Colorful attire and tailored protocols enhance traceability and mitigate contamination in biota microplastic research

Abstract Sample contamination remains a major obstacle to microplastic research; however, evaluations of mitigation strategies are scarce. This study synthesized 89 mitigation measures derived from literature, laboratory observations, and literature-based measures adapted to laboratory conditions. These were categorized into personnel, infrastructure, sample handling, and quality control/ quality assurance measures. To evaluate the efficacy of this framework, we implemented a four-level experimental design for increasing stringency (null, minimum, medium, and maximum) to evaluate airborne deposition in the laboratory, and airborne and cross-contamination during fish biota processing. A central feature of the maximum mitigation level (comprising 32 specific measures) was the incorporation of the red researcher attire as a traceable contamination source, enabling the distinct quantification of researcher-derived (red) vs. background (non-red) fibers. Laboratory and environmental blanks were used to assess airborne particles, while procedural blanks assessed cross-contamination in fish muscle and carcass samples. Microparticles were characterized by shape type, size, and color. Results demonstrate that while total airborne deposition showed inconsistent trends, non-red fiber counts decreased progressively with mitigation stringency, with the maximum level reducing rates by 69% relative to null. During fish processing, environmental blanks showed an 84% reduction in non-red fibers from null to maximum mitigation level, whereas procedural blanks demonstrated strong cross-contamination control, achieving a 97% reduction. Crucially, microparticle counts were 300% higher during carcass processing blanks compared to muscle processing. Characterization revealed a stepwise reduction in color richness with mitigation. Tailored mitigation measures significantly reduce cross-contamination, while the use of colored attire enhances assignment of fibers to process-related airborne sources. Together, these findings provide a validated framework for contamination control and fiber-specific traceability in biota research. We recommend the adoption of step-specific blanks, contamination reference catalogs, and standardized terminology to ensure reproducibility across the field. Graphical Abstract