The Role of Mucin in the Toxicological Impact of Polystyrene Nanoparticles

Assessment of the cytotoxicity micro- and nano-plastic on human intestinal Caco-2 cells and the protective effects of catechin

Micro- and nano-plastics (M/NPs) potentially leach from plastic wrapping into food and beverages. However, the risks of ingested M/NPs to human intestinal health remain unclear. This study aimed to determine the potential risks and mechanisms of PS-M/NPs using a human intestinal epithelial in vitro model and to explore protective measures to reduce these risks. The results showed that polystyrene (PS) M/NPs exhibited size-dependent cytotoxicity (3 μm < 0.3 μm < 80 nm < 20 nm). Additionally, by measuring intracellular reactive oxygen species (ROS) production after exposure to PS-M/NPs and the elimination of ROS by N-acetyl-L-cysteine, we identified oxidative stress as a mechanism of PS-M/NP-induced cytotoxicity. Hazard quotients calculated from the study indicated that the risks of M/NPs derived from plastic teabags exceeded the margin of safety, suggesting that ingested M/NPs potentially pose a risk to human intestinal health. Furthermore, this study found that catechins can reduce the adverse effects of M/NPs, so we propose that drinking tea may offer a protective effect against the harm of M/NPs on the intestinal system.

The alarming link between environmental microplastics and health hazards with special emphasis on cancer

Microplastic contamination is a burgeoning environmental issue that poses serious threats to animal and human health. Microplastics enter the human body through nasal, dermal, and oral routes to contaminate multiple organs. Studies have advocated the existence of microplastics in human breast milk, sputum, faeces, and blood. Microplastics can find their ways to the sub-cellular moiety via active and passive approaches. At cellular level, microplastics follow clathrin and caveolae-dependent pathways to invade the sub-cellular environment. These environmental contaminants modulate the epigenetic control of gene expression, status of inflammatory mediators, redox homeostasis, cell-cycle proteins, and mimic the endocrine mediators like estrogen and androgen to fuel carcinogenesis. Furthermore, epidemiological studies have suggested potential links between the exposure to microplastics and the onset of various chronic diseases. Microplastics trigger uncontrolled cell proliferation and ensue tissue growth leading to various cancers affecting the lungs, blood, breasts, prostate, and ovaries. Additionally, such contamination can potentially affect sub-cellular signaling and injure multiple organs. In essence, numerous reports have claimed microplastic-induced toxicity and tumorigenesis in human and model animals. Nonetheless, the underlying molecular mechanism is still elusive and warrants further investigations. This review provides a comprehensive analysis of microplastics, covering their sources, chemistry, human exposure routes, toxicity, and carcinogenic potential at the molecular level.

In Vitro and In Vivo Genotoxicity of Polystyrene Microplastics: Evaluation of a Possible Synergistic Action with Bisphenol A

The ubiquitous presence of plastics represents a global threat for all ecosystems and human health. In this study, we evaluated, in vitro and in vivo, the genotoxic potential of different concentrations of polystyrene microplastics (PS-MPs) and their possible synergistic interactions with bisphenol-A (BPA). For the in vitro and the in vivo assays, we used human lymphocytes and hemocytes from Lymnaea stagnalis, respectively. The genomic damage was evaluated by the micronucleus assay, and differences in eggs laid and growth of L. stagnalis were also evaluated. In human lymphocytes, PS-MPs alone at the concentration of 200 μg/mL and in association with BPA 0.100 µg/mL significantly increased the frequencies of micronuclei and nuclear buds, indicating a possible in vitro genotoxic additive action of these two compounds. Vice versa, PS-MPs did not result in genotoxicity in hemocytes. Our results indicated that PS-MPs have genotoxic properties only in vitro and at a concentration of 200 µg/mL; moreover, this compound could intensify the genomic damage when tested with BPA, indicating possible cumulative effects. Finally, PS significantly reduced the growth and the number of laid eggs in L. stagnalis.

Nanoplastic Sample Cleanup by Micro-Electromembrane Extraction across Free Liquid Membranes

Sample preparation techniques enabling the separation and cleanup of nanoplastics removing other components present in complex sample matrices are scarce. Herein, micro-electromembrane extraction (μ-EME) has been explored for this purpose based on the extraction of nanoplastic particles across a free liquid membrane (FLM). The extraction unit is based on a perfluoroalkoxy tube sequentially filled with the acceptor solution (20 μL 5 mM phosphate buffer, pH 10.7), FLM (10 μL 1-pentanol), and donor solution (20 μL sample/standard solution). Sulfonated polystyrene beads (200 nm particle size) were selected as a model mimicking negatively charged nanoplastics. At 700 V, nanoplastics transferred from the donor solution into the FLM before moving across the FLM into the acceptor solution. Quantitative nanoplastic measurements after μ-EME were performed by injecting the acceptor solution into a capillary electrophoresis system with diode array detection. μ-EME allowed the rapid nanoplastic sample cleanup, requiring an extraction time of just 90 s and obtaining a nanoplastic transfer yield through the FLM of 60% with RSD values below 9%. The μ-EME technique enabled the efficient sample matrix cleanup of nanoplastics spiked in different tea matrices. Nanoplastic transfer yield through the FLM for black tea and flavored tea matrices were 56% and 47%, respectively, with complete sample matrix removal of UV-absorbing compounds.

Do nanoplastics impact Pb up-taking by Hordeum vulgare L.?

Most studies on nanoplastics (NPs) focus on aquatic environments, overlooking their combined bioaccumulation with pollutants in terrestrial ecosystems. This study addresses a part of this gap by investigating how polystyrene nanoplastics (PS-NPs) affect the bioaccumulation and translocation of lead (Pb) in Hordeum vulgare L. plants. Using the RHIZOtest device for precise soil contamination control, we quantified PS-NPs (50 nm) in plant shoots via pyrolysis-gas chromatography/mass spectrometry (Py-GCMS) after plant KOH digestion. Our findings revealed that PS-NPs reduce Pb bioaccumulation and make adsorbed Pb onto PS-NPs less bioavailable to plants. For the highest Pb concentration, the Pb uptake index (PUI) followed the trend: Free Pb > NPs + Pb > Pb primary adsorbed by NPs, showing reduced Pb translocation to shoots in the presence of PS-NPs. Moreover, the presence of Pb decreased the bioavailability of PS-NPs probably in response to PS-NPs aggregation or modified charge. The PS-NPs concentrations in shoots range from 275.2 to 400 μg g-1, representing 3.9 to 5.75% of the total PS-NPs. This study highlights the intricate interactions between nanoplastics and metals in soil-plant systems and emphasizes the need for further research on their combined effects and potential risks to food safety.

Probiotics an emerging therapeutic approach towards gut-brain-axis oriented chronic health issues induced by microplastics: A comprehensive review

Applications for plastic polymers can be found all around the world, often discarded without any prior care, exacerbating the environmental issue. When large waste materials are released into the environment, they undergo physical, biological, and photo-degradation processes that break them down into smaller polymer fragments known as microplastics (MPs). The time it takes for residual plastic to degrade depends on the type of polymer and environmental factors, with some taking as long as 600 years or more. Due to their small size, microplastics can contaminate food and enter the human body through food chains and webs, causing gastrointestinal (GI) tract pain that can range from local to systemic. Microplastics can also acquire hydrophobic organic pollutants and heavy metals on their surface, due to their large surface area and surface hydrophobicity. The levels of contamination on the microplastic surface are significantly higher than in the natural environment. The gut-brain axis (GB axis), through which organisms interact with their environment, regulate nutritional digestion and absorption, intestinal motility and secretion, complex polysaccharide breakdown, and maintain intestinal integrity, can be altered by microplastics acting alone or in combination with pollutants. Probiotics have shown significant therapeutic potential in managing various illnesses mediated by the gut-brain axis. They connect hormonal and biochemical pathways to promote gut and brain health, making them a promising therapy option for a variety of GB axis-mediated illnesses. Additionally, taking probiotics with or without food can reduce the production of pro-inflammatory cytokines, reactive oxygen species (ROS), neuro-inflammation, neurodegeneration, protein folding, and both motor and non-motor symptoms in individuals with Parkinson's disease. This study provides new insight into microplastic-induced gut dysbiosis, its associated health risks, and the benefits of using both traditional and next-generation probiotics to maintain gut homeostasis.

