Microplastics induce neurotoxicity in aquatic animals at environmentally realistic concentrations: A meta-analysis

The effects of microplastics exposure on quail's hypothalamus: Neurotransmission disturbance, cytokine imbalance and ROS/TGF-β/Akt/FoxO3a signaling disruption

Microplastics (MPs) have become a major focus of environmental toxicology, raising concerns about their potential adverse effects on animal organs and body systems. As these tiny particles infiltrate ecosystems, they may pose risks to the health of organisms across diverse species. In this study, we attempted to examine the neurotoxic effects of MPs exposure on avian hypothalamus by using an animal model-Japanese quail (Coturnix japonica). The quails of 7-day-old were exposed to 0.02 mg/kg, 0.4 mg/kg and 8 mg/kg polystyrene microplastic (PS-MPs) of environmental relevance for 35 days. The results showed PS-MPs exposure did damages to hypothalamic structure characterized by neuron malformation, irregular arrangement and cellular vacuolation after 5-week exposure. PS-MPs exposure also induced Nissl body reduction and dissolution in the hypothalamus. Moreover, the decrease of acetylcholinesterase (AchE) activity and increasing acetylcholine (Ach) indicated that PS-MPs exposure caused hypothalamic neurotransmission disturbance. PS-MPs exposure also led to neuroinflammation by disrupting the balance between proinflammatory and anti-inflammatory cytokines. Moreover, increasing reactive oxygen species (ROS) and malondialdehyde (MDA) generation with reducing antioxidants indicated PS-MPs led to hypothalamic oxidative stress. Additionally, RNA-Seq analysis found that both transforming growth factor-β (TGF-β) signaling and forkhead box O (FoxO) signaling were disturbed in the hypothalamus by PS-MPs exposure. Especially, the increasing ROS led to TGF-β activation and then induced hypothalamic inflammation by nuclear factor κB (NF-κB) activation. The present study concluded that oxidative stress might be an important mechanistic signaling involved in MPs neurotoxicology.

Unlocking the combined impact of microplastics and emerging contaminants on fish: A review and meta-analysis

Microplastics (MPs) possess unique adsorptive properties that render their surfaces prone to absorbing other contaminants. When interacting with these emerging contaminants, MPs may have unpredictable negative impacts on fish. Prior studies have primarily concentrated on the impact of single contaminants, while investigations into combined pollution have not received adequate attention. Therefore, research on combined pollution holds greater practical significance. The physiological indicators of fish affected by emerging contaminants and the mechanisms behind these effects are not yet fully clear. To address this issue, a meta-analysis was performed to evaluate the impact of combined pollution of MPs-containing emerging contaminants on various aspects of fish health, encompassing behavior, consumption, development, and reproduction, along with the assessment of oxidative stress and neurotoxicity of fish. The results of the meta-analysis indicated that combined pollution adversely impacted fish reproduction, development, oxidative stress, and neurotoxicity. Importantly, significant differences were observed between fish species regarding their susceptibility to function and oxidative stress. Further investigation into the mechanisms of the impact of combined pollution on fish revealed that the magnitude of this impact is closely associated with the characteristics of the MPs themselves. MPs with higher adsorption capacities tend to lead to more severe consequences, while the impact of MPs with lower adsorption capacities relies more on their toxicity. Nevertheless, a close correlation between the duration of exposure to combined pollution and the level of oxidative stress in fish was not identified. Through a systematic analysis of existing studies, this review not only explored the cumulative effects of combined pollution on fish but also highlighted the intricate nature of such pollution within aquatic ecosystems. It contributes to the growing body of knowledge on the subject and emphasizes the need for further research to unravel the complexities associated with the combined impact of MPs-containing emerging contaminants on aquatic life.

Amino modifications exacerbate the developmental abnormalities of polystyrene microplastics via mitochondria-mediated apoptosis pathway in zebrafish larvae

Microplastics (MPs) are ubiquitous in the environment and have been identified as a potential threat to ecosystems. However, the mechanisms of toxicity of modified MPs remain unknown. This study investigated the developmental toxicity of amino-modified polystyrene microplastics (PS-NH2) with environmentally relevant concentrations ranging from 0.1 to 100 μg/L in the early developmental stages of zebrafish. Adding amino functional groups resulted in significant alterations in the surface morphology and zeta potential of traditional polystyrene microplastics (PS-MPs). Zebrafish larvae exposed to PS-NH2 exhibited increased developmental toxicity compared to PS-MPs, as indicated by reduced body length, heart rate, and spontaneous movement. The expression of cat1, sod1, gstr1, nrf2a, nrf2b, and HO-1, as well as alterations in ROS, SOD, CAT, and MDA levels, all demonstrated oxidative damage caused by PS-NH2 exposure. Mitochondrial dysfunction was also induced, as evidenced by changes in the expression of cox4i1, ndufs1, and uqcrc1, as well as changes in the levels of ATP, cytochrome c, NAD, and NADH. Furthermore, PS-NH2 exposure disrupted apoptosis regulation, increasing apoptotic cells and caspase activity, along with changes in caspase-3 and bcl-2 expression. Molecular docking showed that PS-NH2 interacts with bcl-2 with high binding energy. This study contributes to understanding the toxic effects and mechanisms of charge-modified MPs in zebrafish.

Environmental behavior and toxic effects of micro(nano)plastics and engineered nanoparticles on marine organisms under ocean acidification: A review

Ocean acidification (OA) driven by human activities and climate change presents new challenges to marine ecosystems. At the same time, the risks posed by micro(nano)plastics (MNPs) and engineered nanoparticles (ENPs) to marine ecosystems are receiving increasing attention. Although previous studies have uncovered the environmental behavior and the toxic effects of MNPs and ENPs under OA, there is a lack of comprehensive literature reviews in this field. Therefore, this paper reviews how OA affects the environmental behavior of MNPs and ENPs, and summarizes the effects and the potential mechanisms of their co-exposure on marine organisms. The review indicates that OA changes the marine chemical environment, thereby altering the behavior of MNPs and ENPs. These changes affect their bioavailability and lead to co-exposure effects. This impacts marine organisms' energy metabolism, growth and development, antioxidant systems, reproduction and immunity. The potential mechanisms involved the regulation of signaling pathways, abnormalities in energy metabolism, energy allocation, oxidative stress, decreased enzyme activity, and disruptions in immune and reproductive functions. Finally, based on the limitations of existing research, actual environment and hot issues, we have outlined future research needs and identified key priorities and directions for further investigation. This review deepens our understanding of the potential effects of MNPs and ENPs on marine organisms under OA, while also aiming to promote further research and development in related fields.

