMPs and their impact on nutrient digestion, absorption, and health are also presented in this review.

Effects of microplastics, pesticides and nano-materials on fish health, oxidative stress and antioxidant defense mechanism

Microplastics and pesticides are emerging contaminants in the marine biota, which cause many harmful effects on aquatic organisms, especially on fish. Fish is a staple and affordable food source, rich in animal protein, along with various vitamins, essential amino acids, and minerals. Exposure of fish to microplastics, pesticides, and various nanoparticles generates ROS and induces oxidative stress, inflammation, immunotoxicity, genotoxicity, and DNA damage and alters gut microbiota, thus reducing the growth and quality of fish. Changes in fish behavioral patterns, swimming, and feeding habits were also observed under exposures to the above contaminants. These contaminants also affect the Nrf-2, JNK, ERK, NF-κB, and MAPK signaling pathways. And Nrf2-KEAP1 signalling modulates redox status marinating enzymes in fish. Effects of pesticides, microplastics, and nanoparticles found to modulate many antioxidant enzymes, including superoxide dismutase, catalase, and glutathione system. So, to protect fish health from stress, the contribution of nano-technology or nano-formulations was researched. A decrease in fish nutritional quality and population significantly impacts on the human diet, influencing traditions and economics worldwide. On the other hand, traces of microplastics and pesticides in the habitat water can enter humans by consuming contaminated fish which may result in serious health hazards. This review summarizes the oxidative stress caused due to microplastics, pesticides and nano-particle contamination or exposure in fish habitat water and their impact on human health. As a rescue mechanism, the use of nano-technology in the management of fish health and disease was discussed.

Functional Trait-Based Evidence of Microplastic Effects on Aquatic Species

Microplastics represent an ever-increasing threat to aquatic organisms. We merged data from two global scale meta-analyses investigating the effect of microplastics on benthic organisms' and fishes' functional traits. Results were compared, allowing differences related to vertebrate and invertebrate habitat, life stage, trophic level, and experimental design to be explored. Functional traits of aquatic organisms were negatively affected. Metabolism, growth, and reproduction of benthic organisms were impacted, and fish behaviour was significantly affected. Responses differed by trophic level, suggesting negative effects on trophic interactions and energy transfer through the trophic web. The experimental design was found to have the most significant impact on results. As microplastics impact an organism's performance, this causes indirect repercussions further up the ecological hierarchy on the ecosystem's stability and functioning, and its associated goods and services are at risk. Standardized methods to generate salient targets and indicators are urgently needed to better inform policy makers and guide mitigation plans.

Multi-biomarkers hazard assessment of microplastics with different polymers by acute embryo test and chronic larvae test with zebrafish (Danio rerio)

Microplastics as emerging contaminants show various composition features in the environment. However, influence of polymer types on the toxicity of microplastics is still unclear, thus affecting evaluation of their toxicity and ecological risks. In this work, toxic effects of microplastics (fragment, 52-74 μm) with different polymer types including polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP) and polystyrene (PS) to zebrafish (Danio rerio) were studied using acute embryo test and chronic larvae test. Silicon dioxide (SiO₂) was used as a control representing natural particles. Results showed microplastics with different polymers had no influence on embryonic development at environmental relevant concentration (10² particles/L), but could lead to accelerated heartbeat rate and increased embryonic death when exposed to SiO₂, PE and PS at higher concentrations (10⁴ and 10⁶ particles/L). Chronic exposure for zebrafish larvae indicated different polymers of microplastics did not affect zebrafish larvae' feeding and growth, nor induce oxidative stress. But larvae' locomotion level and AChE (acetylcholinesterase) activities could be inhibited by SiO₂ and microplastics at 10⁴ particles/L. Our study demonstrated negligible toxicity of microplastics at environmental relevant concentration, while different polymers of microplastics have similar toxic effects as SiO₂ at high concentrations. We suggest that microplastic particles may have the same biological toxicity as natural particles.

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.

