Toxicity and Carcinogenicity of T-Butyl a Lcohol in Rats and Mice Following Chronic Exposure in Drinking Water

Abstract

t-Butyl alcohol (TBA) was administered in drinking water to F344/N rats and B6C3F1 mice for two years using 60 animals/dose/sex/species. Male rats received doses of 0, 1.25, 2.5, or 5 mg/ml and females received 0, 2.5, 5, or 10 mg/ml, resulting in average daily doses of approximately 85, 195, or 420 mg TBA/kg body weight for males and 175, 330, or 650 mg/kg for females. Ten rats per group were evaluated after 15 months. Male and female mice received doses of 0, 5, 10, or 20 mg/ml, resulting in average daily doses of approximately 535, 1,035, or 2,065 mg TBA/kg body weight for males and 510, 1,015, or 2,105 mg/kg for females. Survival was significantly reduced in male rats receiving 5 mg/ml, female rats receiving 10 mg/ml, and male mice receiving 20 mg/ml. Long-term exposure to TBA produced increased incidences of renal tubule adenoma and carcinoma in male rats; transitional epithelial hyperplasia of the kidney in male and female rats; follicular cell adenoma of the thyroid in female mice; and follicular cell hyperplasia of the thyroid and inflammation and hyperplasia of the urinary bladder in male and female mice. In addition, a slight increase in follicular cell adenoma or carcinoma of the thyroid (combined) in male mice may have been related to the administration of TBA.

Aerobic Biodegradation of Methyl tert -Butyl Ether by Aquifer Bacteria from Leaking Underground Storage Tank Sites

“…Several states, including California, have set primary maximum concentration levels for MTBE at or below 20 g/liter, and at an even lower level of 12 g/liter for tert-butyl alcohol (TBA), an MTBE metabolite. The U.S. Environmental Protection Agency has listed MTBE as a possible human carcinogen, whereas TBA is a known animal carcinogen (7). MTBE appears to be more mobile and less biodegradable than BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), and consequently, MTBE plumes have extended over kilometer-scale distances, as is the case at Port Hueneme, Calif., and East Patchogue, N.Y.…”

Comparative Transcriptome Analysis of Methylibium petroleiphilum PM1 Exposed to the Fuel Oxygenates Methyl tert -Butyl Ether and Ethanol

“…MTBE was one of the major oxygenates incorporated into reformulated gasoline to increase the fuel's oxygen content and decrease carbon monoxide and ozone emissions. MTBE and its primary metabolite tert-butyl alcohol (TBA) are suspected and known carcinogens, respectively (1,7,31,57). Recently, alternative oxygenates, such as ethanol, have been substituted for MTBE, but because of the very slow depletion of contaminant mass from spill areas under anoxic conditions, the impacts of MTBE on the subsurface will be felt for many years and likely decades to come (8,29).…”

Scientific Opinion on Flavouring Group Evaluation 18, Revision 2 (FGE.18Rev2): Aliphatic, alicyclic and aromatic saturated and unsaturated tertiary alcohols, aromatic tertiary alcohols and their esters from chemical groups 6 and 8

“…No NOAELs. Rat; M, F 120 None (Cirvello et al, 1995;NTP, 1995b) Fully described NTP study. No NOAELs.…”