Microplastics/nanoplastics and neurological health: An overview of neurological defects and mechanisms

The widespread use of plastic products worldwide has brought about serious environmental issues. In natural environments, it's difficult for plastic products to degrade completely, and so they exist in the form of micro/nanoplastics (M/NPs), which have become a new type of pollutant. Prolonged exposure to M/NPs can lead to a series of health problems in humans, particularly toxicity to the nervous system, with consequences including neurodevelopmental abnormalities, neuronal death, neurological inflammation, and neurodegenerative diseases. Although direct evidence from humans is still limited, model organisms and organoids serve as powerful tools to provide important insights. This article summarizes the effects of M/NPs on the nervous system, focusing on cognitive function, neural development, and neuronal death. Mechanisms such as neurotransmitter synthesis and release, inflammatory responses, oxidative stress, the gut-brain axis, and the liver-brain axis are covered. The neurotoxicity induced by M/NPs may exacerbate or directly trigger neurodegenerative diseases and neurodevelopmental disorders. We particularly emphasize potential therapeutic agents that may counteract the neurotoxic effects induced by M/NPs, highlighting a novel future research direction. In summary, this paper cites evidence and provides mechanistic perspectives on the effects of M/NPs on neurological health, providing clues for eliminating M/NP hazards to human health in the future.

Identification and analysis of microplastic aggregation in CAR-T cells

Microplastics (MPs) are increasingly recognized as contaminants present in various environments and are widely acknowledged as potential hazards to the mammalian immune system. In our study of chimeric antigen receptor T cell (CAR-T) therapy, we observed the presence of MP in CAR-T cell products for the first time. It is worth exploring whether MP could enter CAR-T cells and how they might affect CAR-T cells' functionality. Therefore, we analyzed how MP affected CD19 and BCMA-CAR-T cells. Based on flow cytometry, ELISA, and cytotoxicity analysis of in vitro and in vivo experiments, MP suppressed the activity of CAR-T cells. Subsequent investigation revealed that the exposure of CAR-T cells to varying concentrations of MP resulted in a notable increase in apoptosis, ferroptosis, and exhaustion levels. Furthermore, the hyperactivation of the mTOR signaling pathway in MP-treated CAR-T cells was verified. The partial restoration of CAR-T cell function in MP was achieved by inhibiting the mTOR pathway. MP present a threat to CAR-T cell function due to their role in inducing CAR-T cell apoptosis, ferroptosis, and T-cell exhaustion through the hyperactivation of mTOR signaling pathways.

Chronic effects of irregular and fibril microplastics on Artemia franciscana in a benthic environment: Size and shape-dependent toxicity

Marine ecosystems are contaminated by plastic products, particularly microplastics (MPs), which settle on the seafloor and affect benthic organisms. This study explores the toxicity of irregular fibril-shaped MPs of various sizes and lengths on Artemia franciscana. We exposed juvenile A. franciscana to irregular-shaped MPs of three sizes, small (<20 μm), medium (40-70 μm), and large (>120 μm), and MP fibers of two length categories, short (200-300 μm) and long (3 mm), in a sand-layered benthic system. The concentrations of the MPs were maintained at 0.05-20 mg/L, and the study was conducted over a 28-d of chronic period. Among all the MPs considered in this study, the small and short MPs exerted the most severe effects (causing mortality, growth inhibition, gut damage, alterations in movement, and a decrease in positive phototaxis). Our study highlights the importance of considering the morphological characteristics of MPs for analyzing their toxicity to aquatic eco-receptors.

Microplastic effects on soil nitrogen cycling enzymes: A global meta-analysis of environmental and edaphic factors

Microplastic accumulation in soil ecosystems poses significant environmental concerns, potentially impacting nitrogen cycling processes and ecosystem health. This meta-analysis of 147 studies (1138 data points) assessed the impact of microplastics (MPs) on soil nitrogen-acquisition enzymes. We found that MPs exposure significantly increased soil urease (UE) and leucine aminopeptidase activities by 7.6 % and 8.0 %, respectively, while N-acetyl-β-D-glucosaminidase activity was not significantly affected. Biodegradable MPs showed more pronounced effects compared to conventional MPs. Enzyme activities were influenced by MPs properties (e.g., polymer type, size, concentration), experimental conditions (e.g., field or laboratory setting, temperature, nitrogen fertilization), and soil properties (e.g., clay content, pH, organic carbon, total nitrogen). For instance, acidic soils enhanced UE activity, while neutral soils reduced it. These findings emphasize the complex interactions between MPs and soil ecosystems, highlighting the need for context-specific environmental management strategies and policy-making approaches to mitigate the impacts of MPs pollution on soil health.

Hazardous effects of plastic microfibres from facial masks to aquatic animal health: Insights from zebrafish model

Facial masks are a source of plastic microfibres (PMFs) in the aquatic environment, an emerging risk factor for aquatic organisms. However, little is known concerning its impact during the early developmental stages of fish. Thus, the current study aimed to evaluate the potential interaction and developmental toxicity of PMFs derived from leachate of surgical masks (SC-Msk) and N-95 facial masks (N95-Msk) using a multi-biomarker approach in developing zebrafish (Danio rerio). PMFs from both facial masks were obtained and characterized by multiple techniques. Zebrafish embryos were exposed to environmentally relevant concentrations of PMFs from both facial masks (1000, 10,000, and 100,000 particle L-1), and the toxicity was analysed in terms of mortality, hatching rate, neurotoxicity, cardiotoxicity, morphological changes, reactive oxygen species (ROS) levels, cell viability, and behavioural impairments. The results showed that both facial masks can release PMFs, but the N95-Msk produced a higher concentration of PMFs than SC-Msk. Both PMFs can interact with zebrafish chorion and don't cause effects on embryo mortality and hatching; however, zebrafish embryos showed cardiotoxic effects, and larvae showed increased agitation, average speed, and distance travelled, indicating the behavioural impairments induced by PMFs derived from facial masks. Overall, results showed the risk of PMFs to the health of freshwater fish, indicating the need for greater attention to the disposal and ecotoxicological effects of facial masks on aquatic organisms.

Microplastics predominantly affect gut microbiota by altering community structure rather than richness and diversity: A meta-analysis of aquatic animals

The impacts of microplastics on the gut microbiota, a crucial component of the health of aquatic animals, remain inadequately understood. This phylogenetically controlled meta-analysis aims to identify general patterns of microplastic effects on the alpha diversity (richness and Shannon index), beta diversity, and community structure of gut microbiota in aquatic animals. Data from 63 peer-reviewed articles on the Web of Science were synthesized, encompassing 424 observations across 31 aquatic species. The analysis showed that microplastics significantly altered the community structure of gut microbiota, with between-group distances being 87.75% higher than within-group distances. This effect was significant even at environmentally relevant concentrations (≤1 mg L-1). However, their effects on richness, Shannon index, and beta diversity (community variation) were found to be insignificant. The study also indicated that the effects of microplastics were primarily dependent on their concentration and size, while the phylogeny of tested species explained limited heterogeneity. Furthermore, variations in gut microbiota alpha diversity, beta diversity, and community structure were correlated with changes in antioxidant enzyme activities from the liver and hepatopancreas. This implies that gut microbiota attributes of aquatic animals may provide insights into host antioxidant levels. In summary, this study illuminates the impacts of microplastics on the gut microbiota of aquatic animals and examines the implications of these effects for host health. It emphasizes that microplastics mainly alter the community structure of gut microbiota rather than significantly affecting richness and diversity.

