Evaluation of coexposure to inorganic arsenic and titanium dioxide nanoparticles in the marine shrimp Litopenaeus vannamei

The acute toxicity of titanium dioxide nanoparticles (nTiO2) that occur concomitantly in the aquatic environment with other contaminants such as arsenic (As) is little known in crustaceans. The objective of the present study is to evaluate whether coexposure to nTiO2 can influence the accumulation, metabolism, and oxidative stress parameters induced by arsenic exposure in the gills and hepatopancreas of the shrimp Litopenaeus vannamei. Organisms were exposed by dissolving chemicals in seawater (salinity = 30) at nominal concentrations of 10 μg/L nTiO2 or AsIII, dosed alone and in combination. Results showed that there was not a significant accumulation of As in either tissue type, but the coexposure altered the pattern of the metabolism. In the hepatopancreas, no changes were observed in the biochemical response, while in the gills, an increase in the glutamate-cysteine-ligase (GCL) activity was observed upon exposure to As or nTiO2 alone, an increase in the reduced glutathione (GSH) levels was observed upon exposure to As alone, and an increase in the total antioxidant capacity was observed upon exposure to nTiO2 or nTiO2 + As. However, these modulations were not sufficient enough to prevent the lipid damage induced by nTiO2 exposure. Our results suggest that coexposure to nTiO2 and As does not alter the toxicity of this metalloid in the gills and hepatopancreas of L. vannamei but does alter its metabolism, favoring its accumulation of organic As species considered moderately toxic.