Process-oriented impacts of microplastic fibers on behavior and histology of fish

Microplastic pollution has raised global concern for its hazards to biota. To determine the direct impact of microplastics during their contact with fish, we exposed goldfish (Carassius auratus) to 100 and 1000 items/L waterborne microplastic fibers in the short- and long-term. In the presence of 1000 items/L of microplastic fibers, the coughing behavior of fish increased significantly after 2 h of exposure. Predatory behaviors decreased significantly by 53.0% after 45 d of exposure, and the reduction in daily food intake was negatively related to exposure duration in the 1000 items/L group. In addition, microplastic fibers stimulated dynamic mucus secretion across different fish tissues during the different processes evaluated in this study, with 30.0% and 62.9% overall increases in the secretory capacity of mucus cells in the 100 and 1000 items/L groups, respectively. These behavioral and histological alterations were derived from the ventilation, feeding, and swimming processes of goldfish. We regarded these changes as process-oriented impacts, suggesting the effects of microplastics on fish and how fish cope with microplastics.

Chronic nanoplastic exposure induced oxidative and immune stress in medaka gonad

Nanoplastic (NP) pollution is a global issue because of its widespread occurrence and potential toxicity. Many studies have investigated the impacts of the short-term toxicity of NPs on organisms. Until now, only a few studies have assessed the toxicological effects of prolonged exposure to NPs at low concentrations in fish. In this study, the effects of NPs (nano-polystyrene microspheres, diameter: 100 nm) on immune and oxidative stress response, histopathology, and survival in medaka were evaluated. The effects of different concentrations (0, 10, 10⁴, and 10⁶ particles/L) of nanoplastics were studied in medaka Oryzias latipes after 3 months of exposure. Lysozyme enzyme activity, oxidative stress-related biomarkers (i.e., superoxide dismutase, catalase, and glutathione peroxidase), and malondialdehyde levels were decreased under NP exposure. The gonadal histology showed that high NP exposure (10⁶ particles/L) inhibited the process of spermatogenesis and oogenesis processes, implying delayed maturation of the gonad. Furthermore, the IBR and PCA analysis revealed the potential biotoxicity of NPs and the total survival rate of medaka was significantly reduced due to the long-term exposure to NPs. Overall, prolonged exposure to low concentrations of NPs is harmful to the health of medaka gonads. In the long run, this may threaten the fish reproduction and population, suggesting the need for long-term toxicological studies to predict the aquatic animal health in nature.

Eco-toxicity of nano-plastics and its implication on human metabolism: Current and future perspective

In the current scenario, plastic pollution has become one of the serious environmental hazard problems due to its improper handling and insufficiency in degradation. Nanoplastics (NPs) are formed when plastic fragments are subjected to ultraviolet radiation, natural weathering, and biodegradation. This review paper focuses on the source of origin, bioaccumulation, potential nanoplastics toxicity impact towards environment and human system and management strategies towards plastic pollution. Moreover, this study demonstrates that nanoplastics interfere with metabolic pathways and cause organ dysfunction. A wide range of studies have documented the alteration of organism physiology and behavior, caused by NPs exposure. A major source of NPs exposure is via ingestion because these plastics are found in foods or food packaging, however, they can also enter the human body via inhalation but in a less well-defined form. In recent literature, the studies demonstrate the mechanisms for NP uptake, affecting factors that have been discussed followed by cytotoxic mechanisms of NPs. However, study on challenges regarding NPs toxicity for the risk assessment of human health is limited. It is important to perform and focus more on the possible impacts of NPs on human health to identify the key challenges and explore the potential impacts of their environmental accumulation and its toxicity impacts.

Presence of microplastics and microparticles in Oregon Black Rockfish sampled near marine reserve areas

Measuring the spatial distribution of microparticles which include synthetic, semi-synthetic, and anthropogenic particles is critical to understanding their potential negative impacts on species. This is particularly important in the context of microplastics, which are a form of microparticle that are prevalent in the marine environment. To facilitate a better understanding of microparticle occurrence, including microplastics, we sampled subadult and young juvenile Black Rockfish (Sebastes melanops) at multiple Oregon coast sites, and their gastrointestinal tracts were analyzed to identify ingested microparticles. Of the subadult rockfish, one or more microparticles were found in the GI tract of 93.1% of the fish and were present in fish from Newport, and near four of five marine reserves. In the juveniles, 92% of the fish had ingested one or more microparticles from the area of Cape Foulweather, a comparison area, and Otter Rock, a marine reserve. The subadults had an average of 7.31 (average background = 5) microparticles detected, while the juveniles had 4.21 (average background = 1.8). In both the subadult and juvenile fish, approximately 12% of the microparticles were identified as synthetic using micro-Fourier Infrared Spectroscopy (micro-FTIR). Fibers were the most prevalent morphology identified, and verified microparticle contamination was a complex mixture of synthetic (∼12% for subadults and juveniles), anthropogenic (∼87% for subadults and 85.5% for juveniles), and natural (e.g., fur) materials (∼0.7% for subadults and ∼2.4% for juveniles). Similarities in exposure types (particle morphology, particle number) across life stages, coupled with statistical differences in exposure levels at several locations for subadult fish, suggest the potential influence of nearshore oceanographic patterns on microparticle distribution. A deeper understanding of the impact microplastics have on an important fishery such as those for S. melanops, will contribute to our ability to accurately assess risk to both wildlife and humans.