Impacts of microplastics on ecosystem services and their microbial degradation: a systematic review of the recent state of the art and future prospects

Microplastics are tiny plastic particles with a usual diameter ranging from ~ 1 μ to 5 µm. Recently, microplastic pollution has raised the attention of the worldwide environmental and human concerns. In human beings, digestive system illness, respiratory system disorders, sleep disturbances, obesity, diabetes, and even cancer have been reported after microplastic exposure either through food, air, or skin. Similarly, microplastics are also having negative impacts on the plant health, soil microorganisms, aquatic lives, and other animals. Policies and initiatives have already been in the pipeline to address this problem to deal with microplastic pollution. However, many obstacles are also being observed such as lack of knowledge, lack of research, and also absence of regulatory frameworks. This article has covered the distribution of microplastics in water, soil, food and air. Application of multimodel strategies including fewer plastic item consumption, developing low-cost novel technologies using microorganisms, biofilm, and genetic modified microorganisms has been used to reduce microplastics from the environment. Researchers, academician, policy-makers, and environmentalists should work jointly to cope up with microplastic contamination and their effect on the ecosystem as a whole which can be reduced in the coming years and also to make earth clean.

Merkel cells and corpuscles of Stannius as putative targets for polyethylene terephthalate microfibers in sheepshead minnow larvae

Polyethylene terephthalate (PET) fibers are contaminated in wastewater from various primary sources, such as washing textile waters. PET fibers in the environment can be degraded into microfibers because of weathering processes such as sunlight, physical wear, and heat. Although recent studies reported adverse effects of PET microfibers on aquatic organisms, the lack of information on their toxicity and mode of action hampers the risk assessment of PET microfibers. Therefore, this study aimed to investigate the biological effects of PET microfibers and their underlying mechanisms in early-staged sheepshead minnows (Cyprinodon variegatus). PET microfibers (about 13 μm diameter × 106 μm length) were prepared by cutting PET threads and treated to sheepshead minnow larvae at 10 and 100 mg/L for 10 days. No acute toxicity was found in the minnow, but PET microfibers significantly produced reactive oxygen species and reduced behavioral responses of traveled distance and maximum velocity. The transcriptomic data suggested that Merkel cells (flow sensors) and corpuscles of Stannius (calcium regulator) are putative targets, which were derived from oxidative stress, sensory neuropathy, cognitive impairment, and movement disorders. These findings underscore that although PET microfibers are not directly lethal to sheepshead minnows, they could impact their survival by damaging swimming-related key genes. This study provides new insights into how PET microfibers are toxic to aquatic organisms and disrupt ecosystems beyond survival and pathological changes.

Microplastic ingestion in mussels from the East Mediterranean Sea: Exploring its impacts in nature and controlled conditions

Microplastic ingestion poses a significant concern for a plethora of marine organisms due to its widespread presence in marine ecosystems. Despite growing scientific interest, the effects on marine biota are not yet well understood. This study investigates the ingestion of microplastics (MPs) by mussels from various marine environments and assesses the associated effects that can be induced by MPs and associated toxic chemicals. Biomarkers of oxidative stress (catalase, lipid peroxidation), biotransformation (glutathione S-transferase), genotoxicity (micronuclei frequency) and neurotoxicity (acetylcholinesterase) were employed. Mussels, considered reliable bioindicators of MPs pollution, were sampled by hand from diverse locations under varied anthropogenic pressures, including a highly touristic Marine Protected Area (MPA) in the Ionian Sea, a mussel farm and a fish farm in the Aegean Sea. The results revealed the highest MP ingestion in mussels from the fish farm [0.21 ± 0.04 (SE) MPs/g or 0.63 ± 0.12 (SE) MPs/Ind.], likely due to plastic aquaculture equipment use. Stereoscopic observation revealed fibers, as the predominant shape of ingested MPs across all sites, and μFTIR polymer identification revealed the presence of various types, with polyethylene (PE) and polyamide (PA) being the most abundant. Significant physiological alterations in mussels related to MP ingestion levels were observed through biomarkers indicative of oxidative stress and biotransformation, as well as the Integrated Biomarker Response (IBR index). However, laboratory experiments with mussels exposed to controlled increasing PE concentrations for four weeks, did not show significant effects triggered by the PE ingestion, possibly indicating other environmental factors, such as contaminants from aquaculture environments, may influence biomarker levels in the field. Despite the observed effects, MP ingestion rates in mussels from the field were relatively low compared to other studies. Future research should continue to investigate the interactions between MPs and marine organisms in diverse environments to better understand and mitigate their impacts.

Microplastics and low tide warming: Metabolic disorders in intertidal Pacific oysters (Crassostrea gigas)

Sessile intertidal organisms live in a harsh environment with challenging environmental conditions and increasing anthropogenic pressure such as microplastic (MP) pollution. This study focused on effects of environmentally relevant MP concentrations on the metabolism of intertidal Pacific oyster Crassostrea gigas, and its potential MP-induced vulnerability to warming during midday low tide. Oysters experienced a simulated semidiurnal tidal cycle based on their natural habitat, and were exposed to a mixture of polystyrene microbeads (4, 7.5 and 10 µm) at two environmentally relevant concentrations (0.025 µg L-1 and 25 µg L-1) for 16 days, with tissue samplings after 3 and 12 days to address dose-dependent effects over time. On the last day of exposure, the remaining oysters were additionally exposed to low tide warming (3 °C h-1) to investigate possible MP-induced susceptibility to aerial warming. Metabolites of digestive gland and gill tissues were analysed by using untargeted 1H nuclear magnetic resonance (NMR) based metabolomics. For the digestive gland metabolite profiles were comparable to each other independent of MP concentration, exposure time, or warming. In contrast, gill metabolites were significantly affected by high MP exposure and warming irrespective of MP, initiating the same cellular stress response to counteract induced oxidative stress. The activated cascade of antioxidant defence mechanisms required energy on top of the general energy turnover to keep up homeostasis, which in turn may lead to subtle, and likely sub-lethal, effects within intertidal oyster populations. Present results underline the importance of examining the effects of environmentally relevant MP concentrations not only alone but in combination with other environmental stressors.