The potential impact of nano- and microplastics on human health: Understanding human health risks

Plastics are used all over the world. Unfortunately, due to limited biodegradation, plastics cause a significant level of environmental pollution. The smallest recognized to date are termed nanoplastics (1 nm [nm] up to 1 μm [μm]) and microplastics (1 μm-5 mm). These nano- and microplastics can enter the human body through the respiratory system via inhalation, the digestive tract via consumption of contaminated food and water, or penetration through the skin via cosmetics and clothes contact. Bioaccumulation of plastics in the human body can potentially lead to a range of health issues, including respiratory disorders like lung cancer, asthma and hypersensitivity pneumonitis, neurological symptoms such as fatigue and dizziness, inflammatory bowel disease and even disturbances in gut microbiota. Most studies to date have confirmed that nano- and microplastics can induce apoptosis in cells and have genotoxic and cytotoxic effects. Understanding the cellular and molecular mechanisms of plastics' actions may help extrapolate the risks to humans. The article provides a comprehensive review of articles in databases regarding the impact of nano- and microplastics on human health. The review included retrospective studies and case reports of people exposed to nanoplastics and microplastics. This research highlights the need for further research to fully understand the extent of the impact of plastics on human health.

Science-based evidence on pathways and effects of human exposure to micro- and nanoplastics

Human exposure to plastic particles has raised great concern among all relevant stakeholders involved in the protection of human health due to the contamination of the food chain, surface waters, and even drinking water as well as due to their persistence and bioaccumulation. Now more than ever, it is critical that we understand the biological fate of plastics and their interaction with different biological systems. Because of the ubiquity of plastic materials in the environment and their toxic potential, it is imperative to gain reliable, regulatory-relevant, science-based data on the effects of plastic micro- and nanoparticles (PMNPs) on human health in order to implement reliable risk assessment and management strategies in the circular economy of plastics. This review presents current knowledge of human-relevant PMNP exposure doses, pathways, and toxic effects. It addresses difficulties in properly assessing plastic exposure and current knowledge gaps and proposes steps that can be taken to underpin health risk perception, assessment, and mitigation through rigorous science-based evidence. Based on the existing scientific data on PMNP adverse health effects, this review brings recommendations on the development of PMNP-specific adverse outcome pathways (AOPs) following the AOP Users' Handbook of the Organisation for Economic Cooperation and Development (OECD).

The potential impacts of micro-and-nano plastics on various organ systems in humans

Humans are exposed to micro-and-nano plastics (MNPs) through various routes, but the adverse health effects of MNPs on different organ systems are not yet fully understood. This review aims to provide an overview of the potential impacts of MNPs on various organ systems and identify knowledge gaps in current research. The summarized results suggest that exposure to MNPs can lead to health effects through oxidative stress, inflammation, immune dysfunction, altered biochemical and energy metabolism, impaired cell proliferation, disrupted microbial metabolic pathways, abnormal organ development, and carcinogenicity. There is limited human data on the health effects of MNPs, despite evidence from animal and cellular studies. Most of the published research has focused on specific types of MNPs to assess their toxicity, while other types of plastic particles commonly found in the environment remain unstudied. Future studies should investigate MNPs exposure by considering realistic concentrations, dose-dependent effects, individual susceptibility, and confounding factors.

Polytetrafluorethylene microplastic particles mediated oxidative stress, inflammation, and intracellular signaling pathway alteration in human derived cell lines

Microplastics (MPs) are now widely distributed across the aerial, terrestrial, and aquatic environments. Thus, exposure to MPs via the oral, inhalation, or dermal routes is inevitable. Polytetrafluoroethylene (PTFE)-MPs is mainly used for manufacturing nonstick cookware, semiconductors, and medical devices; however, their toxicity has been rarely studied. In the present study, six different human cell lines, which are representative of tissues and cells that directly or indirectly come into contact with MPs, were exposed to two different sizes of irregular shape PTFE-MPs (with an average diameter of 6.0 or 31.7 μm). PTFE-MPs-mediated cytotoxicity, oxidative stress, and changes in proinflammatory cytokine production were then evaluated. We found that the PTFE-MPs did not induce cytotoxicity under any of the experimental conditions. However, PTFE-MPs (especially average diameter of 6.0 μm) induced nitric oxide and reactive oxygen species production in all the cell lines tested. Moreover, both sizes of PTFE-MPs increased the secretion of tumor necrosis factor alpha and interleukin-6 from the U937 macrophage cell line and the A549 lung epithelial cell line, respectively. In addition, PTFE-MPs activated the MAPK signaling pathways, especially the ERK pathway, in A549 and U937 cells, and in the THP-1 dendritic cell line. We also found that the expression of the NLRP3 inflammasome was reduced in the U937 and THP-1 cell lines following treatment with the PTFE-MPs sized 31.7 μm average diameter. Furthermore, expression of the apoptosis regulator, BCL2, was markedly increased in the A549 and U937 cell lines. Thus, although PTFE-MPs exert different effects on different cell types, our findings suggest that PTFE-MPs-associated toxicity may be specifically linked to the activation of the ERK pathway, which ultimately induces oxidative stress and inflammation.

Evaluation of the pulmonary toxicity of PSNPs using a Transwell-based normal human bronchial epithelial cell culture system

To reduce the nanoplastics (NPs) toxicity assessment error, we established a Transwell-based bronchial epithelial cell exposure system to assess the pulmonary toxicity of polystyrene NPs (PSNPs). Transwell exposure system was more sensitive than submerged culture for toxicity detection of PSNPs. PSNPs adhered to the BEAS-2B cell surface, were ingested by the cell, and accumulated in the cytoplasm. PSNPs induced oxidative stress and inhibited cell growth through apoptosis and autophagy. A noncytotoxic dose of PSNPs (1 ng/cm2) increased the expression levels of inflammatory factors (ROCK-1, NF-κB, NLRP3, ICAM-1, etc) in BEAS-2B cells, whereas a cytotoxic dose (1000 ng/cm2) induced apoptosis and autophagy, which might inhibit the activation of ROCK-1 and contribute to reducing inflammation. In addition, the noncytotoxic dose increased the expression levels of zonula occludens-2 (ZO-2) and α1-antitrypsin (α-AT) proteins in BEAS-2B cells. Therefore, in response to PSNP exposure, a compensatory increase in the activities of inflammatory factors, ZO-2, and α-AT may be triggered at low doses as a mechanism to preserve the survival of BEAS-2B cells. In contrast, exposure to a high dose of PSNPs elicits a noncompensatory response in BEAS-2B cells. Overall, these findings suggest that PSNPs may be harmful to human pulmonary health even at an ultralow concentration.

To what extent are orally ingested nanoplastics toxic to the hippocampus in young adult rats?

As the use of plastic-containing materials in our daily lives becomes increasingly common, exposure to nanoplastics accordingly becomes inevitable. Micro and nanoplastics released from large amounts of plastic waste constitute a serious environmental problem. Therefore, this study aimed to examine the effects of polystyrene nanoplastic (PS-NP) on the hippocampus. MATERIAL AND METHOD: Thirty Wistar albino rats, 15 male and 15 female, aged 6-8 weeks, were used in the research. These were randomly divided into three groups of five males and five females each. A five-minute open field test was applied to all rats on the first and last days of the study. Three groups of rats (Control, NP1 and NP2) received the standard chow and water. Additionally, rats in the first neoplastic group (NP1) received 25 mg/kg PS-NP and rats in the second nanoplastic group (NP2) received 50 mg/kg PS-NP, at the same time each day by oral gavage. The rats were sacrificed under deep anesthesia at the end of four weeks. The hippocampi were removed and subjected to histopathological and biochemical analyses. RESULTS: Green fluorescent dots were detected in the hippocampi of both dose groups receiving nanoplastics (NPs) administered orally to female and male rats. Histopathological examination revealed neuronal degeneration in the hippocampi of male and female rats from both dose groups. However, while no significant difference was observed among the groups in terms of changes in antioxidant enzyme values and open-field test data in male rats, significant differences in peroxidase (POD) and glutathione S-transferase (GST) values and fecal boli and grooming numbers were determined in female rats exposed to NPs. In conclusion, exposure to NP substances extend as far as the hippocampus, causing neuronal damage and behavioral problems.

