A human cell panel for evaluating safe application of nano-ZrO₂/polymer composite in water remediation

Nanomaterials, such as ZrO₂ nanoparticles (ZrO₂ NPs), are very effective in water remediation. However, the safety issues related to nanoparticle release and toxicity to humans remain to be resolved. Here we evaluated the cytotoxicity of ZrO₂ NPs and their adducts with pollutants using a human cell panel containing stomach, intestine, liver and kidney cells. We found that different pollutants or ZrO₂NP/pollutant adducts targeted cells from different organs, suggesting the necessity of a cell panel to model oral exposures. The cooperation of ZrO₂ NPs and pollutants was quite complex, consisting of synergistic, antagonistic, or additive effects. For example, ZrO₂ NPs enhanced the cytotoxicity of Pb²⁺ in GES-1 cells and of Pb²⁺, Cd²⁺ in FHC cells, while alleviating the toxicity of Pb²⁺ and As (III) in HepG2 and Hek293 cells. Our results also indicated that even concentrations of pollutants that meet the national standard, the ZrO₂ NPs concentration should be kept below 17 μg/mL to avoid ZrO₂ NP/pollutant adduct synergistic toxicity.