In what follows, the terms xylene, xylenes, and total xylene are used
interchangeably. There are three forms of xylene in which the methyl groups vary
on the benzene ring: meta-xylene, ortho-xylene, and para-xylene (m-, o-, and p-xylene).
These different forms are referred to as isomers. The term total xylenes refers
to all three isomers of xylene. Mixed xylene is a mixture of the three isomers
and usually also contains 6-15 percent ethylbenzene. Xylene is also known as
xylol or dimethylbenzene. Xylene is primarily a synthetic chemical. Chemical
industries produce xylene from petroleum. Xylene also occurs naturally in
petroleum and coal tar and is formed during forest fires. It is a colorless,
flammable liquid with a sweet odor.
Xylene is one of the top 30 chemicals produced in the United States in terms of
volume. It is used as a solvent (a liquid that can dissolve other substances) in
the printing, rubber, and leather industries. Along with other solvents, xylene
is also used as a cleaning agent, a thinner for paint, and in varnishes. It is
found in small amounts in airplane fuel and gasoline. Xylene is used as a
material in the chemical, plastics, and synthetic fiber industries and as an
ingredient in the coating of fabrics and papers. Isomers of xylene are used in
the manufacture of certain polymers, such as plastics.
Xylene evaporates and burns quickly. Xylene does not mix well with water;
however, it does mix with alcohol and many other chemicals. Most people begin to
smell xylene in air at 0.08-3.7 parts per million parts of air (ppm) and begin
to taste it in water at 0.53-1.8 ppm.
Fate & Transport
Xylene is a liquid, and it can leak into soil, surface water (creeks, streams,
rivers), or groundwater, where it may remain for months or more before it breaks
down into other chemicals. However, because it evaporates easily, most xylene
(if not trapped deep underground) goes into the air, where it stays for several
days. In the air, the xylene is broken down by sunlight into other less harmful
Xylene can enter the environment when it is made, packaged, shipped, or used.
Most xylene that is accidently released evaporates into the air, although some
is released into rivers or lakes. Xylene can also enter soil, water, or air in
large amounts after an accidental spill or as a result of an environmental leak
during storage or burial at a waste site.
Xylene very quickly evaporates into the air from surface soil and water. Xylene
stays in the air for several days until it is broken down by sunlight into other
less harmful chemicals.
Most xylene in surface water evaporates into the air in less than a day. The
rest of it is slowly broken down into other chemicals by small living organisms
in the water. Only very small amounts are taken up by plants, fish, and birds.
We do not know exactly how long xylene stays in water, but we do know that it
stays longer in underground water than in lakes and rivers, probably because it
can evaporate from the latter.
Xylene evaporates from soil surfaces. Xylene below the soil surface stays there
for several days and may travel down through the soil and enter underground
water (groundwater). Small living organisms in soil and groundwater may
transform it into other less harmful compounds, although this happens slowly. It
is not clear how long xylene remains trapped deep underground in soil or
groundwater, but it may be months or years. Xylene stays longer in wet soil than
in dry soil. If a large amount of xylene enters soil from an accidental spill, a
hazardous waste site, or a landfill, it may travel through the soil and
contaminate drinking water wells. Only a small amount of xylene is absorbed by
animals that live in water contaminated with xylene.
You may be exposed to xylene because of its distribution in the environment.
Xylene is primarily released from industrial sources, in automobile exhaust, and
during its use as a solvent. Hazardous waste disposal sites and spills of xylene
into the environment are also possible sources of exposure. You are most likely
to be exposed to xylene by breathing it in contaminated air. Levels of xylene
measured in the air of industrial areas and cities of the United States range
from 1 to 88 parts of xylene per billion parts of air (a part per billion [ppb]
is one thousandth of a part per million [ppm]; one ppm equals 1,000 ppb). Xylene
is sometimes released into water and soil as a result of the use, storage, and
transport of petroleum products. Surface water generally contains less than 1
ppb, although the level may be higher in industrial areas. You can also be
exposed to xylene by drinking or eating xylene-contaminated water or food.
Levels of xylene in public drinking water supplies have been reported to range
from 0 to 750 ppb. Little information exists about the amount of xylene in food.
Xylene levels ranging from 50 to 120 ppb have been found in some fish samples.
Xylene has been found in chicken eggs and in the polystyrene packaging in which
they are sold.
You may also come in contact with xylene from a variety of consumer products,
including cigarette smoke, gasoline, paint, varnish, shellac, and rust
preventives. Breathing vapors from these types of products can expose you to
xylene. Indoor levels of xylene can be higher than outdoor levels, especially in
buildings with poor ventilation. Skin contact with products containing xylene,
such as solvents, lacquers, paint thinners and removers, and pesticides may also
expose you to xylene.
