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PUBLIC HEALTH STATEMENT 

1,1,1-Trichloroethane 

CAS#: 71-55-6 

Division of Toxicology and Environmental Medicine July 2006 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for 

1,1,1-Trichloroethane. 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 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. For more information, 

call the ATSDR Information Center at 

1-888-422-8737. 

This public health statement tells you about 

1,1,1-trichloroethane (also called 1,1,1-TCE) and 

the effects of exposure to it. 

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 

federal long-term cleanup activities. 1,1,1-Trichloroethane has been found in at least 823 of the 

1,662 current or former NPL sites. Although the 

total number of NPL sites evaluated for this 

substance is not known, the possibility exists that 

the number of sites at which 1,1,1-trichloroethane is 

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 this substance may harm you. 

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 1,1,1-trichloroethane 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. 

1.1 WHAT IS 1,1,1-TRICHLOROETHANE? 

1,1,1-Trichloroethane is a synthetic chemical that 

does not occur naturally in the environment. It also 

is known as methylchloroform, methyltrichloromethane, trichloromethylmethane, and α-trichloromethane. Its registered trade names are chloroethene NU® and Aerothene TT®. It is a colorless 

liquid with a sweet, sharp odor. 1,1,1-Trichloroethane dissolves slightly in water. The liquid 

evaporates quickly and becomes a vapor. Most 

people begin to smell 1,1,1-trichloroethane in the 

air when its levels reach 120–500 parts per million 

(ppm). If the chemical makes up 8–10.5% (80,000– 

105,000 ppm) of the air, it can burn easily when it 

contacts a spark or flame. A poisonous gas known 

as phosgene can be produced during welding if 

1,1,1-trichloroethane is used to clean the metal. 

1,1,1-Trichloroethane also can be found in soil and 

water, particularly at hazardous waste sites. 

Because of its tendency to evaporate easily, the 

vapor form is most commonly found in the 

environment. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov 
 

 

 

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PUBLIC HEALTH STATEMENT 

1,1,1-Trichloroethane 

CAS#: 71-55-6 

Division of Toxicology and Environmental Medicine July 2006 

1,1,1-Trichloroethane had many industrial and 

household uses. It was often used as a solvent to 

dissolve other substances, such as glues and paints. 

In industry, it was widely used to remove oil or 

grease from manufactured parts. In the home, it 

used to be an ingredient of products such as spot 

cleaners, glues, and aerosol sprays. No 1,1,1-trichloroethane is supposed to be manufactured for 

domestic use in the United States after January 1, 

2002, because it affects the ozone layer. However, 

until 2005, limited amounts were still allowed to be 

produced for essential purposes, and until 2012, 

production of 1,1,1-trichloroethane is allowed for 

export. About 300 million pounds were produced 

in 2000, but less is being made today. Most of the 

1,1,1-trichloroethane that is manufactured today is 

exported. 

1.2 WHAT HAPPENS TO 1,1,1-TRICHLOROETHANE WHEN IT ENTERS 

THE ENVIRONMENT? 

Most of the 1,1,1-trichloroethane released into the 

environment enters the air. Once in the air, it can 

travel to the upper part of the earth's atmosphere, 

which is called the stratosphere. There, sunlight 

breaks it down into other chemicals that may reduce 

the stratospheric ozone layer. This ozone layer 

blocks certain damaging ultraviolet rays of the sun 

from reaching the earth's surface. Some scientists 

think the gradual thinning of the ozone layer is 

increasing the number of skin cancer cases in 

humans. 

Spills, improper disposal, industrial emissions, and 

consumer use can release 1,1,1-trichloroethane into 

the environment. Contaminated water from 

landfills and hazardous waste sites can contaminate 

surrounding soil and nearby surface water or 

groundwater. However, most of the chemical 

probably will evaporate eventually into the air. It 

will not build up in plants or animals. Industrial 

operations release the largest amount of 1,1,1-trichloroethane into the environment, mostly by 

emissions into the air. The vapor also enters the air 

because many products containing the chemical 

were used in the home and workplace. 

We do not know how long 1,1,1-trichloroethane 

lasts in water or soil. In surface waters, such as 

lakes and rivers, where it partially mixes with water, 

much of the chemical evaporates quickly. 

1,1,1-Trichloroethane also evaporates from soil 

surfaces. Water can easily carry it through soil into 

groundwater. 1,1,1-Trichloroethane in groundwater 

can evaporate and pass through soil as a gas and 

finally be released to the air. Also, organisms that 

live in soil and water may break down 1,1,1-trichloroethane. One study suggests that half of the 

chemical takes 200–300 days to break down in 

contaminated groundwater. However, the number 

of days can vary widely, depending on specific site 

conditions. 

1.3 HOW MIGHT I BE EXPOSED TO 

1,1,1-TRICHLOROETHANE? 

