Sediment toxicity and bioaccumulation of nano and micron-sized aluminum oxide

Abstract

Nano-aluminum oxide (Al2O3) is used commercially in coatings and abrasives. Nano-Al2O3 can also be generated through the oxidation of nano-aluminum in military propellants and energetics. The purpose of the present study was to assess toxicity and bioaccumulation of nano-Al2O3 to a variety of sediment organisms (Tubifex tubifex, Hyalella azteca, Lumbriculus variegatus, and Corbicula fluminea). The bioaccumulation and toxicity of nano-Al2O3 was compared with that of micron-sized Al2O3 to investigate potential size-related effects. Results of the present study show species-specific differences in relative bioaccumulation of nano- and micron-sized Al 2O3. Significant toxic effects (survival and growth) were observed in H. azteca testing, but only at high concentrations unlikely to be found in the environment. Nano-Al2O3 was found to be more toxic than micron-sized Al2O3 to H. azteca survival in a 14-d study in which organisms were in direct contact with a thin layer of 625 or 2,500 mg of Al2O3 dispersed on the surface of either sediment or sand. A significant growth effect was also observed for nano but not micron-sized Al2O3 at the highest treatment level tested (100 g/kg Al2O3) in a 10-d H. azteca bioassay in which Al2O3 was homogenized with sediment. However, differences in measured sediment Al concentrations (micron-sized=55.1 [±0.6] g/kg Al; nano-sized=66.2 [±0.6] g/kg Al) in the nano and micronsized Al 2O3 preclude direct comparison of the toxicity of these two treatments based on particle size. © 2009 SETAC.