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PUBLIC HEALTH STATEMENT 

CHLOROFORM 

CAS#: 67-66-3 

Division of Toxicology September 1997 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for 

Chloroform. 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 

chloroform and the effects of exposure. 

The Environmental Protection Agency (EPA) 

identifies the most serious hazardous waste sites in 

the nation. These sites make up the National 

Priorities List (NPL) and the sites are targeted for 

long-term federal cleanup. Chloroform has been 

found in at least 717 of the 1,430 current or former 

NPL sites, including 6 in Puerto Rico and 1 in the 

Virgin Islands. However, it's unknown how many 

NPL sites have been evaluated for this substance. 

As more sites are evaluated, the sites with 

chloroform may increase. This is important because 

exposure to this substance may harm you and 

because these sites may be sources of exposure. 

When a substance is released from a large area, 

such as an industrial plant, or from a container, such 

as a drum or bottle, it enters the environment. This 

release does not always lead to exposure. You are 

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 chloroform, many factors 

determine whether you'll 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 the other chemicals you're 

exposed to and your age, sex, diet, family traits, 

lifestyle, and state of health. 

1.1 WHAT IS CHLOROFORM? 

Chloroform is also known as trichloromethane or 

methyltrichloride. It is a colorless liquid with a 

pleasant, nonirritating odor and a slightly sweet 

taste. Most of the chloroform found in the 

environment comes from industry. It will only burn 

when it reaches very high temperatures. 

Chloroform was one of the first inhaled anesthetics 

to be used during surgery, but it is not used for 

anesthesia today. Nearly all the chloroform made in 

the United States today is used to make other 

chemicals, but some is sold or traded to other 

countries. We also import chloroform. 

Chloroform enters the environment from chemical 

companies and paper mills. It is also found in waste 

water from sewage treatment plants and drinking 

water to which chlorine has been added. Chlorine is 

added to most drinking water and many waste 

waters to destroy bacteria. Small amounts of 

chloroform are formed as an unwanted product 

during the process of adding chlorine to water. 

Chloroform can enter the air directly from factories 

that make or use it and by evaporating from water 

and soil that contain it. It can enter water and soil 

when waste water that contains chlorine is released 

into water or soil. It may enter water and soil from 

spills and by leaks from storage and waste sites. 

There are many ways for chloroform to enter the 

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 

CHLOROFORM 

CAS#: 67-66-3 

Division of Toxicology September 1997 

environment, so small amounts of it are likely to be 

found almost everywhere. 

1.2 WHAT HAPPENS TO CHLOROFORM 

WHEN IT ENTERS THE 

ENVIRONMENT? 

Chloroform evaporates very quickly when exposed 

to air. Chloroform also dissolves easily in water, 

but does not stick to the soil very well. This means 

that it can travel down through soil to groundwater 

where it can enter a water supply. Chloroform lasts 

for a long time in both the air and in groundwater. 

Most chloroform in the air eventually breaks down, 

but this process is slow. The breakdown products in 

air include phosgene, which is more toxic than 

chloroform, and hydrogen chloride, which is also 

toxic. Some chloroform may break down in soil. 

Chloroform does not appear to build up in great 

amounts in plants and animals, but we may find 

some small amounts of chloroform in foods. 

1.3 HOW MIGHT I BE EXPOSED TO 

CHLOROFORM? 

You are probably exposed to small amounts of 

chloroform in your drinking water and in beverages 

(such as soft drinks) made using water that contains 

chloroform. You can also get chloroform in your 

body by eating food, by breathing air, and by skin 

contact with water that contains it. You are most 

likely to be exposed to chloroform by drinking 

water and breathing indoor or outdoor air 

containing it. The amount of chloroform normally 

expected to be in the air ranges from 0.02 to 0.05 

parts of chloroform per billion parts (ppb) of air and 

from 2 to 44 ppb in treated drinking water. 

However, in some places, chloroform 

concentrations may be higher than 44 ppb. It is 

estimated that the concentration of chloroform in 

surface water is 0.1 ppb, the concentration in 

untreated groundwater is 0.1 ppb, and the amount in 

soil is 0.1 ppb. As much as 610 ppb was found in 

air at a municipal landfill and up to 88 ppb was 

found in treated municipal drinking water. 

