Evaluating the toxicity of urban patterns of oxidant gases. I. An automated chronic gaseous animal inhalation exposure facility

Abstract

An automated animal inhalation exposure facility was designed to conduct chronic exposures of rodents to gaseous pollutants. The facility consisted of 3 walk-in chambers with modular cages to allow for exposure of up to a maximum of 480 mice or 240 adult rats. Critical parameters of operation, such as relative humidity, pollutant concentration, and temperature, were monitored continuously. Failure of the system to maintain parameters within specified limits activated the alarm system. Distribution of test gases in the chambers was evaluated for homogeneity, and the standard deviation was determined to be within +/- 5% of the target concentrations throughout the chamber. The exposure facility was successfully used to expose 720 rats to diurnal patterns of O3 (baseline of 0.06 ppm for 13 h with an exposure peak to 0.25 ppm over 9 h) and NO2 (baseline of 0.5 ppm for 16 h with an exposure peak to 1.5 ppm over 6 h) for a period of 18 mo.

Development of a large-scale computer-controlled ozone inhalation exposure system for rodents

“…Automated, computer-operated feedback control systems have been employed for inhalation exposure studies since 1978 (Davies et al, 1987;Johnson et al, 1995;Johnson and Fechter, 1996;O'Shaughnessy and Hemenway, 1994;Moorman, 1978, 1984a,b). These early systems enabled inhalation exposure studies without operator intervention and typically achieved control to within 5% of the target concentration.…”

“…These early systems enabled inhalation exposure studies without operator intervention and typically achieved control to within 5% of the target concentration. Like our system, some systems included alarms or safety shutoff features when certain parameters were out of range as well as environmental data recording capabilities (Davies et al, 1987;Moorman, 1983, 1984). A primary difference between our system and previous automated systems is the use of modern DasyLab ® control software that requires almost no specialized engineering or programing knowledge.…”