Micro- and nanoplastics (MNPs) and their potential toxicological outcomes: State of science, knowledge gaps and research needs

Plastic waste has been produced at a rapidly growing rate over the past several decades. The environmental impacts of plastic waste on marine and terrestrial ecosystems have been recognized for years. Recently, researchers found that micro- and nanoplastics (MNPs), micron (100 nm - 5 mm) and nanometer (1 - 100 nm) scale particles and fibers produced by degradation and fragmentation of plastic waste in the environment, have become an important emerging environmental and food chain contaminant with uncertain consequences for human health. This review provides a comprehensive summary of recent findings from studies of potential toxicity and adverse health impacts of MNPs in terrestrial mammals, including studies in both in vitro cellular and in vivo mammalian models. Also reviewed here are recently released biomonitoring studies that have characterized the bioaccumulation, biodistribution, and excretion of MNPs in humans. The majority MNPs in the environment to which humans are most likely to be exposed, are of irregular shapes, varied sizes, and mixed compositions, and are defined as secondary MNPs. However, the MNPs used in most toxicity studies to date were commercially available primary MNPs of polystyrene (PS), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and other polymers. The emerging in vitro and in vivo evidence reviewed here suggests that MNP toxicity and bioactivity are largely determined by MNP particle physico-chemical characteristics, including size, shape, polymer type, and surface properties. For human exposure, MNPs have been identified in human blood, urine, feces, and placenta, which pose potential health risks. The evidence to date suggests that the mechanisms underlying MNP toxicity at the cellular level are primarily driven by oxidative stress. Nonetheless, large knowledge gaps in our understanding of MNP toxicity and the potential health impacts of MNP exposures still exist and much further study is needed to bridge those gaps. This includes human population exposure studies to determine the environmentally relevant MNP polymers and exposure concentrations and durations for toxicity studies, as well as toxicity studies employing environmentally relevant MNPs, with surface chemistries and other physico-chemical properties consistent with MNP particles in the environment. It is especially important to obtain comprehensive toxicological data for these MNPs to understand the range and extent of potential adverse impacts of microplastic pollutants on humans and other organisms.

Effects of Digestion, Cell Culture Media, and Mucous on the Physical Properties, Cellular Effects, and Translocation of Polystyrene and Polymethacrylate Nanoparticles

The discovery of plastic and metal nanoparticles in organisms, foods, and beverages has generated numerous studies on the effects of these particles on the barrier cells and their subsequent absorption into the body. Following ingestion, nanoparticles travel down the gastrointestinal tract (GIT), and their physicochemical characteristics change in response to the change in proteins and pH during their digestion. We measured the translocation of digested nanoparticles across a co-culture monolayer of Caco-2 and various combinations (1:9, 5:5, and 9:1) of HT29-MTX-E12. The in vitro model of the intestine was used to determine the translocation of digested 20 nm polymethacrylate (PMA) particles and the accompanying monolayer barrier effects after a 72 h exposure. The in vitro digestion increased the agglomeration and hydrodynamic diameters and decreased the surface charge of the nanoparticles. For NH2-functionalized polymethacrylate nanoparticles (PMA-NH2), the diameters increased from 57 nm (water) to 3800 nm (media), or 2660 nm (chyme). These nanoparticles compromised the integrity of the monolayer (trans-epithelial electrical resistance, Lucifer yellow translocation) and translocated across all the cell ratio configurations. Digestion can have a large effect on nanoparticle agglomeration and surface charge. Excess mucous was not seen as a barrier to the translocation of PMA-NH2.

Label-free detection of polystyrene nanoparticles in Daphnia magna using Raman confocal mapping

Micro- and nanoplastic pollution has emerged as a global environmental problem. Moreover, plastic particles are of increasing concern for human health. However, the detection of so-called nanoplastics in relevant biological compartments remains a challenge. Here we show that Raman confocal spectroscopy-microscopy can be deployed for the non-invasive detection of amine-functionalized and carboxy-functionalized polystyrene (PS) nanoparticles (NPs) in Daphnia magna. The presence of PS NPs in the gastrointestinal (GI) tract of D. magna was confirmed by using transmission electron microscopy. Furthermore, we investigated the ability of NH₂-PS NPs and COOH-PS NPs to disrupt the epithelial barrier of the GI tract using the human colon adenocarcinoma cell line HT-29. To this end, the cells were differentiated for 21 days and then exposed to PS NPs followed by cytotoxicity assessment and transepithelial electrical resistance measurements. A minor disruption of barrier integrity was noted for COOH-PS NPs, but not for the NH₂-PS NPs, while no overt cytotoxicity was observed for both NPs. This study provides evidence of the feasibility of applying label-free approaches, i.e., confocal Raman mapping, to study PS NPs in a biological system.

Nanoplastics are significantly different from microplastics in urban waters

Microplastics (MPs) and nanoplastics (NPs) are ubiquitous and intractable in urban waters. Compared with MPs, the smaller NPs have shown distinct physicochemical features, such as Brownian motion, higher specific surface area, and stronger interaction with other pollutants. Therefore, the qualitative and quantitative analysis of NPs is more challenging than that of MPs. Moreover, these characteristics endow NPs with significantly different environmental fate, interactions with pollutants, and eco-impacts from those of MPs in urban waters. Herein, we critically analyze the current advances in the difference between MPs and NPs in urban waters. Analytical challenges, fate, interactions with surrounding pollutants, and eco-impacts of MPs and NPs are comparably discussed., The characterizations and fate studies of NPs are more challenging compared to MPs. Furthermore, NPs in most cases exhibit stronger interactions with other pollutants and more adverse eco-impacts on living things than MPs. Subsequently, perspective in this field is proposed to stimulate further size-dependent studies on MPs and NPs. This review would benefit the understanding of the role of NPs in the urban water ecosystem and guide future studies on plastic pollution management.

Recent insights into uptake, toxicity, and molecular targets of microplastics and nanoplastics relevant to human health impacts

Microplastics and nanoplastics (M-NPLs) are ubiquitous environmentally, chemically, or mechanically degraded plastic particles. Humans are exposed to M-NPLs of various sizes and types through inhalation of contaminated air, ingestion of contaminated water and food, and other routes. It is estimated that Americans ingest tens of thousands to millions of M-NPLs particles yearly, depending on socioeconomic status, age, and gender. M-NPLs have spurred interest in toxicology because of their abundance, ubiquitous nature, and ability to penetrate bodily and cellular barriers, producing toxicological effects in cells, tissues, organs, and organ systems. The present review paper highlights: (1) The current knowledge in understanding the detrimental effects of M-NPLs in mouse models and human cell lines, (2) cellular organelle localization of M-NPLs, and the underlying uptake mechanisms focusing on endocytosis, (3) the possible pathways involved in M-NPLs toxicity, particularly reactive oxygen species, nuclear factor-erythroid factor 2-related factor 2 (NRF2), Wnt/β-Catenin, Nuclear Factor Kappa B (NF-kB)-regulated inflammation, apoptosis, and autophagy signaling. We also highlight the potential role of M-NPLs in increasing the incubation time, spread, and transport of the COVID-19 virus. Finally, we discuss the future prospects in this field.

Investigating nanoplastics toxicity using advanced stem cell-based intestinal and lung in vitro models

Plastic particles in the nanometer range-called nanoplastics-are environmental contaminants with growing public health concern. As plastic particles are present in water, soil, air and food, human exposure via intestine and lung is unavoidable, but possible health effects are still to be elucidated. To better understand the Mode of Action of plastic particles, it is key to use experimental models that best reflect human physiology. Novel assessment methods like advanced cell models and several alternative approaches are currently used and developed in the scientific community. So far, the use of cancer cell line-based models is the standard approach regarding in vitro nanotoxicology. However, among the many advantages of the use of cancer cell lines, there are also disadvantages that might favor other approaches. In this review, we compare cell line-based models with stem cell-based in vitro models of the human intestine and lung. In the context of nanoplastics research, we highlight the advantages that come with the use of stem cells. Further, the specific challenges of testing nanoplastics in vitro are discussed. Although the use of stem cell-based models can be demanding, we conclude that, depending on the research question, stem cells in combination with advanced exposure strategies might be a more suitable approach than cancer cell lines when it comes to toxicological investigation of nanoplastics.

