Monitoring the ecotoxicity of γ-Al2O3 and Ni/γ-Al 2 O 3 nanomaterials by means of a battery of bioassays

Abstract

The increasing application of nanoparticles (NPs) to a variety of new technologies has become a matter ofconcern due to the potential toxicity of these materials. Many questions about the fate of NPs in the environmentand the subsequent impact on ecosystems need to be answered. The aim of this work was to evaluate theecotoxicity of two alumina-based nanoceramics, γ-Al2O3 (NC) and Ni/ γ-Al2O3 (NiNC) by means of three differentstandardized tests: Biochemical Oxygen Demand (BOD5), bioassay with luminescent bacteria (Vibrio fischeri;Microtox), and bioassay on amphibian larvae (Rhinella arenarum) (AMPHITOX). BOD5 values of a verybiodegradable mixture (glucose/glutamic acid) decreased with the addition of NiNC(43.8%) and NC (31.6%)with respect to control samples (52.9%). Microtox test results indicated that NiNC presents higher toxicity thanNC, with EC50s values of 16.1% and 29.9% respectively; a reduced toxicity was observed, however, in presenceof organic matter, thus obtaining EC50s of 37.8% and 19.4%. The results of AMPHITOX test showed a significantincrease in the toxicity of both substances over time, the NiNC toxicity being greater than that of NC. The valuesof 96 h-LC50 and 504 h-LC50 determined for NiNC were 1.58 and 0.83 mg/L, respectively, and 14.5 and10.5 mg/L for NC samples. Amphibian larvae exhibited collapsed cavities, edema, axial flexures, and behavioralalterations as hyperkinesia and reduced movements. These results evidence the vulnerability of wildlife to xenobioticsand the need to develop specific standardized ecotoxicity tests in order to help environmental sustainabilityand natural species conservation.