The nephrotoxic potential of polystyrene microplastics at realistic environmental concentrations

Studies on adsorption and synergistic biological effects induced by microplastic particles and the Platanus pollen allergenic protein 3(Pla a3)

Microplastics (MPs) are pervasive as emerging pollutants in ambient particles and may pose a potential threat to human health through respiratory exposure. Especially, impact of climate change has led to an extended blooming period for many plants, resulting in elevated pollen levels in the air, and leading to a continuous increase in the number of individuals suffering from allergenic diseases. However, the interactions between the MPs and allergenic proteins, remain largely unexplored. In this study, we investigated cellular toxicity of the MPs and Platanus pollen allergenic protein (Pla a3) based on the characterization of two typical microplastics (polystyrene, PS and polyethylene, PE). Our results indicated that UV irradiation could make surface alterations of the MPs, including breakage, particle size reduction, and an increase in surface oxygen-containing functional groups. These changes significantly enhanced the adsorption of the Pla a 3 protein. The 'protein coronas' formed by the MPs and the Pla a3 caused more damage to the A549 cells than Pla a3 alone. Reactive oxygen species (ROS) generation and elevated superoxide dismutase (SOD) levels increased significantly after the A549 cells were exposure to the protein coronas. This excessive oxidative stress led to significant inflammation and cytokine production increase, with IL-1β, IL-4, IFN-γ, and TNF-α levels rising by 1.84 ± 0.01, 2.37 ± 0.04, 1.94 ± 0.09, and 2.19 ± 0.05-fold times respectively compared to that of the Pla a 3 exposure alone. This study provided a fundamental data for further research for the allergenicity induced by the pollen proteins.

Toxicological effects and mechanisms of renal injury induced by inhalation exposure to airborne nanoplastics

Micro-nanoplastics (MNPs) are ubiquitously present in various natural habitats, and the kidney plays a critical role in eliminating metabolic waste from the body. Therefore, nephrotoxicity studies of MNPs are necessary. Consequently, we conducted a study utilizing a mouse model that underwent autonomous inhalation of polystyrene nanoplastics (PS-NPs) to investigate the impact of airborne nanoplastics (NPs) on kidney. The results demonstrated that airborne NPs could accumulate within the kidney subsequent to pulmonary entry. Transcriptome analysis showed that exposure to airborne NPs persistently interfered with important signaling pathways including oxidative stress, inflammation, and coagulation, which activated the NR4A1/CASP3 and TF/F12 signaling pathways. In vitro studies have shown that NPs were internalized by human kidney proximal tubular epithelial (HK-2) cells, leading to a range of pathological responses, and ultimately affecting cell fate. Furthermore, we pioneered the exposure of NPs to human kidney organoids. Our findings revealed a heightened sensitivity in kidney organoids towards NPs as compared to immortalized cell lines. This suggested that exposure to NPs could potentially inflict a more substantial toxic effect on the development of embryonic kidneys. In conclusion, this study has revealed the deleterious effects of exposure to airborne NPs on the mouse kidney.

Microplastic pollution: Critical analysis of global hotspots and their impact on health and ecosystems

This paper examines microplastic hotspots and their drastic effects on human health and the environment pointing out microplastic pollution as one of the biggest global issues. Besides, it analyses the key sources including industrial effluent discharge, littered plastic wastes, and deterioration of synthetic products together with pathways and routes of exposure. The review also focuses on microplastic contamination in food systems such as meat, plant-based products, dairy, and seafood, detailing their entry into the food chain via soil, water, and air. On the other hand, this work also focuses on human health issues including cellular absorption, and bioaccumulation, which results in tissue oxidative stress, inflammation, hormonal imbalance and adverse long-term effects, including carcinogenicity and organ toxicity. The ultimate effects of microplastic pollution on the condition of the soil, water, and fauna and flora of the ecosystem, highlighting on the need for the prevention measures, were also addressed. This paper seeks to critically ascertain the problems posed by microplastics, including their slow biodegradation limit, the absence of proper regulations, and lack of a universally accepted standard. It also highlights that microplastic pollution requires interdisciplinary analyses, future studies, and high standards-compliant policies and regulations. This work raises the alarm for a collective international effort to protect the public health, food, and the earth.

Exposure to polystyrene microplastics with different functional groups: Implications for blood pressure and heart

The association between microplastics (MPs) exposure and cardiovascular disease is largely unknown. It is still unclear what effects MPs exposure have on blood pressure and how it affects the heart. As MPs age, their surfaces undergo modifications that may alter how the MPs interact with cells, which may affect the extent of their toxic effects. Here, we used three different surface functional-group polystyrene microplastics (PS-MPs), and exposed 5-week-old SD rats to them over 42 days. Compared with the control group, the mean blood pressure of the MPs exposed rats increased by 22-40%. Exposure to PS-MPs caused oxidative damage to the heart, and induced cardiomyocyte hypertrophy. More interestingly, MPs modified by functional groups induced enhanced adverse effects than unmodified PS-MPs, with amino-modified PS-MPs exhibiting more significant blood pressure elevation and myocardial hypertrophy. Proteomic analysis of cardiac differential proteins focused on factor XII activation, negative regulation of proteolysis, collectively pointed to the downregulation of kininogen. We demonstrated that MPs exposure induced ERK activation, the down-regulation of bradykinin, and inhibition of the downstream nitric oxide signaling pathway. This study demonstrates the different effects of MPs with different functional groups on blood pressure elevation and myocardial hypertrophy, and sheds light on the mechanisms responsible for microplastic-induced cardiovascular toxicity.

Microplastic pollution inhibits the phagocytosis of E. coli by earthworm immune cells in soil

It has not been known how immune responses in soil invertebrates occur against microplastics (MPs). This study aims to investigate the effects of MPs on endocytosis, including phagocytosis and pinocytosis, of immune cells of soil invertebrates in the soil ecosystem in the process of bacterial infection. We employed polystyrene microplastics (∼ 1 μm PS MPs) to treat earthworm Eisenia andrei during the infection of Escherichia coli for in vitro (1, 5, 10, and 50 mg/L) and in vivo (1, 10, and 1000 mg/kg dry soil) assays. The results of in vitro migration assay revealed that MPs caused inhibitory effects on the phagocytosis, pinocytosis and oxidative stress in coelomocytes. Soil bioassay also confirmed that endocytosis of coelomocytes and mitochondrial damages in the intestinal epithelium were significantly altered in the polluted soil with MPs. Thus, MPs induced adverse effects to inhibit bacterial endocytosis, which may disturb the immune system of soil invertebrates. This study is the first report on the inhibition of phagocytosis in the soil invertebrates by MPs. These findings contribute to understanding the response of soil invertebrates, which play important roles in the soil food web with cellular level towards microplastic pollution in soil.

Microplastics induce human kidney development retardation through ATP-mediated glucose metabolism rewiring

Recent research has revealed an accumulation of microplastics (MPs) in the environment and human tissues, giving rise to concerns about their potential toxicity. The kidney is a vital organ responsible for various physiological functions. Early kidney development is crucial for ensuring proper structure and function. Nevertheless, the impact of MPs on renal development is unclear. In the current study, we examined the effect of MPs on nephrogenesis using human kidney organoids. The environmentally relevant concentrations of MPs were applied. Following MP exposure, the kidney organoids exhibited reduced size and abnormal tubular structures. MPs caused an increased level of mitochondrial reactive oxygen species and DNA damage. Transcriptomic and central carbon metabolism analysis data revealed significant alterations in metabolic pathways after MP exposure, with a decrease in glycolysis and an increase in tricarboxylic acid cycle activity. Moreover, glycolysis inhibition was identified as a contributing factor to the reduced size and abnormal tubular structure of the kidney organoids. These results emphasize the negative effects of MPs on renal development through metabolic reprogramming. Our study provides a novel perspective of MP-induced nephron toxicity mechanisms. The affected pathways and metabolites identified here may act as early biomarkers and therapeutic targets for PS-MP-induced renal toxicity.

