Carcinogenic effects of diisopropanolinitrosamine in Sprague-Dawley rats.

The carcinogenic effects of diisopropanolinitrosamine (DIPN) were tested in Sprague-Dawley rats and were then compared with results produced earlier by the same substance in Syrian hamsters. In addition to the similarities, several differences were noted; for example, DIPN caused pancreatic tumors in all the hamsters, but only 1 pancreatic tumor was observed among the 150 rats. Administration of DIPN to rats led to the development of neoplasms in the nasal and paranasal cavities, lungs, thyroid gland, esophagus, liver, and kidneys. The highest tumor incidence in rats was in the nasal cavities. Almost all the pulmonary neoplasms were malignant and were usually squamous cell carcinomas. We found a 15.4-50% incidence of malignant tumors of the thyroid gland; we also noted that thyroid neoplasms occurred at almost the same rate (36.4-50%) in the groups given 1/5, 1/10, and 1/20 the median lethal dose.