Short- and long-term polystyrene nano- and microplastic exposure promotes oxidative stress and divergently affects skin cell architecture and Wnt/beta-catenin signaling

Nano- and microplastic particles (NMP) are strong environmental contaminants affecting marine ecosystems and human health. The negligible use of biodegradable plastics and the lack of knowledge about plastic uptake, accumulation, and functional consequences led us to investigate the short- and long-term effects in freshly isolated skin cells from mice. Using fluorescent NMP of several sizes (200 nm to 6 µm), efficient cellular uptake was observed, causing, however, only minor acute toxicity as metabolic activity and apoptosis data suggested, albeit changes in intracellular reactive species and thiol levels were observed. The internalized NMP induced an altered expression of various targets of the nuclear factor-2-related transcription factor 2 pathway and were accompanied by changed antioxidant and oxidative stress signaling responses, as suggested by altered heme oxygenase 1 and glutathione peroxide 2 levels. A highly increased beta-catenin expression under acute but not chronic NMP exposure was concomitant with a strong translocation from membrane to the nucleus and subsequent transcription activation of Wnt signaling target genes after both single-dose and chronic long-term NMP exposure. Moreover, fibroblast-to-myofibroblast transdifferentiation accompanied by an increase of α smooth muscle actin and collagen expression was observed. Together with several NMP-induced changes in junctional and adherence protein expression, our study for the first time elucidates the acute and chronic effects of NMP of different sizes in primary skin cells' signaling and functional biology, contributing to a better understanding of nano- and microplastic to health risks in higher vertebrates.

Nanoplastics: Focus on the role of microRNAs and long non-coding RNAs

When plastic objects in our surroundings are degraded, they may produce particles ranging in size from 1 to 100 nm therefore called nanoplastics. The environmental chemicals including nanoplastics may be able to affect biological processes in the nuclear level like altering DNA methylation and regulating microRNAs (miRNAs) as well as long non-coding RNAs (lncRNAs) expression and therefore are implicated in chronic human diseases like neoplasms. The regulatory role of miRNAs and lncRNAs in gene expression is appreciated. In vitro as well as in vivo experiments have shown that environmental elements including nanoplastics are able to dysregulate miRNAs and lncRNAs expression with possible genetic consequences that increase the risk of cancer development. In the current article, we review the biological effects of miRNAs and lncRNAs alterations following nanoplastics exposure.

Fluoride enhances polystyrene nanoparticles cytotoxicity in colonocytes in vitro model

Human gastrointestinal cells can be exposed to different xenobiotics present in food or drinking water. In this work, we assessed the cytotoxicity of polystyrene nanoparticles (PS-NPs) and how it is impacted by fluoride (F^-) presence. We decided to examine PS-NPs and F^- which can be easily found in drinking water and food. Commercially available amine-modified 100 nm PS-NPs were used in the study. Scanning Electron Microscopy with Electron Dispersive Spectroscopy (SEM-EDS) and Dynamic Light Scattering (DLS) were used to characterize PS-NPs. The colon cell lines (HT-29, Caco-2, CCD 841 CoN) were used. Cytotoxicity of PS-NPs and F^- alone or in co-exposition were assessed with MTT assay in a time- and concentration-dependent manner. Flow cytometry was used to measure reactive oxygen species (ROS) production, cell cycle distribution, and apoptosis analysis. Transmission electron microscopy (TEM) was used to determine whether PS-NPs and/or F^- can cause ultrastructure changes in the cells. We have shown that PS-NPs are cytotoxic to human colon cells in a time- and concentration-dependent manner. PS-NPs did not impact neither intracellular ROS production nor the cells cell cycle distribution. However, if HT-29 cells were co-exposed to PS-NPs and F^-, an increased number of cells in G0/G1 phase and decreased number of cells in G2/M were observed. PS-NPs can cause apoptosis in HT-29 cells, this effect was enhanced if cells were co-exposed to PS-NP and F^-. PS-NPs were internalised by the cells and caused ultrastructure changes. Fluoride itself (1 mM) was not cytotoxic to the cells and did not cause any changes in the ultrastructure of the cells. We have proven that polystyrene nanoparticles can be cytotoxic to human gastrointestinal cells and this effect is enhanced by fluoride.

A review on microplastics and nanoplastics in the environment: Their occurrence, exposure routes, toxic studies, and potential effects on human health

Microplastics (MPs) and nanoplastics (NPs) are emerging environmental pollutants, having a major ecotoxicological concern to humans and many other biotas, especially aquatic animals. The physical and chemical compositions of MPs majorly determine their ecotoxicological risks. However, comprehensive knowledge about the exposure routes and toxic effects of MPs/NPs on animals and human health is not fully known. Here this review focuses on the potential exposure routes, human health impacts, and toxicity response of MPs/NPs on human health, through reviewing the literature on studies conducted in different in vitro and in vivo experiments on organisms, human cells, and the human experimental exposure models. The current literature review has highlighted ingestion, inhalation, and dermal contacts as major exposure routes of MPs/NPs. Further, oxidative stress, cytotoxicity, DNA damage, inflammation, immune response, neurotoxicity, metabolic disruption, and ultimately affecting digestive systems, immunology, respiratory systems, reproductive systems, and nervous systems, as serious health consequences.

Polystyrene nanoplastics induce profound metabolic shift in human cells as revealed by integrated proteomic and metabolomic analysis

Nanoplastics (NPLs) are widespread in our environment. However, their impacts on human health and precise toxicity mechanisms remain poorly understood. Here we studied the internalization, release, and cytotoxicity of polystyrene nanoplastics (PSNPs) using the renal tubular epithelial cell line HKC and human derived liver cell line HL-7702. We also employed an integrated proteomic and metabolomic approach to investigate the potential biological effects of PSNPs on HKC cells. The abundances of 4770 proteins and 100 metabolites were quantified, with 785 proteins and 17 metabolites detected with altered levels in response to PSNPs. Most of the differential proteins and metabolites were enriched in a variety of metabolic pathways, for example, glycolysis, citrate cycle, oxidative phosphorylation, and amino acid metabolism, suggesting the potential effects of NPLs on global cellular metabolism shift in human cells. The altered energy metabolism induced by PSNPs was further confirmed by a Seahorse analysis. Moreover, lysosomal distribution study and western blotting showed that mTORC1 signaling, a central regulator of cellular metabolism, was inhibited upon nanoplastic exposure, likely serving as the link between lysosome dysfunction and metabolic defects. Taken together, our findings systematically mapped the key molecular changes induced by PSNPs in human cells and provide comprehensive biological insights for the risk estimation of NPLs contamination.

Nanoplastic Toxicity: Insights and Challenges from Experimental Model Systems

Nanoplastic particles (NPs) can be produced or derived from the degradation of several daily used products and can therefore be found in the air, water, and food. Every day, these microscopic particles are confronted by different routes of exposure. Recent investigations have shown the internalization of these particles, differing in size and modification, in vivo in aquatic organisms and terrestrial organisms, as well as in vitro in different human cell lines. During the last years, the number of studies investigating the effects of NPs using widely different model systems and experimental approaches is exponentially growing, thus providing information about NPs, especially about polystyrene particle toxicity on health. To facilitate the grasping of the most relevant information, an overview is provided on the toxic effects of NPs coming from studies in cellular systems and in vivo in model organisms and on aspects which can be of particular relevance for particle toxicity (e.g., particle internalization mechanisms and structural modifications). Major achievements and gaps in the field as well as the point of view on how more systematic studies and exploitation of in vivo model organisms may improve the knowledge on important aspects of NPs are also pointed out.

