What is Methyl tert-butyl ether?

Methyl tert-butyl ether is an organic compound with a structural formula (CH₃)₃COCH₃. MTBE is a volatile, flammable, and colorless liquid that is sparingly soluble in water.


Nearly all methyl tert-butyl ether produced in the United States is used as an additive in unleaded gasoline to increase octane levels and reduce carbon monoxide emissions. It was also used in the past to produce isobutene.

Sources & Potential Exposure

Methyl tert-butyl ether is used as a gasoline additive. Exposure may occur by breathing air contaminated with auto exhaust or gasoline fumes while refueling autos. Respiratory irritation, dizziness, and disorientation have been reported by some motorists and occupationally exposed workers. Acute (shortterm) exposure of humans to methyl tert-butyl ether also has occurred during its use as a medical treatment to dissolve cholesterol gallstones. Chronic (long-term) inhalation exposure to methyl tert-butyl ether has resulted in central nervous system (CNS) effects, respiratory irritation, liver and kidney effects, and decreased body weight gain in animals. Developmental effects have been reported in rats and mice exposed via inhalation.

Federal Regulations

EPA has not classified methyltert-butyl ether with respect to potential carcinogenicity.

REGENESIS Treatment Products – Methyl tert-butyl ether