Subchronic inhalation toxicity of hexamethylenediamine in rats

Four groups of 15 male and 15 female Sprague-Dawley-derived (CD) rats each were exposed to aqueous hexamethylenediamine (HMD) aerosols for 6 hr/day, 5 days/week for 13 weeks at mean analytical concentrations of 0, 12.8, or 51 mg/m3. Because of exposure-related deaths in a group of male and female rats similarly exposed to 215 mg/m3 HMD, this group was terminated during the seventh week of the study. Signs of respiratory and conjunctival irritation were observed in rats at both the 51 and 215 mg/m3 HMD test levels. Body weight gain was significantly reduced in both sexes exposed to 215 mg/m3 HMD. At the 5-week study interval, slight hemopoietic stimulation of peripheral blood parameters was observed in rats of both sexes exposed to 215 mg/m3 HMD. Treatment-related microscopic lesions were seen only in rats exposed to 215 mg/m3 MD and were confined to the trachea, nasal passages, and lungs. The no-effect level in this study is considered to be 12.8 mg/m3 HMD.