Digestible Fluorescent Coatings for Cumulative Quantification of Microplastic Ingestion

The ubiquitous presence of microplastics in the environment makes it imperative to understand their effects. In particular, we must understand exposure, i.e., how many microplastics are ingested by organisms. This has proved difficult because counting microplastics in an organism's gut content provides only a snapshot in time. Here, we show a method that uses a digestible fluorescent coating (DFC) to quantify cumulative microplastic ingestion. Our method enables precise and automated enumeration of cumulative microplastic ingestion with the flexibility to track different microplastic types and sizes with distinct fluorescent tracers. We confirm the coating is not acutely toxic and is not preferentially ingested by several invertebrate species. This method provides a unique and reliable approach to quantify cumulative microplastic ingestion in laboratory exposure studies, and can be used to advance our understanding of the impact of microplastics to wildlife.