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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