Development and use of a single-animal whole-body system for inhalation exposure

Inhalation exposure studies, in which test subjects are fully or partially immersed in an atmosphere containing a compound of interest, are usually carried out using one of two possible exposure systems: large whole-body chambers or systems that expose only the animal's nose or head. Whole-body chambers may require large quantities of test compound, which can pose a problem if the chemical is expensive or available in limited quantities. Nose- or head-only systems can help conserve test compound but may cause stress or injury to animals. To address these concerns, the authors developed an exposure system consisting of small single-animal whole-body chambers. They exposed 80 mice and 80 rats to five test compounds at various concentrations. Though the system was labor-intensive for animal care technicians, it effectively exposed animals to precise chemical doses without causing adverse effects, using less test compound than would have been required in a conventional whole-body chamber.