Subchronic Inhalation and Oral Toxicity of Hydrogenated Terphenyls in Rats

The subchronic toxicity of a commercial blend of partially hydrogenatedterphenyl was evaluated in rats by inhalation and oral routesof exposure. Animals were exposed to target concentrations of0, 10, 100, or 500 mg/m³ for 6 hr/day, 5 days/week or were offereddiets daily with concentrations of 0, 50, 200, or 2000 ppm.Each study lasted approximately 14 weeks. The study designsincluded observations for clinical signs, body weights, ophthalmicexams, hematology and clinical chemistry, major organ weights,and gross and histopathology. No treatment-related effects werenoted in the ophthalmic exams. Body weights were slightly depressedin high-dose males from the inhalation study and high-dose femalesin the dietary study. Liver and liver/body weights were increasedin high-dose animals of both sexes and high-and mid-dose malesin the dietary and inhalation studies, respectively. In thehigh-dose females of the dietary study, kidney and kidney/bodyweights were increased with increased adrenal and adrenal/bodyweights were also observed. No compound-related gross lesionsnor pathological correlates to the organ weight changes wereobserved in either study. The no-adverse effect levels wereconsidered to be 100 mg/m³ and 200 ppm (15.9 mg/kg) for theinhalation and dietary studies, respectively. These data indicatethat a wide margin of safety exists for hydrogenated terphenylworkplace exposure.