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tert-Butyl Methyl Ether

General Description

  • Synonyms: Methyl-t-Butyl Ether; Methyl-tert-Butyl Ether; Methoxy-2-Methyl Propane; MTBE
  • OSHA IMIS Code Number: B146
  • Chemical Abstracts Service (CAS) Registry Number: 1634-04-4
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: KN5250000
  • Chemical Description and Physical Properties:
    • molecular formula: C5H12O
    • molecular weight: 88.17
    • boiling point: 55.2°C
    • vapor pressure: kPa at 20°C: 27
    • melting point: -109°C

Exposure Limits

  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 50 ppm TWA; Appendix A3 - Confirmed Animal Carcinogen with Unknown Relevance to Humans

Health Factors

  • Potential Symptoms: Drowsiness, dizziness, headache, weakness, unconsciousness; redness of skin and eyes; Acute ingestion: Nausea, vomiting, abdominal pain; chemical pneumonitis (by aspiration).
  • Health Effects: Irritation-Eyes, skin---mild (HE16); Nervous system disturbances (HE7); Explosive, flammable (HE18)
  • Affected Organs: Central nervous system, skin, eyes
  • Notes:
    1. MTBE is used as a major gasoline additive (up to 15%) and experimentally for dissolving cholesterol gall stones.
    2. Metabolism of MTBE by hepatic CYP2A6 (which also metabolizes coumarin and nicotine) is strongly inhibited by the drugs, methoxsalen and tranylcypromine.
    3. Systemic exposure can occur via absorption through the skin. Most symptoms claimed for airborne MTBE exposure have not been rigorously documented, as occupational exposure is rarely to the pure compound alone. Its potent odor is recognized at 90-130 ppb.
  • Literature Basis:
    • (symptoms; organs affected) International Chemical Safety Cards (WHO/IPCS/ILO): Methyl tert-butyl ether
    • (absorption; metabolism) Draper, A.J., Madan, A. and Parkinson, A.: Inhibition of coumarin 7-hydroxylase activity in human liver microsomes. Arch. Biolchem. Biophys. 341(1): 47-61, 1997.
    • Prah, J.D., Blount, B., Cardinali, F.L., Ashley, D.L., Leavens, T. and Case, M.W.: The development and testing of a dermal exposure system for pharmacokinetic studies of administered and ambient water contaminants. J. Pharmacol. Toxicol. Methods 47(3): 189-195, 2002.
    • (clinical use) Hellstern, A., et al.: Dissolution of gallbladder stones with methyl tert-butyl ether and stone recurrence: a European survey. Dig. Dis. Sci. 43(5): 911-920, 1998.
    • (general reviews) Borak, J., Pastides, H., Van Ert, M., Russi, M. and Herzstein J.: Exposure to MTBE and acute human health effects: a critical literature review. Human and Ecological Risk Assessment 4(1): 177-200, 1998.
    • No Authors. Methyl tert-butyl ether (PDF). IARC Monogr. Eval. Carcinog. Risks Hum. 73: 339-383, 1999.
  • Date Last Revised: 11/05/2003

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):
  • Two Charcoal Tubes in Series (Front is 400 mg/ Back is 200 mg; 20/40 mesh)
  • maximum volume: 96 Liters
  • maximum flow rate: 0.2 L/min
  • current analytical method: Gas Chromatography; GC/FID
  • analytical solvent: Carbon Disulfide
  • method reference: NIOSH Manual of Analytical Methods (NIOSH 1615 (PDF))
  • method classification: Partially Validated
  • note: Store samples at reduced temperature until shipment.

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