Biotransport and toxic effects of micro- and nanoplastics in fish model and their potential risk to humans: A review

The growing body of scientific evidence suggests that micro- and nanoplastics (MPs/NPs) pose a significant threat to aquatic ecosystems and human health. These particles can enter organisms through ingestion, inhalation, dermal contact, and trophic transfer. Exposure can directly affect multiple organs and systems (respiratory, digestive, neurological, reproductive, urinary, cardiovascular) and activate extensive intracellular signaling, inducing cytotoxicity involving mechanisms such as membrane disruption, extracellular polymer degradation, reactive oxygen species (ROS) production, DNA damage, cellular pore blockage, lysosomal instability, and mitochondrial depolarization. This review focuses on current research examining the in vivo and in vitro toxic effects of MPs/NPs on aquatic organisms, particularly fish, in relation to particulate toxicity aspects (such as particle transport mechanisms and structural modifications). Meanwhile, from the perspectives of the food chain and environmental factors, it emphasizes the comprehensive threats of MPs/NPs to human health in terms of both direct and indirect toxicity. Additionally, future research needs and strategies are discussed to aid in mitigating the potential risks of particulate plastics as carriers of toxic trace elements to human health.

Comparative toxicity of microplastics obtained from human consumer products on human cell-based models

Originally developed to conserve natural resources, plastic has become a global pollution issue due to inadequate waste management. The dispersion and weathering of plastic waste in the environment generate micro-sized particles. Despite extensive research on the toxicological effects of pristine polymers, the impact of microplastics (MPs) from consumer plastics is poorly understood. This study investigated the cytotoxic and genotoxic effects of cryo-milled single-use plastic products (fork and cup) on eight cell lines (Caco-2, HEK001, MRC-5, HMEC-1, HepaRG, HMC-3, and T47D) at concentrations from 0.01 to 100 μg/mL. Results showed that 100 μg/mL of MPs did not significantly affect cell viability in Caco-2, HEK001, MRC-5, and T47D. However, HMEC-1 and HMC-3 exhibited decreased viability with 10-100 μg/mL of fork particles, while HMC-3 and HepaRG showed reduced viability with 100 μg/mL of cup particles. Conversely, cup particles increased HMEC-1 proliferation at 0.1-100 μg/mL. Comet assay data indicated that both fork and cup exposure led to elevated DNA fragmentation in HMEC-1 and HMC-3 cells. These findings indicate that MPs from consumer-grade plastics may exhibit cytotoxic and genotoxic effects, with endothelial and microglial cells being particularly susceptible.

Rising Concern About the Carcinogenetic Role of Micro-Nanoplastics

In recent years, awareness regarding micro-nanoplastics' (MNPs) potential effects on human health has progressively increased. Despite a large body of evidence regarding the origin and distribution of MNPs in the environment, their impact on human health remains to be determined. In this context, there is a major need to address their potential carcinogenic risks, since MNPs could hypothetically mediate direct and indirect carcinogenic effects, the latter mediated by particle-linked chemical carcinogens. Currently, evidence in this field is scarce and heterogeneous, but the reported increased incidence of malignant tumors among younger populations, together with the ubiquitous environmental abundance of MNPs, are rising a global concern regarding the possible role of MNPs in the development and progression of cancer. In this review, we provide an overview of the currently available evidence in eco-toxicology, as well as methods for the identification and characterization of environmental MNP particulates and their health-associated risks, with a focus on cancer. In addition, we suggest possible routes for future research in order to unravel the carcinogenetic potential of MNP exposure and to understand prognostic and preventive implications of intratumoral MNPs.

Evaluation of the health impacts and deregulation of signaling pathways in humans induced by microplastics

This review assesses the diverse health risk factors associated with microplastic (MP) exposure and their impact on cellular signaling pathways. MPs induce chronic inflammation, oxidative stress, endocrine disruption, apoptosis, and immune dysregulation. They activate signaling pathways such as NF-κB, MAPK, and Nrf2, exacerbating inflammatory responses, oxidative damage, and hormonal imbalances. Understanding the interplay between MPs and signaling pathways is crucial for elucidating the mechanisms underlying MP-induced health effects. Effective risk assessment and management strategies are essential to mitigate the adverse health impacts of MPs on human populations. This research underscores the urgent need for interdisciplinary collaboration to safeguard human health and environmental sustainability in the face of rising MP pollution. In this paper, we also assess the risk factors caused by the microplastics in the pregnant women and the development of the fetus. This review explores the potential risks and challenges associated with MP exposure in newborn babies. It is quite concerning that microplastic particles were recently found in the placental tissue of newborn children for the first time. Although it is unclear how these tiny particles affect different organs, researchers believe that these tiny particles could potentially carry harmful chemicals or disrupt the developing immune system of the fetus. This review overall focuses on the impact of microplastic disrupting different signaling including reproductive health in humans.

Microplastics exposure disrupts nephrogenesis and induces renal toxicity in human iPSC-derived kidney organoids

Microplastics (MPs) have emerged as a pervasive environmental pollutant of global concern. Their detection within the human placenta and fetal organs has prompted apprehension regarding the potential hazards of MPs during early organogenesis. The kidney, a vital multifunctional organ, is susceptible to damage from MPs in adulthood. However, the precise adverse effects of MP exposure on human nephrogenesis remain ambiguous due to the absence of a suitable model. Here, we explore the potential impact of MPs on early kidney development utilizing human kidney organoids in vitro. Human kidney organoids were subjected to polystyrene-MPs (PS-MPs, 1 μm) during the nephron progenitor cell (NPC) stage, a critical phase in early kidney development and patterning. We delineate the effects of PS-MPs on various stages of nephrogenesis, including NPC, renal vesicle, and comma-shaped body, through sequential examination of kidney organoids. PS-MPs were observed to adhere to the surface of cells during the NPC stage and accumulate within glomerulus-like structures within kidney organoids. Moreover, both short- and long-term exposure to PS-MPs resulted in diminished organoid size and aberrant nephron structure. PS-MP exposure heightened reactive oxygen species (ROS) production, leading to NPC apoptosis during early kidney development. Increased apoptosis, diminished cell viability, and NPC reduction likely contribute to the observed organoid size reduction under PS-MP treatment. Transcriptomic analysis at both NPC and endpoint stages revealed downregulation of Notch signaling, resulting in compromised proximal and distal tubular structures, thereby disrupting normal nephron patterning following PS-MP exposure. Our findings highlight the significant disruptive impact of PS-MPs on human kidney development, offering new insights into the mechanisms underlying PS-MP-induced nephron toxicity.

Micro/nano plastics in the urinary system: Pathways, mechanisms, and health risks

Micro/Nano plastics (MNPs) pollutants are widespread in the environment, raising significant concerns about their biosafety. Emerging studies indicate that the urinary system is a primary accumulation site for MNPs, leading to severe tissue and functional damage. This review aims to summarize recent research on the potential hazards that MNPs may pose to the urinary system, highlighting the mechanisms of toxicity and the current state of knowledge. Studies have shown that MNPs enter the human body through drinking water, the food chain, inhalation, and skin contact. They may penetrate the bloodstream via the digestive, respiratory, and skin systems, subsequently dispersing to various organs, including the urinary system. The potential accumulation of MNPs in the urinary system might induce cellular oxidative stress, inflammation, apoptosis, autophagy, the "intestine-kidney axis", and other possible toxic mechanisms. These processes could disrupt kidney metabolic functions and promote tissue fibrosis, thereby potentially increasing the risk of urinary system diseases. Despite ongoing research, the understanding of MNPs' impact on the urinary system remains limited. Therefore, this review provides a comprehensive overview of MNPs' potential toxicity mechanisms in the urinary system, highlights key challenges, and outlines future research directions. It offers a theoretical basis for the development of effective protective measures and policies.

Nanopolystyrene and phoxim pollution: A threat to hepatopancreas toxicity in Chinese mitten crab (Eriocheir sinensis)

Significant concerns have been raised by the widespread pollutants phoxim (PHO) and nanopolystyrene (NP) in the natural environment. This study evaluated the toxicity effects on the hepatopancreas of Eriocheir sinensis caused by NP and/or PHO at concentrations found in the environment. Subchronic exposure to NP and/or PHO triggered hepatopancreas histological damage within a 21-day exposure period. The NP, PHO, and co-exposure (NPO) groups exhibited fewer blister-like (B) cells, along with the appearance of vacuolation. Furthermore, these exposures induced impairment in the hepatic tubule mucus barrier and mechanical barrier, as evidenced by altered expression of oxidative stress-related genes, mucin-related genes, and TJ-related genes. Additionally, alterations in immunity-related genes and inflammatory cytokine genes expression were observed. The findings showed that hepatopancreas inflammation was caused by both individual and combined exposure to NP and PHO and that the inflammatory response was exacerbated by the co-exposure. The possible pathways of hepatopancreas toxicity were further investigated by transcriptomic analysis. Hepatopancreas inflammation was brought on by subchronic exposure to PHO and co-exposure; this inflammation was exacerbated by co-exposure and was backed by the activation of NF-κB signaling pathway via targeting-related genes. In summary, this research represents the initial documentation, to the best of our understanding of the detrimental effects of exposured to NP and/or PHO at levels found in the environment disrupt the hepatopancreas mucus and mechanical barrier in crustaceans, triggering inflammatory responses. These findings highlight the significance of NP and/or PHO pollution for hepatopancreas health.