Polystyrene nanoplastics penetrate across the blood-brain barrier and induce activation of microglia in the brain of mice

Microplastics (MPs) have been well demonstrated as potential threats to the ecosystem, whereas the neurotoxicity of MPs in mammals remains to be elucidated. The current study was designed to investigate whether 50 nm polystyrene nanoplastics (PS-NPs) could pass through the blood-brain barrier (BBB), and to elucidate the underlying mechanisms and the following neurotoxic manifestation. In vivo study showed that PS-NPs (0.5-50 mg/kg. bw PS-NPs for 7 days) significantly induced the increase of permeability of BBB, and dose-dependently accumulated in the brain of mice. In addition, PS-NPs were found to be present in microglia, and induced microglia activation and neuron damage in the mouse brain. In vitro studies using the immortalized human cerebral microvascular endothelial cell (hCMEC/D3), the most commonly used cell model for BBB-related studies, revealed that PS-NPs could be internalized into cells, and caused reactive oxygen species (ROS) production, nuclear factor kappa-B (NF-κB) activation, tumor necrosis factors α (TNF-α) secretion, and necroptosis of hCMEC/D3 cells. Furthermore, PS-NPs exposure led to disturbance of the tight junction (TJ) formed by hCMEC/D3, as demonstrated by the decline of transendothelial electrical resistance (TEER) and decreased expression of occludin. Lastly, PS-NPs exposure resulted in the activation of murine microglia BV2 cells, and the cell medium of PS-NPs-exposed BV2 induced obvious damage to murine neuron HT-22 cells. Collectively, these results suggest that PS-NPs could pass through BBB and induce neurotoxicity in mammals probably by inducing activation of microglia.

Bioanalytical approaches for the detection, characterization, and risk assessment of micro/nanoplastics in agriculture and food systems

This review discusses the most recent literature (mostly since 2019) on the presence and impact of microplastics (MPs, particle size of 1 μm to 5 mm) and nanoplastics (NPs, particle size of 1 to 1000 nm) throughout the agricultural and food supply chain, focusing on the methods and technologies for the detection and characterization of these materials at key entry points. Methods for the detection of M/NPs include electron and atomic force microscopy, vibrational spectroscopy (FTIR and Raman), hyperspectral (bright field and dark field) and fluorescence imaging, and pyrolysis-gas chromatography coupled to mass spectrometry. Microfluidic biosensors and risk assessment assays of MP/NP for in vitro, in vivo, and in silico models have also been used. Advantages and limitations of each method or approach in specific application scenarios are discussed to highlight the scientific and technological obstacles to be overcome in future research. Although progress in recent years has increased our understanding of the mechanisms and the extent to which MP/NP affects health and the environment, many challenges remain largely due to the lack of standardized and reliable detection and characterization methods. Most of the methods available today are low-throughput, which limits their practical application to food and agricultural samples. Development of rapid and high-throughput field-deployable methods for onsite screening of MP/NPs is therefore a high priority. Based on the current literature, we conclude that detecting the presence and understanding the impact of MP/NP throughout the agricultural and food supply chain require the development of novel deployable analytical methods and sensors, the combination of high-precision lab analysis with rapid onsite screening, and a data hub(s) that hosts and curates data for future analysis.

Reduction in Toxicity of Polystyrene Nanoplastics Combined with Phenanthrene through Binding of Jellyfish Mucin with Nanoplastics

Mucin (Mu), a biological substance extracted from jellyfish (Aurelia aurita), was used to reduce the toxic effect of polystyrene nanoplastics (PS-NP) combined with phenanthrene (Phe) in the aquatic environment of zebrafish (Danio rerio), among other aquatic organisms. Mu showed a high binding capacity, as it bound to 92.84% and 92.87% of the PS-NPs (concentration of 2.0 mg/L) after 0.5 h and 8 h, respectively. A zebrafish embryo development test was conducted to check for any reduction in toxicity by Mu. When exposed to PS-NP + Mu and PS-NP + Phe + Mu, respectively, the hatching rates were 88.33 ± 20.21% and 93.33 ± 2.89%, respectively; these results were not significantly different from those of the control group. However, the hatching rate with the addition of Mu increased, compared to that of the PS-NP (71.83 ± 13.36%) and Phe (37.50 ± 19.83%) treatments, and the morphological abnormality rate decreased. The presence of Mu was also found to obstruct the absorption of PS-NP and PS-NP + Phe by the zebrafish. When zebrafish embryos were exposed to PS-NP at a concentration of 5.0 mg/L, the hatching rate differed significantly from that of the control group, and the expression of CAT and p53 genes increased significantly, but the expression of Bcl-2 decreased significantly. An mRNA sequence analysis revealed that the gene expression levels of the test group containing Mu were similar to those of the control group. These results infer that Mu can be used as a biological material to collect and remove PS-NPs from aquatic environments and reduce toxicity.

In vitro study on the toxicity of nanoplastics with different charges to murine splenic lymphocytes

Nanoplastics can be ingested by organisms and penetrate biological barriers to affect multiple physiological functions. However, few studies have focused on the effects of nanoplastics on the mammalian immune system. We evaluated the effects and underlying mechanism of nanoplastics of varying particle sizes and surface charges on murine splenic lymphocytes. We found that nanoplastics penetrated into splenic lymphocytes and that nanoplastics of a diameter of 50 nm were absorbed more efficiently by the cells. The nanoplastics decreased cell viability, induce cell apoptosis, up-regulated apoptosis-related protein expression, elicited the production of reactive oxygen species, altered mitochondrial membrane potential, and impaired mitochondrial function. Positively charged nanoplastics exerted the strongest toxicity. Negatively charged and uncharged nanoplastics caused oxidative stress and mitochondrial structural damage in lymphocytes, while positively charged nanoplastics induced endogenous apoptosis directly. Moreover, nanoplastics inhibited the expression of activated T cell markers on the T cell surface, while inhibiting the differentiation of CD8⁺ T cells and the expression of helper T cell cytokines. In terms of the mechanism, a series of key signaling molecules in the pathways of T cell activation and function were markedly down-regulated after exposure to nanoplastics.

Tiered testing of micro- and nanoplastics using intestinal in vitro models to support hazard assessments

The uncertainty of potential risks associated with micro- and nanoplastics (MNPs) are of growing public concern. However, the diversity of MNPs in the environment makes a systematic analysis of potential health effects challenging. New tools and approaches are necessary to investigate biological effects of MNPs. With this quick scoping review, we aim to analyse the suitability of in vitro models for assessing the interaction of MNPs with intestinal cells. Our analysis revealed that currently the majority of in vitro tests are based on the three cell lines Caco-2, HT-29, and HCT-116. They have particularly been used to assess endpoints related to basal cytotoxicity, the internalisation of MNPs and effects on the intestinal barrier. When co-cultured with various cell lines, they also allow to investigate additional effects such as inflammation, metabolic actions and the relevance of the intestinal mucus. However, methodological gaps remain regarding the assessment of a potential accumulation of MNPs, leaching of additives/impurities and in resulting long-term effects as well as cell-type specific toxicities. In addition, only few in vitro studies investigated effects of MNPs on the microbiome. Stem cell-based assays using, for example, the emerging organoid technology are promising for analysing MNP effects on tissue-like structures, while avoiding the particular characteristics of the currently used cancer derived cell lines. The various cell lines and culture techniques can be combined in testing strategies, to better elucidate potential biological interaction of MNPs with biological systems. We suggest to implement a tiered testing strategy, in which monocultures can serve as a tool for high-throughput testing of MNPs. In the next steps co-cultures can be used to assess the potential of a systemic uptake of MNPs and organ-on-a-chip models will provide more reliable insights into relevant doses triggering biological effects. Finally, organoids can help to discover new and more complex reactions initiated by MNPs.