You are not likely to be exposed to large enough 

amounts of 1,1,1-trichloroethane to cause adverse 

health effects. 1,1,1-Trichloroethane has been 

found in air samples taken from all over the world. 

In the United States, city air typically contains 

about 0.1–1.0 parts per billion (ppb) of 1,1,1-trichloroethane; rural air usually contains less than 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov 
 

 

 

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PUBLIC HEALTH STATEMENT 

1,1,1-Trichloroethane 

CAS#: 71-55-6 

Division of Toxicology and Environmental Medicine July 2006 

0.1 ppb. Because 1,1,1-trichloroethane was used so 

frequently in home and office products, much more 

was found in the air inside buildings (0.3–4.4 ppb) 

than in the outside air (0.1–0.9 ppb). Since this 

chemical was found in many building materials, 

new buildings used to have higher indoor levels 

than old buildings. Thus, you were likely to be 

exposed to 1,1,1-trichloroethane vapor at higher 

levels indoors than outdoors or near hazardous 

waste sites. However, since 2002, 1,1,1-trichloroethane is not expected to be commonly used, and 

therefore, the likelihood of being exposed to it is 

remote. 

Common consumer products that used to contain 

1,1,1-trichloroethane included glues, household 

cleaners, and aerosol sprays. In the workplace, you 

could have been exposed to 1,1,1-trichloroethane 

while using some metal degreasing agents, paints, 

glues, and cleaning products. You could have been 

exposed to 1,1,1-trichloroethane by breathing the 

vapors from these products or by letting the liquid 

contact your skin. High levels of exposure have 

occurred in people who deliberately inhaled the 

vapors, as in glue-sniffing or solvent abuse. 

1,1,1-Trichloroethane has been found in rivers and 

lakes (up to 0.01 ppm), in soil (up to 120 ppm), in 

drinking water (up to 0.0035 ppm), and in drinking 

water from underground wells (up to 5.4 ppm). In 

one case, drinking water from a private well 

contained up to 12 ppm, possibly as a result of 

illegal discharge or spill from a nearby industrial 

plant. Releases during manufacture and 

transportation and during industrial or household 

use can cause these high levels, but the levels vary 

substantially from one location to another. Certain 

foods you eat and water you drink or bathe in may 

be contaminated with 1,1,1-trichloroethane. 

However, you can be exposed to 1,1,1-trichloroethane primarily by drinking contaminated water 

and eating contaminated food. 

1.4 HOW CAN 1,1,1-TRICHLOROETHANE 

ENTER AND LEAVE MY BODY? 

1,1,1-Trichloroethane can quickly enter your body 

if you breathe in air containing it in vapor form. It 

also enters your body if you drink water or eat food 

containing 1,1,1-trichloroethane. If you spill 

1,1,1-trichloroethane on your skin, most of it 

quickly evaporates into the air, but small amounts 

enter your body through your skin. Regardless of 

how 1,1,1-trichloroethane enters your body, nearly 

all of it quickly leaves your body in the air you 

exhale. The small amount that is not breathed out 

can be changed in your body into other substances, 

known as metabolites. Most of the metabolites 

leave your body in the urine and breath within a few 

days. 

1.5 HOW CAN 1,1,1-TRICHLOROETHANE 

AFFECT MY HEALTH? 

Scientists use many tests to protect the public from 

harmful effects of toxic chemicals and to find ways 

for treating people who have been harmed. 

One way to learn whether a chemical will harm 

people is to determine how the body absorbs, uses, 

and releases the chemical. For some chemicals, 

animal testing may be necessary. Animal testing 

may also help identify health effects such as cancer 

or birth defects. Without laboratory animals, 

scientists would lose a basic method for getting 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov 
 

 

 

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PUBLIC HEALTH STATEMENT 

1,1,1-Trichloroethane 

CAS#: 71-55-6 

Division of Toxicology and Environmental Medicine July 2006 

information needed to make wise decisions that 

protect public health. Scientists have the 

responsibility to treat research animals with care 

and compassion. Scientists must comply with strict 

animal-care guidelines because laws today protect 

the welfare of research animals. 

If you breathe air containing high levels of 1,1,1-trichloroethane (1,000 ppm or higher) for a short time, 

you may become dizzy and lightheaded and 

possibly lose your coordination. These effects 

rapidly disappear after you stop breathing 

contaminated air. If you breathe in much higher 

levels of 1,1,1-trichloroethane, either intentionally 

or accidentally, you may become unconscious, your 

blood pressure may decrease, and your heart may 

stop beating. Whether breathing low levels of 

1,1,1-trichloroethane for a long time causes harmful 

effects is not known. Studies in animals show that 

breathing air that contains very high levels of 

1,1,1-trichloroethane (higher than 2,000 ppm) 

damages the breathing passages and causes mild 

effects in the liver, in addition to affecting the 

nervous system. There are no studies in humans 

that determine whether eating food or drinking 

water contaminated with 1,1,1-trichloroethane could 

harm health. Placing large amounts of 1,1,1-trichloroethane in the stomachs of animals has caused 

effects on the nervous system, mild liver damage, 

unconsciousness, and even death. If your skin 

contacts 1,1,1-trichloroethane, you might feel some 

irritation. Studies in animals suggest that repeated 

exposure of the skin might affect the liver and that 

very large amounts on the skin can cause death. 

