SMC 資料庫

Background：

*In this study, the nanoplastics used were all 100 nanometers in size.

*According to the U.S. FDA, nanoplastics are commonly regarded as smaller than 1 micrometer, although there is currently no standardized definition for the size of microplastics or nanoplastics.

*For reference, 100-nanometer nanoplastics are about 1/700 the width of a human hair.

Expert reaction:

【劉勃佑 Po-Yu Liu 】【羅月霞 Yueh-Hsia Luo 】【李昇翰 Sheng-Han Lee 】

2025/06/09
Po-Yu Liu

Assistant Professor, School of Medicine, National Sun Yat-sen University, Taiwan.

Researchers from National Cheng Kung University and National Chiayi University have uncovered new evidence suggesting that long-term exposure to nanoplastics could harm mice's intestinal health. The study, published in Nature Communications, demonstrates that nanoplastics can penetrate cells, disrupt the gut barrier, and alter the balance of gut microbiota.

Due to their extremely small size, nanoplastics are able to penetrate intestinal cells and trigger the release of signaling molecules that regulate tight junction proteins. This process increases intestinal permeability, also known as "leaky gut." Leaky gut compromises the intestinal microenvironment, allowing bacteria and inflammatory molecules to enter the bloodstream—a factor closely linked to disease development and microbiota imbalance (dysbiosis).

The researchers used polystyrene nanoplastics, a material widely found in disposable tableware and foam products, to model real-world exposure. Their findings raise concerns over the potential health risks posed by everyday plastics, particularly given the prevalence of polystyrene in consumer goods.

While the study reveals significant effects on gut tissues and microbiota composition, there is no need for public panic. The experiments were conducted under continuous, high-dose exposure conditions, which exceed typical daily human exposure levels. However, the long-term effects of chronic, low-level exposure remain a cause for concern. Reducing plastic use, particularly in food packaging and household items, is recommended as a precautionary measure.

Importantly, the study employed fluorescently labeled nanoplastics to trace their presence inside gut microbes. The researchers observed that nanoplastics disrupted host-microbe communication, resulting in an increase in harmful bacteria and a decrease in probiotics such as Lactobacilli. The novel method developed to detect nanoplastics within fecal samples and microbial cells offers a promising tool for future human exposure assessments.

As plastics remain an indispensable part of modern life, there is an urgent need for further clinical and epidemiological research to fully understand the long-term health effects of nanoplastic exposure.

Declared of interests: None.

2025/06/09
Yueh-Hsia Luo

Associate Professor, Department of Life Sciences, National Central University; Environmental Biomedicine Technology Center (EBMTC), College of Health Sciences & Technology, National Central University, Taiwan. 

Q1: Why is this study important? How can it support future research on the health effects of nanoplastics in humans?

This study is the first to demonstrate that polystyrene (PS) nanoplastics can alter exosome secretion by intestinal goblet cells, thereby promoting the growth of Ruminococcaceae and contributing to gut microbiota dysbiosis. Furthermore, PS nanoplastics can be internalized by Lachnospiraceae, which subsequently secrete extracellular vesicles that inhibit intestinal mucus secretion. 

These changes collectively lead to a reduction in tight junction protein expression in epithelial cells, compromising the intestinal barrier function. The mechanisms revealed in this study provide critical insights into how nanoplastics disrupt gut health and identify potential biomarkers that could serve as indicators of intestinal exposure to nanoplastics in future human health assessments.  

Q2: How should the general public interpret the results of this study? Should we be concerned that nanoplastics could harm intestinal function? Do we need to change our diets?

Currently, there is insufficient evidence to suggest that typical daily exposure to nanoplastics poses a significant risk to intestinal health. The exposure levels used in this study were much higher than those humans normally encounter. Therefore, the public does not need to be overly concerned or make immediate changes to their diet based on these findings.  

Q3: What are the inferential limitations of this study? Are there aspects we should interpret with caution?

While this study offers valuable insights into the biological mechanisms by which nanoplastics may affect gut health, it should not be interpreted as evidence of an immediate health threat to humans. Several important limitations should be considered when interpreting the findings:  

1. High exposure dosage: In vitro effects were only observed at concentrations of 100,000 particles per mL, and the 12-week in vivo experiment involved a total exposure of approximately 10¹² particles—substantially higher than typical human exposure levels. Therefore, the findings cannot be directly extrapolated to real-world human exposure scenarios.  
2. Species differences: Mouse models do not fully replicate human intestinal physiology. Differences in species-specific sensitivity and nanoplastic metabolism may limit the direct applicability of these results to humans.  
3. Limited human exposure assessment: Current estimates suggest humans may ingest several hundred nanoplastic particles daily, but the proportion that falls within the nanoscale is unknown. Due to limited experimental data and the absence of established biodistribution models, it remains difficult to accurately assess nanoplastic accumulation and distribution in the human body.  
4. Single material type: This study examined only one type of nanoplastic—100 nm polystyrene (PS). Since nanoplastics can vary widely in size, shape, and chemical composition, it is unclear whether the same biological effects would occur with other types of nanoplastics.  