Drinking water derived from well water near a 

hazardous waste site contained 1,900 ppb, and 

groundwater taken near a hazardous waste site also 

contained 1,900 ppb. Surface water containing 394 

ppb has also been found near a hazardous waste 

site; however, no more than 0.13 ppb has been 

found in soil at hazardous waste sites. Chloroform 

has been found in the air from all areas of the 

United States and in nearly all of the public 

drinking water supplies. We do not know how 

many areas have surface water, groundwater, or soil 

that contains chloroform. 

The average amount of chloroform that you might 

be exposed to on a typical day by breathing air in 

various places ranges from 2 to 5 micrograms per 

day (μg/day) in rural areas, 6 to 200 μg/day in 

cities, and 80 to 2,200 μg/day in areas near major 

sources of the chemical. The estimated amount of 

chloroform you probably are exposed to in drinking 

water ranges from 4 to 88 μg/day. We cannot 

estimate the amounts that you may be exposed to by 

eating food and by coming into contact with water 

that has chloroform in it. People who swim in 

swimming pools absorbed chloroform through their 

skin. People who work at or near chemical plants 

and factories that make or use chloroform can be 

exposed to higher-than-normal amounts of 

chloroform. Higher exposures might occur in 

workers at drinking-water treatment plants, waste 

water treatment plants, and paper and pulp mills. 

People who operate waste-burning equipment may 

also be exposed to higher than normal levels. The 

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 

CHLOROFORM 

CAS#: 67-66-3 

Division of Toxicology September 1997 

National Institute for Occupational Safety and 

Health (NIOSH) estimated that 95,778 persons in 

the United States have occupational exposure to 

chloroform. 

1.4 HOW CAN CHLOROFORM ENTER AND 

LEAVE MY BODY? 

Chloroform can enter your body if you breathe air, 

eat food, or drink water that contains chloroform. 

Chloroform easily enters your body through the 

skin. Therefore, chloroform may also enter your 

body if you take a bath or shower in water 

containing chloroform. In addition, you can breathe 

in chloroform if the shower water is hot enough for 

chloroform to evaporate. Studies in people and in 

animals show that after you breathe air or eat food 

that has chloroform in it, the chloroform can 

quickly enter your bloodstream from your lungs or 

intestines. Inside your body, chloroform is carried 

by the blood to all parts of your body, such as the 

fat, liver, and kidneys. Chloroform usually collects 

in body fat; however, its volatility ensures that it 

will eventually be removed once the exposure has 

been removed. Some of the chloroform that enters 

your body leaves unchanged in the air that you 

breathe out, and some chloroform in your body is 

broken down into other chemicals. These chemicals 

are known as breakdown products or metabolites, 

and some of them can attach to other chemicals 

inside the cells of your body and may cause harmful 

effects if they collect in high enough amounts in 

your body. Some of the metabolites also leave the 

body in the air you breathe out. Only a small 

amount of the breakdown products leaves the body 

in the urine and stool. 

1.5 HOW CAN CHLOROFORM AFFECT MY 

HEALTH? 

To protect the public from the harmful effects of 

toxic chemicals and to find ways to treat people 

who have been harmed, scientists use many tests. 

One way to see if a chemical will hurt people is to 

learn how the chemical is absorbed, used, and 

released by the body; for some chemicals, animal 

testing may be necessary. Animal testing may also 

be used to identify health effects such as cancer or 

birth defects. Without laboratory animals, scientists 

would lose a basic method to get information 

needed to make wise decisions to protect public 

health. Scientists have the responsibility to treat 

research animals with care and compassion. Laws 

today protect the welfare of research animals, and 

scientists must comply with strict animal care 

guidelines. 

In humans, chloroform affects the central nervous 

system (brain), liver, and kidneys after a person 

breathes air or drinks liquids that contain large 

amounts of chloroform. Chloroform was used as an 

anesthetic during surgery for many years before its 

harmful effects on the liver and kidneys were 

recognized. Breathing about 900 parts of 

chloroform in a million parts of air (900 ppm or 

900,000 ppb) for a short time causes fatigue, 

dizziness, and headache. If you breathe air, eat 

food, or drink water containing elevated levels of 

chloroform, over a long period, the chloroform may 

damage your liver and kidneys. Large amounts of 

chloroform can cause sores when the chloroform 

touches your skin. 