Molecular and Cellular Effects of Microplastics and Nanoplastics: Focus on Inflammation and Senescence

Microplastics and nanoplastics (MNPs) are ubiquitous environmental contaminants. Their prevalence, persistence, and increasing industrial production have led to questions about their long-term impact on human and animal health. This narrative review describes the effects of MNPs on oxidative stress, inflammation, and aging. Exposure to MNPs leads to increased production of reactive oxygen species (ROS) across multiple experimental models, including cell lines, organoids, and animal systems. ROS can cause damage to cellular macromolecules such as DNA, proteins, and lipids. Direct interaction between MNPs and immune cells or an indirect result of oxidative stress-mediated cellular damage may lead to increased production of pro-inflammatory cytokines throughout different MNP-exposure conditions. This inflammatory response is a common feature in the pathogenesis of neurodegenerative, cardiovascular, and other age-related diseases. MNPs also act as cell senescence inducers by promoting mitochondrial dysfunction, impairing autophagy, and activating DNA damage responses, exacerbating cellular aging altogether. Increased senescence of reproductive cells and transfer of MNPs/induced damages from parents to offspring in animals further corroborates the transgenerational health risks of the tiny particles. This review aims to provoke a deeper investigation into the notorious effects these pervasive particles may have on human well-being and longevity.

Plastic induced urinary tract disease and dysfunction: a scoping review

INTRODUCTION

In 2019 the World Health Organisation published a report which concluded microplastics in drinking water did not present a threat to human health. Since this time a plethora of research has emerged demonstrating the presence of plastic in various organ systems and their deleterious pathophysiological effects.

METHODS

A scoping review was undertaken in line with recommendations from the Johanna Briggs Institute. Five databases (PubMed, SCOPUS, CINAHL, Web of Science and EMBASE) were systematically searched in addition to a further grey literature search.

RESULTS

Eighteen articles were identified, six of which investigated and characterised the presence of microplastics and nanoplastics (MNPs) in the human urinary tract. Microplastics were found to be present in kidney, urine and bladder cancer samples. Twelve articles investigated the effect of MNPs on human cell lines associated with the human urinary tract. These articles suggest MNPs have a cytotoxic effect, increase inflammation, decrease cell viability and alter mitogen-activated protein kinases (MAPK) signalling pathways.

CONCLUSION

Given the reported presence MNPs in human tissues and organs, these plastics may have potential health implications in bladder disease and dysfunction. As a result, institutions such as the World Health Organisation need to urgently re-evaluate their position on the threat of microplastics to public health.

IMPACT STATEMENT

This scoping review highlights the rapidly emerging threat of microplastic contamination within the human urinary tract, challenging the World Health Organisation's assertion that microplastics pose no risk to public health. The documented cytotoxic effects of microplastics, alongside their ability to induce inflammation, reduce cell viability and disrupt signalling pathways, raise significant public health concerns relating to bladder cancer, chronic kidney disease, chronic urinary tract infections and incontinence. As a result, this study emphasises the pressing need for further research and policy development to address the challenges surrounding microplastic contamination.

Micro/Nanoplastic Exposure on Placental Health and Adverse Pregnancy Risks: Novel Assessment System Based upon Targeted Risk Assessment Environmental Chemicals Strategy

Micro/nanoplastics (MNPs), as emerging pollutants, have been detected in both the maternal and fetal sides of the placenta in pregnant women, and their reproductive toxicity has been demonstrated in in vivo and in vitro experimental models. The Targeted Risk Assessment of Environmental Chemicals (TRAEC) strategy has been innovatively devised to facilitate valid risk assessment, encompassing a comprehensive evaluation of reliability, correlation, outcome fitness, and integrity across four dimensions based on the included published evidence and our own findings. This study serves as an application case of TRAEC, with 40 items of research evidence on the toxicity of MNPs to the placenta, which were rigorously screened and incorporated into the final scoring system. The final score for this TRAEC case study is 5.63, suggesting a moderate-to-low risk of reproductive toxicity associated with MNPs in the placenta, which may potentially increase with decreasing particle size. It is essential to emphasize that the findings also report original data from assays indicating that exposure to high-dose groups (100 μg/mL, 200 μg/mL) of 50 nm and 200 nm polystyrene nanoplastics (PS-NPs) induces HTR8/SVneo cell cycle arrest and cell apoptosis, which lead to reproductive toxicity in the placenta by disrupting mitochondrial function. Overall, this study employed the TRAEC strategy to provide comprehensive insight into the potential reproductive health effects of ubiquitous MNPs.

Research Progress on Micro(nano)plastic-Induced Programmed Cell Death Associated with Disease Risks

Due to their robust migration capabilities, slow degradation, and propensity for adsorbing environmental pollutants, micro(nano)plastics (MNPs) are pervasive across diverse ecosystems. They infiltrate various organisms within different food chains through multiple pathways including inhalation and dermal contact, and pose a significant environmental challenge in the 21st century. Research indicates that MNPs pose health threats to a broad range of organisms, including humans. Currently, extensive detection data and studies using experimental animals and in vitro cell culture indicate that MNPs can trigger various forms of programmed cell death (PCD) and can induce various diseases. This review provides a comprehensive and systematic analysis of different MNP-induced PCD processes, including pyroptosis, ferroptosis, autophagy, necroptosis, and apoptosis, based on recent research findings and focuses on elucidating the links between PCD and diseases. Additionally, targeted therapeutic interventions for these diseases are described. This review provides original insights into the opportunities and challenges posed by current research findings. This review evaluates ways to mitigate various diseases resulting from cell death patterns. Moreover, this paper enhances the understanding of the biohazards associated with MNPs by providing a systematic reference for subsequent toxicological research and health risk mitigation efforts.

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

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

The triple exposure nexus of microplastic particles, plastic-associated chemicals, and environmental pollutants from a human health perspective

The presence of microplastics (MPs) is increasing at a dramatic rate globally, posing risks for exposure and subsequent potential adverse effects on human health. Apart from being physical objects, MP particles contain thousands of plastic-associated chemicals (i.e., monomers, chemical additives, and non-intentionally added substances) captured within the polymer matrix. These chemicals are often migrating from MPs and can be found in various environmental matrices and human food chains; increasing the risks for exposure and health effects. In addition to the physical and chemical attributes of MPs, plastic surfaces effectively bind exogenous chemicals, including environmental pollutants (e.g., heavy metals, persistent organic pollutants). Therefore, MPs can act as vectors of environmental pollution across air, drinking water, and food, further amplifying health risks posed by MP exposure. Critically, fragmentation of plastics in the environment increases the risk for interactions with cells, increases the presence of available surfaces to leach plastic-associated chemicals, and adsorb and transfer environmental pollutants. Hence, this review proposes the so-called triple exposure nexus approach to comprehensively map existing knowledge on interconnected health effects of MP particles, plastic-associated chemicals, and environmental pollutants. Based on the available data, there is a large knowledge gap in regard to the interactions and cumulative health effects of the triple exposure nexus. Each component of the triple nexus is known to induce genotoxicity, inflammation, and endocrine disruption, but knowledge about long-term and inter-individual health effects is lacking. Furthermore, MPs are not readily excreted from organisms after ingestion and they have been found accumulated in human blood, cardiac tissue, placenta, etc. Even though the number of studies on MPs-associated health impacts is increasing rapidly, this review underscores that there is a pressing necessity to achieve an integrated assessment of MPs' effects on human health in order to address existing and future knowledge gaps.