Besides painters and paint industry workers, others who may be exposed to xylene
include biomedical laboratory workers, distillers of xylene, wood processing
plant workers, automobile garage workers, metal workers, and furniture
refinishers also may be exposed to xylene. Workers who routinely come in contact
with xylene-contaminated solvents in the workplace are most likely to be exposed
to high levels of xylene.
Xylene is most likely to enter your body when you breathe xylene vapors. Less
often, xylene enters the body through the skin following direct contact. It is
rapidly absorbed by your lungs after you breathe air containing it. Exposure to
xylene may also take place if you eat or drink xylene-contaminated food or
water. The amount of xylene retained ranges from 50% to 75% of the amount of
xylene that you inhale. Physical exercise increases the amount of xylene
absorbed by the lungs. Absorption of xylene after eating food or drinking water
containing is both rapid and complete. Absorption of xylene through the skin
also occurs rapidly following direct contact with xylene. Absorption of xylene
vapor through the skin is lower than absorption of xylene vapor by the lungs.
However, it is not known how much of the xylene is absorbed through the skin. At
hazardous waste sites, breathing xylene vapors, drinking well water contaminated
with xylene, and direct contact of the skin with xylene are the most likely ways
you can be exposed. Xylene passes into the blood soon after entering the body.
In people and laboratory animals, xylene is broken down into other chemicals
especially in the liver. This process changes most of the xylene that is
breathed in or swallowed into a different form. Once xylene breaks down, the
breakdown products rapidly leave the body, mainly in urine, but some unchanged
xylene also leaves in the breath from the lungs. One of the breakdown products
of xylene, methylbenzaldehyde, is harmful to the lungs of some animals. This
chemical has not been found in people exposed to xylene. Small amounts of
breakdown products of xylene have appeared in the urine of people as soon as 2
hours after breathing air containing xylene. Usually, most of the xylene that is
taken in leaves the body within 18 hours after exposure ends. Storage of xylene
in fat or muscle may prolong the time needed for xylene to leave the body.
Short-term exposure of people to high levels of xylene can cause irritation of
the skin, eyes, nose, and throat; difficulty in breathing; impaired function of
the lungs; delayed response to a visual stimulus; impaired memory; stomach
discomfort; and possible changes in the liver and kidneys. Both short- and
long-term exposure to high concentrations of xylene can also cause a number of
effects on the nervous system, such as headaches, lack of muscle coordination,
dizziness, confusion, and changes in one's sense of balance. People exposed to
very high levels of xylene for a short period of time have died. Most of the
information on long-term exposure to xylene is from studies of workers employed
in industries that make or use xylene. Those workers were exposed to levels of
xylene in air far greater than the levels normally encountered by the general
population. Many of the effects seen after their exposure to xylene could have
been caused by exposure to other chemicals that were in the air with xylene.
Results of studies of animals indicate that large amounts of xylene can cause
changes in the liver and harmful effects on the kidneys, lungs, heart, and
nervous system. Short-term exposure to very high concentrations of xylene causes
death in animals, as well as muscular spasms, incoordination, hearing loss,
changes in behavior, changes in organ weights, and changes in enzyme activity.
Long-term exposure of animals to low concentrations of xylene has not been well
Information from animal studies is not adequate to determine whether or not
xylene causes cancer in humans. Both the International Agency for Research on
Cancer (IARC) and EPA have found that there is insufficient information to
determine whether or not xylene is carcinogenic and consider xylene not
classifiable as to its human carcinogenicity.
Exposure of pregnant women to high levels of xylene may cause harmful effects to
the fetus. Studies of unborn animals indicate that high concentrations of xylene
may cause increased numbers of deaths, decreased weight, skeletal changes, and
delayed skeletal development. In many instances, these same concentrations also
cause damage to the mothers. The higher the exposure and the longer the exposure
to xylene, the greater the chance of harmful health effects. Lower
concentrations of xylene are not so harmful.
Information excerpted from
Toxicological Profile for Xylene August 1995 Update
Below from http://chemfinder.cambridgesoft.com
Agency for Toxic Substances and Disease Registry
United States Public Health Service
aquatic solvent 3501; xylene, mixed or all isomers, except p-; Xylenes (mixed);
m & p-xylene; Xylene (mixed); Xylene (o-, m-, p-isomers); except p-xylene,
mixed or all isomers; Xylene mixture (m-xylene, o-xylene, p-xylene); Total
xylenes; Xylene mixture (60% m-xylene, 9% o-xylene, 14% p-xylene, 17%
ethylbenzene); Xylenes mixed isomers; Xylenes (o-, m-, p-isomers);
Dimethylbenzenes; Dimethylbenzene (mixed isomers); Xylene (mixed isomers);
xylenes; Dimethylbenzene; Xylol; Xylene; Xylene mixture; Xylene, (total);
m-,p-,o-Xylene; o-,m-,p-Xylene; Xylenes ; Xylene (o-,m-,p-);
1307 Flammable liquid
liquid with aromatic odors
0.0175 g/100 mL