Abstract
The sensory irritation potential of dimethylamine (DMA) inhalation on male Fischer-344 rats and male Swiss-Webster mice was evaluated by measuring the reflex decrease in respiratory rate. In addition, the six hour LC50 for rats exposed to dimethylamine was established. Groups of 3 or 4 rats and mice were exposed for 10 minutes to concentrations of DMA ranging from 49 to 1576 ppm during which time the respiratory rate was monitored and recorded. Sensory irritation concentration-response curves were obtained and RD50 values (concentration which elicits a 50% decrease in respiratory rate) were determined to be 573 and 511 ppm for rats and mice, respectively. In another set of experiments seven groups of male rats were exposed to concentrations of DMA ranging from 600 to 6119 ppm for six hours. Mortality counts were made during and for 48 hours post exposure. The six hour LC50 was determined to be 4540 ppm. Histopathologic examination of the respiratory tract revealed concentration related changes ranging from ulceration and necrosis to rhinitis, tracheitis, and emphysema. Overall, DMA was found to be less potent as a sensory irritant than other airborne irritants.