Microplastics and Oxidative Stress-Current Problems and Prospects

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

Environmental toxicants and nephrotoxicity: Implications on mechanisms and therapeutic strategies

Kidneys are one of the most important organs in the human body. In addition to filtering 200 liters of fluid every 24 hours, the kidney also regulates acid-base balance, maintains electrolyte balance, and removes waste and toxicants from the body. Nephrotoxicity is the term used to describe the deterioration of kidney function caused by the harmful effects of medications and various types of environmental toxicants. Exposure to environmental toxicants is an inevitable side effect in the world's increasing industrialization and even more prevalent in underdeveloped nations. Growing data over the past few years has illuminated the probable connection between environmental toxicants and nephrotoxicity. Phthalates, microplastics, acrylamide and bisphenol A are environmental toxicants of particular concern, which are known to have nephrotoxic effects. Such toxicants may accumulate in the kidneys of humans after being consumed, inhaled, or come into contact with the skin. They can enter cells through endocytosis and accumulate in the cytoplasm. Small-sized nephrotoxicants can cause a variety of ailments including inflammation with increased production of pro-inflammatory cytokines, oxidative stress, mitochondrial dysfunction, autophagy, and apoptosis. This study uncovers the potential for new insights concerning the relationship between various environmental toxicants and kidney health. The objectives of this review is to establish information gaps, assess and identify the toxicity mechanisms of different nephrotoxicants, identify innovative pharmacological therapies that demonstrate promising therapeutic benefits/ relevance, and discuss the predictions for the future based on the analysis of the literature.

Co-exposure of arsenic and polystyrene-nanoplastics induced kidney injury by disrupting mitochondrial homeostasis and mtROS-mediated ferritinophagy and ferroptosis

Arsenic (As) and polystyrene nanoplastics (PSNPs) co-exposure induced biotoxicity and ecological risks have attracted wide attention. However, the combined effects of As and PSNPs on the kidney and their underlying mechanisms of toxicities remain to be explored. Here, we investigated the effects of As and PSNPs co-exposure on structure and function in mice kidney, and further explored the possible mechanisms. In this study, we identified that co-exposure to As and PSNPs exhibited conspicuous renal structural damage and pathological changes, accompanied by renal tissue fibrosis (increased protein expression of Collagen I and α-SMA and deposition of collagen fibers), whereas alone exposure to As or PSNPs does not exhibit nephrotoxicity. Subsequently, our results further showed that combined action of As and PSNPs induced mitochondrial oxidative damage and impaired mitochondrial dynamic balance. Furthermore, co-treatment with As and PSNPs activated NCOA4-mediated ferritinophagy and ferroptosis in mice kidney and TCMK-1 cells, which was confirmed by the changes in the expression of ferritinophagy and ferroptosis related indicators (NCOA4, LC3, ATG5, ATG7, FTH1, FTL, GPX4, SLC7A11, FSP1, ACSL4 and PTGS2). Meaningfully, pretreatment with the mtROS-targeted scavenger Mito-TEMPO significantly attenuated As and PSNPs co-exposure induced mitochondrial damage, ferritinophagy and ferroptosis. In conclusion, these findings demonstrated that mtROS-dependent ferritinophagy and ferroptosis are important factors in As and PSNPs co-exposure induced kidney injury and fibrosis. This study provides a new insight into the study of combined toxicity of nanoplastics and heavy metal pollutants.

Mind over Microplastics: Exploring Microplastic-Induced Gut Disruption and Gut-Brain-Axis Consequences

As environmental plastic waste degrades, it creates an abundance of diverse microplastic particles. Consequently, microplastics contaminate drinking water and many staple food products, meaning the oral ingestion of microplastics is an important exposure route for the human population. Microplastics have long been considered inert, however their ability to promote microbial dysbiosis as well as gut inflammation and dysfunction suggests they are more noxious than first thought. More alarmingly, there is evidence for microplastics permeating from the gut throughout the body, with adverse effects on the immune and nervous systems. Coupled with the now-accepted role of the gut-brain axis in neurodegeneration, these findings support the hypothesis that this ubiquitous environmental pollutant is contributing to the rising incidence of neurodegenerative diseases, like Alzheimer's disease and Parkinson's disease. This comprehensive narrative review explores the consequences of oral microplastic exposure on the gut-brain-axis by considering current evidence for gastrointestinal uptake and disruption, immune activation, translocation throughout the body, and neurological effects. As microplastics are now a permanent feature of the global environment, understanding their effects on the gut, brain, and whole body will facilitate critical further research and inform policy changes aimed at reducing any adverse consequences.

Aged polystyrene microplastics exacerbate alopecia associated with tight junction injuries and apoptosis via oxidative stress pathway in skin

Microplastics (MPs) are pervasive pollutants in the natural environment and contribute to increased levels of illness in both animals and humans. However, thespecific impacts of MPs on skin damage and alopeciaare not yet well understood. In this study, we have examined the effects of two types of polystyrene MPs (pristine and aged) on skin and hair follicle damage in mice. UV irradiation changed the chemical and physical properties of the aged MPs, including functional groups, surface roughness, and contact angles. In both in vivo and in vitro experiments, skin and cell injuries related to oxidative stress, apoptosis, tight junctions (TJs), alopecia, mitochondrial dysfunction, and other damages were observed. Mechanistically, MPs and aged MPs can induce TJs damage via the oxidative stress pathway and inhibition of antioxidant-related proteins, and this can lead to alopecia. The regulation of cell apoptosis was also observed, and this is involved in the ROS-mediated mitochondrial signaling pathway. Importantly, aged MPs showed exacerbated toxicity, which may be due to their elevated surface irregularities and altered chemical compositions. Collectively, this study suggests a potential therapeutic approach for alopecia and hair follicle damage caused by MPs pollution.

Toxicological effects of microplastics in renal ischemia-reperfusion injury

The widespread presence of microplastics (MPs) in the environment poses a significant threat to biological survival and human health. However, our understanding of the toxic effects of MPs on the kidneys remains limited. This study aimed to investigate the underlying mechanism of the toxic effects of MPs on the kidneys using an ischemia-reperfusion (IR) mouse model. Four-week-old ICR mice were exposed to 0.5 μm MPs for 12 weeks prior to IR injury. The results showed that MPs exposure could aggravate the IR-induced damage to renal tubules and glomeruli. Although there were no significant changes in blood urea nitrogen and serum creatinine levels 7 days after IR, MPs treatment resulted in a slight increase in both parameters. In addition, the expression levels of inflammatory factors (MCP-1 and IL-6) at the mRNA level, as well as macrophage markers (CD68 and F4/80), were significantly higher in the MPs + IR group than in the Sham group after IR. Furthermore, MPs exposure exacerbated IR-induced renal fibrosis. Importantly, the expression of pyroptosis-related genes, including NLRP3, ASC, GSDMD, cleaved caspase-1, and IL-18, was significantly upregulated by MPs, indicating that MPs exacerbate pyroptosis in the context of renal IR. In conclusion, our findings suggest that MPs exposure can aggravate renal IR-induced pyroptosis by activating NLRP3-GSDMD signaling.

Polystyrene microplastic-induced extracellular vesicles cause kidney-related effects in the crosstalk between tubular cells and fibroblasts

Plastic waste accumulation and its degradation into microplastics (MPs) and nanoplastics (NPs) pose environmental concerns. Previous studies have indicated that polystyrene (PS)-MPs harm living animals. Extracellular vesicles (EVs) are associated with metabolic reprogramming and mitochondrial dysfunction in various kidney diseases. In this article, we evaluated how PS-MPs affected tubular cells and fibroblasts. The results demonstrated that PS-MPs increased EV production in human tubular cells and caused endoplasmic reticulum (ER) stress-related proteins without inducing inflammation-related proteins in human tubular cells. The uptake of PS-MPs and incubation with the conditioned medium of PS-MPs induced reactive oxygen species (ROS) production and ER stress-related proteins in fibroblast cells. The fibroblast cells treated with the conditioned medium of PS-MPs also increased the expression of fibrosis-related proteins. Our findings suggested that the expression of EV-related markers increased in tubular cells via Beclin 1 after PS-MP treatment. In addition, PS-MPs induced ROS production in vitro and in vivo. We found that PS-MPs also altered the expression of EV markers in urine, and CD63 expression was also increased in vitro and in vivo after PS-MP treatment. In conclusion, PS-MP-induced EVs lead to ER stress-related proteins, ROS production and fibrosis-related proteins in tubular cells and fibroblasts.