Uptake and toxicity of polystyrene micro/nanoplastics in gastric cells: Effects of particle size and surface functionalization

Toxicity of micro or nanoplastics (MP/NP) in aquatic life is well-documented, however, information about the consequences of exposure to these particles in terrestrial species is scarce. This study was used to evaluate the uptake and/or toxicity of polystyrene MP/NP in human gastric cells, comparing doses, particle sizes (50, 100, 200, 500, 1000 or 5000 nm) and surface functionalization (aminated, carboxylated or non-functionalized). In general, the uptake of 50 nm particles was significantly higher than 1000 nm particles. Among the 50 nm particles, the aminated particles were more avidly taken up by the cells and were cytotoxic at a lower concentration (≥ 7.5 μg/mL) compared to same sized carboxylated or non-functionalized particles (≥ 50 μg/mL). High toxicity of 50 nm aminated particles corresponded well with significantly high rates of apoptosis-necrosis induced by these particles in 4 h (29.2% of total cells) compared to all other particles (≤ 16.8%). The trend of apoptosis-necrosis induction by aminated particles in 4 h was 50 > 5000 > 1000 > 500 > 200 > 100 nm. The 50 nm carboxylated or non-functionalized particles also induced higher levels of apoptosis-necrosis in the cells compared to 100, 1000 and 5000 nm particles with same surface functionalization but longer exposure (24 h) to 50 nm carboxylated or non-functionalized particles significantly (p<0.0001) increased apoptosis-necrosis in the cells. The study demonstrated that the toxicity of MP/NP to gastric cells was dependent on particle size, dose surface functionalization and exposure period.

Mimicking the Gastrointestinal Mucus Barrier: Laboratory-Based Approaches to Facilitate an Enhanced Understanding of Mucus Permeation

The gastrointestinal mucus layer plays a significant role in maintaining gut homeostasis and health, offering protective capacities against the absorption of harmful pathogens as well as commensal gut bacteria and buffering stomach acid to protect the underlying epithelium. Despite this, the mucus barrier is often overlooked during preclinical pharmaceutical development and may pose a significant absorption barrier to high molecular weight or lipophilic drug species. The complex chemical and physical nature of the dynamic mucus layer has proven problematic to reliably replicate in a laboratory setting, leading to the development of multiple mucus models with varying complexity and predictive capacity. This, coupled with the wide range of analysis methods available, has led to a plethora of possible approaches to quantifying mucus permeation; however, the field remains significantly under-represented in biomedical research. For this reason, the development of a concise collation of the available approaches to mucus permeation is essential. In this review, we explore widely utilized mucus mimics ranging in complexity from simple mucin solutions to native mucus preparations for their predictive capacity in mucus permeation analysis. Furthermore, we highlight the diverse range of laboratory-based models available for the analysis of mucus interaction and permeability with a specific focus on in vitro, ex vivo, and in situ models. Finally, we highlight the predictive capacity of these models in correlation with in vivo pharmacokinetic data. This review provides a comprehensive and critical overview of the available technologies to analyze mucus permeation, facilitating the efficient selection of appropriate tools for further advancement in oral drug delivery.

Systematic toxicity evaluation of polystyrene nanoplastics on mice and molecular mechanism investigation about their internalization into Caco-2 cells

There is a growing concern regarding the toxic effects of nanoplastics (NPs) on aquatic and marine organism, while relatively few studies about their toxicity evaluation on mammals are conducted. In the present study, we observed accumulation of polystyrene NPs (PS NPs) in mice spleen, lung, kidney, small intestine, large intestine, testis, and brain after oral exposure to PS NPs (~100 nm, 10 mg/mL, 100 μL) for 28 days, and NPs were identified to induce cell apoptosis, inflammation, and structure disorder in these tissues. We also found that PS NPs could bring about hematological system injury and lipid metabolism disorder. Further in vitro studies identified that PS NPs could be absorbed by the intestinal epithelial Caco-2 cells by macropinocytosis and clathrin-mediated endocytosis, and induced disruption of tight junction between Caco-2 cells. Moreover, we found that it was easier for PS-NH₂ and PS-COOH to enter into Caco-2 cells, which may be associated with observed stronger toxicity of PS-NH₂ and PS-COOH NPs. In summary, this study demonstrated that NPs exposure brings about toxic effects to mice. This study could provide new insights regarding the distribution of NPs in humans, and helps us to evaluate the potential physiological risks of NPs to human beings.

Key mechanisms of micro- and nanoplastic (MNP) toxicity across taxonomic groups

Micro- and nanoplastics (MNPs) are ubiquitous in aquatic and terrestrial environments, and detrimental biological effects have been observed on a variety of organisms, from bacteria and alga to plants and animals. A fast-growing number of toxicological studies report diverse responses and wide species-dependent sensitivity upon MNP exposure. While studies are dominated by in vivo animal tests, our understanding of cellular toxicity and the corresponding toxicity mechanisms is still limited. This challenges the proper assessment of environmental hazards and health risks of MNPs. In this review, we gathered and analyzed the up-to-date studies on humans, animals, plants, alga, and bacteria, and identified the similarities and differences in key toxicity mechanisms of MNPs across different taxonomic groups. Particularly, human cell-based studies at the cellular level provide fundamental and valuable information on the key toxicity mechanisms, which are essential to answer the question of whether and how MNPs pose health threats. In general, toxicity mechanisms of MNPs depend on their size, surface characteristics, polymer type, as well as cell type. Plausible toxicity mechanisms mainly include membrane disruption, extracellular polymeric substance disruption, reactive oxygen species generation, DNA damage, cell pore blockage, lysosome destabilization, and mitochondrial depolarization. A deeper understanding of these key mechanisms in different taxonomic groups can also improve both in vivo and in vitro models useful for predictive impact assessments of plastic pollution on the environment and human health.

Microplastics in aquatic environments: A review on occurrence, distribution, toxic effects, and implications for human health

Microplastics (MPs) are fragments, fibers, granules, flakes and spheres with a diameter or length of less than 5 mm. These may eventually end up in the aquatic environment by the progressive breakdown of larger plastics or via domestic and industrial sewage spillage. In order to better understand the current knowledge in this field, we carried out and extensive literature research to retrieve articles mainly focusing on the occurrence and distribution of MPs in aquatic matrix as well as their impacts on aquatic organisms and human derived cells. Once in the environment, MPs may be transported via wind and water movement, affecting their spatial distribution. Furthermore, density may also affect the buoyancy and vertical distribution of these pollutants. Consequently, MPs are ubiquitously distributed in fresh- and marine- water systems, posing a real threat to aquatic organisms. Furthermore, trophic transfer and biomagnification processes represent a viable route for the input of MPs to humans. This paper focuses on (1) Outline the occurrence of MPs in worldwide aquatic ecosystems; (2) Investigate the factors affecting the abundance and distribution of MPs in aquatic ecosystems; (3) Provide an in-depth discussion about the harmful effects that MPs poses to aquatic organisms; (4) Summarizes the possible mechanisms by which MPs may induce toxic effects on humans.

Current research trends on micro- and nano-plastics as an emerging threat to global environment: A review

Micro-and nano-plastics (MNPs) (size < 5 mm/<100 nm) epitomize one of the emergent environmental pollutants with its existence all around the globe. Their high persistence nature and release of chemicals/additives used in synthesis of plastics materials may pose cascading impacts on living organism across the globe. Natural connectivity of all the environmental compartments (terrestrial, aquatic, and atmospheric) leads to migration/dispersion of MNPs from one compartment to others. Nevertheless, the information on dispersion of MNPs across the environmental compartments and its possible impacts on living organisms are still missing. This review first acquaints with dispersion mechanisms of MNPs in the environment, its polymeric/oligomeric and chemical constituents and then emphasized its impacts on living organism. Based on the existing knowledge about the MNPs' constituent and its potential impacts on the viability, development, lifecycle, movements, and fertility of living organism via several potential mechanisms, such as irritation, oxidative damage, digestion impairment, tissue deposition, change in gut microbial communities' dynamics, impaired fatty acid metabolism, and molecular damage are emphasized. Finally, at the end, the review provided the challenges associated with remediation of plastics pollutions and desirable strategies, policies required along with substantial gaps in MNPs research were recommended for future studies.

