A SUBCHRONIC INHALATION STUDY OF FISCHER 344 RATS EXPOSED TO 0, 0.4, 1.4 OR 4.0 PPM ACROLEIN.

Fischer 344 rats were exposed to 0.0, 0.4, 1.4, or 4.0 ppm acrolein for 62 days. The major objective of the study was to relate the results of a series of pulmonary function tests to biochemical and pathological alterations observed in the lung. Cytological and reproductive potential endpoints were also assessed after acrolein exposure. Rats were exposed to acrolein for 6 hours/day, 5 days/week for 62 days. Mortality was observed only in the 4.0 ppm chamber where 32 of 57 exposed males died; however, none of the 8 exposed females died. Most of the mortality occurred within the first 10 exposure days. Histologic examination indicated that the animals died of acute bronchopneumonia. The surviving males and females exposed to 4.0 ppm acrolein gained weight at a significantly slower rate than control animals. The growth of both sexes in the 0.4 and 1.4 ppm groups was similar to that of their respective controls. Histopathologic examination of animals after 62 days of exposure revealed bronchiolar epithelial necrosis and sloughing, bronchiolar edema with macrophages, and focal pulmonary edema in the 4.0 ppm group. These lesions were, in some cases, associated with edema of the trachea and peribronchial lymph nodes, and acute rhinitis which indicated an upper respiratory tract effect of acrolein. Of particular interest was the variability of response between rats in the 4.0 ppm group, some not affected at all while others were moderately affected. Intragroup variability in toxicity was also apparent in the 1.4 ppm exposure group where only 3 of 31 animals examined had lesions directly related to acrolein exposure. Extra respiratory organs appeared unaffected