The goal of this project is to evaluate the chronic toxicity and carcinogenicity of sulfolane in rats and mice, following exposure in drinking water. There are concerns over the potential toxicity of sulfolane following exposure in contaminated ground water, particularly in Alaska. 2-Year chronic toxicity and carcinogenicity studies of sulfolane are in the in life phase. These studies include an assessment of developmental landmarks, subchronic toxicity and immunotoxicity. Keywords: toxicity, carcinogenicity, drinking water, sulfolane