Beyond the exposure phase: Microplastic depuration and experimental implications

Currently, most studies focus on the effect of microplastics (MPs) in the exposure phase, but pay limited attention to the depuration phase. Depuration is a promising practice to achieve safe aquaculture production, which is also helpful to understand the long-term impact of MPs. Therefore, investigating the post-exposure scenarios of MPs has great practical significance. In order to provide implications for future research, this work attempted to systematize the current findings and knowledge gaps regarding the depuration of MPs. More specifically, three methods, including direct fitting, one-compartment kinetic model and interval observation, for estimating the retention time of MPs to further determine the minimum depuration time were introduced, in which the one-compartment kinetic model could also be used to calculate the depuration rate constant and biological half-life of MPs. Moreover, the post-exposure effect of MPs generally presented three scenarios: incomplete reversal (legacy effect), return to control level (recovery) and stimulatory response (hormesis-like effect). In addition, the possible tissue translocation of MPs, the influence of food abundance and body shape on MPs egestion, and the potential interaction with environmental factors, have aroused great scientific concerns and need further exploration and clarification.

Environmentally relevant concentrations of butyl benzyl phthalate triggered oxidative stress and apoptosis in adult zebrafish (Danio rerio) liver: Combined analysis at physiological and molecular levels

Butyl benzyl phthalate (BBP), a typical phthalate plasticizer, is frequently detected in aquatic environments, but its possible effects on fish liver are unknown. In this study, adult zebrafish were exposed to 5-500 μg/L BBP and cultured for 28 days. The toxicity mechanism of environmentally relevant concentrations of BBP in the liver was explored using integrated biomarker response (IBR), molecular docking, and histopathological analysis, based on the tests of oxidative stress, apoptosis, and tissue damage, respectively. The results revealed that exposure to 500 μg/L BBP caused lipid peroxidation and DNA damage and induced inflammatory responses in the liver and intestinal tissues. The accumulation of reactive oxygen species (ROS) is the primary manifestation of BBP toxicity and is accompanied by changes in the activities of antioxidant and detoxification enzymes. Notably, the pro-apoptotic genes (p53 and caspase-3) were still significantly upregulated in the 50 μg/L and 500 μg/L treatment groups on day 28. Moreover, BBP interfered with apoptosis by forming a stable complex with apoptosis proteins (P53 and Caspase-3). Our findings are helpful for understanding the toxicity mechanisms of BBP, which could further promote the assessment of the potential environmental risks of BBP.

Adverse effects of polystyrene microplastics in the freshwater commercial fish, grass carp (Ctenopharyngodon idella): Emphasis on physiological response and intestinal microbiome

Microplastics (MPs) pollution in aquatic environment has attracted global attention in recent years. To evaluate the potential toxic effects of MPs in freshwater cultured fish, grass carps (Ctenopharyngodon idella) (body length: 7.7 ± 0.1 cm, wet weight: 6.28 ± 0.23 g) were exposed to different sizes (0.5 μm, 15 μm) and concentrations (100 μg/L, 500 μg/L) of polystyrene microplastics (PS-MPs) suspension for 7 and 14 days, followed by 7 days of depuration, detecting the variations in growth rate, histological structure, oxidative response and intestinal microbiome. Our results indicate that MP toxicity elicited significant size- and concentration-dependent responses by grass carp. MP exposure caused obvious decrease in growth rate on day 14 but not on day 7. Additionally, MPs with large size and high concentration caused more severe intestinal damage and less weight gain, while MP particles with small size and high concentration induced more severe liver congestion and stronger oxidative stress. MP exposure dramatically shifted the gut microbial composition, with the top 10 genera in abundance being associated with the diameter and concentration of the MPs. After 7 days of depuration, only superoxide dismutase and malondialdehyde in liver, showed a tendency to recover to the initial values. Even though the differences in the gut microbial community between the control and treatment groups disappeared, and the proportion of potential pathogenic bacteria in intestine was still high. Thus, it is clear that a short-term depuration period of 7 days is not enough for complete normalization.