Behind conventional (micro)plastics: An ecotoxicological characterization of aqueous suspensions from End-of-Life Tire particles

Million tons of tires become waste every year, and the so-called End-of-Life Tires (ELTs) are ground into powder (ELT-dp; size < 0.8 mm) and granules (ELT-dg; 0.8 < size < 2.5 mm) for recycling. The aim of this study was to evaluate the sub-lethal effects of three different concentrations (0.1, 1, and 10 mg/L) of aqueous suspensions from ELT-dp and ELT-dg on Danio rerio (zebrafish) larvae exposed from 0 to 120 h post-fertilization (hpf). Chronic effects were assessed through biomarkers, real-time PCR, and proteomics. We observed a significant increase in swimming behavior and heart rate only in specimens exposed to ELT-dp suspensions at 1 and 10 mg/L, respectively. Conversely, the activities of detoxifying enzymes ethoxyresorufin-O-deethylase (EROD) and glutathione-S-transferase (GST) showed significant modulation only in specimens exposed to ELT-dg groups. Although no effects were observed through real-time PCR, proteomics highlighted alterations induced by the three ELT-dp concentrations in over 100 proteins involved in metabolic pathways of aromatic and nitrogen compounds. The results obtained suggest that the toxic mechanism of action (MoA) of ELT suspensions is mainly associated with the induction of effects by released chemicals in water, with a higher toxicity of ELT-dp compared to ELT-dg.

In-situ detection of microplastics in the aquatic environment: A systematic literature review

Microplastics are ubiquitous in the aquatic environment and have emerged as a significant environmental issue due to their potential impacts on human health and the ecosystem. Current laboratory-based microplastic detection methods suffer from various drawbacks, including a lack of standardisation, limited spatial and temporal coverage, high costs, and time-consuming procedures. Consequently, there is a need for the development of in-situ techniques to detect and monitor microplastics to effectively identify and understand their sources, pathways, and behaviours. Herein, we adopt a systematic literature review method to assess the development and application of experimental and field technologies designed for the in-situ detection and monitoring of aquatic microplastics, without the need for sample preparation. Four scientific databases were searched in March 2023, resulting in a review of 62 relevant studies. These studies were classified into seven sensor categories and their working principles were discussed. The sensor classes include optical devices, digital holography, Raman spectroscopy, other spectroscopy, hyperspectral imaging, remote sensing, and other methods. We also looked at how data from these technologies are integrated with machine learning models to develop classifiers capable of accurately characterising the physical and chemical properties of microplastics and discriminating them from other particles. This review concluded that in-situ detection of microplastics in aquatic environments is feasible and can be achieved with high accuracy, even though the methods are still in the early stages of development. Nonetheless, further research is still needed to enhance the in-situ detection of microplastics. This includes exploring the possibility of combining various detection methods and developing robust machine-learning classifiers. Additionally, there is a recommendation for in-situ implementation of the reviewed methods to assess their effectiveness in detecting microplastics and identify their limitations.

Oral Exposure to Microplastics Affects the Neurochemical Plasticity of Reactive Neurons in the Porcine Jejunum

Plastics are present in almost every aspect of our lives. Polyethylene terephthalate (PET) is commonly used in the food industry. Microparticles can contaminate food and drinks, posing a threat to consumers. The presented study aims to determine the effect of microparticles of PET on the population of neurons positive for selected neurotransmitters in the enteric nervous system of the jejunum and histological structure. An amount of 15 pigs were divided into three groups (control, receiving 0.1 g, and 1 g/day/animal orally). After 28 days, fragments of the jejunum were collected for immunofluorescence and histological examination. The obtained results show that histological changes (injury of the apical parts of the villi, accumulations of cellular debris and mucus, eosinophil infiltration, and hyperaemia) were more pronounced in pigs receiving a higher dose of microparticles. The effect on neuronal nitric oxide synthase-, and substance P-positive neurons, depends on the examined plexus and the dose of microparticles. An increase in the percentage of galanin-positive neurons and a decrease in cocaine and amphetamine-regulated transcript-, vesicular acetylcholine transporter-, and vasoactive intestinal peptide-positive neurons do not show such relationships. The present study shows that microparticles can potentially have neurotoxic and pro-inflammatory effects, but there is a need for further research to determine the mechanism of this process and possible further effects.

Special Distribution of Nanoplastics in the Central Nervous System of Zebrafish during Early Development

There is growing concern about the distribution of nanoplastics (NPs) in the central nervous system (CNS), whereas intrusion is poorly understood. In this study, fluorescent-labeled polystyrene NPs (PS-NPs) were microinjected into different areas of zebrafish embryo to mimic different routes of exposure. PS-NPs were observed in the brain, eyes, and spinal cord through gametal exposure. It indicated that maternally derived PS-NPs were specially distributed in the CNS of zebrafish during early development. Importantly, these NPs were stranded in the CNS but not transferred to other organs during development. Furthermore, using neuron GFP-labeled transgenic zebrafish, colocalization between NPs and the neuron cells revealed that NPs were mostly enriched in the CNS surrounded but not the neurons. Even so, the intrusion of NPs into the CNS induced the significant upregulation of some neurotransmitter receptors, leading to an inhibited effect on the movement of zebrafish larvae. This work provides insights into understanding the intrusion and distribution of NPs in the CNS and the subsequent potential adverse effects.

Role of UV radiation and oxidation on polyethylene micro- and nanoplastics: impacts on cadmium sorption, bioaccumulation, and toxicity in fish intestinal cells

This study investigated the role of ultraviolet (UV) radiation and oxidation in high-density polyethylene microplastics (2-15 μm) and nanoplastics (0.2-9.9 μm) (NMPs) on particle chemistry, morphology, and reactivity with cadmium (Cd). Additionally, toxicity of NMPs alone and with Cd was evaluated using RTgutGC cells, a model of the rainbow trout (Oncorhynchus mykiss) intestine. The role on NMPs on Cd bioaccumulation in RTgutGC cells was also evaluated. Dynamic light scattering indicated that after UV radiation NPs agglomerated size increased from 0.8 to 28 µm, and to 8 µm when Cd was added. Oxidized MPs agglomerated size increased from 11 and 7 to 46 and 27 µm in non-UV- and UV-aged oxidized MPs when adding Cd, respectively. Cd-coated particles exhibited generally significantly higher zeta potential than non-Cd-coated particles, while attenuated total reflectance-Fourier transform infrared spectroscopy showed that the functional chemistry of the particles was oxidized and modified after being exposed to UV radiation. Presence of NMPs resulted in a significant decrease in Cd bioaccumulation in RTgutGC cells (100.5-87.9 ng Cd/mg protein) compared to Cd alone (138.1 ng Cd/mg protein), although this was not quite significant for co-exposures with UV-aged NPs (105.7 ng Cd/mg protein). No toxicity was observed in RTgutGC cells exposed to NMPs alone for 24 h. Moreover, co-exposures with Cd indicated that NMPs reduce the toxicity of Cd. Altogether these results show that UV aging enhances NMP surface reactivity, increasing Cd absorption in solution, which resulted in a reduction in Cd bioavailability and toxicity.

