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[This corrects the article DOI: 10.1371/journal.pone.0289473.].

[This corrects the article DOI: 10.1371/journal.pone.0289473.].[This corrects the article DOI: 10.1371/journal.pone.0289473.].

Evidence exists that humans are exposed to plastic microparticles via diet. Data on intestinal particle uptake and health-related effects resulting from microplastic exposure are scarce. Aim of the study was to analyze the uptake and effects of microplastic particles in human in vitro systems and in rodents in vivo. The gastrointestinal uptake of microplastics was studied in vitro using the human intestinal epithelial cell line Caco-2 and thereof-derived co-cultures mimicking intestinal M-cells and goblet cells. Different sizes of spherical fluorescent polystyrene (PS) particles (1, 4 and 10 µm) were used to study particle uptake and transport. A 28-days in vivo feeding study was conducted to analyze transport at the intestinal epithelium and oxidative stress response as a potential consequence of microplastic exposure. Male reporter gene mice were treated three times per week by oral gavage with a mixture of 1 µm (4.55 × 107 particles), 4 µm (4.55 × 107 particles) and 10 µm (1.49 × 106 particles) microplastics at a volume of 10 mL/kg/bw. Effects of particles on macrophage polarization were investigated using the human cell line THP-1 to detect a possible impact on intestinal immune cells. Altogether, the results of the study demonstrate the cellular uptake of a minor fraction of particles. In vivo data show the absence of histologically detectable lesions and inflammatory responses. The particles did not interfere with the differentiation and activation of the human macrophage model. The present results suggest that oral exposure to PS microplastic particles under the chosen experimental conditions does not pose relevant acute health risks to mammals.

Although the fates of microplastics (0.1–5 mm in size) and nanoplastics (<100 nm) in marine environments are being increasingly well studied1,2, little is known about the behaviour of nanoplastics in terrestrial environments3–6, especially agricultural soils7. Previous studies have evaluated the consequences of nanoplastic accumulation in aquatic plants, but there is no direct evidence for the internalization of nanoplastics in terrestrial plants. Here, we show that both positively and negatively charged nanoplastics can accumulate in Arabidopsis thaliana. The aggregation promoted by the growth medium and root exudates limited the uptake of amino-modified polystyrene nanoplastics with positive surface charges. Thus, positively charged nanoplastics accumulated at relatively low levels in the root tips, but these nanoplastics induced a higher accumulation of reactive oxygen species and inhibited plant growth and seedling development more strongly than negatively charged sulfonic-acid-modified nanoplastics. By contrast, the negatively charged nanoplastics were observed frequently in the apoplast and xylem. Our findings provide direct evidence that nanoplastics can accumulate in plants, depending on their surface charge. Plant accumulation of nanoplastics can have both direct ecological effects and implications for agricultural sustainability and food safety.The accumulation of nanoplastics in terrestrial plants is directly linked to the nanoparticles’ charge and can have ecological effects and implications for agricultural sustainability and food safety.

Polystyrene Nanoparticles (PS-NPs) used for packaging foam, disposable cups, and food containers. Therefore, this study aimed to evaluate PS- NPs toxic effects on kidney of adult male albino rats. A total of 30 rats divided into three groups ( n  = 10): group I negative control group; group II orally administered 3% PS-NPs (3 mg/kg body weight/day) and group III orally administered 3% PS-NPs (10 mg/kg body weight/day) for 35 days. Blood and kidney samples collected and processed for biochemical, histopathological, and immunohistochemical examinations. Results showed that low and high doses PS-NPs had significantly increased serum blood urea nitrogen (BUN), creatinine, malondialdehyde, significantly further reduced glutathione, downregulation of nuclear factor erythroid 2–related factor 2 and glutathione peroxidase, upregulation of caspase-3 and Cytochrome-c. Histopathological examination revealed several alterations. Low dose of PS-NPs exhibited dilated glomerular capillaries, hypotrophy of some renal corpuscles significantly decreases their diameter to 62 μm. Some proximal convoluted tubules and distal convoluted tubules showed loss of cellular architecture with pyknotic nuclei. Hyalinization and vacuolation in renal medulla. In high dose PS-NPs, alterations increased in severity. A significant increase in percentage area of cyclooxygenase-2 in low and high-doses. In conclusion , PS-NPs are a nephrotoxic causing renal dysfunction.

