Bioaccumulative and Toxic Effects of Ingested Clean and PBT-Saturated Microplastics on Oryzias latipes (Japanese Medaka Fish): Method Development towards Physiological and Chemical Analysis

Microplastics are major and often overlooked components of this global accumulation of plastic debris. Recent marine surveys in Puget Sound have found microplastic contamination in benthic communities such as forage fish and mussel populations, indicating the prevalence of microplastics throughout the water column and marine environment. In light of rapid and increasing accumulation of plastic debris and chemical pollutants in marine environments, the transfer of toxic chemicals to biota via microplastic ingestion is of significant concern. Preliminary research on the toxic effects of pollutants on biotic systems has identified microplastics as a transport mechanism for persistent bioaccumulative toxins (such as polychlorinated biphenyls, or PCBs), which adsorb onto plastic via a chemical process called partitioning. These microplastics are then ingested by marine organisms, depositing high concentrations of toxic and bioaccumulative chemicals into biotic tissue and the larger food web. In spite of these findings, very few laboratory studies have been conducted assessing the specific bioavailability of absorbed chemicals to marine organisms via ingestion. This study was an attempt to assess the mechanism of PCB bioaccumulation and its metabolic effects on Japanese Medaka fish, using polyethylene (PE) as a possible transference vector. Notable differences in health and PCB bioaccumulation were observed in those fish exposed to control and PCB-saturated microplastic conditions. By comparing bioavailability and toxicity of chemical pollutants via this microplastic vector, we may improve our understanding of pollutant transfer and prioritize critical microplastics and toxins for reclassification and replacement.