Toxicological effects and bioaccumulation of fullerene C60 (FC60) in the marine bivalve Ruditapes philippinarum

Abstract

Fullerene C₆₀ (FC₆₀), with its unique physical properties, has been used in many applications in recent decades. The increased likelihood of direct release into the environment has raised interest in understanding the biological effects of FC₆₀ to aquatic organisms. Nowadays, only few studies have analysed FC₆₀ effects and bioaccumulation in marine organisms following in vivo exposure. To provide new data about FC₆₀ toxicity, Ruditapes philippinarum was selected as target species to assess potential adverse effects of the contaminant. Clams were exposed for 1, 3 and 7 days to predicted environmental concentrations of FC₆₀ (1 and 10 μg/L) and cellular and biochemical responses were evaluated in clams' gills, digestive gland and haemolymph. The FC₆₀ content in gills and digestive gland was determined in all experimental conditions after 7 days of exposure. Results showed an increase in oxidative stress. In particular, a significant modulation in antioxidant enzyme activities, and changes in glutathione S-transferase activity were observed in gills. Moreover, damage to lipids and proteins was detected in FC₆₀-treated (10 µg/L) clams. In digestive gland, slighter variations in antioxidant enzyme activities and damage to molecules were detected. CAT activity was significantly affected throughout the exposure, whereas damage to lipids was evident only at the end of exposure. FC₆₀ accumulation was revealed in both gills and digestive gland, with values up to twelve-fold higher in the latter. Interestingly, haemolymph parameters were slightly affected by FC₆₀ compared to the other tissues investigated. Indeed, only Single Cell Gel Electrophoresis and Neutral Red uptake assays showed increased values in FC₆₀-exposed clams. Moreover, volume and diameter of haemocytes, haemocyte proliferation, and micronucleus assay highlighted significant variations in treated clams, but only in the first phases of exposure, and no changes were detected after 7 days. Our results suggested clam gills as the target tissue for FC₆₀ toxicity under the exposure conditions tested: the high damage detected to lipids and proteins could contribute to long-term problems for the organism.

Keywords: Bioaccumulation; Biomarkers; Clams; Fullerene; Nanoparticles.