A Noninvasive Quantitative Method for Evaluating Intestinal Exposure to Microplastics Based on the Excretion and Metabolism Patterns of Microplastics and Their Additives.

Microplastics (MPs) pose potential health risks to the intestinal tract and gut microbiota, a topic that has garnered significant attention. However, the absence of quantitative assessment methods for human gut MP exposure impedes related health risk assessments. Here, we performed long-term continuous exposure experiments on mice using MPs that mimic actual human exposure characteristics. The daily excretion of fecal MPs and the concentrations of phthalates (PAEs) and their metabolites (mPAEs) in serum and urine were detected. The cumulative excretion rate of fecal MPs remains stable at about 93%. A significant linear correlation was observed between MP exposure and concentration of mPAEs in urine for both low MP (LMP; 150 µg of MPs/d) (R2 = 0.90) and high MP (HMP; 360 µg of MPs/d) groups (R2 = 0.97). Moreover, a strong correlation was found between daily PAEs exposure and total MP-associated PAEs exposure in both LMP (R2 = 0.77) and HMP (R2 = 0.88) groups. Based on these findings, we established a noninvasive model and evaluated multiple MP exposure parameters in the human gut across 6 continents, 30 countries, and 133 individuals. This study offers novel insights for the quantitative assessment of in vivo MP exposure and provides technical support for assessing the health risks of MPs.

Using Data-Driven Methods and Aging Information to Quantitatively Identify Microplastic Environmental Sources and Establish a Comprehensive Discrimination Index.

The global distribution of microplastics (MPs) across various environmental compartments has garnered significant attention. However, the differences in the characteristics of MPs in different environments remain unclear, and there is still a lack of quantitative analysis of their environmental sources. In addition, the inclusion of aging in source apportionment is a novel approach that has not been widely explored. In this study, we conducted a meta-analysis of the literature from the past 10 years and extracted conventional and aging characteristic data of MPs from 321 sampling points across 7 environmental compartments worldwide. We established a data-driven analysis framework using these data sets to identify different MP communities across environmental compartments, screen key MP features, and develop an environmental source analysis model for MPs. Our results indicate significant differences in the characteristics of MP communities across environments. The key features of differentiation were identified using the LEfSe method and include the carbonyl index, hydroxyl index, fouling index, proportions of polypropylene, white, black/gray, and film/sheet. These features were screened for each environmental compartment. An environmental source identification model was established based on these features with an accuracy of 75.1%. In order to accurately represent the single/multisource case in a more probabilistic manner, we proposed the MP environmental source index (MESI) to provide a probability estimation of the sample having multiple sources. Our findings contribute to a better understanding of MP migration trends and fluxes in the plastic cycle and inform effective prevention and control strategies for MP pollution.

Effects of chronic exposure to different sizes and polymers of microplastics on the characteristics of activated sludge.

Wastewater treatment plants (WWTPs) have become an important source of microplastics (MPs) contamination and most MPs remain in the sludge inducing potential impacts on sludge disposal. However, little is known about the influence of MPs on the characteristics of sludge, which is essential for sludge disposal. In this study, the dewaterability of activated sludge in response to chronic exposure (60 days) to MPs of different sizes (213.7 nm ~ 4.2 mm) and polymers (polystyrene, polyethylene, and polyvinyl chloride) were investigated. Overall, different particle sizes caused more evident effects on sludge dewatering than different polymer types did. Millimeter MPs (~4 mm) dramatically reduced the dewaterability of sludge by 29.6% ~ 47.7%. These effects were mainly caused by the physical crushing of MPs on sludge flocs, except polyvinyl chloride (PVC)-MPs, possibly containing additives, induced toxicity on sludge. Moreover, 100 mg/L nano-size MPs (213 nm) also reduced the dewatering performance of sludge. The potential mechanism is that nano-size MPs inhibited sludge activity and decreased the abundance of key microorganisms, which subsequently altered the composition and spatial distribution of extracellular polymeric substances (EPS), and finally impeded sludge dewatering. Our results highlight the impacts of different sizes of MPs on the characteristics of sludge, affecting the final disposal of sludge.