Comparison of Genotoxicity and Cytotoxicity of Polyvinyl Chloride and Poly(methyl methacrylate) Nanoparticles on Normal Human Lung Cell Lines

High concentrations of micro- and nanoparticles of common plastic materials present in the environment are causing an adverse health impact on living organisms. As a model study, here we report the synthesis and characterization of luminescent polyvinyl chloride (PVC) and poly(methyl methacrylate) (PMMA) nanoparticles and investigate the interaction with normal human lung fibroblast cells (IMR 90) to understand the uptake, translocation, and toxicity of PVC and PMMA nanoparticles. The synthesized particles are in the size range of 120-140 nm with a negative surface potential. The colocalization and uptake efficiency of the nanoparticles were analyzed, and the cytotoxicity assay shows significant reduction in cell viability. Cellular internalization was investigated using colocalization and dynasore inhibitor tests, which showed that the PVC and PMMA nanoparticles enter into the cell via endocytosis. The polymer nanoparticles induced a reduction in viability, decrease in adenosine triphosphate, and increase in reactive oxygen species and lactate dehydrogenase concentrations. In addition, the polymer nanoparticles caused cell cycle arrest at sub-G₁, G₀/G₁, and G2/M phases, followed by apoptotic cell death. Our results reported here are important to the emerging data on understanding the impact of common polymer particles on human health.

Mucin corona delays intracellular trafficking and alleviates cytotoxicity of nanoplastic-benzopyrene combined contaminant

Nanoplastics have recently become a worldwide concern as newly emerging airborne pollutants, which can associate with polycyclic aromatic hydrocarbons (PAHs) and form combined contaminant nanoparticles (CCNPs). After being inhaled in the respiratory system, the CCNPs would first encounter the mucous gel layer being rich in mucin. Herein, polystyrene-benzopyrene (PS@Bap) NPs were prepared as CCNPs model and their interaction with mucin and the resultant biological responses were studied. It was observed that mucin corona stably attached to the CCNPs surface, which significantly altered the fate of the CCNPs in lung epithelial cells (A 549 cell line). The mucin corona would 1) stably adsorbed on PS@Bap at the early stages of endocytosis until degraded during the lysosomal transport and maturation process, 2) delay intracellular trafficking of PS@Bap and the progress of Bap detached from PS, 3) enhance uptake of PS@Bap but reduce the cytotoxicity elicited by PS@Bap, as indicated by cell viability, generation of reactive oxygen species, impairment on mitochondrial function, and further cell apoptosis. In addition, in vivo study also verified the enhanced effect of PS on the development of an acute lung inflammatory response induced by Bap. This study highlights the significance of incorporating the effects of mucin for precisely assessing the respiratory system toxicity of nanoplastics based CCNPs in atmospheric environments.

Potential human health risks due to environmental exposure to nano- and microplastics and knowledge gaps: A scoping review

Microplastics are an emerging global environmental contaminant that are affecting multiple spheres. Despite their ubiquity in all spheres of life and ecology, little is known about the health effects of microplastics exposure to humans. This scoping review explores the existing evidence on the potential human health effects of microplastics and subsequent knowledge gaps. An electronic search of published articles in PubMed, Scopus, EMBASE, Cochrane databases, and Google Scholar was conducted using a combination of subject headings and keywords relating to microplastics and human health effects. The initial search resulted in 17,043 published articles and grey literature documents. After a full review of published articles and their references, 129 publications were identified for further detailed review. These articles indicate that human exposure to microplastics can occur through ingestion, inhalation, and dermal contact due to their presence in food, water, air, and consumer products. Microplastics exposure can cause toxicity through oxidative stress, inflammatory lesions, and increased uptake or translocation. Several studies have demonstrated the potentiality of metabolic disturbances, neurotoxicity, and increased cancer risk in humans. Moreover, microplastics have been found to release their constituent compounds as well as those that are adsorbed onto their surface. Further research is needed to quantify the effects of microplastics on human health and their pathogenesis.

Impact of Microplastics and Nanoplastics on Human Health

Plastics have enormous impacts to every aspect of daily life including technology, medicine and treatments, and domestic appliances. Most of the used plastics are thrown away by consumers after a single use, which has become a huge environmental problem as they will end up in landfill, oceans and other waterways. These plastics are discarded in vast numbers each day, and the breaking down of the plastics from micro- to nano-sizes has led to worries about how toxic these plastics are to the environment and humans. While, there are several earlier studies reported the effects of micro- and nano-plastics have on the environment, there is scant research into their impact on the human body at subcellular or molecular levels. In particular, the potential of how nano-plastics move through the gut, lungs and skin epithelia in causing systemic exposure has not been examined thoroughly. This review explores thoroughly on how nanoplastics are created, how they behave/breakdown within the environment, levels of toxicity and pollution of these nanoplastics, and the possible health impacts on humans, as well as suggestions for additional research. This paper aims to inspire future studies into core elements of micro- and nano-plastics, the biological reactions caused by their specific and unusual qualities.

Environmental fate, toxicity and risk management strategies of nanoplastics in the environment: Current status and future perspectives

Tiny plastic particles considered as emerging contaminants have attracted considerable interest in the last few years. Mechanical abrasion, photochemical oxidation and biological degradation of larger plastic debris result in the formation of microplastics (MPs, 1 μm to 5 mm) and nanoplastics (NPs, 1 nm to 1000 nm). Compared with MPs, the environmental fate, ecosystem toxicity and potential risks associated with NPs have so far been less explored. This review provides a state-of-the-art overview of current research on NPs with focus on currently less-investigated fields, such as the environmental fate in agroecosystems, migration in porous media, weathering, and toxic effects on plants. The co-transport of NPs with organic contaminants and heavy metals threaten human health and ecosystems. Furthermore, NPs may serve as a novel habitat for microbial colonization, and may act as carriers for pathogens (i.e., bacteria and viruses). An integrated framework is proposed to better understand the interrelationships between NPs, ecosystems and the human society. In order to fully understand the sources and sinks of NPs, more studies should focus on the total environment, including freshwater, ocean, groundwater, soil and air, and more attempts should be made to explore the aging and aggregation of NPs in environmentally relevant conditions. Considering the fact that naturally-weathered plastic debris may have distinct physicochemical characteristics, future studies should explore the environmental behavior of naturally-aged NPs rather than synthetic polystyrene nanobeads.

Biological effects, including oxidative stress and genotoxic damage, of polystyrene nanoparticles in different human hematopoietic cell lines

In recent years the terms "micro-/nanoplastics" (MNPLs) have caught special attention due to the increasing levels by which humans are exposed. Among MNPLs, polystyrene nanoparticles (PSNPs) are one of the most represented MNPLs in the environment. These tiny particles may enter into the human body, translocate through human barriers, interacting with blood and lymphatic immune cells, and reaching secondary organs. By using three different human leukocytic cell lines: Raji-B (B-lymphocytes), TK6 (lymphoblasts) and THP-1 (monocytes), we pursued to determine the effects of these PSNPs on the immune cell population. With this aim, the three cell lines were exposed to spherical PSNPs of about 50 nm of diameter and cytotoxicity, cellular uptake, reactive oxygen species (ROS) production, and genotoxicity were assessed at different time-points. Results show differences in all the measured endpoints, among the selected cell lines. Thus, whilst the monocytic THP-1 cells showed the highest particle internalization, no adverse effects were observed in such cells. On the other side, although Raji-B and TK6 showed lesser PSNPs uptake, mild toxicity, ROS production and genotoxicity were detected. These results highlight the importance of the cell line selection when the biological effects of PSNPs are evaluated.

Micro- and nanoplastics - current state of knowledge with the focus on oral uptake and toxicity

The production and use of plastics has constantly increased over the last 30 years. Over one third of the plastics is used in disposables, which are discarded within three years of their production. Despite efforts towards recycling, a substantial volume of debris has accumulated in the environment and is slowly degraded to micro- and nanoplastics by weathering and aging. It has recently been discovered that these small particles can enter the food chain, as for example demonstrated by the detection of microplastic particles in honey, beer, salt, sea food and recently in mineral water. Human exposure has further been documented by the detection of plastic microparticles in human feces. Potential toxic consequences of oral exposure to small plastic particles are discussed. Due to lacking data concerning exposure, biodistribution and related effects, the risk assessment of micro- and nanoplastics is still not possible. This review focuses on the oral uptake of plastic and polymer micro- and nanoparticles. Oral exposure, particle fate, changes of particle properties during ingestion and gastrointestinal digestion, and uptake and transport at the intestinal epithelium are reviewed in detail. Moreover, the interaction with intestinal and liver cells and possibly resulting toxicity are highlighted.

