Acute inhalation study of allyl alcohol for derivation of acute exposure guideline levels.

An acute, whole-body inhalation study for allyl alcohol in Sprague-Dawley rats was designed to support derivation of AEGL values, with emphasis on establishing NOAELs for irreversible effects of different exposure concentrations and durations. Groups of 10 rats were exposed for 1 hour (0, 50, 200, or 400 ppm), 4 hours (0, 20, 50, or 100 ppm), or 8 hours (0, 10, 20, or 50 ppm). Clinical evaluations were performed during exposure and in an open field within 22-71 minutes after termination of exposure. Clinical pathology, gross necropsy, and histopathology (nasal tissues, larynx, trachea, lungs/bronchi, liver, and kidneys) were evaluated 14 days after exposure. Mortality was limited to 1 male exposed for 8 hours to 50 ppm. Clinical findings of gasping, rales, increased respiration noted at higher exposure levels were rapidly reversed. No treatment-related findings were observed in the liver and kidneys, or in the lungs of surviving animals. Histopathology in the nasal cavity was noted at all exposure levels following 1, 4, or 8 hours of exposure. Mild nasal inflammation was found at the lowest exposure levels (50-ppm/1-hour, 20-ppm/4-hour, and 10-ppm/8-hour). These effects were considered reversible and were not associated with related clinical signs. Severe, irreversible nasal olfactory epithelial lesions were present in 50 ppm/8-hour males. The NOELs for irreversible effects were 400-ppm/1-hour, 100-ppm/4-hour, and 20-ppm/8-hour. The incidence of severe findings was positively dependent on both concentration and the exposure duration. In contrast, the incidence of mild reversible findings did not appear to be dependent on duration.