Unraveling the micro- and nanoplastic predicament: A human-centric insight

Micro- and nanoplastics are vast anthropogenic pollutants in our direct surroundings with a robust environmental stability and a potential for a long-lasting and increasing global circulation. This has raised concerns among the public and policy makers for human health upon exposure to these particles. The micro- and nanoplastic burden on humans is currently under debate, along with criticism on the experimental approaches used in hazard assessment. The present review presents an overview of the human-relevant aspects associated with the current micro-and nanoplastic burden. We focus on environmental circulation and the estimation of exposure quantities to humans, along with a state-of-the-art overview of particle accumulation in over 15 human organs and other specimen. Additionally, data regarding particle characteristics used in toxicity testing was extracted from 91 studies and discussed considering their environmental and human relevance.

A global review on the abundance and threats of microplastics in soils to terrestrial ecosystem and human health

Soil is the source and sink of microplastics (MPs), which is more polluted than water and air. In this paper, the pollution levels of MPs in the agriculture, roadside, urban and landfill soils were reviewed, and the influence of MPs on soil ecosystem, including soil properties, microorganisms, animals and plants, was discussed. According to the results of in vivo and in vitro experiments, the possible risks of MPs to soil ecosystem and human health were predicted. Finally, in light of the current status of MPs research, several prospects are provided for future research directions to better evaluate the ecological risk and human health risk of MPs. MPs concentrations in global agricultural soils, roadside soils, urban soils and landfill soils had a great variance in different studies and locations. The participation of MPs has an impact on all aspects of terrestrial ecosystems. For soil properties, pH value, bulk density, pore space and evapotranspiration can be changed by MPs. For microorganisms, MPs can alter the diversity and abundance of microbiome, and different MPs have different effects on bacteria and fungi differently. For plants, MPs may interfere with their biochemical and physiological conditions and produce a wide range of toxic effects, such as inhibiting plant growth, delaying or reducing seed germination, reducing biological and fruit yield, and interfering with photosynthesis. For soil animals, MPs can affect their mobility, growth rate and reproductive capacity. At present epidemiological evidences regarding MPs exposure and negative human health effects are unavailable, but in vitro and in vivo data suggest that they pose various threats to human health, including respiratory system, digestive system, urinary system, endocrine system, nervous system, and circulation system. In conclusion, the existence and danger of MPs cannot be ignored and requires a global effort.

Polystyrene micro- and nanoplastics induce gastric toxicity through ROS mediated oxidative stress and P62/Keap1/Nrf2 pathway

Microplastics (MPs) exist widely in the environment and can enter the human body indirectly through the food chain or directly through inhalation or ingestion. The primary organ that MPs contaminated food or water enters the human body through the digestive tract is the stomach. However, at present, the effects of MPs on the stomach and the related mechanism remain unclear. In this study, our results indicated that 50 nm and 250 nm polystyrene MPs (PS-MPs) at environmental related dose significantly decreased stomach organ coefficient, inhibited gastric juice secretion and mucus secretion, disrupted gastric barrier function and suppressed antioxidant ability in mice. In vitro experiments showed that PS-MPs inhibited cell viability, increased ROS generation, and induced apoptosis through mitochondria-dependent pathway. Simultaneously, PS-MPs also decreased mitochondrial membrane potential, ATP level, disrupted mitochondrial kinetic homeostasis, and activated P62 / Nrf2 / Keap1 pathway. Furthermore, blocking ROS (NAC) partially alleviated ROS and apoptosis caused by PS-MPs. Based on above findings, the potential adverse outcome pathway (AOP) of PS-MPs-caused gastric toxicity was proposed which provides a new insight into the risk assessment of MP related gastric damage. Our study unveils the gastric injury induced by PS MPs is dependent on ROS - mediated P62 / Nrf2 / Keap1 signaling pathway, and provides scientific basis for further exploration the mechanism of gastric toxicity of PS MPs.

Impact of Chlorella vulgaris Bioremediation and Selenium on Genotoxicity, Nephrotoxicity and Oxidative/Antioxidant Imbalance Induced by Polystyrene Nanoplastics in African Catfish (Clarias gariepinus)

Contamination of the environment with nano- and microplastic particles exerts a threatening impact on the aquatic ecosystems and sustainable catfish aquaculture. The presence of nanoplastics has been found to have a detrimental impact on both aquatic and terrestrial ecosystems. The present study examines the effect of polystyrene nanoplastics (PS NPs) on the DNA, erythrocytes, oxidative status and renal histology of catfish, in addition to the potential protective effects of Chlorella vulgaris bioremediation and selenium to hinder this effect. Six equal groups of fish were used as follows: Group 1 served as a control group and received water free from PS NPs; Group 2 was exposed to PS NPs at a concentration of 5 mg/L; Group 3 was exposed to PS NPs (5 mg/L) + selenium (1 mg/kg diet); Group 4 was exposed to PS NPs (5 mg/L) + C. vulgaris (25 g/kg diet); Group 5 was supplemented with C. vulgaris (25 g/kg diet); and Group 6 was supplemented with selenium (1 mg/kg diet). The exposure period was 30 days. The results indicated that PS NPs induced oxidative stress by significantly elevating malondialdehyde activities and slightly reducing antioxidant biomarkers, resulting in DNA damage, increased frequency of micronuclei, erythrocyte alterations, and numerous histopathological alterations in kidney tissue. Selenium and C. vulgaris significantly ameliorated the oxidative/antioxidant status, reducing DNA damage, micronucleus frequency, erythrocyte alterations, and improving the morphology of kidney tissue. Nevertheless, further research is needed for a profound understanding of the mechanism behind the toxicity of nano-microplatics in aquatic systems.

Effects of partial reduction of polystyrene micro-nanoplastics on the immunity, gut microbiota and metabolome of mice

Microplastic (MP) and nanoplastic (NP) could cause gut microbiota alterations. Although micro/nanoplastic (MNP) degradation is attracting increasing scientific interest, the evaluation of MNP reduction in gut needs to be further investigated. This study aimed to determine whether partial reduction of polystyrene MNP in gut could affect the immunity, gut microbiota and metabolome of mice. Serum eotaxin/CCL11 was at a lower level in the mice exposed to 200 μg and 500 μg NP (i.e., 2NP and 5NP groups, respectively) compared to those exposed to 500 μg MP (i.e., 5 MP group), while serum IL-2 and IL-4 were both greater in the 5NP group compared to the 5 MP group. The gut bacterial alpha diversity, fungal diversity and evenness were all similar among the MNP and control groups. However, the gut fungal richness was greater in both the 5NP and 5 MP groups compared to the control group. The gut bacterial and fungal compositions were both different between the MNP and control groups. Multiple gut bacteria and fungi showed different levels between the 2NP and 5NP groups, as well as between the 2NP and 5 MP groups. Increased Staphylococcus and decreased Glomus were determined in the 2NP group compared to both the 5NP and 5 MP groups. A Lactobacillus phylotype was found as the sole gatekeeper in the bacterial network of the 2NP group, while a Bifidobacterium phylotype contributed most to the stability of the bacterial networks of both the 5NP and 5 MP groups. Multiple differential gut metabolic pathways were found between the 2NP and 5NP/5 MP groups, and mTOR signaling pathway was largely upregulated in the 2NP group compared to both the 5NP and 5 MP groups. The relevant results could help with the evaluation of partial reduction of MNP in gut.

