Evaluation of subchronic inhalation toxicity of methylcyclopentane in rats

The aim of this study was to verify subchronic inhalation toxicity of methylcyclopentane (CAS No. 96-37-7) in Sprague-Dawley rats. Four groups of 10 rats of each gender were exposed to methylcyclopentane vapor by whole-body inhalation at concentrations of 0, 290, 1300, or 5870 ppm for 6 h per day, 5 days/week over a 13-week period. During the study period, clinical signs, mortality, body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross pathology, organ weights, and histopathology were examined. Exposure-related clinical signs (salivation and rubbing) were observed in both genders of the 5870 ppm group. There was an increase in liver weight for both genders but the kidney weight was only higher in females than controls. However, no toxicologically significant changes were observed in body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, necropsy findings, or histopathology in any of the treatment groups. Under the present experimental conditions, the target organs were determined to be kidney and liver in rats. The no-observed-adverse-effect concentration was considered to be 1300 ppm/6 h/day in rats.