Alleviation of aqueous nitrogen loss from paddy fields by growth and decomposition of duckweed (Lemna minor L.) after fertilization

Runoff loss of nitrogen from paddy fields has received increasing attention in recent years. Duckweed is an aquatic plant frequently found in paddy fields. In this study, the effects of duckweed (Lemna minor L.) in floodwater on aqueous nitrogen losses from paddy fields were systematically investigated. Results demonstrated that the growth of duckweed decreased total nitrogen concentrations in floodwater and nitrogen runoff loss from paddy fields by 16.7%-18.3% and 11.2%-13.6%, respectively. Moreover, compared with NO₃^-, NH₄⁺ was preferentially removed by duckweed. ¹⁵N isotope tracer experiments revealed that the growth and decomposition of duckweed acted as a "buffer" against the nitrogen variation in floodwater after fertilization. During the growth of duckweed, leaves were found to be the principal organ to assimilate NH₄⁺ and release NO₃^- by using non-invasive micro-test technology. Duckweed degradation increased the content of hydrophobic acids and marine humic-like substances in floodwater, which promoted the migration of nitrogen from floodwater to soil. Redundancy analysis and structural equation models further illustrated that pH and temperature variation in floodwater caused by duckweed played a greater role in aqueous nitrogen loss reduction than the nitrogen accumulation in duckweed. This study suggested that the growth of duckweed in paddy fields was an effective supplementary method for controlling aqueous nitrogen loss during agricultural production.

Hazard of polystyrene micro-and nanospheres to selected aquatic and terrestrial organisms

Plastics contamination in the environment is a major concern. Risk assessment of micro- and nanoplastics (MPL and NPL) poses significant challenges due to MPL and NPL heterogeneity regarding compositional polymers, particle sizes and morphologies in the environment. Yet, there exists considerable toxicological literature on commercial polystyrene (PS) micro- and nanospheres. Although such particles do not directly represent the environmental MPL and NPL, their toxicity data should be used to advance the hazard assessment of plastics. Here, toxicity data of PS micro- and nanospheres for microorganisms, aquatic and terrestrial invertebrates, fish, and higher plants was collected and analyzed. The evaluation of 294 papers revealed that aquatic invertebrates were the most studied organisms, nanosized PS was studied more often than microsized PS, acute exposures prevailed over chronic exposures, the toxicity of PS suspension additives was rarely addressed, and ∼40 % of data indicated no organismal effects of PS. Toxicity mechanisms were mainly studied in fish and nematode Caenorhabditis elegans, providing guidance for relevant studies in higher organisms. Future studies should focus on environmentally relevant plastics concentrations, wide range of organisms, co-exposures with other pollutants, and method development for plastics identification and quantification to fill the gap of bioaccumulation assessment of plastics.

Effects of the Antidepressant Amitriptyline on Juvenile Brown Trout and Their Modulation by Microplastics

Pharmaceuticals such as antidepressants are designed to be bioactive at low concentrations. According to their mode of action, they can also influence non-target organisms due to the phylogenetic conservation of molecular targets. In addition to the pollution by environmental chemicals, the topic of microplastics (MP) in the aquatic environment came into the focus of scientific and public interest. The aim of the present study was to investigate the influence of the antidepressant amitriptyline in the presence and absence of irregularly shaped polystyrene MP as well as the effects of MP alone on juvenile brown trout (Salmo trutta f. fario). Fish were exposed to different concentrations of amitriptyline (nominal concentrations between 1 and 1000 µg/L) and two concentrations of MP (104 and 105 particles/L; <50 µm) for three weeks. Tissue cortisol concentration, oxidative stress, and the activity of two carboxylesterases and of acetylcholinesterase were assessed. Furthermore, the swimming behavior was analyzed in situations with different stress levels. Exposure to amitriptyline altered the behavior and increased the activity of acetylcholinesterase. Moreover, nominal amitriptyline concentrations above 300 µg/L caused severe acute adverse effects in fish. MP alone did not affect any of the investigated endpoints. Co-exposure caused largely similar effects such as the exposure to solely amitriptyline. However, the effect of amitriptyline on the swimming behavior during the experiment was alleviated by the higher MP concentration.

