United States       EPA 749-F-94-022 ,
        Environmental Protection December 1994
        Agency    )                f
               ' j

        Office of Pollution Prevention and Toxics (7401)
oEFft Chemicals in the
        Environment
        1,2,4-TRlMETHYLBENZENE

        (CAS NO. 95-63-6)

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Chemicals can l?e released to the environment
as a result of their manufacture, processing,
and use.  The R PA has developed information
summaries on selected chemicals to describe
how you might be exposed to these chemi-
cals, 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.
liPA is committed to reducing environmental
releases of chemicals through source reduc-
tion and other practices that reduce creation
of pollutants.

 WHAT IS  1,2,4-TRIMETHYLBENZENE,
 HOW IS IT USED, AND HOW MIGHT I
             BE EXPOSED?

         1,2,4-Trimethylbenzene (also called
 1MB) is a colorless, flammable liquid.  It
 occurs naturally in coal tar and petroleum
 crude oil1. It is a major component (typically
 40%) of a petroleum refinery distillation
 fraction known as the C9 aromatic fraction
 (or simply the C9 fraction).  Oil refineries
 produce large amounts (an estimated 80
 billion pounds) of the C9 fraction each year.
 Most of the C9 fraction is not isolated.
 Refineries pump this "unrecovered" C9
 fraction to some other location where it is
 usually added directly to gasoline. Refineries
  isolate less than one-half percent of the C9
  fraction. Companies add this "recovered" C9
  fraction to  protective surface coatings and
  cleaners.

          Oil refineries generally do  not
  isolate  1,2,4-trimethylbenzene from crude oil
  or from the C9 fraction. Currently only one
  refinery in the United States "recovers"
  1MB.  The Environmental Protection Agency
  estimates that the amount of "recovered"
  1,2,4-trimethylbenzene is in excess  of 10
  million pounds per year.  US demand for this
  isolated 1,2,4-trimethylbenzene is likely to

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 remain stable. The largest users of isolated
 1,2,4-trimethy(benzene are chemical companies
 that make trimellitic anhydride. Companies also
 use it to make dyes and drugs.

        Exposure to 1,2,4 i trimethylbenzene can
 occur in the workplace or in the environment
 following releases to air, water, land, or ground-
 water.  Exposure can also occur when people use
 gasoline or certain paints and cleaners.
 1,2,4-Trimethylbenzene enters the body when
 breathed in with contaminated air or when con-
 sumed with contaminated (bod or water. It can
 also be absorbed through skin contact.  It may
 remain in  the body, stored in fat, before its re-
 moval in expired air or in urine.
            WHAT HAPPENS TO
    1,2,4-TRIMETHYLBiENZENE IN THE
              ENVIRONMENT?

         1,2,4-Trimethylbenzene evaporates when
exposed to air. It dissolves only slightly when
mixed with water. Most direct releases of
1,2,4-trimethyIbenzene to the environment are to
air. It also evaporates from water and soil ex-
posed to air.. Once in air, il! breaks down to other
chemicals.  Microorganisms that live in water and
in soil can also break down 1MB. Because it is a
liquid that does not bind well to soil,
1,2,4-trimethyIbenzene that makes its way into
the ground can move through the ground and
enter groundwater. Plants and animals living in
environments contaminated with TMB  can store
small amounts of the chemical.
  HOW DOES 1,2,4-TRIMETHYLBENZENE
   AFFECT HUMAN HEALTH AND THE
              ENVIRONMENT?
                        I
        Effects of 1,2,4-trimethylbenzene on
human health and the environment depend on
how much TMB is present and the length and

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 frequency of exposure.  Effects also
 depend on the health of a person or the
 condition of the environment when
 exposure occurs.

         Breathing large amounts of
 1,2,4-lrimelhylbenzerie for short periods
 of time adversely affects the human
 nervous system. Effects range from
 headaches to fatigue and drowsiness.
 TMB vapor irritates the nose and the
 throat.  Prolonged contact with liquid
 TMB irritates the skin.  These effects are
 not likely to occur at levels of
 1,2,4-trimethylbenzerie that are normally
 found in the environment.
         I luman health effects associated
 with breathing or otherwise consuming
 smaller amounts of 1 j2,4-trimelhylben-
 ^ene are not known. jThe petroleum
 industry has conducted several studies on
 the C9 fraction in response to an EPA
 request for testing.  These studies show
 that repeat exposure to this mixture of
 chemicals in air adversely affects the
 reproductive system and the developing
 fetus of animals.  EPA believes that
 adverse effects associated with exposure
 to the C9 fraction are similar to those
 expected to occur as a result of exposure
 to individual chemicals, like
 1,2,4-trimethylbenzene, that make up this
 mixture.        .'!.--

       ,  1,2,4-Trimethylbenzene by
 itself is not likely to cause environmental
 harm at levels normally found in the
environment.  TMB can contribute to the
 formation of photochemical smog when it
reacts with other volatile organic carbon
substance in air.

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