A 72-hour exposure study with Eastern oysters, Crassostrea virginica, and the nanomaterial graphene oxide.

Graphene is a two-dimensional nanomaterial with unique mechanical, thermal, electrical, and optical properties. With increasing applications of graphene-family nanomaterials (GFNs) in electronics, biomedicine, and surface coatings, concern for their impacts on aquatic ecosystems is rising. Current information on the toxicity of GFNs, including graphene oxide (GO), is scarce. Filter-feeding bivalves, such as Eastern oysters, are good models for nanomaterial exposure studies. We present results from a 72-hour static renewal oyster study using 1 and 10 mg/L GO which, to our knowledge, is the first report on in vivo effects of GO exposures in marine bivalves. Water samples were analyzed for GO concentration and size assessments. Gill and digestive gland (DG) tissues were evaluated for lipid peroxidation and glutathione-s-transferase (GST) activity. Additionally, gill sections were fixed for histopathological analyses. Elevated lipid peroxidation was noted in oysters exposed to 10 mg/L GO. No significant changes in GST activity were observed, but reduced total protein levels were found in DG tissues of exposed oysters at both concentrations. Loss of mucous cells, hemocytic infiltration, and vacuolation were observed in gills of exposed oysters. Results indicate that short-term GO exposures can induce oxidative stress, epithelial inflammation, and adversely affect overall oyster health. Further investigations regarding fate and sublethal effects of GO are critical to understanding the risks associated with a rapidly growing graphene consumer market. This article is protected by copyright. All rights reserved.