Adverse effects of microplastics on earthworms: A critical review

Microplastics are widely distributed in terrestrial environments and have been known to adversely affect earthworms. Based on 65 publications, we summarized the effects of microplastics on the growth, behavior, oxidative responses, gene expression, and gut microbiota of earthworms. Since microplastics are often present simultaneously with other pollutants, especially heavy metals and hydrophobic organic chemicals (HOCs), the interactions and combined effects of microplastics and these pollutants on earthworms have also been discussed. It has been shown that earthworms can selectively ingest microplastics, preferring to those with smaller particle size (especially smaller than 50 μm) and biodegradable compositions. Generally, microplastics with higher concentrations (especially those > 0.5%, w/w) and smaller sizes (e.g., 100 nm) have greater adverse effects on earthworms. Additionally, microplastics can facilitate the accumulation of heavy metals and organic pollutants by earthworms and pose severer damages. Current knowledge gaps and perspectives for future work are pointed out.

High-performance micro/nanoplastics characterization by MALDI-FTICR mass spectrometry

Micro/nanoplastics (MNPs) are widespread environmental pollutants that cause high health risks. However, high heterogeneity in particle sizes and chemical compositions of MNPs make their accurate characterization extremely challenging. Herein, we established a matrix-assisted laser desorption ionization-Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR MS) strategy for the unambiguous characterization of different types of MNPs with high performance, including polystyrene, polyethylene glycol terephthalate, polyamide, polymethyl methacrylate, acrylonitrile butadiene styrene copolymer, and polycarbonate. The MNP sample preparation and detection conditions were systematically optimized by using response surface methodology, and the MS detection signal-to-noise ratios were improved 1.5 times on average. The ultrahigh mass resolution of FTICR MS is crucial to the unambiguous elucidation of MNP structures. We demonstrate that this MS strategy is highly efficient in the characterization of polymer constitutions of environmental MNPs derived from foam, bottles, cable ties, and compact discs, providing a promising tool for MNP detection and safety evaluation.

Microplastics as Contaminants in Water Bodies and Their Threat to the Aquatic Animals: A Mini-Review

Microplastics (MPs), which are particles with a diameter of less than 5 mm, have been extensively studied due to their serious global pollution. Typically, MPs in water originate from terrestrial input. A number of studies have reported the presence of MPs as a stressor in water environments worldwide, and their potential threat to the aquatic animals, affecting the growth, oxidative stress responses, body composition, histopathology, intestinal flora, and immune and reproduction systems. During the plastic degradation process, a large variety of toxic substances are released. MPs have been proposed to be the carriers of toxic chemicals and harmful microorganisms. A study of the literature on MP pollution and stress on the aquatic animals associated with MPs was carried out.

Dietary exposure to polystyrene nanoplastics impairs fasting-induced lipolysis in adipose tissue from high-fat diet fed mice

The health concerns of microplastics (MPs) and nanoplastics (NPs) surge, but the key indicators to evaluate the adverse risks of MPs/NPs are elusive. Recently, MPs/Ps were found to disturb glucose and lipid metabolism in rodents, suggesting that MPs/NPs may play a role in obesity progression. In this study, we firstly demonstrated that the distribution of fluorescent polystyrene nanoplastics (nPS, 60 nm) white adipose tissue (WAT) of mice. Furthermore, nPS could traffic across adipocytes in vitro and reduced lipolysis under β-adrenergic stimulation in adipocytes in vitro and ex vivo. Consistently, chronic oral exposure to nPS at the dietary exposure relevant concentrations (3 and 223 μg/kg body weight) impaired fasting-induced lipid mobilization in obese mice and subsequently contributed to larger adipocyte size in the subcutaneous WAT. In addition, the chronic exposure of nPS induced macrophage infiltration in the small intestine and increased lipid accumulation in the liver, accelerating the disruption of systemic metabolism. Collectively, our findings highlight the potential obesogenic role of nPS via diminishing lipid mobilization in WAT of obese mice and suggest that lipolysis relevant parameters may be used for evaluating the adverse effect of MPs/NPs in clinics.