Micro- and nano-plastics activation of oxidative and inflammatory adverse outcome pathways

Microplastics (MPs) and nanoplastics (NPs) have attracted considerable attention in the recent years as potential threats to the ecosystem and public health. This review summarizes current knowledge of pathological events triggered by micro- and nano-plastics (MP/NPs) with focus on oxidative damages at different levels of biological complexity (molecular, cellular, tissue, organ, individual and population). Based on published information, we matched the apical toxicity endpoints induced by MP/NPs with key event (KE) or adverse outcomes (AO) and categorized them according to the Adverse Outcome Pathway (AOP) online knowledgebase. We used existing AOPs and applied them to highlight formal mechanistic links between identified KEs and AOs in two possible scenarios: first from ecological, and second from public health perspective. Ecological perspective AOP based literature analysis revealed that MP/NPs share formation of reactive oxygen species as their molecular initiating event, leading to adverse outcomes such as growth inhibition and behavior alteration through oxidative stress cascades and inflammatory responses. Application of AOP on literature data related to public health perspective of MP/NPs showed that oxidative stress and its responding pathways, including inflammatory responses, could play the role of key events. However insufficient information prevented precise definitions of AOPs at this level. To overcome this knowledge gap, further mammalian model and epidemiological studies are necessary to support development and construction of detailed AOPs with public health focus.

An Enteric-Coated Polyelectrolyte Nanocomplex Delivers Insulin in Rat Intestinal Instillations when Combined with a Permeation Enhancer

The use of nanocarriers is being researched to achieve oral peptide delivery. Insulin-associated anionic polyelectrolyte nanoparticle complexes (PECs) were formed that comprised hyaluronic acid and chitosan in an optimum mass mixing ratio of 5:1 (MR 5), followed by coating with a pH-dependent polymer. Free insulin was separated from PECs by size exclusion chromatography and then measured by HPLC. The association efficiency of insulin in PECs was >95% and the loading was ~83 µg/mg particles. Dynamic light scattering and nanoparticle tracking analysis of PECs revealed low polydispersity, a negative zeta potential range of −40 to −50 mV, and a diameter range of 95–200 nm. Dissolution studies in simulated small intestinal fluid (FaSSIF-V2) revealed that the PECs were colloidally stable. PECs that were coated with Eudragit^® L-100 delayed insulin release in FaSSIF-V2 and protected insulin against pancreatin attack more than uncoated PECs. Uncoated anionic PECs interacted weakly with mucin in vitro and were non-cytotoxic to Caco-2 cells. The coated and uncoated PECs, both concentrated further by ultrafiltration, permitted dosing of 50 IU/kg in rat jejunal instillations, but they failed to reduce plasma glucose or deliver insulin to the blood. When ad-mixed with the permeation enhancer (PE), sucrose laurate (100 mM), the physicochemical parameters of coated PECs were relatively unchanged, however blood glucose was reduced by 70%. In conclusion, the use of a PE allowed for the PEC-released bioactive insulin to permeate the jejunum. This has implications for the design of orally delivered particles that can release the payload when formulated with enhancers.

A Detailed Review Study on Potential Effects of Microplastics and Additives of Concern on Human Health

The distribution and abundance of microplastics into the world are so extensive that many scientists use them as key indicators of the recent and contemporary period defining a new historical epoch: The Plasticene. However, the implications of microplastics are not yet thoroughly understood. There is considerable complexity involved to understand their impact due to different physical-chemical properties that make microplastics multifaceted stressors. If, on the one hand, microplastics carry toxic chemicals in the ecosystems, thus serving as vectors of transport, they are themselves, on the other hand, a cocktail of hazardous chemicals that are added voluntarily during their production as additives to increase polymer properties and prolong their life. To date, there is a considerable lack of knowledge on the major additives of concern that are used in the plastic industry, on their fate once microplastics dispose into the environment, and on their consequent effects on human health when associated with micro and nanoplastics. The present study emphasizes the most toxic and dangerous chemical substances that are contained in all plastic products to describe the effects and implications of these hazardous chemicals on human health, providing a detailed overview of studies that have investigated their abundance on microplastics. In the present work, we conducted a capillary review of the literature on micro and nanoplastic exposure pathways and their potential risk to human health to summarize current knowledge with the intention of better focus future research in this area and fill knowledge gaps.

Hazard assessment of small-size plastic particles: is the conceptual framework of particle toxicology useful?

Humans are exposed to plastic particles, but there are no studies on environmental plastics in cell cultures or animals. The toxicological understanding arises from model particles like polystyrene, polyethylene or non-plastic particles like food-grade titanium dioxide. The majority of studies on polystyrene particles show toxicological effects on measures of oxidative stress, inflammation, mitochondrial dysfunction, lysosomal dysfunction and apoptosis. The toxic effects in cell cultures mainly occur at high concentrations. Polyethylene particles seem to generate inflammatory reactions, whereas other toxicological effects have not been assessed. There are very few studies on effects of polystyrene particles in animal models and these have not demonstrated overt indices of toxicity. Studies in animals are the likely way for hazard assessment of micro- or nanoplastics. However, co-culture systems that mimic the complex architecture of mammalian tissues can cost-efficiently determine the hazards of micro- and nanoplastics. Future studies should include low doses of micro- and nanoplastic particles, which are more relevant in the assessment of health risk than the extrapolation of effects from high doses to realistic doses. Based on studies on model particles, environmental exposure to micro- and nanoplastic particles may be a hazard to human health.

Individual and Environmental Factors Associated with Proteinuria in Korean Children: A Multilevel Analysis

Proteinuria is a significant sign of childhood renal disorders. However, little is known about how sociodemographic and environmental factors are related to the presence of proteinuria among children and adolescents. This paper focuses on the prevalence of proteinuria and its risk factors among children and adolescents. This study conducted a secondary analysis of data from the 2016 Sample Schools Raw Data of Health Examination for School Students (SSRDHESS). Data collected from 27,081 students who had undergone a health screening were analyzed using Chi-square tests, independent t-tests, and multilevel logistic regression analysis. The prevalence of proteinuria was higher in the thin group than in the normal weight group (adjusted odds ratio (aOR) = 1.77; 95% confidence interval (CI) = 1.34–2.33) and lower in the overweight/obese group (aOR = 0.64; 95% CI = 0.51–0.80). Additionally, those in metropolitan and small–medium sized cities had a proteinuria prevalence about 1.5-fold higher than that of those in rural areas (95% CI = 1.08–2.02, 95% CI = 1.19–1.92, respectively). Proteinuria was associated with environmental pollution, including smoking rate, ambient particulate matter and heavy metals in drinking water (aOR = 1.10; 95% CI = 1.01–1.20; aOR = 1.06; 95% CI = 1.01–1.11, aOR = 1.001; 95% CI = 1.0001–1.0015). These results suggest that to improve health management effectiveness, kidney disease prevention efforts for children and adolescents should focus on geographical area and environmental pollution, as well as body weight as individual factors.

Emergence of Nanoplastic in the Environment and Possible Impact on Human Health

On account of environmental concerns, the fate and adverse effects of plastics have attracted considerable interest in the past few years. Recent studies have indicated the potential for fragmentation of plastic materials into nanoparticles, i.e., "nanoplastics," and their possible accumulation in the environment. Nanoparticles can show markedly different chemical and physical properties than their bulk material form. Therefore possible risks and hazards to the environment need to be considered and addressed. However, the fate and effect of nanoplastics in the (aquatic) environment has so far been little explored. In this review, we aim to provide an overview of the literature on this emerging topic, with an emphasis on the reported impacts of nanoplastics on human health, including the challenges involved in detecting plastics in a biological environment. We first discuss the possible sources of nanoplastics and their fates and effects in the environment and then describe the possible entry routes of these particles into the human body, as well as their uptake mechanisms at the cellular level. Since the potential risks of environmental nanoplastics to humans have not yet been extensively studied, we focus on studies demonstrating cell responses induced by polystyrene nanoparticles. In particular, the influence of particle size and surface chemistry are discussed, in order to understand the possible risks of nanoplastics for humans and provide recommendations for future studies.