Background There has been an exponential increase in the number of studies reporting on the toxicological effects associated with exposure to nano and microplastic particles (NMPs). The majority of these studies, however, have used monodispersed polystyrene microspheres (PSMs) as ‘model’ particles. Here we review the differences between the manufacture and resulting physicochemical properties of polystyrene used in commerce and the PSMs most commonly used in toxicity studies. Main body In general, we demonstrate that significant complexity exists as to the properties of polystyrene particles. Differences in chemical composition, size, shape, surface functionalities and other aspects raise doubt as to whether PSMs are fit-for-purpose for the study of potential adverse effects of naturally occurring NMPs. A realistic assessment of potential health implications of the exposure to environmental NMPs requires better characterisation of the particles, a robust mechanistic understanding of their interactions and effects in biological systems as well as standardised protocols to generate relevant model particles. It is proposed that multidisciplinary engagement is necessary for the development of a timely and effective strategy towards this end. We suggest a holistic framework, which must be supported by a multidisciplinary group of experts to work towards either providing access to a suite of environmentally relevant NMPs and/or developing guidance with respect to best practices that can be adopted by research groups to generate and reliably use NMPs. It is emphasized that there is a need for this group to agree to a consensus regarding what might best represent a model NMP that is consistent with environmental exposure for human health, and which can be used to support a variety of ongoing research needs, including those associated with exposure and hazard assessment, mechanistic toxicity studies, toxicokinetics and guidance regarding the prioritization of plastic and NMPs that likely represent the greatest risk to human health. It is important to acknowledge, however, that establishing a multidisciplinary group, or an expert community of practice, represents a non-trivial recommendation, and will require significant resources in terms of expertise and funding. Conclusion There is currently an opportunity to bring together a multidisciplinary group of experts, including polymer chemists, material scientists, mechanical engineers, exposure and life-cycle assessment scientists, toxicologists, microbiologists and analytical chemists, to provide leadership and guidance regarding a consensus on defining what best represents environmentally relevant NMPs. We suggest that given the various complex issues surrounding the environmental and human health implications that exposure to NMPs represents, that a multidisciplinary group of experts are thus critical towards helping to progress the harmonization and standardization of methods.

Nanoplastics (NPs) pose health concerns worldwide. However, robust quantitative data on their absorption, distribution, and excretion in mammals remain scarce. Here, we provide a comprehensive assessment of polystyrene (PS) NP biodistribution and elimination in rats using 14 C-radiolabeling, the most accurate and quantitative method available. Pregnant rats were exposed to 14 C-labeled 20 nm or 100 nm PS NPs (PS 20 or PS 100 ) via oral gavage, intratracheal aerosolization, or intravenous injection, and tissue distribution and excretion were determined by radioactivity measurements. We found that PS NPs were exclusively excreted through faeces, irrespective of the exposure routes, without urinary elimination. Both PS 20 and PS 100 crossed multiple biological barriers, yet only PS 20 reached the brain. Maternal transfer of PS 20 occurred through both placenta and milk, while PS 100 transferred solely via milk. A physiologically based toxicokinetic model further simulated accumulation kinetics across tissues. This study establishes the most comprehensive and reliable quantitative profile of PS NP biodistribution in mammals to date, revealing distinct size-dependent translocation patterns that provide a robust foundation for evaluating their health impacts. Previous studies on biodistribution of microplastics showed discrepancies. This study provides quantitative data to date on how nanoplastics distribute and eliminate from the body using carbon-14-radiolabelled particles in rats.

