Toxicological effects of tire wear particles on mummichogs and fathead minnows

Recent studies on the distribution of microplastics in the Charleston Harbor, SC, revealed that a large part of the microplastic particles that are found in the intertidal sediments are tire wear particles. These particles originate from the wear of tire treads on roadways, and wash into the estuary during rain events. The abundance of these particles has raised questions about potential toxicity to aquatic organisms that may ingest these particles. The synthetic rubber in car tires consist of a large variety of chemicals, which can vary between brands, but usually contains styrene-butadiene rubber, carbon black and zinc. To investigate the potential toxicity of tire wear particles, both fathead minnow and Atlantic killifish were exposed to different concentrations of tire crumb particles (38 – 355 µm) in a 7-day exposure. Dissection of the fish revealed that particles were ingested and accumulated in the intestinal tract. At the highest concentration tested (6000 mg/l) we observed partial mortality in the fathead minnow, which is therefore close to the LC50. To investigate if polynuclear aromatic hydrocarbons were leaching from the particles, bile fluorescence was measured, together with potential induction of cytochrome P450-1A through the EROD assay. Elevated levels of 2-, 4-, and 5-, ring structures resembling polynuclear aromatic hydrocarbons were detected in the bile of exposed animals. Induction of CYP1A was also observed in exposed animals at environmentally relevant concentrations (\u3c1-2 g/l)

Endocrine Disruption in Largemouth Bass (Micropterus Salmoides) from a Pcb-Contaminated Reservoir

There are numerous cases of intersex condition in fish, specifically immature oocytes in testicular tissue, documented in recent literature. Typically, these cases identify a point source input of endocrine disrupting compounds impacting the fish, such as wastewater treatment effluent. Legacy contaminants such as polychlorinated biphenyls (PCBs) have been suggested as endocrine disruptors in fish species. The objective of this study was to assess endocrine disruption in wild largemouth bass (Micropterus salmoides) from exposure to PCBs at a Superfund site in South Carolina on Lake Hartwell (SV-107), where high levels of PCBs in sediment and fish tissue samples have been detected for many years. A less severely PCB-contaminated site on Lake Hartwell (SV-535) and a reference site upstream on Lake Keowee (SV-311) were also sampled. Endocrine disruption in fish was measured by analyzing plasma vitellogenin (VTG), intersex severity, and intersex prevalence. Measurable levels of plasma VTG, an egg yolk precursor protein, were detected in male fish from all sites. There were no cases of intersex observed in females collected for this study. Intersex in males manifested as testicular oocytes (TO). Histological analysis indicated that testicular oocytes were present in 23 of 33 (69%) of male largemouth bass sampled and was found in fish from all three sites. These data suggest there may be a significant association between PCB concentration in fish tissue and endocrine disruption in the form of VTG production, intersex severity, and intersex prevalence in male largemouth bass