Toxicity of engineered nanomaterials and their transformation products following wastewater treatment on A549 human lung epithelial cells

Here we characterize the toxicity of environmentally-relevant forms of engineered nanomaterials (ENMs), which can transform during wastewater treatment and persist in aqueous effluents and biosolids. In an aerosol exposure scenario, cytotoxicity and genotoxicity of effluents and biosolids from lab-scale sequencing batch reactors (SBRs) to A549 human lung epithelial cells were examined. The SBRs were dosed with nanoAg, nano zero-valent iron (NZVI), nanoTiO2 and nanoCeO2 at sequentially increasing concentrations from 0.1 to 20 mg/L. Toxicities were compared to outputs from SBRs dosed with ionic/bulk analogs, undosed SBRs, and pristine ENMs. Pristine nanoAg and NZVI showed significant cytotoxicity to A549 cells in a dose-dependent manner from 1 to 67 μg/mL, while nanoTiO2 and nanoCeO2 only exerted cytotoxicity at 67 μg/mL. Only nanoAg induced a genotoxic response, at 9, 33 and 53 μg/mL. However, no significant cytotoxic or genotoxic effects of the SBR effluents or biosolids containing nanomaterials were observed.