Dermal toxicity study of rice bran supercritical CO2 extract in Sprague-Dawley rats

The present study was carried out to evaluate the dermal toxicity of topically administered rice bran supercritical CO2 extract (RB-SCE; 500, 1,000, and 2,000 mg/kg) in male and female rats when given as a single dose and a 4-week repeated dose. In all rats that underwent the single-dose toxicity test, there were no abnormal changes in clinical signs or body weight and no deaths or abnormal gross necropsy findings related to RB-SCE. Based on the above results, the LD50 is >2,000 mg/kg in both sexes. In all rats that underwent the 4-week repeated dermal toxicity test, there were no abnormal RB-SCEassociated changes with respect to external signs, urine and blood, or organs. The no-observed-adverse-effect level (NOAEL) of RB-SCE was thus considered to be 2,000 mg/kg/day for both sexes and the target organ. RB-SCE can be regarded as a very safe agent for topical dermal administration at a moderate dose.