Polystyrene nanoplastics cause reproductive toxicity in zebrafish: PPAR mediated lipid metabolism disorder

The ubiquitous presence of micro-and nanoplastics (MNPs) in the environment and everyday products has attracted attention due to their hazardous risks. However, the effects of MNPs on reproduction and the underlying mechanisms remain unclear. The present study investigated the impact of polystyrene (PS) nanoplastics of 80, 200 and 500 nm diameters on zebrafish reproduction at an environmentally relevant concentration of 0.5 mg/L. Exposure to PS delayed spermatogenesis and caused aberrant follicular growth, resulting in dysgenesis in F0 adults and impacting F1 embryo development. Notably, the reproductive toxicity exhibited size-dependency, with the 500 nm PS being the most detrimental. Combined analyses of transcriptomics and metabolomics in ovary tissue revealed that treatment with 500 nm PS affected the peroxisome proliferator-activated receptor (PPAR) signaling pathway, dysregulated lipid transport, binding and activity processes, and led to dysgenesis in zebrafish. Specifically, the ovulatory dysfunction induced by PS exposure resembled clinical manifestations of polycystic ovary syndrome (PCOS) and can be attributed to lipid metabolism disorder involving glycerophospholipid, sphingolipid, arachidonic acid, and alpha-linolenic acid. Collectively, our results provide new evidence revealing the molecular mechanisms of PS-induced reproductive toxicity, highlighting that MNPs may pose a risk to female reproductive health.

When antibiotics encounter microplastics in aquatic environments: Interaction, combined toxicity, and risk assessments

Antibiotics and microplastics (MPs), known as emerging pollutants, are bound to coexist in aquatic environments due to their widespread distribution and prolonged persistence. To date, few systematic summaries are available for the interaction between MPs and antibiotics in aquatic ecosystems, and a comprehensive reanalysis of their combined toxicity is also needed. Based on the collected published data, we have analyzed the source and distribution of MPs and antibiotics in global aquatic environments, finding their coexistence occurs in a lot of study sites. Accordingly, the presence of MPs can directly alter the environmental behavior of antibiotics. The main influencing factors of interaction between antibiotics and MPs have been summarized in terms of the characteristics of MPs and antibiotics, as well as the environmental factors. Then, we have conducted a meta-analysis to evaluate the combined toxicity of antibiotics and MPs on aquatic organisms and the related toxicity indicators, suggesting a significant adverse effect on algae, and inapparent on fish and daphnia. Finally, the environmental risk assessments for antibiotics and MPs were discussed, but unfortunately the standardized methodology for the risk assessment of MPs is still challenging, let alone assessment for their combined toxicity. This review provides insights into the interactions and environment risks of antibiotics and MPs in the aquatic environment, and suggests perspectives for future research.

Behavioral toxicity and neurotoxic mechanisms of PLA-PBAT biodegradable microplastics in zebrafish

Escalation of ecological concern due to biodegradable plastics has attracted the attention of many contemporary researchers. This study searched to investigate the acute and sub-chronic toxicity of polylactic acid (PLA) and polybutyleneadipate-co-terephthalate (PLA-PBAT) bio-microplastics on 3-month-old zebrafish to elucidate their potential toxic mechanisms. Acute toxicity assessments revealed 96 h-LC50 value of 12.69 mg/L for PLA-PBAT. Sub-chronic exposure of over 21 days revealed deviations in critical behavioral patterns and physiological indicators. In treated groups, weight gain and specific growth rates were significantly lower than those obtained for the control group, such that high doses induced significant reductions in total organ coefficient (p < 0.05). A positive correlation was observed between zebrafish mortality and increased doses. Detailed behavioral evaluations revealed a dose-dependent decrease in the speed and range of swimming, along with modifications in shoaling behavior, anxiety-like responses, and avoidance behaviors. Brain tissues transcriptomic analyses revealed the molecular responses underlying sub-chronic exposure to PLA-PBAT. Totally 702 DEGs and 5 KEGG pathways were significantly identified in low-dose group, with the top 2 significant pathways being ribosome pathway and cytokine-cytokine receptor interaction pathway. Totally 650 DEGs and 5 KEGG pathways were significantly identified in medium-dose group, with the top 2 significant pathways being Herpes simplex virus 1 infection pathway and complement and coagulation cascades pathway. Totally 1778 DEGs and 16 KEGG pathways were significantly identified in high-dose group, with the top 2 significant pathways being metabolism of xenobiotics by cytochrome P450 and drug metabolism - cytochrome P450 pathway. Most significantly enriched pathways are associated with immune responses. The validation of key gene in cytokine-cytokine receptor interaction pathway also confirmed its high correlation with behavioral indicators. These results indicate that PLA-PBAT is likely to cause behavioral abnormalities in zebrafish by triggering immune dysregulation in the brain.

Nanoplastics and Neurodegeneration in ALS

Plastic production, which exceeds one million tons per year, is of global concern. The constituent low-density polymers enable spread over large distances and micro/nano particles (MNPLs) induce organ toxicity via digestion, inhalation, and skin contact. Particles have been documented in all human tissues including breast milk. MNPLs, especially weathered particles, can breach the blood-brain barrier, inducing neurotoxicity. This has been documented in non-human species, and in human-induced pluripotent stem cell lines. Within the brain, MNPLs initiate an inflammatory response with pro-inflammatory cytokine production, oxidative stress with generation of reactive oxygen species, and mitochondrial dysfunction. Glutamate and GABA neurotransmitter dysfunction also ensues with alteration of excitatory/inhibitory balance in favor of reduced inhibition and resultant neuro-excitation. Inflammation and cortical hyperexcitability are key abnormalities involved in the pathogenic cascade of amyotrophic lateral sclerosis (ALS) and are intricately related to the mislocalization and aggregation of TDP-43, a hallmark of ALS. Water and many foods contain MNPLs and in humans, ingestion is the main form of exposure. Digestion of plastics within the gut can alter their properties, rendering them more toxic, and they cause gut microbiome dysbiosis and a dysfunctional gut-brain axis. This is recognized as a trigger and/or aggravating factor for ALS. ALS is associated with a long (years or decades) preclinical period and neonates and infants are exposed to MNPLs through breast milk, milk substitutes, and toys. This endangers a time of intense neurogenesis and establishment of neuronal circuitry, setting the stage for development of neurodegeneration in later life. MNPL neurotoxicity should be considered as a yet unrecognized risk factor for ALS and related diseases.

