Scientists analyzing urine samples from more than 1,300 children found widespread microplastic exposure and intriguing links between dietary patterns and the types of plastics detected, raising new questions about how everyday food choices may shape environmental exposures early in life.
Study: Microplastic exposure and the role of dietary patterns in school-aged children. Image Credit: xalien / Shutterstock
In a recent study published in the journal Environment International, researchers report widespread MP exposure among school-aged children and suggest that diet may play a role. Analyzing urine samples from 1,308 participants, the team identified 19 different microplastic types, with particles detected in over 91% of samples and a median concentration of 250 particles per milliliter. Notably, small-sized particles, which may more readily cross biological barriers, accounted for the vast majority of detections. PTFE, commonly used in non-stick cookware, was the most abundant polymer. Importantly, stronger adherence to the MedDiet was associated with distinct patterns of MP exposure, suggesting that dietary habits may influence exposure levels.
Defined as plastic particles ranging from 0.1 to 5,000 μm in diameter, MPs have emerged as pervasive environmental contaminants that have drawn global concern. These particles have been detected in air, soil, and water, and are increasingly found in commonly consumed foods and bottled drinks. Although growing evidence links MP exposure to potential health risks, most research has focused on adults. School-age children may face heightened exposure due to more varied diets, greater outdoor activity, and frequent contact with packaged foods. Fruits, vegetables, and milk have all been shown to contain microplastics, which may enter the gastrointestinal tract, cross biological barriers, and accumulate in tissues, raising concerns about long-term health effects.
About the study
In the present study, researchers evaluated the association between dietary patterns and urinary MP exposure in school-aged children.
The team collected midstream urine samples from 1,308 10-year-old participants enrolled in the Ma’anshan Birth Cohort (MABC) between January 2024 and 2025. They used LDIR spectroscopic imaging to identify and measure MP particles. They classified particles as small (20–100 μm) and large (100–500 μm). Only particles with a spectral match exceeding 65% against a reference MP library were considered valid.
To minimize MP contamination, the researchers implemented stringent plastic-free protocols throughout sample handling and analysis. They replaced plastic consumables with glass pipettes, bottles, and containers. In addition, they repeatedly cleaned all equipment with ethanol, sonicated for over 30 minutes, and calcined at 500°C for four hours. Liquids underwent triple filtration and pre-testing to confirm the absence of MPs. Laboratory personnel wore cotton lab coats, nitrile gloves, and activated carbon masks during procedures.
The researchers assessed children’s dietary patterns using the Mediterranean Diet Quality Index for Children and Adolescents (KIDMED), which enabled evaluation of adherence to the MedDiet. They constructed directed acyclic graphs (DAGs) to inform the selection of potential confounders, including maternal age, education, household income, residential area, and child age and sex.
The team used a zero-inflated negative binomial (ZINB) regression model to examine the associations between KIDMED scores and urinary MP levels. As part of the sensitivity analyses, they stratified participants by urban versus rural residence and used a stricter 75% spectral-matching threshold.
Results
The study cohort included 52% boys and 48% girls. Based on the KIDMED scores, 7.2% of participants demonstrated low adherence to the MedDiet, 49% moderate adherence, and 43% good adherence. More than 28% of mothers had attained a bachelor’s degree, and approximately 90% of families resided in urban areas.
The analysis of urine samples revealed 19 distinct MP types. The most prevalent polymers were PTFE, PAM, PA, PE, and PU. The median overall MP level reached 250 particles per mL, with MPs detected in 91% of samples. PTFE was the most frequently detected polymer, identified in over 50% of samples. Notably, small particles constituted 98% of the total detected MPs.
The team found that dietary adherence was significantly associated with MP exposure patterns. Higher KIDMED scores were associated with a higher likelihood of no detectable urinary levels of EVA, PVA, and PLA. At the same time, higher scores corresponded with increased non-zero levels of PA and decreased non-zero concentrations of PTFE. No significant association was observed between KIDMED scores and total urinary microplastic abundance or particle size. Collectively, stronger adherence to the Mediterranean diet was associated with lower detection rates of PLA, EVA, and PVA, alongside distinct shifts in polymer profiles. Sensitivity analyses in urban children yielded consistent findings, supporting the robustness of the results.
Conclusions
Overall, the study detected 19 types of MPs in the urine of 10-year-old children, with a median concentration of 250 particles/mL, highlighting widespread early-life exposure. PTFE was the dominant polymer, underscoring its prominence in human MP exposure. Higher adherence to the MedDiet was consistently linked to distinct shifts in urinary microplastic profiles. The findings suggest that dietary habits may shape both exposure sources and internal accumulation patterns.
However, because the study used a cross-sectional design, the findings cannot establish a causal relationship between dietary patterns and microplastic exposure. Differences in detection methods limit cross-study comparisons, and urinary measurements likely capture only a portion of the total body burden. In addition, because the vast majority of participants lived in urban areas, the findings may primarily reflect exposure patterns among urban children. Future longitudinal and interventional research incorporating behavioral factors and toxicokinetic modeling is required to clarify causal pathways and improve understanding of MP distribution and excretion.
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