Single-cell RNA-seq analysis decodes the kidney microenvironment induced by polystyrene microplastics in mice receiving a high-fat diet

In recent years, the environmental health issue of microplastics has aroused an increasingly significant concern. Some studies suggested that exposure to polystyrene microplastics (PS-MPs) may lead to renal inflammation and oxidative stress in animals. However, little is known about the essential effects of PS-MPs with high-fat diet (HFD) on renal development and microenvironment. In this study, we provided the single-cell transcriptomic landscape of the kidney microenvironment induced by PS-MPs and HFD in mouse models by unbiased single-cell RNA sequencing (scRNA-seq). The kidney injury cell atlases in mice were evaluated after continued PS-MPs exposure, or HFD treated for 35 days. Results showed that PS-MPs plus HFD treatment aggravated the kidney injury and profibrotic microenvironment, reshaping mouse kidney cellular components. First, we found that PS-MPs plus HFD treatment acted on extracellular matrix organization of renal epithelial cells, specifically the proximal and distal convoluted tubule cells, to inhibit renal development and induce ROS-driven carcinogenesis. Second, PS-MPs plus HFD treatment induced activated PI3K-Akt, MAPK, and IL-17 signaling pathways in endothelial cells. Besides, PS-MPs plus HFD treatment markedly increased the proportions of CD8+ effector T cells and proliferating T cells. Notably, mononuclear phagocytes exhibited substantial remodeling and enriched in oxidative phosphorylation and chemical carcinogenesis pathways after PS-MPs plus HFD treatment, typified by alterations tissue-resident M2-like PF4+ macrophages. Multispectral immunofluorescence and immunohistochemistry identified PF4+ macrophages in clear cell renal cell carcinoma (ccRCC) and adjacent normal tissues, indicating that activate PF4+ macrophages might regulate the profibrotic and pro-tumorigenic microenvironment after renal injury. In conclusion, this study first systematically revealed molecular variation of renal cells and immune cells in mice kidney microenvironment induced by PS-MPs and HFD with the scRNA-seq approach, which provided a molecular basis for decoding the effects of PS-MPs on genitourinary injury and understanding their potential profibrotic and carcinogenesis in mammals.

Micro-algal astaxanthin ameliorates polystyrene microplastics-triggered necroptosis and inflammation by mediating mitochondrial Ca2+ homeostasis in carp's head kidney lymphocytes (Cyprinus carpio L.)

Polystyrene microplastics (PM) is a pressing global environmental concern, posing substantial risks to aquatic ecosystems. Microalgal astaxanthin (MA), a heme pigment, safeguards cells against oxidative damage induced by free radicals, which contributes to various health conditions, including aging, inflammation and chronic diseases. Herein, we investigated the potential of MA in ameliorating the immunotoxicity of PM on carp (Cyprinus carpio L.) based on head kidney lymphocytes treated with PM (250 μM) and/or MA (100 μM). Firstly, CCK8 results showed that PM resulted in excessive death of head kidney lymphocytes. Secondly, head kidney lymphocytes treated with PM had a higher proportion of necroptosis, and the levels of necroptosis-related genes in head kidney lymphocytes were increased. Thirdly, the relative red fluorescence intensity of JC-1 and MitoSox showed decreased mitochondrial membrane potential and increased mtROS in head kidney lymphocytes treated with PM. MitoTracker® Green FM fluorescence analysis revealed enhanced mitochondrial Ca2+ levels in PM-treated lymphocytes, corroborating the association between PM exposure and elevated intracellular Ca2+ dynamics. PM exposure resulted in upregulation of calcium homeostasis-related gene (Orail, CAMKIIδ and SLC8A1) in lymphocytes. Subsequent investigations revealed that PM exposure reduced miR-25-5p expression while increasing levels of MCU, MICU1, and MCUR1. Notably, these effects were counteracted by treatment with MA. Furthermore, PM led to the elevated secretion of inflammatory factors (IFN-γ, IL-1β, IL-2 and TNF-α), thereby inducing immune dysfunction in head kidney lymphocytes. Encouragingly, MA treatment effectively mitigated the immunotoxic effects induced by PM, demonstrating its potential in ameliorating necroptosis, mitochondrial dysfunction and immune impairment via regulating the miR-25-5p/MCU axis in lymphocytes. This study sheds light on safeguarding farmed fish against agrobiological threats posed by PM, highlighting the valuable applications of MA in aquaculture.

Maternal exposure to polystyrene microplastics impairs social behavior in mouse offspring with a potential neurotoxicity

As plastic production has been increasing steadily, environmental pollution resulting from microplastics (MPs) continues to draw considerable attention of the researchers. Several studies have reported that MPs are risk factors for various cellular and systemic dysfunctions. However, the effects of chronic MP exposure from the embryonic stage to adulthood on mouse brain remain unclear. Accordingly, determining the impacts of maternal exposure to MPs on mouse offspring was the main goal of this study. To this end, single cells of primary cortical neurons were isolated from mouse embryos. Subsequently, the cells were exposed to 2 µm polystyrene microplastics (PS-MPs), which resulted in a notable reduction in dendritic length, and PS-MPs cannot pass through the cellular membrane of neurons. Moreover, exposure to PS-MPs caused the proliferation increase and apoptosis in primary cortical neuronal cells. We then evaluated the neurotoxicity associated with chronic PS-MP exposure from the embryonic stage to adulthood in C57BL/6 J mouse offspring. PS-MPs were found to accumulate in the digestive and excretory organs of the offspring but not in the brain tissue. However, offspring exposed to PS-MPs exhibited no differences in the levels of expression of genes related to brain cell markers or synaptic organization. Nevertheless, PS-MP-exposed mice exhibited impaired social novelty preferences; however, no changes were observed in the emotional, compulsive, or cognitive behaviors. Taken together, these results demonstrate the potential neurotoxic effects of chronic exposure to PS-MPs in mouse offspring.

Biomarkers of oxidative stress, inflammation, and genotoxicity to assess exposure to micro- and nanoplastics. A literature review

The increased awareness about possible health effects arising from micro- and nanoplastics (MNPs) pollution is driving a huge amount of studies. Many international efforts are in place to better understand and characterize the hazard of MNPs present in the environment. The literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology in two different databases (PubMed and Embase). The selection of articles was carried out blind, screening titles and abstracts according to inclusion and exclusion criteria. In general, these studies rely on the methodology already in use for assessing hazard from nanomaterials and particles of concern. However, only a limited number of studies have so far directly measured human exposure to MNPs and examined the relationship between such exposure and its impact on human health. This review aims to provide an overview of the current state of research on biomarkers of oxidative stress, inflammation, and genotoxicity that have been explored in relation to MNPs exposure, using human, cellular, animal, and plant models. Both in-vitro and in-vivo models suggest an increased level of oxidative stress and inflammation as the main mechanism of action (MOA) leading to adverse effects such as chronic inflammation, immunotoxicity and genotoxicity. With the identification of such biological endpoints, representing critical key initiating events (KIEs) towards adaptive or adverse outcomes, it is possible to identify a panel of surrogate biomarkers to be applied and validated especially in occupational settings, where higher levels of exposure may occur.

Research progress on the cellular toxicity caused by microplastics and nanoplastics

Microplastics (MPs) are plastic particles of a diameter of less than 5 mm and a major carrier of pollution. In accordance with its diameter range, MPs can be divided into microplastics (100-5 mm) and nanoplastics (<100 nm). In recent years, in addition to the impact of MPs on the environment, the ways in which MPs affect the body has also attracted continuous attention. However, relevant studies on the cytotoxicity of MPs are not comprehensive. Based on the current research, this paper summarizes four main cytotoxic mechanisms of MPs, inducing oxidative stress, damaging cell membrane organelles, inducing immune response, and genotoxicity. Generally, MPs cause cytotoxicity such as oxidative stress, damage to cell membranes and organelles, activation of immune responses, and genotoxicity through mechanical damage or induction of cells to produce reactive oxygen species. Understanding these toxic mechanisms is helpful for the evaluation and prevention of human toxicity of MPs. This paper also analyzes the limitations of current research and prospects for future research into cellular MPs, with the aim of providing a scientific basis and reference for further research into the toxic mechanism of MPs.