Size-dependent seizurogenic effect of polystyrene microplastics in zebrafish embryos

The effects of polystyrene microplastic (PS-MP) size on neurotoxicity remain to be evaluated at various microsizes, and the seizurogenic effects of PS-MPs are unknown. This study aimed to evaluate the swimming behavior of zebrafish larvae under light-dark transitions after exposure to four PS-MP sizes (i.e., 1, 6, 10, and 25 μm) at concentrations of 500, 5,000, and 50,000 particles/mL. Changes in electroencephalographic signals, seizure-related gene expression, and neurochemical concentrations were measured. Locomotor activity was inhibited only by 10-μm PS-MPs. According to electroencephalographic signals, the number and total duration of seizure-like events significantly increased by 10-μm PS-MPs, which was confirmed by the altered expression of seizure-related genes c-fos and pvalb5. Additionally, an increase in the levels of neurochemicals choline, betaine, dopamine, 3-methoxytyramine, and gamma-aminobutyric acid indicated that the observed hypoactivity and seizure-like behavior were associated with the dysregulation of the cholinergic, dopaminergic, and GABAergic systems. Overall, these findings demonstrate that exposure to PS-MPs can potentially cause seizurogenic effects in developing zebrafish embryos, and we highlight that PS-MPs 10 µm in size dominantly affect neurotoxicity.

Nanoplastics and Microplastics May Be Damaging Our Livers

Plastics in the environment can be degraded and even broken into pieces under the action of natural factors, and the degraded products with a particle size of less than 5 mm are called microplastics (MPs). MPs exist in a variety of environmental media that come into contact with the human body. It can enter the body through environmental media and food chains. At present, there are many studies investigating the damage of MPs to marine organisms and mammals. The liver is the largest metabolizing organ and plays an important role in the metabolism of MPs in the body. However, there is no available systematic review on the toxic effects of MPs on the liver. This paper summarizes the adverse effects and mechanisms of MPs on the liver, by searching the literature and highlighting the studies that have been published to date, and provides a scenario for the liver toxicity caused by MPs.

The legacy effect of microplastics on aquatic animals in the depuration phase: Kinetic characteristics and recovery potential

The prevalence of microplastics (MPs) in global aquatic environments has received considerable attention. Currently, concerns have been raised regarding reports that the adverse effect of MPs on aquatic animals in the exposure phase may not be (completely) reversed in the depuration phase. In order to provide insights into the legacy effect of MPs from the depuration phase, this study evaluated the kinetic characteristics and recovery potential of aquatic animals after the exposure to MPs. More specifically, a total of 68 depuration kinetic curves were highly fitted to estimate the retention time of MPs. It was shown that the retention time ranged from 1.26 to 3.01 days, corresponding to the egestion of 90 % to 99 % of ingested MPs. The retention time decreased with the increased retention rate. Furthermore, variables potentially affecting the retention time were ranked by the decision tree-based eXtreme Gradient Boosting (XGBoost) algorithm, suggesting that the particle size and tested species were of great importance for explaining the difference in retention time of MPs. Moreover, a biomarker profile was recompiled to determine the toxic changes. Results indicated that the MPs-induced toxicity significantly reduced in the depuration phase, evidenced by the recovery of energy reserves and metabolism, hepatotoxicity, immunotoxicity, hematological parameters, neurotoxicity and oxidative stress. However, the continuous detoxification and remarkable genotoxicity implied that the toxicity was not completely alleviated. In addition, the current knowledge gaps are also highlighted, with recommendations proposed for future research.

Microplastics, both non-biodegradable and biodegradable, do not affect the whole organism functioning of a marine mussel

Microplastics are ubiquitous in the marine environment, and their uptake by many organisms has been well documented. Concern about increasing plastic waste in ecosystems and organisms has led to the production of biodegradable alternatives. However, long breakdown times of biodegradable plastics in natural environments mean they still have the potential to induce ecological impacts. The impacts of microplastics on organisms remain unclear, especially as many experimental microplastic exposures employ particle concentrations orders of magnitude greater than those found in natural ecosystems. Here, we exposed the ecosystem engineer, the Asian green mussel Perna viridis, to non-biodegradable and biodegradable microplastics at two environmentally relevant concentrations (~17-20 particles L^-1 and ~ 135-140 particles L^-1). After four weeks of exposure, there were no significant effects of microplastic type or concentration on the mortality, oxygen consumption rate, clearance rate, or condition index of P. viridis. With the increasing body of microplastic literature, future exposure studies considering biotic effects should make efforts to employ environmentally relevant concentrations. Further, we suggest that, while a high-profile threat to ecosystems, investigating the effects of microplastics on ecosystems should be conducted alongside, and not draw focus away from, other major threats such as climate change.