We do not know whether chloroform causes 

harmful reproductive effects or birth defects in 

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 

CHLOROFORM 

CAS#: 67-66-3 

Division of Toxicology September 1997 

people. Miscarriages occurred in rats and mice that 

breathed air containing elevated levels (30 to 300 

ppm) of chloroform during pregnancy and in rats 

that ate chloroform during pregnancy. Abnormal 

sperm were found in mice that breathed air 

containing elevated levels (400 ppm) of chloroform 

for a few days. Offspring of rats and mice that 

breathed chloroform during pregnancy had birth 

defects. 

Results of studies of people who drank chlorinated 

water showed a possible link between the 

chloroform in chlorinated water and the occurrence 

of cancer of the colon and urinary bladder. Cancer 

of the liver and kidneys developed in rats and mice 

that ate food or drank water that had large amounts 

of chloroform in it for a long time. We do not know 

whether liver and kidney cancer would develop in 

people after long-term exposure to chloroform in 

drinking water. Based on animal studies, the 

Department of Health and Human Services (DHHS) 

has determined that chloroform may reasonably be 

anticipated to be a carcinogen (a substance that 

causes cancer). The International Agency for 

Research on Cancer (IARC) has determined that 

chloroform is possibly carcinogenic to humans 

(2B). The EPA has determined that chloroform is a 

probable human carcinogen. 

1.6 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO CHLOROFORM? 

Although we can measure the amount of chloroform 

in the air that you breathe out, and in blood, urine, 

and body tissues, we have no reliable test to 

determine how much chloroform you have been 

exposed to or whether you will experience any 

harmful health effects. The measurement of 

chloroform in body fluids and tissues may help to 

determine if you have come into contact with large 

amounts of chloroform. However, these tests are 

useful only a short time after you are exposed to 

chloroform because it leaves the body quickly. 

Because it is a breakdown product of other 

chemicals (chlorinated hydrocarbons), chloroform 

in your body might also indicate that you have 

come into contact with those other chemicals. 

Therefore, small amounts of chloroform in the body 

may indicate exposure to these other chemicals and 

may not indicate low chloroform levels in the 

environment. From blood tests to determine the 

amount of liver enzymes, we can tell whether the 

liver has been damaged, but we cannot tell whether 

the liver damage was caused by chloroform. 

1.7 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. Federal 

agencies that develop regulations for toxic 

substances include EPA, the Occupational Safety 

and Health Administration (OSHA), and the Food 

and Drug Administration (FDA). 

Recommendations provide valuable guidelines to 

protect public health but cannot be enforced by law. 

Federal organizations that develop 

recommendations for toxic substances include the 

Agency for Toxic Substances and Disease Registry 

(ATSDR) and the National Institute for 

Occupational Safety and Health (NIOSH). 

Regulations and recommendations can be expressed 

in not-to-exceed levels in air, water, soil, or food 

that are usually based on levels that affect animals; 

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 

CHLOROFORM 

CAS#: 67-66-3 

Division of Toxicology September 1997 

then they are adjusted to help protect people. 

Sometimes these not-to-exceed levels differ among 

federal organizations because of different exposure 

times (an 8-hour workday or a 24-hour day), the use 

of different animal studies, or other factors. 

Recommendations and regulations are also 

periodically updated 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 chloroform include the 

following: 

The EPA sets rules for the amount of chloroform 

allowed in water. The EPA limit for total 

trihalomethanes, a class of chemicals that includes 

chloroform, in drinking water is 100 micrograms 

per liter (μg/L, 1 μg/L = 1 ppb in water). 

Furthermore, EPA requires that spills of 10 pounds 

or more of chloroform into the environment be 

reported to the National Response Center. 

OSHA sets the levels of chloroform allowed in 

workplace air in the United States. A permissible 

occupational exposure limit is 50 ppm or 240 

mg/m3 (ceiling value) in air during an 8-hour 

workday, 40-hour workweek. 

1.8 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: 

Agency for Toxic Substances and Disease Registry 

Division of Toxicology 

1600 Clifton Road NE, Mailstop F-32 

Atlanta, GA 30333 

Information line and technical assistance: 

Phone: 888-422-8737 

FAX: (770)-488-4178 

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. 

To order toxicological profiles, contact: 

National Technical Information Service 

5285 Port Royal Road 

Springfield, VA 22161 

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

Reference 

Agency for Toxic Substances and Disease Registry 

(ATSDR). 1997. Toxicological profile for 

chloroform. Atlanta, GA: U.S. Department of 

Health and Human Services, Public Health Service. 

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