Toxicity of abrasive nanoparticles (SiO 2 , CeO 2 , and Al 2 O 3 ) on Aliivibrio fischeri and human bronchial epithelial cells (16HBE14o-)

SiO 2 , CeO 2 , and Al 2 O 3 nanoparticles (NPs) are used as abrasive particles in chemical and mechanical planarization (CMP), a key process in semiconductor fabrication. The CMP process generates high volumes of effluents containing abrasive NPs. Since no regulations are available limiting the release of these NPs, there are concerns about their potential environmental and health risks. This study investigates four industry relevant model CMP slurries including colloidal silica (c-SiO 2 ), fumed silica (f-SiO 2 ), cerium oxide (CeO 2 ), and aluminum oxide (Al 2 O 3 ) for their inhibition on bioluminescence activity of the marine bacterium, Aliivibrio fischeri . Additionally, the cytotoxicity of the slurries on human bronchial epithelial cells (16HBE14o-) was evaluated using a novel impedance-based real-time cell analysis (RTCA) system. The results showed that f-SiO 2 and CeO 2 slurries had no acute toxicity on A. fischeri at concentrations up to 1136 and 909 mg/L, respectively. A concentration of 1364 mg/L of c-SiO 2 and Al 2 O 3 led to 37.6% and 28.4% inhibition on microbial activity after 30 min of exposure. High concentrations of c-SiO 2 and f-SiO 2 slurries (250 and 500 mg/L) led to cell death in the RTCA assay. This study further demonstrated that the toxicity of the model CMP slurries was due to the abrasive NPs but not to other additives in the slurry. In contrast, CeO 2 and Al 2 O 3 slurries were not inhibitory or only showed limited inhibitory effect on the viability and proliferation of 16HBE14o- cells after 24 h of exposure. These results indicate that the abrasive NPs used in CMP are not likely to cause acute environmental and health risks at environmentally relevant concentrations.