Anthropogenic Debris in Bivalves Sold for Human Consumption in Northern California: A Cross-Sectional Follow-Up Study

Abstract Microplastics have emerged as a major environmental concern due to their widespread presence and potential health impacts. Growing water contamination has raised concerns about its presence in seafood consumed by humans. In this single-center, cross-sectional study, we collected a sample of 10 Pacific oysters sold locally in Northern California. We compared microplastic content with a prior study performed at the same location in 2015 (Rochman et al.). Anthropogenic debris was extracted from the whole tissue of shellfish using a 10% KOH solution and quantified under a dissecting microscope. Microplastics were found in all ten samples (compared with 4/12 samples in 2015), from three to greater than 40 particles per sample. These anthropogenic debris were primarily filaments from 0.2 to 2 mm long. Our study findings suggest that microplastics in bivalves sold for human consumption have increased in the past ten years, with potential human health concerns.