The chronic toxicity and tumorigenicity of chloroform (67663) was studied in male Osborne-Mendel-rats and female B6C3F1-mice exposed to the chemical at doses of 200, 400, 900, and 1800 parts per million (ppm) in their drinking water. Water consumption increased over the course of the study with the amount of the increase being inversely proportional to the dose level during the first 18 months. A significant degree of early mortality was noted in mice treated at 900 and 1800ppm. Blood levels of chloroform from assays taken at 18 months indicated 7.5, 22.1, 75.4, and 124 parts per billion (ppb) readings for the 200, 400, 900, and 1800ppm groups, respectively in the rats. Similar readings taken at 24 months were 18.2, 13.8, 80.8, and 135ppb. In the 1800ppm rat group there was a significant increase in liver fat after 6 months. Similar increases were noted in mice at the 400 through 1800ppm levels at 3 months and in all treatment groups at 6 months. White blood cell counts were lower in the 1800ppm treatment group of rats. Potassium, phosphorus, bilirubin, alkaline-phosphatase, total iron, albumin, and the albumin/globulin ratio were higher in the treated groups of rats sacrificed at 6, 12, and 18 months. Chloride, cholesterol, triglycerides, lactate-dehydrogenase and globulin were lower in treated groups.
Proceedings of the Second NCI/EPA/NIOSH Collaborative Workshop: Progress on Joint Environmental and Occupational Cancer Studies, September 9-11, 1981, Rockville, Maryland