Pulmonary toxicity induced by electric charged soot particles in mice

Toxicity attributable to the particle charge remains unclear. The objective of this study was to investigate pulmonary effects of the electric charge of particles. We established a stably charged aerosol particle generation system for whole-body exposure in BALB/c mice, which produced positively, negatively, and neutrally charged soot particles in a wide range of numbers and mass concentrations. The charged soot particles on average carried 1.16~1.35 electric charges, and the mode sizes for particles under different charging statuses were all fixed at 69.6~71.8 nm. After inhalation, the positively and negatively charged soot particles arrested the body weight increase in mice. Pulmonary cytotoxicity of lactate dehydrogenase, oxidative stress 8-isoprostane, and the benzo(a)pyrene diolepoxide protein adduct occurred in dose-dependent manners by negatively charged soot particles. We further observed that positively and negatively charged soot particles induced systemic interleukin-6 production in dose-dependent responses in mice. Our findings suggest that inhalation of particles carrying negative electric ions could cause lung toxicity that should be of concern in terms of pulmonary health protection.