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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

This Public Health Statement is the summary chapter from the Toxicological Profile for 

Trichlorobenzenes. It is one in a series of Public Health Statements about hazardous substances and their 

health effects. A shorter version, the ToxFAQsTM, is also available. This information is important 

because these substances 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. For more information, call the ATSDR Information Center at 1-800-232-4636. 

This public health statement tells you about trichlorobenzenes and the effects of exposure to them. 

The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the 

nation. These sites are then placed on the National Priorities List (NPL) and are targeted for long-term 

federal clean-up activities. 1,2,3-Trichlorobenzene, 1,2,4-trichlorobenzene, and 1,3,5-trichlorobenzene 

have been identified in at least 31, 187, and 4 1 of the 1,699 current or former NPL sites, respectively. 

Although the total number of NPL sites evaluated for these substances is not known, the possibility exists 

that the number of sites at which trichlorobenzenes are found may increase in the future as more sites are 

evaluated. This information is important because these sites may be sources of exposure and exposure to 

these substances may be harmful. 

When a substance is released either from a large area, such as an industrial plant, or from a container, 

such as a drum or bottle, it enters the environment. Such a release does not always lead to exposure. You 

can be exposed to a substance only when you come in contact with it. You may be exposed by breathing, 

eating, or drinking the substance, or by skin contact. 

If you are exposed to trichlorobenzenes, many factors will determine whether you will be harmed. These 

factors include the dose (how much), the duration (how long), and how you come in contact with it. You 

must also consider any other chemicals you are exposed to and your age, sex, diet, family traits, lifestyle, 

and state of health. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

1.1 WHAT ARE TRICHLOROBENZENES? 

Description Trichlorobenzenes are human-made 

compounds that occur in three different 

chemical forms. Although they have the same 

molecular weight and molecular formula, they 

differ structurally by where the chlorine atoms 

are attached to the benzene ring. Compounds 

like these are referred to as isomers. 

1,2,3-Trichlorobenzene and 1,3,5-trichlorobenzene are colorless solids, while 1,2,4-

trichlorobenzene is a colorless liquid. 

Although the three isomers of trichlorobenzene 

are structurally similar, they each may have 

different chemical and toxicological properties. 

Uses Trichlorobenzenes have primarily been used as 

solvents and chemical intermediates to 

produce other compounds. In the past, mixed 

isomers of trichlorobenzene had been used for 

termite control, but this is not a current use. 

One of the isomers (1,2,4-trichlorobenzene) is 

produced in large quantities and is used as a 

solvent to dissolve such special materials as 

oils, waxes, resins, greases, and rubber. It is 

also frequently used to produce dyes and 

textiles. The other two isomers, 

1,2,3-trichlorobenzene and 1,3,5-trichlorobenzene, are produced in lower quantities and 

have fewer uses. 

1.2 WHAT HAPPENS TO TRICHLOROBENZENES WHEN THEY ENTER THE 

ENVIRONMENT? 

Air Trichlorobenzenes are volatile substances and 

may therefore partition to 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. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

Trichlorobenzenes have been detected in 

groundwater, drinking water, and surface water 

(rivers and lakes). Trichlorobenzenes have a 

tendency to evaporate over time from water, but 

can also adsorb to suspended solids and 

sediment in water. 

Water 

Trichlorobenzenes evaporate from soils and are 

slowly broken down by microorganisms in soil 

and sediment. 

Soil and sediment 

Trichlorobenzenes in water and soil may be 

absorbed or ingested by animals. High levels of 

trichlorobenzenes are often detected in fish or 

other species living in contaminated waters 

because trichlorobenzenes can accumulate in 

fatty tissues. 

Land and aquatic animals 

1.3 HOW MIGHT I BE EXPOSED TO TRICHLOROBENZENES? 

Environmental exposure Monitoring data suggest that the general 

population may be exposed to trichlorobenzenes 

by inhaling air and through the ingestion of food 

and drinking water. Other substances that have 

been released into the environment, such as 

higher chlorinated benzenes, or the formerly 

used pesticide, lindane, can break down into 

trichlorobenzene. Therefore, if you live in an 

area where these products were used or 

disposed of (hazardous waste sites) you may 

potentially be exposed to trichlorobenzenes as 

well. 

Ingestion of food and fish Trichlorobenzenes have been identified in a 

variety of food items including vegetables, milk, 

eggs/meat, and oils produced from corn, 

soybeans, peanuts, walnuts, hazelnuts, and 

rape, sunflower, sesame, and poppy seeds. 

People who eat large quantities of fish from 

areas contaminated by trichlorobenzenes may 

have higher exposure to these substances since 

fish tend to accumulate trichlorobenzenes in their 

fatty tissues. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

You can be exposed to trichlorobenzenes by 

inhalation and dermal contact with these 

substances if you are employed in an occupation 

where trichlorobenzenes are manufactured or 

used. According to the National Occupational 

Exposure Survey (NOES), workers employed in 

textile mill production and electric and electronic 

manufacturing tend to have the greatest potential 

exposure to trichlorobenzenes. 

Occupational exposure 

1.4 HOW CAN TRICHLOROBENZENES ENTER AND LEAVE MY BODY?
 

Enter your body There is not enough information to determine 

how much or how fast trichlorobenzenes can 

enter your body if you inhale vapors or 

contaminated air, if you swallow these 

chemicals, or if they get onto your skin. 

Studies in animals suggest that 

trichlorobenzenes can rapidly enter the body 

through the lungs and the gastrointestinal tract. 

Less is known about entering the body through 

the skin. 

Leave the body There is no information on how these 

compounds could leave the body in humans, 

but based on studies in animals they probably 

leave principally in the urine. 

In animals, trichlorobenzenes are transformed 

in the body into other chemicals, which are 

eliminated in the urine, feces, and bile in a few 

days. 

Studies in animals suggest that 

trichlorobenzenes do not accumulate in the 

body of mammals, but accumulate in fish. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

1.5 HOW CAN TRICHLOROBENZENES AFFECT MY HEALTH? 

This section looks at studies concerning potential health effects in animal and human studies. 

Effects in humans There is virtually no information regarding 

health effects of trichlorobenzenes in humans 

other than reports of minimal eye and throat 

irritation in certain people exposed to vapors of 

1,2,4-trichlorobenzene and a report of a woman 

who developed a blood disorder due to 

prolonged inhalation of trichlorobenzenes from 

her husband’s work clothes. 

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. 

Laboratory animals Studies in animals indicate that oral 

administration of trichlorobenzenes for short or 

long periods produces mainly alterations in the 

liver and kidneys. 

Prolonged administration of 

1,2,4-trichlorobenzene to rats did not affect 

their capacity to reproduce. 

Placing trichlorobenzenes on the skin or the 

eyes of animals produced transitory irritation. 

It should be noted that, in general, animals 

have been exposed to considerably higher 

amounts of trichlorobenzenes than the amounts 

that humans can encounter in the environment. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

There are no studies of cancer in humans 

exposed to trichlorobenzenes. 

Cancer 

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. 

1.6 HOW CAN TRICHLOROBENZENES AFFECT CHILDREN? 

This section discusses potential health effects in humans from exposures during the period from 

conception to maturity at 18 years of age. 

Effects in children There are no studies of children exposed to 

trichlorobenzenes. 

Laboratory animals For the most part, studies in rats and mice given 

1,2,4-trichlorobenzene during pregnancy have 

not found adverse effects in their pups at birth or 

later during the growing period. However, a 

study in rats found lesions in the eyes of the 

pups. 

Breast milk Trichlorobenzenes have been found in human 

breast milk, which means that mothers can 

transfer these chemicals to their babies by 

nursing. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

1.7 HOW CAN FAMILIES REDUCE THE RISK OF EXPOSURE TO 

TRICHLOROBENZENES? 

Avoid sources of trichlorobenzenes Trichlorobenzenes do not have widespread use 

in consumer products that are readily available 

to the general public. However, 1,2,4-trichlorobenzene is often detected in air, water, and 

aquatic species such as fish. The highest 

levels are typically encountered 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 these areas 

will reduce your risk of exposure to 

trichlorobenzenes and other chemicals. 

Avoiding high consumption of root crops and 

fish living in contaminated environments will 

reduce the risk of exposure. 

1.8 IS THERE A MEDICAL TEST TO DETERMINE WHETHER I HAVE BEEN EXPOSED TO 

TRICHLOROBENZENES? 

Detecting exposure Trichlorobenzenes can be measured in blood 

and body fat, but the tests used are not routinely 

available in the doctor’s office. 

There is not enough information to determine 

whether trichlorobenzenes detected in your 

body indicate that you have been exposed 

recently to a high amount or you are 

continuously exposed to lower amounts. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

Detecting trichlorobenzenes in your body 

generally means that you were exposed to these 

compounds. However, 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. 

Measuring exposure 

The presence of trichlorobenzenes in your body 

does not necessarily mean that you will suffer 

adverse health effects. 

1.9 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? 

The federal government develops regulations and recommendations to protect public health. Regulations 

can be enforced by law. The EPA, the Occupational Safety and Health Administration (OSHA), and the 

Food and Drug Administration (FDA) are some federal agencies that develop regulations for toxic 

substances. Recommendations provide valuable guidelines to protect public health, but cannot be 

enforced by law. The Agency for Toxic Substances and Disease Registry (ATSDR) and the National 

Institute for Occupational Safety and Health (NIOSH) are two federal organizations that develop 

recommendations for toxic substances. 

Regulations and recommendations can be expressed as “not-to-exceed” levels. These are levels of a toxic 

substance in air, water, soil, or food that do not exceed a critical value. This critical value is usually based 

on levels that affect animals; they are then adjusted to levels that will help protect humans. Sometimes 

these not-to-exceed levels differ among federal organizations because they used different exposure times 

(an 8-hour workday or a 24-hour day), different animal studies, or other factors. 

Recommendations and regulations are also updated periodically as more information becomes available. 

For the most current information, check with the federal agency or organization that provides it. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

Some regulations and recommendations for trichlorobenzenes include the following: 

Levels in drinking water set by EPA The EPA has determined that exposure to 

1,2,4-trichlorobenzene 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 EPA established a maximum contaminant 

level (MCL) of 0.07 mg/L for 

1,2,4-trichlorobenzene in drinking water. 

Bottled water The FDA has determined that the concentration 

of 1,2,4-trichlorobenzene in bottled drinking 

water should not exceed 0.7 mg/L. 

1.10 WHERE CAN I GET MORE INFORMATION? 

If you have any more questions or concerns, please contact your community or state health or 

environmental quality department, or contact ATSDR at the address and phone number below. 

ATSDR can also tell you the location of occupational and environmental health clinics. These clinics 

specialize in recognizing, evaluating, and treating illnesses that result from exposure to hazardous 

substances. 

Toxicological profiles are also available on-line at www.atsdr.cdc.gov and on CD-ROM. You may 

request a copy of the ATSDR ToxProfilesTM CD-ROM by calling the toll-free information and technical 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov 
 

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PUBLIC HEALTH STATEMENT 

Trichlorobenzenes 

Division of Toxicology and Environmental Medicine September 2010 

assistance number at 1-800-CDCINFO (1-800-232-4636), by e-mail at cdcinfo@cdc.gov, or by writing 

to: 

Agency for Toxic Substances and Disease Registry 

Division of Toxicology and Environmental Medicine 

 1600 Clifton Road NE 

 Mailstop F-62 

 Atlanta, GA 30333

 Fax: 1-770-488-4178
 

Organizations for-profit may request copies of final Toxicological Profiles from the following: 

National Technical Information Service (NTIS) 

5285 Port Royal Road

 Springfield, VA 22161

 Phone: 1-800-553-6847 or 1-703-605-6000
 

Web site: http://www.ntis.gov/
 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-800-232-4636 Fax: 770-488-4178 E-Mail: cdcinfo@cdc.gov