Automated aerosolization, dispersion, and concentration control of silica powder for use in inhalation exposure studies.
McKinney-W; Afshari-A; Chen-B; Frazer-D
Toxicologist 2010 Mar; 114(1):317
Inhalation exposure systems are necessary tools for determining the dose response relationship of inhaled toxicants under a variety of exposure conditions. The objective of this project was to develop an automated computer controlled system to expose small laboratory animals to precise concentrations of uniformly dispersed airborne silica particles. An acoustical aerosol generator was developed which was capable of suspending a respirable fraction of particles from bulk powder [Mckinney et al. Inhal Toxicol 21(12):1053-1061]. The aerosolized silica output from the generator was introduced into the throat of a venturi tube. The high velocity air stream within the ventui tube further broke up and dispersed the aerosolized powder. This air was then used to expose small laboratory animals to constant aerosol concentrations, up to 20 mg/m3, for durations lasting as long as 8 hours. Particle distribution and morphology of the silica aerosol delivered to the exposure chamber were measured to verify that a fully dispersed and respirable aerosol was being delivered to the animals' breathing space. The inhalation exposure system utilized a combination of air flow controllers, particle monitors, data acquisition devices, and custom software with automatic feedback control to achieve constant and repeatable exposure chamber temperature, relative humidity, pressure, aerosol mass concentration, and particle size distribution. The automatic control algorithm was capable of delivering median aerosol concentrations to within +/- 0.2 mg/m3 of a user selected target value during inhalation exposures lasting from 4 to 8 hours. The system was capable of reaching 95% of the target value in less than 15 minutes during the start up phase of an inhalation exposure. This exposure system provides a highly automated tool for exposing small laboratory animals to precise concentrations of uniformly dispersed airborne silica particles.
Aerosol-particles; Airborne-particles; Biological-effects; Cell-biology; Cellular-reactions; Chemical-hypersensitivity; Cytotoxic-effects; Exposure-assessment; Exposure-levels; Exposure-methods; Inhalation-studies; Laboratory-animals; Laboratory-testing; Lung-disorders; Lung-irritants; Particle-aerodynamics; Particulates; Pulmonary-disorders; Pulmonary-system; Pulmonary-system-disorders; Respiratory-hypersensitivity; Respiratory-irritants; Respiratory-system-disorders; Silica-dusts; Toxins
The Toxicologist. Society of Toxicology 49th Annual Meeting and ToxExpo, March 7-11, 2010, Salt Lake City, Utah