The emerging role of microplastics in systemic toxicity: Involvement of reactive oxygen species (ROS)

Plastic pollution is one of the most pressing environmental threats the world is facing currently. The degradation of macroplastics into smaller forms viz. microplastics (MPs) or Nanoplastics (NPs) is a potential threat to both terrestrial and marine ecosystems and also to human health by directly affecting the organs and activating a plethora of intracellular signaling, that may lead to cell death. There is accumulating evidence that supports the serious toxicity caused by MP/NPs at all levels of biological complexities (biomolecules, organelles, cells, tissues, organs, and organ systems) and the involvement of the reactive oxygen species (ROS) in this process. Studies indicate that MPs or NPs can accumulate in mitochondria and further disrupt the mitochondrial electron transport chain, cause mitochondrial membrane damage, and perturb the mitochondrial membrane potential or depolarization of the mitochondria. These events eventually lead to the generation of different types of reactive free radicals, which can induce DNA damage, protein oxidation, lipid peroxidation, and compromization of the antioxidant defense pool. Furthermore, MP-induced ROS was found to trigger a plethora of signaling cascades, such as the p53 signaling pathway, Mitogen-activated protein kinases (MAPKs) signaling pathway including the c-Jun N-terminal kinases (JNK), p38 kinase, and extracellular signal related kinases (ERK1/2) signaling cascades, Nuclear factor erythroid 2-related factor 2 (Nrf2)-pathway, Phosphatidylinositol-3-kinases (PI3Ks)/Akt signaling pathway, and Transforming growth factor-beta (TGF-β) pathways, to name a few. As a consequence of oxidative stress caused by the MPs/NPs, different types of organ damage are observed in living species, including humans, such as pulmonary toxicity, cardiotoxicity, neurotoxicity, nephrotoxicity, immunotoxicity, reproductive toxicity, hepatotoxicity, etc. Although presently, a good amount of research is going on to access the detrimental effects of MPs/NPs on human health, there is a lack of proper model systems, multi-omics approaches, interdisciplinary research, and mitigation strategies.

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.

Microplastics and Kidneys: An Update on the Evidence for Deposition of Plastic Microparticles in Human Organs, Tissues and Fluids and Renal Toxicity Concern

Plastic pollution became a main challenge for human beings as demonstrated by the increasing dispersion of plastic waste into the environment. Microplastics (MPs) have become ubiquitous and humans are exposed daily to inhalation or ingestion of plastic microparticles. Recent studies performed using mainly spectroscopy or spectrometry-based techniques have shown astounding evidence for the presence of MPs in human tissues, organs and fluids. The placenta, meconium, breast milk, lung, intestine, liver, heart and cardiovascular system, blood, urine and cerebrovascular liquid are afflicted by MPs' presence and deposition. On the whole, obtained data underline a great heterogeneity among different tissue and organs of the polymers characterized and the microparticles' dimension, even if most of them seem to be below 50-100 µm. Evidence for the possible contribution of MPs in human diseases is still limited and this field of study in medicine is in an initial state. However, increasing studies on their toxicity in vitro and in vivo suggest worrying effects on human cells mainly mediated by oxidative stress, inflammation and fibrosis. Nephrological studies are insufficient and evidence for the presence of MPs in human kidneys is still lacking, but the little evidence present in the literature has demonstrated histological and functional alteration of kidneys in animal models and cytotoxicity through apoptosis, autophagy, oxidative stress and inflammation in kidney cells. Overall, the manuscript we report in this review recommends urgent further study to analyze potential correlations between kidney disease and MPs' exposure in human.

Face mask derived micro(nano)plastics and organic compounds potentially induce threat to aquatic ecosystem security revealed by toxicogenomics-based assay

Micro(nano)plastics widely detected in aquatic environments have caused serious threat to water quality security. However, as a potential important source of micro(nano)plastics in surface water during the COVID-19 pandemic, the ecological risks of face mask waste to aquatic environments remain poorly understood. Herein, we comprehensively characterized the micro(nano)plastics and organic compounds released from four daily used face masks in aqueous environments and further evaluated their potential impacts on aquatic ecosystem safety by quantitative genotoxicity assay. Results from spectroscopy and high-resolution mass spectrum showed that plastic microfibers/particles (∼11%-83%) and leachable organic compounds (∼15%-87%) were dominantly emitted pollutants, which were significantly higher than nanoplastics (< ∼5%) based on mass of carbon. Additionally, a toxicogenomics approach using green fluorescence protein-fused whole-cell array revealed that membrane stress was the primary response upon the exposure to micro(nano)plastics, whereas the emitted organic chemicals were mainly responsible for DNA damage involving most of the DNA repair pathways (e.g., base/nucleotide excision repair, mismatch repair, double-strand break repair), implying their severe threat to membrane structure and DNA replication of microorganisms. Therefore, the persistent release of discarded face masks derived pollutants might exacerbate water quality and even adversely affect aquatic microbial functions. These findings would contribute to unraveling the potential effects of face mask waste on aquatic ecosystem security and highlight the necessity for more developed management regulations in face mask disposal.

Biological effects of polystyrene micro- and nano-plastics on human intestinal organoid-derived epithelial tissue models without and with M cells

Micro- and nano-plastics (MPs and NPs) released from plastics in the environment can enter the food chain and target the human intestine. However, knowledge about the effects of these particles on the human intestine is still limited due to the lack of relevant human intestinal models to validate data obtained from animal studies or tissue models employing cancer cells. In this study, human intestinal organoids were used to develop epithelia to mimic the cell complexity and functions of native tissue. Microfold cells (M cells) were induced to distinguish their role when exposure to MPs and NPs. During the exposure, the M cells acted as sensors, capturers and transporters of larger sized particles. The epithelial cells internalized the particles in a size-, concentration-, and time-dependent manner. Importantly, high concentrations of particles significantly triggered the secretion of a panel of inflammatory cytokines linked to human inflammatory bowel disease (IBD).

Size dependent effects of nanoplastics and microplastics on the nitrogen cycle of microbial flocs

NANO: and microplastics (NPs/MPs) are a new type of persistent environmental pollutant. Microbial flocs are a type of microbial aggregate commonly used in aquaculture. To investigate the impact of NPs/MPs on microbial flocs with different particle sizes: NPs/MPs-80 nm (M 0.08), NPs/MPs-800 nm (M 0.8), and NPs/MPs-8 μm (M 8), NPs/MPs exposure tests (28 days) and ammonia nitrogen conversion tests (24 h) were conducted. The results showed that the particle size was significantly higher in the M 0.08 group when compared with the control group (C group). The TAN (total ammonia nitrogen) content of each group maintained the order of M 0.08 > M 0.8 > M 8 > C from days 12-20. The nitrite content in the M 0.08 group was significantly higher on day 28 than that in the other groups. In the ammonia nitrogen conversion test, the nitrite content of the C group was significantly lower than that of the NPs/MPs exposure groups. The results suggested that NPs contributed to microbial aggregation and affected microbial colonization. In addition, NPs/MPs exposure could reduce microbial nitrogen cycling capacity, with a size-dependent toxicity difference of NPs > MPs. The findings of this study are expected to fill the research gap on the mechanisms of NPs/MPs' impact on microorganisms and the nitrogen cycle in aquatic ecosystems.

NLRP3 inflammasome as a sensor of micro- and nanoplastics immunotoxicity

Micro- and nanoplastics (MNPs) are emerging pollutants with scarcely investigated effects on human innate immunity. If they follow a similar course of action as other, more thoroughly investigated particulates, MNPs may penetrate epithelial barriers, potentially triggering a cascade of signaling events leading to cell damage and inflammation. Inflammasomes are intracellular multiprotein complexes and stimulus-induced sensors critical for mounting inflammatory responses upon recognition of pathogen- or damage-associated molecular patterns. Among these, the NLRP3 inflammasome is the most studied in terms of activation via particulates. However, studies delineating the ability of MNPs to affect NLRP3 inflammasome activation are still rare. In this review, we address the issue of MNPs source and fate, highlight the main concepts of inflammasome activation via particulates, and explore recent advances in using inflammasome activation for assessment of MNP immunotoxicity. We also discuss the impact of co-exposure and MNP complex chemistry in potential inflammasome activation. Development of robust biological sensors is crucial in order to maximize global efforts to effectively address and mitigate risks that MNPs pose for human health.

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.

Evaluation of toxicity of polystyrene microplastics under realistic exposure levels in human vascular endothelial EA.hy926 cells

Microplastics (MPs) have emerged as a global concern, with a recent study being the first to detect them in the bloodstream of healthy people. However, precise information regarding the toxic effects of MPs on the human vascular system is currently lacking. In this study, we used human vascular endothelial EA. hy926 cells to examine the toxic potential of polystyrene MPs (PSMPs) under realistic blood concentrations. Our findings indicated that PSMPs can cause oxidative stress by reducing the expression of antioxidants, thereby leading to apoptotic cytotoxicity in EA. hy926 cells. Furthermore, the protective potential of heat shock proteins can be reduced by PSMPs. PSMP-induced apoptosis might also lower the expression of rho-associated protein kinase-1 and nuclear factor-κB expression, thus dampening LRR- and pyrin domain-containing protein 3 in EA. hy926 cells. Moreover, we observed that PSMPs induce vascular barrier dysfunction via the depletion of zonula occludens-1 protein. However, although protein expression of the nuclear hormone receptor 77 was inhibited, no significant increase in ectin-like oxidized low-density lipoprotein receptor-1 was noted in PSMP-treated EA. hy926 cells. These results demonstrate that exposure to PSMPs may not sufficiently increase the risk of developing atherosclerosis. Overall, our research signifies that exposure to realistic blood concentrations of PSMPs is associated with low atherosclerotic cardiovascular risk in humans.

