Acute and Subacute Inhalation Toxicity Study in Rats Exposed to Pyrotechnically-Disseminated M18 Red Smoke

This toxicology study was conducted to provide toxicity data relevant to the exposure in rats to test atmospheres of pyrotechnically disseminated M18 red smoke. Acute nose-only inhalation exposure to an average atmospheric concentration of 1.92 mg/L red smoke for 30 minutes did not induce mortality in male and female rats. Subacute (2-week) nose-only inhalation exposure to average atmospheric concentrations of 0, 0.1, 0.5, and 1.5 mg/L red smoke for 30 minutes/day did not result in any mortality or significant clinical signs at any exposure level. Test article-related histopathological findings were primarily observed in the anterior regions of the nose in male and female rats at all exposure levels. Increased incidence of nasal mucosal degeneration was identified as the critical endpoint in this study and was used to derive BMDL10 of 0.351 and 0.054 mg/L for male and female rats, respectively. Red smoke-induced histopathological findings at the 1.5 mg/L exposure level exhibited a regression of injury following a 4-week recovery period.