OPPT Chemical Fact Sheet                                EPA 749-F-94-017

CHEMICALS IN THE ENVIRONMENT: METHYL-TERT-BUTYL ETHER (CAS NO. 1634-04-4)
                                 prepared by
                   OFFICE OF POLLUTION PREVENTION AND TOXICS
                     U.S. ENVIRONMENTAL PROTECTION AGENCY
                                 August 1994
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Chemicals can be released to the environment as a result of their 
manufacture, processing, and use.  EPA has developed information 
summaries on selected chemicals to describe how you might be exposed to 
these chemicals, how exposure to them might affect you and the environment, 
what happens to them in the environment, who regulates them, and whom to 
contact for additional information.  EPA is committed to reducing 
environmental releases of chemicals through source reduction and other 
practices that reduce creation of pollutants.
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WHAT IS METHYL TERTIARY-BUTYL ETHER, HOW IS IT USED, AND HOW MIGHT I BE
EXPOSED?

     Methyl tertiary-butyl ether (also called MTBE) is a colorless, 
flammable liquid with a strong odor.  It does not occur naturally but is 
produced in very large amounts (9.1 billion pounds in 1992) by 27 
companies in the United States.  US demand for MTBE is likely to continue 
to grow rapidly.  The almost exclusive users of MTBE are companies that 
add the chemical to gasoline.  MTBE is added to gasoline to improve 
combustion and to reduce harmful carbon monoxide emissions.  It is added 
to gasoline to improve the overall quality of air.  The goal is to help 
cities meet air quality standards mandated by EPA and the Clean Air Act.  
Companies use small amounts of MTBE to make high purity isobutylene.

     Exposure to MTBE can occur in the workplace or in the environment
following releases to air, water, land, or groundwater.  Exposure can also
occur when people:

    * are in places where gasoline is being pumped into vehicles,
    * fill gasoline-powered home maintenance equipment,
    * live near bulk gasoline loading and unloading facilities, or
    * live near facilities that can leak gasoline from underground
         storage containers.

Use of MTBE-blended gasoline is likely to be at its peak during the winter
season, especially in areas that use it to meet air quality standards.  
MTBE enters the body when breathed in with contaminated air or when 
consumed with contaminated food or water.  It is also absorbed through skin 
contact.  Methyl tertiary-butyl ether does not remain in the body due to 
its breakdown and removal.

WHAT HAPPENS TO MTBE IN THE ENVIRONMENT?

     Methyl tertiary-butyl ether evaporates when exposed to air.  It
dissolves when mixed with water.  Most direct releases of MTBE to the
environment are to air.  MTBE also evaporates from water and soil exposed 
to air.  Once in air, it is expected to break down to other chemicals.  
Because it is a liquid that does not bind well to soil, MTBE that makes its 
way into the ground can move through the ground and enter groundwater.  
Plants and animals are not likely to store methyl tertiary-butyl ether.

HOW DOES MTBE AFFECT HUMAN HEALTH AND THE ENVIRONMENT?

     Effects of methyl tertiary butyl ether on human health and the
environment depend on how much MTBE is present and the length and frequency 
of exposure.  Effects also depend on the health of a person or the 
condition of the environment when exposure occurs.

     Human health effects associated with breathing or otherwise consuming
large amounts of MTBE for short periods of time are not known.  Laboratory
studies show that breathing large amounts of MTBE for short periods of time
adversely affects the nervous system of animals.  Effects range from
hyperactivity and incoordination to convulsions and unconsciousness.

     Human health effects associated with breathing or otherwise consuming
smaller amounts of MTBE over long periods of time are not known.  
Laboratory studies show that repeat exposure to large amounts of MTBE in 
air causes kidney damage and adversely affects the developing fetus of 
animals.  Studies also show that lifetime exposure to MTBE in air causes 
cancer in animals.  The Agency is currently reviewing potential health 
effects of MTBE in humans.

     Methyl tertiary butyl ether by itself is not likely to cause
environmental harm at levels normally found in the environment.  MTBE can
contribute to the formation of photochemical smog when it reacts with other
volatile organic carbon substances in air. 

WHAT EPA PROGRAM OFFICES REGULATE METHYL-TERT-BUTYL ETHER, AND UNDER WHAT
LAWS IS IT REGULATED?
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  EPA OFFICE            LAW                                PHONE NUMBER
__________________________________________________________________________
  Pollution Prevention  Toxic Substances Control Act       (202) 554-1404
   & Toxics             Emergency Planning and Community
                          Right-to-Know Act (EPCRA)
                          Regulations (Sec. 313)           (800) 424-9346
                          Toxics Release Inventory data    (202) 260-1531
  Air                   Clean Air Act                      (919) 541-0888
  Solid Waste &         Comprehensive Environmental
   Emergency Response    Response, Compensation, and
                         Liability Act (Superfund)/
                        Resource Conservation and Recovery
                         Act / EPCRA (Sec. 304/311/312)    (800) 424-9346
  Water                 Safe Drinking Water Act            (800) 426-4791

A technical support document can be requested from the TSCA Assistance
Information Service, (202) 554-1404.

WHAT OTHER FEDERAL AGENCIES OR GROUPS CAN I CONTACT FOR INFORMATION ON
METHYL-TERT-BUTYL ETHER?
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  AGENCY/GROUP                                              PHONE NUMBER
__________________________________________________________________________
  Agency for Toxic Substances and Disease Registry         (404) 639-6000
  American Industrial Hygiene Association                  (703) 849-8888
  Consumer Product Safety Commission                       (301) 504-0994