Chronic toxicity and oncogenicity bioassay of inhaled ethyl acrylate in Fischer 344 rats and B6C3F1 mice.

Male and female Fischer 344 rats and B6C3F1 mice were exposed to 0, 25 or 75 ppm (0, 0.10 or 0.31 mg/l) ethyl acrylate vapors, 6 hours per day, 5 days per week, for a total of 27 months. Additional rats and mice were exposed to 225 ppm (0.92 mg/l) for 6 months and then held for 21 additional months post-exposure. Histopathologic changes in olfactory portions of the nasal mucosa were present in animals in all of these three exposure groups. These microscopic exposure-related changes were concentration-dependent, primarily in terms of distribution of the lesions within the nasal cavity. Generally those areas of the nasal mucosa normally lined by olfactory epithelium were altered, while the regions lined by respiratory epithelium were relatively unaffected. There was no indication of an oncogenic response in any organ or tissue in either rats or mice. A follow-up study in which Fischer 344 rats and B6C3F1 mice were exposed to 5 ppm (0.02 mg/l) for 24-months revealed no treatment-related changes in the nasal mucosa.