Microplastic contamination in wastewater: Sources, distribution, detection and remediation through physical and chemical-biological methods

Microplastics are tiny plastic particles smaller than 5 mm. that have been widely detected in the environment, including in wastewater. They originate from various sources including breakdown of larger plastic debris, release of plastic fibres from textiles, and microbeads commonly used in personal care products. In wastewater, microplastics can pass through the treatment process and enter the environment, causing harm to biodiversity by potentially entering the food chain. Additionally, microplastics can act as a vector for harmful pollutants, increasing their transport and distribution in the environment. To address this issue, there is a growing need for effective wastewater treatment methods that can effectively remove microplastics. Currently, several physical and chemical methods are available, including filtration, sedimentation, and chemical degradation. However, these methods are costly, low efficiency and generate secondary pollutants. Furthermore, lack of standardization in the measurement and reporting of microplastics in wastewater, makes it difficult to accurately assess microplastic impact on the environment. In order to effectively manage these issues, further research and development of effective and efficient methods for removing microplastics from wastewater, as well as standardization in measurement and reporting, are necessary to effectively manage these detrimental contaminants.

Polystyrene Nano- and Microplastic Particles Induce an Inflammatory Gene Expression Profile in Rat Neural Stem Cell-Derived Astrocytes In Vitro

Microplastics are considered an emerging environmental pollutant due to their ubiquitous presence in the environment. However, the potential impact of microplastics on human health warrants further research. Recent studies have reported neurobehavioral and neurotoxic effects in marine and rodent models; however, their impact on the underlying cellular physiology in mammals remains unclear. Herein, we exposed neural stem cells and neural stem cell-derived astrocytes, oligodendrocytes, and neurons to various sizes and concentrations of polystyrene nano- and microplastics. We investigated their cellular uptake, impact on cytotoxicity, and alteration of gene expression through transcriptome profiling. The cell type most affected by decreased viability were astrocytes after 7 days of repeated exposure. Transcriptional analysis showed that 1274 genes were differentially expressed in astrocytes exposed to 500 nm microplastics, but only 531 genes were altered in astrocytes exposed to 50 nm nanoplastics. Both canonical pathway and Kyoto Encyclopedia of Genes and Genomes analysis showed that upregulated pathways were involved in neuroinflammation, innate and adaptive immunity, cell migration, proliferation, extracellular matrix remodeling, and cytoskeleton structures. The downregulated pathways were involved in lipid metabolism, specifically fatty acid oxidation and cholesterol metabolism. Our results show that neural stem cell-derived astrocytes repeatedly exposed to nano- and microplastics for 7 days undergo changes that are hallmarks of astrogliosis.

Polystyrene nanoplastics induced size-dependent developmental and neurobehavioral toxicities in embryonic and juvenile zebrafish

Because of widespread environmental contamination, there is growing concern that nanoplastics may pose a risk to humans and the environment. Due to their small particle size, nanoplastics may cross the blood-nerve barrier and distribute within the nervous system. The present study systematically investigated the uptake/distribution and developmental/neurobehavioral toxicities of different sizes (80, 200, and 500 nm) of polystyrene nanoplastics (PS) in embryonic and juvenile zebrafish. The results indicate that all three sizes of PS could cross the chorion, adsorb by the yolk, and distribute into the intestinal tract, eye, brain, and dorsal trunk of zebrafish, but with different patterns. The organ distribution and observed developmental and neurobehavioral effects varied as a function of PS size. Although all PS exposures induced cell death and inflammation at the cellular level, only exposures to the larger PS resulted in oxidative stress. Meanwhile, exposure to the 80 nm PS increased the expression of neural and optical-specific mRNAs. Collectively, these studies indicate that early life-stage exposures to PS adversely affect zebrafish neurodevelopment and that the observed toxicities are influenced by particle size.

Microplastics cause hepatotoxicity in diabetic mice by disrupting glucolipid metabolism via PP2A/AMPK/HNF4A and promoting fibrosis via the Wnt/β-catenin pathway

In recent years, microplastics (MPs) have gained significant attention as a persistent environmental pollutant resulting from the decomposition of plastics, leading to their accumulation in the human body. The liver, particularly of individuals with type 2 diabetes mellitus (T2DM), is known to be more susceptible to the adverse effects of environmental pollutants. Therefore, to investigate the potential impact of MPs on the liver of diabetic mice and elucidate the underlying toxicological mechanisms, we exposed db/db mice to 0.5 μm MPs for 3 months. Our results revealed that MPs exposure resulted in several harmful effects, including decreased body weight, disruption of liver structure and function, elevated blood glucose levels, impaired glucose tolerance, and increased glycogen accumulation in the hepatic tissue of the mice. Furthermore, MPs exposure was found to promote hepatic gluconeogenesis by perturbing the PP2A/AMPK/HNF4A signaling pathway. In addition, MPs disrupt redox balance, leading to oxidative damage in the liver. This exposure also disrupted hepatic lipid metabolism, stimulating lipid synthesis while inhibiting catabolism, ultimately resulting in the development of fatty liver. Moreover, MPs were found to induce liver fibrosis by activating the Wnt/β-catenin signaling pathway. Furthermore, MPs influenced adaptive thermogenesis in brown fat by modulating the expression of uncoupling protein 1 (UCP1) and genes associated with mitochondrial oxidative respiration thermogenesis in brown fat. In conclusion, our study demonstrates that MPs induce oxidative damage in the liver, disturb glucose and lipid metabolism, promote hepatic fibrosis, and influence adaptive thermogenesis in brown fat in diabetic mice. These findings underscore the potential adverse effects of MPs on liver health in individuals with T2DM and highlight the importance of further research in this area.

PLASTAMINATION: Outcomes on the Central Nervous System and Reproduction

BACKGROUND

Environmental exposures to non-biodegradable and biodegradable plastics are unavoidable. Microplastics (MPs) and nanoplastics (NPs) from the manufacturing of plastics (primary sources) and the degradation of plastic waste (secondary sources) can enter the food chain directly or indirectly and, passing biological barriers, could target both the brain and the gonads. Hence, the worldwide diffusion of environmental plastic contamination (PLASTAMINATION) in daily life may represent a possible and potentially serious risk to human health.

OBJECTIVE

This review provides an overview of the effects of non-biodegradable and the more recently introduced biodegradable MPs and NPs on the brain and brain-dependent reproductive functions, summarizing the molecular mechanisms and outcomes on nervous and reproductive organs. Data from in vitro, ex vivo, non-mammalian and mammalian animal models and epidemiological studies have been reviewed and discussed.

