Agent Name

Methyl tert-butyl ether

Alternative Name


CAS Number




Major Category



MTBE; 2-Methoxy-2-methylpropane; 2-Methyl-2-methoxypropane; Ether, tert-butyl methyl; MTBE; Methyl 1,1-dimethylethyl ether; Methyl tert-butyl ether; Methyl tertiary-butyl ether; Methyl-tert-butyl ether; Propane, 2-methoxy-2-methyl-; t-Butyl methyl ether; tert-Butyl methyl ether; [ChemIDplus] UN2398


Ethers (<C12)


A colorless liquid with a distinctive anesthetic-like odor; [CAMEO]


Used as a additive for unleaded gasolines to improve combustion; it has been used to dissolve gallstones by delivering MTBE into the gallbladder through surgical tubing; [ATSDR ToxFAQs]


Occupational exposure levels to MBTE for Peak (30 min.) and TWA (time weighted average) were measured: Transporting Peak = 11 ppm; TWA = 0.24 ppm; Blending Peak = 4.7 ppm; TWA = 0.77 ppm; Service station attendants Peak = 3.3 ppm; TWA = 0.33 ppm; [HSDB] Central nervous system depression and eye irritation have been observed as effects in controlled animal studies. [Sullivan, p. 837] MTBE is in the list of "Some volatile substances which may be abused by inhalation" published on the web site of the U.N. International Drug Control Programme, indicating its potential to cause narcosis in workers. [Reference #1] Effects on the liver in high-dose animal experiments; [HSDB] Causes renal damage in rats exposed to high concentrations; [ACGIH] A skin and eye irritant; Inhalation of high concentrations can cause CNS depression; [ICSC] "Methyl tert-butyl ether did not induce developmental toxicity in rats or rabbits exposed via inhalation to concentrations that affected maternal food consumption. In one study in mice, increased incidences of postimplantation loss and cleft palate were seen at doses that also induced hypoactivity, ataxia and reduced food consumption in the dams. Another study in mice, conducted at lower doses that were less toxic to dams, did not provide evidence of developmental toxicity." [IARC]


EPA announced in March 2000 plans to ban MTBE because of problems with groundwater contamination.

Reference Link

Volatile Substance Abuse

Exposure Assessment
Skin Designation (ACGIH)

Insufficient data


50 ppm


50 ppm

Vapor Pressure

250 mm Hg

Odor Threshold Low

0.05 ppm

Odor Threshold High

0.13 ppm

Lethal Concentration

LC50 (rat) = 23,576 ppm/4h

Explanatory Notes

Flash point = -14 deg F; Odor thresholds from CHEMINFO;

Reference Link

ATSDR - ToxFAQs - Methyl tert-Butyl Ether (MTBE)

Adverse Effects

CNS Solvent Syndrome


Hepatotoxin, Secondary



IARC Carcinogen

Not Classifiable

ACGIH Carcinogen

Confirmed Animal

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information


Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap

Occupational diseases associated with exposure to this agent: