ToxFAQs™ for Dichlorobenzenes
CAS#: 1,2-Dichlorobenzene 95-50-1; 1,3-Dichlorobenzene
541-73-1; 1,4-Dichlorobenzene 106-46-7
PDF Versionpdf icon[59.5 KB]
This fact sheet answers the most frequently asked health questions about
dichlorobenzenes. For more information, you may call the ATSDR Information
Center at 1-888-422-8737. 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.
Exposure to dichlorobenzenes mostly occurs from breathing
indoor air or workplace air. Exposure to high levels of 1,2- or 1,4-
dichlorobenzene may be very irritating to your eyes and nose and cause difficult
breathing, and an upset stomach. Extremely high exposures to 1,4-
dichlorobenzene can result in dizziness, headaches, and liver problems. 1,2-,
1,3-, and 1,4-Dichlorobenzenes have been identified in at least 281, 175, and
330, respectively, of the 1,662 National Priorities List sites identified by the
Environmental Protection Agency (EPA).
What are dichlorobenzenes?
There are three dichlorobenzene isomers- 1,2-dichlorobenzene,
1,3-dichlorobenzene, and 1,4-dichlorobenzene.
Dichlorobenzenes do not occur naturally. 1,2-Dichlorobenzene
is a colorless to pale yellow liquid used to make herbicides. 1,3-
Dichlorobenzene is a colorless liquid used to make herbicides,
insecticides, medicine, and dyes. 1,4-Dichlorobenzene, the most
important of the three chemicals, is a colorless to white solid
with a strong, pungent odor. When exposed to air, it slowly
changes from a solid to a vapor. Most people can smell 1,4-
dichlorobenzene in the air at very low levels.
What happens to dichlorobenzenes when they enter
- 1,4-Dichlorobenzene enters the environment when it is used
in mothballs and in toilet-deodorizer blocks. Very little enters
the environment from hazardous waste sites.
- Some 1,2- and 1,3-dichlorobenzenes are released into the
environment when used to make herbicides and when people
use products that contain these chemicals
- Dichlorobenzenes do not dissolve easily in water, the small
amounts that enter water quickly evaporate into the air.
- Sometimes, dichlorobenzenes bind to soil and sediment.
Dichlorobenzenes in soil usually are not easily broken down by soil organisms. Evidence suggests that plants and fish absorb
How might I be exposed to dichlorobenzenes?
- You may be exposed to 1,4-dichlorobenzene by breathing
vapors from products used in the home or in buildings, such as
air fresheners, mothballs, and toilet-deodorizer blocks. 1,2-
dichlorobenzene and 1,3-dichlorobenzene are not found
frequently in the air of homes and buildings because these
chemicals are not used in household products.
- You may be exposed to very low levels of dichlorobenzenes
in drinking water. You are not likely to be exposed to
dichlorobenzenes in soil.
- You may also be exposed to low levels of dichlorobenzenes
in beef, pork, chicken, eggs, baked goods, soft drinks, butter,
peanut butter, fruits, vegetables, and fish.
How can dichlorobenzenes affect my health?
Very little is known about the health effects of 1,3-
dichlorobenzene, especially in humans, but they are likely to be
similar to those of 1,2- and 1,4-dichlorobenzene.
Inhaling the vapor or dusts of 1,2-dichlorobenzene and 1,4-
dichlorobenzene at very high concentrations could be very
irritating to your eyes and nose and cause burning and tearing of the eyes, coughing, difficult breathing, and an upset stomach.
Dizziness, headaches, and liver problems have also been observed
in people exposed to very high levels of 1,4-dichlorobenzene.
There is limited evidence that inhaling 1,4-dichlorobenzene may
decrease lung function.
People who have eaten 1,4-dichlorobenzene products regularly
for long periods (months to years) developed skin blotches and
anemia. 1,4-Dichlorobenzene might cause a burning feeling in
your skin if you hold mothballs or toilet-deodorizer blocks against
your skin for a long time.
Breathing or eating any of the dichlorobenzenes caused harmful
effects in the liver of laboratory animals. Animal studies also
found that 1,2- and 1,4-dichlorobenzene caused effects in the
kidneys and blood, and that 1,3-dichlorobenzene caused thyroid
and pituitary effects.
How likely are dichlorobenzenes to cause cancer?
The Department of Health and Human Services (DHHS) has
determined that 1,4-dichlorobenzene may reasonably be
anticipated to be a carcinogen. There is no direct evidence that
1,4-dichlorobenzene can cause cancer in humans. However,
animals given very high levels in water developed liver tumors.
1,2-Dichlorobenzene was not carcinogenic in laboratory animals
and 1,3-dichlorobenzene has not been tested for its potential to
cause cancer. Both the International Agency for Research on
Cancer (IARC) and the EPA concluded that 1,2- and 1,3-
dichlorobenzene are not classifiable as to human carcinogenicity.
How can dichlorobenzenes affect children?
Children who are exposed to dichlorobenzenes are likely to exhibit
the same effects as adults, although this is not known for certain.
Children can also be exposed to dichlorobenzenes prenatally,
because all three isomers have been detected in placenta samples,
as well as through breast feeding. There is no reliable evidence
suggesting that dichlorobenzenes cause birth defects, although
animal data raise concern for effects of 1,4-dichlorobenzene on
postnatal development of the nervous system.
How can families reduce the risk of exposure to
Exposure of children to 1,4-dichlorobenzene can be minimized
by discouraging them from playing with, swallowing, or having
skin contact with products containing 1,4-dichlorobenzene. These
items should be stored out of reach of young children and kept
in their original containers to prevent accidental poisonings. Keep
your Poison Control Center's number by the phone.
Is there a medical test to show whether I've been
exposed to dichlorobenzenes?
Several tests can be used to show if you have been exposed to
dichlorobenzenes. The most commonly used tests measure their
dichlorophenol breakdown products in urine and blood. The
presence of the dichlorophenol breakdown products in the urine
indicates a person has been exposed to dichlorobenzenes within
the previous day or two. Another test measures the levels of
dichlorobenzenes in your blood, but this is used less often. These
tests require special equipment that is not routinely available in
a doctor's office, but they can be performed in a special laboratory.
Neither of these tests can be used to show how high the level
of dichlorobenzene exposure was or to predict whether harmful
health effects will follow.
Has the federal government made recommendations to
protect human health?
EPA regulates the levels of dichlorobenzenes that are allowable
in drinking water. The highest level of 1,4-dichlorobenzene
allowed in drinking water is 0.075 parts 1,4-dichlorobenzene per
1 million parts of water (0.075 ppm).
The Occupational Safety and Health Administration (OSHA) has set a limit for 1,4-dichlorobenzene of 75 parts 1,4-dichlorobenzene
per 1 million parts of air (75 ppm) in the workplace.
Agency for Toxic Substances and Disease Registry (ATSDR). 2006.
Toxicological Profile for Dichlorobenzenes.
Atlanta, GA: U.S. Department of Health and Human Services, Public Health
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
Office of Innovation and Analytics, Toxicology Section
4770 Buford Highway
Chamblee, GA 30341-3717
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.