Unraveling microplastic behavior in simulated digestion: Methods, insights, and standardization

Area of Science:

• Environmental Science
• Toxicology
• Analytical Chemistry

Background:

• In vitro digestion studies on microplastics (MPs) are rapidly expanding but lack standardized methodologies.
• Inconsistent protocols hinder cross-study comparisons, risk assessments, and understanding MP fate in the gastrointestinal tract.
• A comprehensive synthesis is needed to address fragmentation and establish a unified research direction.

Purpose of the Study:

• To systematically evaluate 85 in vitro digestion studies on microplastics published between 2020 and 2024.
• To consolidate key findings, identify methodological challenges, and assess disparities in digestion protocols.
• To provide a foundation for improving reproducibility and advancing standardization efforts in microplastic research.

Main Methods:

• Systematic literature review of 85 studies (2020-2024) on in vitro microplastic digestion.
• Analysis of variations in digestion protocols, fluid compositions, and exposure conditions (pH, enzymes, temperature, time).
• Synthesis of findings on bio-corona formation, structural changes, contaminant bioaccessibility, and enzyme interactions.

Main Results:

• Significant disparities exist in digestion protocols, fluid compositions, and exposure conditions across studies.
• Microplastic behavior and physicochemical transformations are heavily influenced by factors like pH, enzyme activity, and residence time.
• Bio-corona formation, structural modifications, and contaminant bioaccessibility vary based on experimental conditions.

Conclusions:

• The field of in vitro microplastic digestion is fragmented due to methodological inconsistencies, particularly in human-based models.
• There is an urgent need for standardized methodologies to improve reproducibility and enable reliable risk assessments.
• Addressing these gaps will enhance understanding of microplastic ingestion risks to human health.