These effects occurred only when evaporation was 

prevented. 

Available information does not indicate that 

1,1,1-trichloroethane causes cancer. The 

International Agency for Research on Cancer 

(IARC) has determined that 1,1,1-trichloroethane is 

not classifiable as to its carcinogenicity in humans. 

EPA has also determined that 1,1,1-trichloroethane 

is not classifiable as to its human carcinogenicity. 

The likelihood is very low that exposure to 1,1,1-trichloroethane levels found near hazardous waste 

sites would cause significant health effects. 

1.6 HOW CAN 1,1,1-TRICHLOROETHANE 

AFFECT CHILDREN? 

This section discusses potential health effects in 

humans from exposures during the period from 

conception to maturity at 18 years of age. 

Children exposed to large amounts of 1,1,1-trichloroethane probably would be affected in the 

same manner as adults. In animals, it has been 

shown that 1,1,1-trichloroethane can pass from the 

mother’s blood into a fetus. When pregnant mice 

were exposed to high levels of 1,1,1-trichloroethane 

in air, their babies developed more slowly than 

normal and had some behavioral problems. 

However, whether similar effects occur in humans 

has not been demonstrated. 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO 1,1,1-TRICHLOROETHANE? 

If your doctor finds that you have been exposed to 

substantial amounts of 1,1,1-trichloroethane ask 

whether your children might also have been 

exposed. Your doctor might need to ask your state 

health department to investigate. 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov 
 

 

 

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PUBLIC HEALTH STATEMENT 

1,1,1-Trichloroethane 

CAS#: 71-55-6 

Division of Toxicology and Environmental Medicine July 2006 

Children can be exposed to 1,1,1-trichloroethane in 

household products, such as adhesives and cleaners 

that were manufactured before 2002. Parents 

should store household chemicals out of reach of 

young children to prevent accidental poisonings or 

skin irritation. Always store household chemicals 

in their original labeled containers. Never store 

household chemicals in containers that children 

would find attractive to eat or drink from, such as 

old soda bottles. Keep your Poison Control 

Center’s number near the phone. 

Sometimes older children sniff household chemicals 

in an attempt to get “high”. Your children may be 

exposed to 1,1,1-trichloroethane by inhaling 

products containing it. Talk with your children 

about the dangers of sniffing chemicals. 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO 1,1,1-TRICHLOROETHANE? 

Samples of your breath, blood, and urine can be 

tested to determine if you have recently been 

exposed to 1,1,1-trichloroethane. In some cases, 

these tests can estimate how much 1,1,1-trichloroethane has entered your body. To be of any value, 

samples of your breath or blood have to be taken 

within hours after exposure, and samples of urine 

have to be taken within 2 days after exposure. 

However, these tests will not tell you whether your 

health will be affected by exposure to 1,1,1-trichloroethane. The exposure tests are not routinely 

available in hospitals and clinics because they 

require special analytical equipment. 

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, that is, levels of a toxic 

substance in air, water, soil, or food that do not 

exceed a critical value that 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. 

Some regulations and recommendations for 

1,1,1-trichloroethane include the following: 

DEPARTMENT of HEALTH AND HUMAN SERVICES, Public Health Service
 

Agency for Toxic Substances and Disease Registry 

www.atsdr.cdc.gov/ Telephone: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov 
 

 

 

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PUBLIC HEALTH STATEMENT 

1,1,1-Trichloroethane 

CAS#: 71-55-6 

Division of Toxicology and Environmental Medicine July 2006 

EPA regulates the levels of 1,1,1-trichloroethane 

that are allowable in drinking water. The highest 

level of 1,1,1-trichloroethane allowed in drinking 

water is 0.2 ppm. Any releases or spills of 1,1,1-trichloroethane of 1,000 pounds or more must be 

reported to the National Response Center. OSHA 

regulates 1,1,1-trichloroethane levels in the 

workplace. The workplace exposure limit for an 

8-hour workday, 40-hour workweek is 350 ppm in 

air. 

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 CDROM by calling the toll-free information and 

technical assistance number at 1-888-42ATSDR 

(1-888-422-8737), by e-mailing atsdric@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-32 

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: 1-888-422-8737 Fax: 770-488-4178 E-Mail: atsdric@cdc.gov