Q4: What are the most urgent research directions to confirm the potential health risks of nanoplastics to the human gut and microbiota?

Future research should prioritize the following areas:

1. Development of high-sensitivity detection methods: Establishing analytical techniques capable of accurately identifying and quantifying nanoplastics in human biological samples is essential for assessing exposure levels and potential health risks.  
2. Epidemiological studies: Investigating how different populations respond to nanoplastic exposure and analyzing correlations with gut microbiota composition, immune responses, and intestinal dysfunction. 
3. Realistic exposure modeling: Using animal models or human intestinal organoids to simulate chronic, low-dose exposure scenarios and track the biodistribution and metabolic pathways of nanoplastics under conditions that reflect daily human exposure.  
4. Comparative studies of plastic materials: Evaluating the effects of different types of plastics on the gut to provide a more comprehensive assessment of the health risks associated with various nanoplastics.  

Given current limitations in nanoplastic detection technologies and the uncertainties associated with extrapolating animal model results to humans, continued research is critical to accurately evaluate the potential long-term health effects of nanoplastics in humans.

Declaration of interest: No conflicts of interest.

2025/06/09
Sheng-Han Lee

Assistant Professor, School of Medicine, College of Medicine, National Sun Yat-sen University, Taiwan.

The importance of this study lies in demonstrating that exposure to nanoplastics can affect intestinal health by altering the interaction of gut symbiotic bacteria in mice—a toxicological mechanism that may also occur in humans. The study also identified specific gut microbes associated with intestinal dysfunction triggered by nanoplastics, which may be used in future human studies to explore the interactions among nanoplastic exposure, gut microbiota, and intestinal function.

However, the findings focus primarily on changes at the cellular and molecular levels (e.g., gene and protein expression). In the mouse model exposed to nanoplastics for 12 weeks, aside from reduced intestinal mucus secretion, no other apparent pathological signs in the intestine were observed.

These results suggest that under the exposure conditions tested in this study, nanoplastics are unlikely to cause immediate or overt intestinal damage. Instead, nanoplastics may gradually and persistently disrupt normal physiological functions of the intestinal environment. Whether long-term exposure to such stressors could affect intestinal or systemic health in humans is a question that warrants further investigation.

Considering these findings and acknowledging that risk perception varies among the public, there is no need to feel excessive anxiety over everyday exposure to nanoplastics. Instead, we should continue to monitor the emerging scientific evidence on health risks, while also taking steps（where feasible and without disrupting daily routines as a premise）to reduce potential exposure to plastic particles. For example, using non-plastic containers or packaging for hot foods and beverages may be a practical preventive measure.

The author said:

【 李保宏 Bao-Hong Lee 】【 徐瑋萱 Wei-Hsuan Hsu 】

2025/06/09
Bao-Hong Lee （The expert is the corresponding author of this study）

Assistant Professor, Department of Horticultural Sciences, National Chiayi University, Chiayi, Taiwan. 

Plastic particle pollution has become a global concern. This study investigates how nanoscale plastic particles affect the mouse's gut microbiota and barrier integrity through the lens of extracellular vesicles and microRNAs. It provides the first evidence that nanoplastics not only alter the gut microenvironment but may also disrupt host–microbe communication, leading to microbial imbalance and impaired gut barrier function in mice. Nanoplastics are capable of entering biological cells and potentially crossing the gut barrier, posing risks to tissues and organs. Maintaining gut barrier integrity is therefore critical for intestinal and overall health.

2025/06/09
Wei-Hsuan Hsu（The expert is the first author of this study）

Associate Professor, Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan, Taiwan.

This study is the first to show that plastic particles can interfere with the microRNA carried by extracellular vesicles between mouse's intestinal cells and specific gut microbes, disrupting host–microbe communication and altering microbial composition in ways that may harm gut health of mice. The research identifies a molecular mechanism by which plastic particles disturb gut microbiota. Since mice and humans differ in their gut microbial profiles, direct inference to human health risks is not yet possible. Long-term exposure and dose–response studies are still needed. The team has also developed a simulator of human intestinal microbiota ecosystem to evaluate the effects of nanoplastics and other substances on human gut microbiota.