The uptake pathways of nanoplastics by edible plants have recently been qualitatively investigated. There is an urgent need to accurately quantify nanoplastics accumulation in plants. Polystyrene (PS) particles with a diameter of 200 nm were doped with the europium chelate Eu–β-diketonate (PS-Eu), which was used to quantify PS-Eu particles uptake by wheat (Triticum aestivum) and lettuce (Lactuca sativa), grown hydroponically and in sandy soil using inductively coupled plasma mass spectrometry. PS-Eu particles accumulated mainly in the roots, while transport to the shoots was limited (for example, <3% for 5,000 μg PS particles per litre exposure). Visualization of PS-Eu particles in the roots and shoots was performed with time-gated luminescence through the time-resolved fluorescence of the Eu chelate. The presence of PS-Eu particles in the plant was further confirmed by scanning electron microscopy. Doping with lanthanide chelates provides a versatile strategy for elucidating the interactions between nanoplastics and plants.The uptake and transfer of nanoplastics in the roots and shoots of lettuce and wheat were quantified by doping polystyrene nanoparticles with Eu–β-diketonate and using inductively coupled plasma mass spectrometry, time-gated luminescence and scanning electron microscopy.

Microplastics (MPs) are small particles of plastic ( in diameter). In recent years, oral exposure to MPs in living organisms has been a cause of concern. Leaky gut syndrome (LGS), associated with a high-fat diet (HFD) in mice, can increase the entry of foreign substances into the body through the intestinal mucosa. We aimed to evaluate the pathophysiology of intestinal outcomes associated with consuming a high-fat diet and simultaneous intake of MPs, focusing on endocrine and metabolic systems. C57BL6/J mice were fed a normal diet (ND) or HFD with or without polystyrene MP for 4 wk to investigate differences in glucose tolerance, intestinal permeability, gut microbiota, as well as metabolites in serum, feces, and liver. In comparison with HFD mice, mice fed the HFD with MPs had higher blood glucose, serum lipid concentrations, and nonalcoholic fatty liver disease (NAFLD) activity scores. Permeability and goblet cell count of the small intestine (SI) in HFD-fed mice were higher and lower, respectively, than in ND-fed mice. There was no obvious difference in the number of inflammatory cells in the SI lamina propria between mice fed the ND and mice fed the ND with MP, but there were more inflammatory cells and fewer anti-inflammatory cells in mice fed the HFD with MPs in comparison with mice fed the HFD without MPs. The expression of genes related to inflammation, long-chain fatty acid transporter, and cotransporter was significantly higher in mice fed the HFD with MPs than in mice fed the HFD without MPs. Furthermore, the genus was significantly more abundant in the intestines of mice fed the HFD with MPs in comparison with mice fed the HFD without MPs. gene expression was decreased when palmitic acid and microplastics were added to the murine intestinal epithelial cell line MODE-K cells, and Muc2 gene expression was increased when IL-22 was added. Our findings suggest that in this study, MP induced metabolic disturbances, such as diabetes and NAFLD, only in mice fed a high-fat diet. These findings suggest that LGS might have been triggered by HFD, causing MPs to be deposited in the intestinal mucosa, resulting in inflammation of the intestinal mucosal intrinsic layer and thereby altering nutrient absorption. These results highlight the need for reducing oral exposure to MPs through remedial environmental measures to improve metabolic disturbance under high-fat diet conditions. https://doi.org/10.1289/EHP11072.

Conducting polymers are promising material candidates in diverse applications including energy storage, flexible electronics, and bioelectronics. However, the fabrication of conducting polymers has mostly relied on conventional approaches such as ink-jet printing, screen printing, and electron-beam lithography, whose limitations have hampered rapid innovations and broad applications of conducting polymers. Here we introduce a high-performance 3D printable conducting polymer ink based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) for 3D printing of conducting polymers. The resultant superior printability enables facile fabrication of conducting polymers into high resolution and high aspect ratio microstructures, which can be integrated with other materials such as insulating elastomers via multi-material 3D printing. The 3D-printed conducting polymers can also be converted into highly conductive and soft hydrogel microstructures. We further demonstrate fast and streamlined fabrications of various conducting polymer devices, such as a soft neural probe capable of in vivo single-unit recording. Conducting polymers are promising materials for diverse applications but the fabrication of conducting polymers mostly relies on conventional fabrication techniques. Here the authors introduce a high performance 3D printable conducting polymer ink to take full advantage of advanced 3D printing.