Effects of acute and repeated inhalation of dimethyl sulfoxide in rats

Abstract

Primary dermal and ocular irritant tests on New Zealand albino rabbits with dimethyl sulfoxide (DMSO) showed a low order of toxicity. The oral LD50 of DMSO in Sprague-Dawley rats was found to be 14.5 g/kg with 95% confidence limits of 13.4 to 15.7 g/kg, and the intravenous LD50 in Swiss mice was found to be 3.1 g/kg with 95% confidence limits of 2.7 to 3.5 g/kg. Sprague-Dawley rats were exposed to DMSO at concentrations of approximately 2900 mg/m 3 for 24 hours, 2000 mg/m 3 for 40 hours, or 1600 mg/m 3 for 4 hours. Others were exposed to 200 mg/m 3 7 hours a day, 5 days a week for a total of 30 exposures. No significant alterations were noted in hemoglobin concentrations, microhematocrit, total leukocyte counts, reticulocyte counts, serum glutamic-pyruvic and glutamic-oxaloacetic transaminase activities, liver alkaline phosphatase activity, or liver lactate concentrations. The concentration of serum urea nitrogen was slightly elevated in rats exposed to approximately 2900 mg/m 3 for 24 hours but was within normal limits in all other animals. Histopathologic edematous changes were noted in lungs of some of the animals used in the acute exposures which were not seen in controls. Hemorrhage and pneumocyte infiltrations were seen in the lungs of both experimental and control rats.