Polystyrene microplastics induced nephrotoxicity associated with oxidative stress, inflammation, and endoplasmic reticulum stress in juvenile rats

Introduction

Unintended intake of microplastic particles has been demonstrated to exert adverse health effects, however, studies on relevant nephrotoxicity in juvenile mammals are lacking.

Methods

Therefore, we investigated the potential nephrotoxicity of oral-exposed polystyrene microplastics (PSMPs) (1,000 nm, 2.0 mg/kg/d) for 28 days in juvenile rats. Levels of oxidative stress, inflammation, and endoplasmic reticulum (ER) stress in kidneys were analyzed.

Results and discussion

Results revealed that PSMPs noticeably decreased the growth rate of bodyweight, and organ index of the kidney, cardiac, and ovary. The intestinal injury caused by PSMPs exposure was also observed, which was distinctly alleviated with N-acetyl-cysteine (NAC) and Salubrinal (Sal) treatment compared with the single PSMPs group. PSMPs caused histological lesions of the kidney via disrupting the serum blood urea nitrogen (BUN), creatinine (CRE), and pro-inflammatory mediators IL-1β, IL-6, and TNF-α. Furthermore, PSMPs exposure induced ER stress and inflammation presumably potentially mediated by oxidative stress in kidneys of rats. Eventually, PSMPs also promoted renal cells apoptosis, manifested as an obvious increase in the number of positive cells for the dUTP nick end labeling of Terminal deoxynucleotidyl transferase, which also can be confirmed by the elevated expression of genes associated with apoptosis Bcl-2, Bax, Caspase-12, Caspase-9, Caspase-3, and IHC score of Caspase-12 in the PSMPs group. Supplementation of NAC and Sal not only ameliorated the PSMPs-induced oxidative stress and ER stress but also the inflammation and apoptosis in the kidney. Collectively, this study suggested that PSMPs caused nephrotoxicity in juvenile rats potentially through oxidative damage and ER stress, which call for greater efforts to be taken on regulating the PSMPs ingestion in children.

Polystyrene nanoplastics promote the apoptosis in Caco-2 cells induced by okadaic acid more than microplastics

Microplastics (MPs) are widespread in the environment and can be ingested through food, water, and air, posing a threat to human health. In addition, MPs can have a potential combined effect with other toxic compounds. Polystyrene (PS) has been shown to enhance the cytotoxicity of okadaic acid (OA). However, it remains unclear whether this enhancement effect is related to the size of PS particles. In this study, we investigated the mechanism of the combined effect of PS microplastics (PS-MPs) or PS nanoplastics (PS-NPs) and OA on Caco-2 cells. The results indicated that PS-NPs enhanced the cytotoxicity of OA and induced endoplasmic reticulum (ER) stress-mediated apoptosis in Caco-2 cells, compared to PS-MPs. Specifically, PS-NPs and OA cause more severe oxidative stress, lactate dehydrogenase (LDH) release, and mitochondrial membrane depolarization. Furthermore, it induced intracellular calcium overload through store-operated channels (SOCs) and activated the PERK/ATF-4/CHOP pathway to cause ER stress. ER stress promoted mitochondrial damage and finally activated the caspase family to induce apoptosis. This study provided an indirect basis for the assessment of the combined toxicity of MPs or NPs with OA.

Recent consequences of micro-nanaoplastics (MNPLs) in subcellular/molecular environmental pollution toxicity on human and animals

Microplastics and Nanoplastics (MNPLs) pollution has been recognized as the important environmental pollution caused by human activities in addition to global warming, ozone layer depletion and ocean acidification. Most of the current studies have focused on the toxic effects caused by plastics and have not actively investigated the mechanisms causing cell death, especially at the subcellular level. The main content of this paper focuses on two aspects, one is a review of the current status of MNPLs contamination and recent advances in toxicological studies, which highlights the possible concentration levels of MNPLs in the environment and the internal exposure of humans. It is also proposed to pay attention to the compound toxicity of MNPLs as carriers of other environmental pollutants and pathogenic factors. Secondly, subcellular toxicity is discussed and the modes of entry and intracellular distribution of smaller-size MNPLs are analyzed, with particular emphasis on the importance of organelle damage to elucidate the mechanism of toxicity. Importantly, MNPLs are a new type of environmental pollutant and researchers need to focus not only on their toxicity, but also work with governments to develop measures to reduce plastic emissions, optimize degradation and control plastic aggression against organisms, especially humans, from multiple perspectives.

Combined toxicity of micro/nanoplastics loaded with environmental pollutants to organisms and cells: Role, effects, and mechanism

Micro/nanoplastics (MPs/NPs) are ubiquitous in the environment and living organisms have been exposed to these substances for a long time. When MPs/NPs enter different organisms, they transport various pollutants, including heavy metals, persistent organic pollutants, drugs, bacteria, and viruses, from the environment. On this basis, this paper summarizes the combined toxicity induced by MPs/NPs accumulating contaminants from the environment and entering organisms through a systematic review of 162 articles. Moreover, the factors influencing toxic interactions are critically discussed, thus highlighting the dominant role of the relative concentrations of contaminants in the combined toxic effects. Furthermore, for the first time, we describe the threats posed by MPs/NPs combined with other pollutants to human health, as well as their cytotoxic behavior and mechanism. We found that the "Trojan horse" effect of nanoplastics can increase the bioaccessibility of environmental pollutants, thus increasing the carcinogenic risk to humans. Simultaneously, the complex pollutants entering the cells are observed to be constantly dissociated due to the transport of lysosomes. However, current research on the intracellular release of MP/NP-loaded pollutants is relatively poor, which hinders the accurate in vivo toxicity assessment of combined pollutants. Based on the findings of our critical review, we recommend analyzing the toxic effects by clarifying the dose relationship of each component pollutant in cells, which is challenging yet crucial to exploring the toxic mechanism of combined pollution. In the future, our findings can contribute to establishing a system modeling the complete load-translocation toxicological mechanism of MP/NP-based composite pollutants.

Quantitative assessment of interactions of hydrophilic organic contaminants with microplastics in natural water environment

The interaction between microplastics (MPs) and hydrophilic organic contaminants (HOCs) in natural water environment has recently raised great public attentions due to the potential toxicity to humans. However, the quantitative assessment is less studied. In this study, the interaction between ciprofloxacin (CIP) and ofloxacin (OFL) (two important HOCs) and virgin and aged polystyrene (PS) was investigated. The aged PS showed higher adsorption rate and capacity than the virgin PS, due to its larger surface area and more O-containing groups. The pH-dependent adsorption of CIP was higher than OFL on both virgin and aged PS; the maximum adsorption for both HOCs occurred at pH 5. The sequential orders of functional groups for the adsorption were discovered according to the study by the 2D correlation Fourier transform infrared spectroscopy. Several mechanisms existed for the interaction: (1) at 3.0 < pH < 5.0, the electrostatic attraction (EA) was inhibited while H-bond (HB) was dominant, accounting for > 60% of the total uptake; (2) at 5.0 < pH < 8.0, the contribution of EA increased to around 50-60% while HB decreased to 30-40%; (3) at 8.0 < pH < 10.0, EA, HB and π-π conjugation caused 30-40%, 25-40% and 20-45% of the total uptake, respectively; (4) at 10.0 < pH < 12.0, π-π conjugation accounted for 90-100%. Notably, higher adsorption of CIP was mainly attributed to the presence of secondary amino groups and its higher pK_a value, correspondingly leading to the additional ordinary HB and negative charge-assisted HB, and EA interactions with PS. This study further provides clear evidences on the risk of MPs and HOCs on humans and aqueous living organisms.