Hazard Narrative for Tertiary - Butyl Alcohol (TBA), CAS Number 75 - 65 - 0 The purpose of this investigation was to conduct a quantitative risk assessment according to U.S. Environm ental Protection Agency guidelines in which data on the mode of action by which TBA induced renal tumors in rats and thyroid tumors in mice was consid ered. When data from animal studies, such as the TBA bioassays, are extrapo lated to humans to provide estimates of lifetime cancer risk s, then potential differe nces in pharmacokinetics (metabolism) and pharma codynamics (sensitivity and mode of action) between the animal species and humans is considered in the estimation of human equivalent doses and in extrapol ation from high doses typically used in the animal bioassays to low dose s to which humans may be potentially exposed. Pharmacokinetic, toxicity, and mode of action data for TBA were reviewed and data selected for qu antitative dose - response modeling