Organism's responses to a long-term inhalation of silica-containing submicron particles of an industrial aerosol

Abstract

Female white rats were exposed during up to 6 months 5 times a week, 4 hr per day in a "nose only" inhalation device to an aerosol containing predominantly submicron (nanoscale included) particles of amorphous silica in the concentration 2.6±0.6 or 10.6±2.1 mg/m3. In an auxiliary experiment with a single-shot intratracheal instillation of these particles, it was shown that they induced a pulmonary cell response comparable with that to highly cytotoxic and fibrogenic standard quartz powder DQ12. However, in the long-term inhalation test, the studied aerosol proved to be of very low systemic toxicity and fibrogenicity. This paradox may be explained by low SiO2 retention in lungs and other organs due to a relatively high in vivo solubility of these nanoparticles. Nevertheless, their genotoxic action and transnasal penetration into the brain should make one give a cautious overall assessment of this aerosol as an occupational or environmental hazard. © Published under licence by IOP Publishing Ltd.