RESULTS

MPs and NPs from non-biodegradable plastics affect organs, tissues and cells from sensitive systems such as the brain and reproductive organs. Both MPs and NPs induce oxidative stress, chronic inflammation, energy metabolism disorders, mitochondrial dysfunction and cytotoxicity, which in turn are responsible for neuroinflammation, dysregulation of synaptic functions, metabolic dysbiosis, poor gamete quality, and neuronal and reproductive toxicity. In spite of this mechanistic knowledge gained from studies of non-biodegradable plastics, relatively little is known about the adverse effects or molecular mechanisms of MPs and NPs from biodegradable plastics.

CONCLUSION

The neurological and reproductive health risks of MPs/NPs exposure warrant serious consideration, and further studies on biodegradable plastics are recommended.

Exposure to polystyrene nanoplastics and PCB77 induced oxidative stress, histopathological damage and intestinal microbiota disruption in white hard clam Meretrix lyrata

The toxic effects of organic pollutants and nanoplastics on fish have been extensively studied, but there is limited research available on their combined toxicity to bivalves. This research aimed to investigate the accumulation and ecotoxicological impacts such as antioxidant capacity, histopathology and intestinal microbiota in white hard clam Meretrix lyrata, resulting from 7 days of single and mixture exposure to 3,3',4,4'-tetrachlorobiphenyl (PCB77, 0.1 mg/L) and polystyrene nanoplastics (PS-NPs, 80 nm, 1 mg/L). Our findings revealed that PS-NPs accumulated in various tissues such as the intestine, gill, mantle, foot, and siphon. And when compared to the PCB-PSNPs (PP) co-exposure group, the intestinal fluorescence intensity mediated by plastic particles in the PS-NPs (PS group) was significantly higher. The gill, digestive gland, and intestine were all damaged to varying extent by single exposure to PS-NPs or PCB77, according to histopathological analysis, which was aggravated by PP group. Moreover, the co-exposure induced a higher level of oxidative stress, which reflected by increase of activities of superoxide dismutase, catalase, glutamate oxaloacetate transaminase and glutamic-pyruvic transaminase and malondialdehyde content. In addition, the intestine microbial composition was dramatically altered by the combined exposure, reducing the abundance of probiotics such as Firmicutes, thereby posing a great threat to the health and metabolism of M. lyrata. In conclusion, our findings showed that PS-NPs and PCB77 co-exposure induced a higher toxicity to M. lyrata, including histopathological changes, altered antioxidant capacity and intestinal microbiota disruption. This study provides novel insights into PCB77 and PS-NPs' combined toxicity to marine organisms and its underlying molecular mechanisms of ecotoxicological effects.

Size- and surface charge-dependent hormetic effects of microplastics on bacterial resistance and their interactive effects with quinolone antibiotic

The facilitation of microplastics (MPs) on bacterial resistance has attracted wide concern, due to the widespread presence of MPs in environmental media and their ubiquitous contact with bacteria strains. Furthermore, MPs possibly co-exist with antibiotics to trigger combined stress on bacterial survival. Therefore, it is significant to reveal the dose-responses of MPs and MP-antibiotic mixtures on bacterial endogenous and exogenous resistance. In this study, 0.1 and 5 μm polystyrenes with no surface functionalization (PS-NF, no charge), surface functionalized with amino groups (PS-NH2, positive charge) and carboxyl groups (PS-COOH, negative charge) were selected as the test MPs, and norfloxacin (NOR) was set as the representative of antibiotics. It was found that six types of PS all inhibited the growth of Escherichia coli (E. coli) but induced hormetic dose-responses on the mutation frequency (MF) and conjugative transfer frequency (CTF) of RP4 plasmid in E. coli. Moreover, these hormetic effects exhibited size- and surface charge-dependent features, where 0.1 μm PS-NH2 (100 mg/L) triggered the maximum stimulatory rates on MF (363.63 %) and CTF (74.80 %). The hormetic phenomena of MF and CTF were also observed in the treatments of PS-NOR mixtures, which varied with the particle size and surface charge of PS. In addition, the interactive effects between PS and NOR indicated that the co-existence of PS and NOR might trigger greater resistance risk than the single pollutants. Mechanistic exploration demonstrated that the increase of cellular reactive oxygen species and the variation of cell membrane permeability participated in the hormetic effects of PS and PS-NOR mixtures on bacterial resistance. This study provides new insights into the individual effects of MPs and the combined effects of MP-antibiotic mixtures on bacterial resistance, which will promote the development of environmental risk assessment of MPs from the perspective of bacterial resistance.

Combined effects of a high-fat diet and polyethylene microplastic exposure induce impaired lipid metabolism and locomotor behavior in larvae and adult zebrafish

Microplastics (MP), tiny plastic particles, can be ingested by fish through their habitat or contaminated food sources. When combined with a high-fat diet (HFD), MP exposure may lead to increased MP accumulation in fish and negative impacts on their health. However, the underlying mechanisms of how MP and HFD interact to promote fat accumulation in fish remain poorly understood. In this study, we aimed to evaluate the combined effect of HFD and polyethylene MP (PE-MP) in the zebrafish model (Danio rerio) and decipher its molecular mechanisms. Adult zebrafish exposed to the combined HFD and PE-MP showed elevated lipid accumulation, total cholesterol, triglycerides, and abnormal swimming behavior compared to HFD-fed fish. Histological and gene expression analysis revealed severe hepatic inflammation and injury, resembling nonalcoholic fatty liver disease (NAFLD) in the HFD + PE-MP exposed zebrafish. Moreover, HFD and PE-MP exposure upregulated genes related to lipogenesis (SREBP1, FAS, and C/EBPα) and inflammation (tnfα, il1β, and il-6) in the liver. These findings underscore the interactive effect of environmental pollutants and fish diet, emphasizing the importance of improving fish culture practices to safeguard fish health and human consumers from microplastic contamination through the food chain. This research sheds light on the complex interactions between microplastics and diet, providing valuable insights into the potential risks of microplastic pollution in aquatic ecosystems and the implications for human health. Understanding the underlying molecular mechanisms will contribute to international research efforts to mitigate the adverse effects of microplastics on both environmental and public health.

Prolonged exposure to environmental levels of microcystin-LR triggers ferroptosis in brain via the activation of Erk/MAPK signaling pathway

While existing research has illuminated the environmental dangers and neurotoxic effects of MC-LR exposure, the molecular underpinnings of brain damage from environmentally-relevant MC-LR exposure remain elusive. Employing a comprehensive approach involving RNA sequencing, histopathological examination, and biochemical analyses, we discovered genes differentially expressed and enriched in the ferroptosis pathway. This finding was associated with mitochondrial structural impairment and downregulation of Gpx4 and Slc7a11 in mice brains subjected to low-dose MC-LR over 180 days. Mirroring these findings, we noted reduced cell viability and GSH/GSSH ratio, along with an increased ROS level, in HT-22, BV-2, and bEnd.3 cells following MC-LR exposure. Intriguingly, MC-LR also amplified phospho-Erk levels in both in vivo and in vitro settings, and the effects were mitigated by treatment with PD98059, an Erk inhibitor. Taken together, our findings implicate the activation of the Erk/MAPK signaling pathway in MC-LR-induced ferroptosis, shedding valuable light on the neurotoxic mechanisms of MC-LR. These insights could guide future strategies to prevent MC-induced neurodegenerative diseases.

