Subchronic inhalation and oral toxicity of hydrogenated terphenyls in rats

The subchronic toxicity of a commercial blend of partially hydrogenated terphenyl was evaluated in rats by inhalation and oral routes of exposure. Animals were exposed to target concentrations of 0, 10, 100, or 500 mg/m3 for 6 hr/day, 5 days/week or were offered diets daily with concentrations of 0, 50, 200, or 2000 ppm. Each study lasted approximately 14 weeks. The study designs included observations for clinical signs, body weights, ophthalmic exams, hematology and clinical chemistry, major organ weights, and gross and histopathology. No treatment-related effects were noted in the ophthalmic exams. Body weights were slightly depressed in high-dose males from the inhalation study and high-dose females in the dietary study. Liver and liver/body weights were increased in high-dose animals of both sexes and high- and mid-dose males in the dietary and inhalation studies, respectively. In the high-dose females of the dietary study, kidney and kidney/body weights were increased with increased adrenal and adrenal/body weights were also observed. No compound-related gross lesions nor pathological correlates to the organ weight changes were observed in either study. The no-adverse effect levels were considered to be 100 mg/m3 and 200 ppm (15.9 mg/kg) for the inhalation and dietary studies, respectively. These data indicate that a wide margin of safety exists for hydrogenated terphenyl workplace exposure.