Fourteen-and Ninety-Day Oral Toxicity Studies of Methyl Tertiary-Butyl Ether in Sprague-Dawley Rats

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Abstract
Male and female Sprague-Dawley rats were gavaged with methyl tertiary-butyl ether (MtBE) for 14 or 90 days to evaluate subacute and subchronic toxicity. Five daily dose levels ranged from 0 to 1428 mg/kg body weight for the 14 day study and 0 to 1200 mg/kg body weight for the 90-day exposure. Controls received the corn oil vehicle. At or above dose levels of 1200 mg/kg, MtBE-induced anesthesia lasted about 2 h, followed by uneventful recovery. Diarrhea was common in all treatment groups, but no deaths were attributed to MtBE toxicity. In the subacute study, lung weights were reduced in high-dose females. Trends in the 14-day exposure also included increased cholesterol in both females and males and decreased blood-urea nitrogen (BUN) and creatinine in females. In the 90-day study, females exhibited elevated cholesterol and decreased BUN, while creatinine was decreased in high-dose males. Microscopic findings in most organs were unremarkable, except for high-dose males where renal changes were compatible with alpha 2-globulin nephropathy and were considered to have little toxicologic significance for humans. Both studies indicated that dose levels below those which induce anesthesia (1200 mg/kg) do not result in significant pathophysiologic changes.
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