Teratogenic effects of environmental concentration of plastic particles on freshwater organisms

Given the widespread presence of plastics, especially in micro- and nanoscale sizes, in freshwater systems, it is crucial to identify a suitable model organism for assessing the potential toxic and teratogenic effects of exposure to plastic particles. Until now, the early life stage of freshwater organisms and the regeneration capacity in relation to plastic particles exposure is a still poorly investigated topic. In this study, we examine the teratogenic effect on diatom Cocconeis placentula and cnidarian Hydra vulgaris under controlled exposure conditions of poly(styrene-co-methyl methacrylate) (P(S-co-MMA)) particles. Significant effects were observed at the lowest concentrations (0.1 μg/L). A significant increase in the teratological frequency in C. placentula and a significant decrease in the regeneration rate in H. vulgaris were found at the lowest concentration. The delay in hydra regeneration impaired the feeding capacity and tentacles reactivity at 96 h of exposure. No effects on diatom growth were observed upon exposure to P(S-co-MMA) particles (0.1, 1, 100, 10,000 μg/L) for 28 days and these findings agree with other studies investigating algal growth. The application of the Teratogenic Risk Index, modified for diatoms, highlighted a moderate risk for the lowest concentration evaluating C. placentula and low risk at the lowest and the highest concentrations considering H. vulgaris. This study suggests the importance of testing organisms belonging to different trophic levels as diverse teratogenic effects can be found and the need to evaluate environmentally relevant concentrations of plastic particles.

The neurodevelopmental toxicity induced by combined exposure of nanoplastics and penicillin in embryonic zebrafish: The role of aging processes

As ubiquitous contaminants, nanoplastics and antibiotics are frequently co-presence and widely detected in the freshwater environment and biota, posing a high co-exposure risk to aquatic organisms and even humans. More importantly, how the aging process of nanoplastics affects the joint toxic potential of nanoplastics and antibiotics has not been explored. Here, we generated two aged polystyrene nanoplastics (PS) by UV radiation (UV-PS) and ozonation (O3-PS). Non-teratogenic concentrations of pristine PS (80 nm) and antibiotics penicillin (PNC) co-exposure synergistically suppressed the embryo heart beating and behaviors of spontaneous movement, touch response, and larval swimming behavioral response. Pristine PS and aged UV-PS, but not aged O3-PS, showed similar effects on zebrafish embryo/larval neurodevelopment. However, when co-exposure with PNC, both aged PS, but not pristine PS, showed antagonistic effects. In late-stage juvenile social behavior testing, we found that PS decreased the exploration in light/dark preference assay. The synergistic effect of aged PS with PNC was further explored, including cellular apoptosis, ROS formation, and neurotransmitter metabolite regulation. Mechanistically, aged UV-PS but not O3-PS significantly increased the adsorption rate of PNC compared to pristine PS, which may account for the toxicity difference between the two aged PS. In conclusion, our results confirmed that PS served as a carrier for PNC, and the environmental aging process changed their neurobehavioral toxicity pattern in vivo.

Sources, Degradation, Ingestion and Effects of Microplastics on Humans: A Review

Celluloid, the predecessor to plastic, was synthesized in 1869, and due to technological advancements, plastic products appear to be ubiquitous in daily life. The massive production, rampant usage, and inadequate disposal of plastic products have led to severe environmental pollution. Consequently, reducing the employment of plastic has emerged as a pressing concern for governments globally. This review explores microplastics, including their origins, absorption, and harmful effects on the environment and humans. Several methods exist for breaking down plastics, including thermal, mechanical, light, catalytic, and biological processes. Despite these methods, microplastics (MPs, between 1 and 5 mm in size) continue to be produced during degradation. Acknowledging the significant threat that MPs pose to the environment and human health is imperative. This form of pollution is pervasive in the air and food and infiltrates our bodies through ingestion, inhalation, or skin contact. It is essential to assess the potential hazards that MPs can introduce. There is evidence suggesting that MPs may have negative impacts on different areas of human health. These include the respiratory, gastrointestinal, immune, nervous, and reproductive systems, the liver and organs, the skin, and even the placenta and placental barrier. It is encouraging to see that most of the countries have taken steps to regulate plastic particles. These measures aim to reduce plastic usage, which is essential today. At the same time, this review summarizes the degradation mechanism of plastics, their impact on human health, and plastic reduction policies worldwide. It provides valuable information for future research on MPs and regulatory development.

Interactive effects of polystyrene nanoplastics and 6:2 chlorinated polyfluorinated ether sulfonates on the histomorphology, oxidative stress and gut microbiota in Hainan Medaka (Oryzias curvinotus)

Nanoplastics adsorb surrounding organic contaminants in the environment, which alters the physicochemical properties of contaminants and affects associated ecotoxicological effects on aquatic life. The current work aims to explore the individual and combined toxicological implications of polystyrene nanoplastics (80 nm) and 6:2 chlorinated polyfluorinated ether sulfonate (Cl-PFAES, trade name: F-53B) in an emerging freshwater fish model Hainan Medaka (Oryzias curvinotus). Therefore, O. curvinotus were exposed to 200 μg/L of PS-NPs or 500 μg/L of F-53B in the single or mixture exposure for 7 days to investigate the effects on fluorescence accumulation, tissue damage, antioxidant capacity and intestinal flora. The PS-NPs fluorescence intensity was significantly higher in the single exposure treatment than it in combined exposure treatment (p < 0.01). Histopathological results showed that exposure to PS-NPs or F-53B inflicted varying degree of damages to the gill, liver, and intestine, and these damage were also present in the corresponding tissues of the combined treatment group, illustrating a stronger extent of destruction of these tissues by the combined treatment. Compared to the control group, combined exposure group elevated the malondialdehyde (MDA) content, superoxide dismutase (SOD) and catalase (CAT) activities except in the gill. In addition, the adverse contribution of PS-NPs and F-53B on the enteric flora in the single and combined exposure groups was mainly characterised in the form of reductions in the number of probiotic bacteria (Firmicutes) and this reduction was aggravated by the combined exposure group. Collectively, our results indicated that the toxicological effects of PS-NPs and F-53B on pathology, antioxidant capacity and microbiomics of medaka may be modulated by the interaction of two contaminants with mutually interactive effects. And our work offers fresh information on the combined toxicity of PS-NPs and F-53B to aquatic creatures along with a molecular foundation for the environmental toxicological mechanism.