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

Nano‐aluminum oxide (Al 2 O 3 ) is used commercially in coatings and abrasives. Nano‐Al 2 O 3 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‐Al 2 O 3 to a variety of sediment organisms ( Tubifex tubifex , Hyalella azteca , Lumbriculus variegatus , and Corbicula fluminea ). The bioaccumulation and toxicity of nano‐Al 2 O 3 was compared with that of micron‐sized Al 2 O 3 to investigate potential size‐related effects. Results of the present study show species‐specific differences in relative bioaccumulation of nano and micron‐sized Al 2 O 3 . 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‐Al 2 O 3 was found to be more toxic than micron‐sized Al 2 O 3 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 Al 2 O 3 dispersed on the surface of either sediment or sand. A significant growth effect was also observed for nano but not micron‐sized Al 2 O 3 at the highest treatment level tested (100 g/kg Al 2 O 3 ) in a 10‐d H. azteca bioassay in which Al 2 O 3 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 micron‐sized Al 2 O 3 preclude direct comparison of the toxicity of these two treatments based on particle size. Environ. Toxicol. Chem. 2010;29:422–429. © 2009 SETAC