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ToxFAQsTM for Trichlorobenzenes


September 2010

CAS#: 12002-48-1

ToxFAQsâ„¢ PDF PDF Version, 54 KB

This fact sheet answers the most frequently asked health questions about trichlorobenzenes. For more information, you may call the ATSDR Information Center at 1-800-232-4636. This fact sheet is one in a series of summaries about hazardous substances and their health effects. This information is important because this substance may harm you. The effects of exposure to any hazardous substance depend on the dose, the duration, how you are exposed, personal traits and habits, and whether other chemicals are present.


Trichlorobenzenes have been used as solvents. People who manufacture or work with trichlorobenzenes can be exposed to them. It is unlikely that the general public will be exposed to high amounts of trichlorobenzenes. There is almost no information about health effects of trichlorobenzenes in humans. 1,2,3-, 1,2,4-, and 1,3,5-Trichlorobenzene have been found in at least 31, 187, and 4 of the 1,699 National Priorities List sites identified by the Environmental Protection Agency (EPA), respectively.

What are trichlorobenzenes?

Trichlorobenzenes are human-made compounds that occur in three different chemical forms or isomers: 1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzene. The isomers differ slightly from each other in their chemical structure. 1,2,3-Trichlorobenzene and 1,3,5-trichloro�benzene are colorless solids, while 1,2,4-trichloro�benzene is a colorless liquid.

Trichlorobenzenes have primarily been used as solvents and chemical intermediates to produce other compounds. 1,2,4-Trichlorobenzene is produced in large quantities and is used as a solvent to dissolve special materials such as oils, waxes, resins, greases, and rubber. It is also frequently used to produce dyes and textiles. 1,2,3-Trichlorobenzene and 1,3,5-trichlorobenzene , are produced in lower quantities and have fewer uses.

What happens to trichlorobenzenes when they enter the environment?

  • Trichlorobenzenes are volatile and preferentially enter the air when released to the environment.
  • The half-life (the time it takes for 50% of the compound to degrade) of trichlorobenzenes in air is about 1 month.
  • Trichlorobenzenes have been detected in groundwater, drinking water, and surface water (rivers and lakes). Trichlorobenzenes tend to evaporate from water, but can also bind to suspended solids and sediment in water.
  • Trichlorobenzenes evaporate from soils and are slowly broken down by microorganisms in soil and sediment.
  • High levels of trichlorobenzenes are often detected in fish or other species living in contaminated waters because trichlorobenzenes can accumulate in fatty tissues.

How might I be exposed to trichlorobenzenes?

  • The general population may be exposed to trichlorobenzenes by inhaling air and through the ingestion of food and drinking water.
  • Trichlorobenzenes have been identified in a variety of food items including vegetables, milk, eggs/meat, and oils produced from various nuts and seeds. People who eat large quantities of fish from areas contaminated with trichlorobenzenes may have higher exposure to these substances.
  • Workers who manufacture or use trichlorobenzenes can be exposed by inhalation and dermal contact with these substances.

How can trichlorobenzenes affect my health?

There is virtually no information regarding health effects of trichlorobenzenes in humans. However, based on results from studies in animals, it is reasonable to predict that humans exposed to high amounts of trichlorobenzenes may develop liver problems.

Studies in animals indicate that oral administration of trichlorobenzenes for short or long periods produces mainly alterations in the liver and kidneys. Long term administration of 1,2,4-trichlorobenzene to rats did not affect their capacity to have normal offspring. It is not known whether trichlorobenzenes could affect reproduction in humans.

How likely are trichlorobenzenes to cause cancer?

There are no studies of cancer in people exposed to trichlorobenzenes. Mice given 1,2,4-trichlorobenzene in the food for 2 years developed cancer of the liver. The EPA has stated that 1,2,4-trichlorobenzene is not classifiable as to human carcinogenicity. However, this was based on studies conducted prior to 1990; newer information has not been evaluated.

How can trichlorobenzenes affect children?

There are no studies of children exposed to trichlorobenzenes. For the most part, studies in animals given trichloro�benzenes during pregnancy have not found adverse effects in the pups at birth or during the growing period. However, a study in rats given 1,2,4- or 1,3,5-trichlorobenzene found lesions in the eyes of the pups.

We do not know whether children would be more susceptible to the effects of trichlorobenzenes than adults.

Trichlorobenzenes have been found in human breast milk, which means that mothers can transfer these chemicals to their babies by nursing.

How can families reduce the risks of exposure to trichlorobenzenes?

  • Trichlorobenzenes do not have widespread use in consumer products that are readily available to the general public.
  • Avoid areas near facilities that manufacture and use trichlorobenzenes and other chlorinated substances or hazardous waste sites at which these substances may have been disposed of.
  • Avoiding high consumption of root crops and fish living in contaminated environments will reduce the risk of exposure.

Is there a medical test to determine whether I�ve been exposed to trichlorobenzenes?

Trichlorobenzenes can be measured in blood and body fat, but the tests used are not routinely available in the doctor�s office.

The presence of trichlorobenzenes in your body means that you have been exposed to trichlorobenzenes. Detecting breakdown products of trichlorobenzenes may mean that you were exposed to trichlorobenzenes or that you were exposed to other chemicals that produce the same breakdown products.

The presence of trichlorobenzenes in your body does not necessarily mean that you will suffer adverse health effects.

Has the federal government made recommendations to protect human health?

The EPA has determined that exposure to 1,2,4-trichloro�benzene and 1,3,5-trichlorobenzene in drinking water at concentrations of 0.1 and 0.6 milligrams per liter (mg/L), respectively, for 1 or 10 days is not expected to cause any adverse effects in a child.

The EPA has determined that lifetime exposure to 0.07 mg/L 1,2,4-trichlorobenzene and 0.04 mg/L 1,3,5-trichlorobenzene is not expected to cause any adverse effects.

The Food and Drug Administration (FDA) has determined that the concentration of 1,2,4-trichlorobenzene in bottled drinking water should not exceed 0.7 mg/L.


Agency for Toxic Substances and Disease Registry (ATSDR). 2010. Toxicological Profile for Trichlorobenzenes. (Draft for Public Comment). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.

Where can I get more information?

If you have questions or concerns, please contact your community or state health or environmental quality department or:

For more information, contact:
Agency for Toxic Substances and Disease Registry
Division of Toxicology and Human Health Sciences
1600 Clifton Road NE, Mailstop F-57
Atlanta, GA 30333
Phone: 1-800-CDC-INFO · 888-232-6348 (TTY)
Email: Contact CDC-INFO

ATSDR can also tell you the location of occupational and environmental health clinics. These clinics specialize in recognizing, evaluating, and treating illnesses resulting from exposure to hazardous substances.

Information line and technical assistance:
Phone: 888-422-8737

To order toxicological profiles, contact:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Phone: 800-553-6847 or 703-605-6000

Some PDF files may be electronic conversions from paper copy or other electronic ASCII text files. This conversion may have resulted in character translation or format errors. Users are referred to the original paper copy of the toxicological profile for the official text, figures, and tables. Original paper copies can be obtained via the directions on the toxicological profile home page, which also contains other important information about the profiles.

The information contained here was correct at the time of publication. Please check with the appropriate agency for any changes to the regulations or guidelines cited.

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