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PUBLIC HEALTH STATEMENT 

CHLOROPHENOLS 

Division of Toxicology July 1999 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for 

Chlorophenols. 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 

chlorophenols 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 are the sites targeted for 

long-term federal cleanup activities. Chlorophenols 

has been found in at least 116 of the 1,467 current 

or former NPL sites. However, the total number of 

NPL sites evaluated for this substance is not known. 

As more sites are evaluated, the sites at which 

chlorophenols are found may increase. This 

information 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 chlorophenols, 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 ARE CHLOROPHENOLS? 

Chlorophenols are a group of chemicals in which 

chlorines (between one and five) have been added 

to phenol. Phenol is an aromatic compound derived 

from benzene, the simplest aromatic hydrocarbon, 

by adding a hydroxy group to a carbon to replace a 

hydrogen. There are five basic types of 

chlorophenols: mono[one]chlorophenols, 

di[two]chlorophenols, tri[three]chlorophenols, 

tetra[four]chlorophenols, and 

penta[five]chlorophenols. In all, there are 19 

different chlorophenols. Eight are discussed in this 

document: 2-chlorophenol, 4-chlorophenol, 2,4-

dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-

trichlorophenol, 2,3,4,5-tetrachlorophenol, 2,3,4,6-

tetrachlorophenol, and 2,3,5,6-tetrachlorophenol. 

Pentachlorophenol is discussed in another 

document. 

Except for 2-chlorophenol, which is a liquid at 

room temperature, all of the chlorophenols are 

solids. The chlorophenols have a strong medicinal 

taste and odor; small amounts (at parts per billion 

[ppb] to parts per million [ppm] concentrations) can 

be tasted in water. Very small amounts of 

chlorophenols can also make fish taste bad. All the 

compounds discussed are or were produced 

commercially. 

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 

CHLOROPHENOLS 

Division of Toxicology July 1999 

Chlorophenols with at least two chlorines either 

have been used directly as pesticides or converted 

into pesticides. Also, chlorophenols, especially 4-

chlorophenol, have been used as antiseptics. In 

addition to being produced commercially, small 

amounts of some chlorophenols, especially the 

mono- and dichlorophenols, may be produced when 

waste water or drinking water is disinfected with 

chlorine, if certain contaminants are present in the 

raw water. They are also produced during the 

bleaching of wood pulp with chlorine when paper is 

being produced. 

1.2 WHAT HAPPENS TO CHLOROPHENOLS 

WHEN THEY ENTER THE 

ENVIRONMENT? 

Chlorophenols can enter the environment while they 

are being made or used as pesticides. Most of the 

chlorophenols released into the environment go into 

water, with very little entering the air. The 

compounds that are most likely to go into the air are 

the mono- and dichlorophenols because they are the 

most volatile (that is, have the greatest tendency to 

form vapors or gases). Once in the air, sunlight 

helps destroy these compounds and rain washes 

them out of the air. Chlorophenols stick to soil and 

to sediments at the bottom of lakes, rivers, or 

streams. However, low levels of chlorophenols in 

water, soil, or sediment are broken down by 

microorganisms and are removed from the 

environment within a few days or weeks. 

1.3 HOW MIGHT I BE EXPOSED TO 

CHLOROPHENOLS? 

Most people are exposed to very low levels of 

chlorophenols in drinking water that has been 

disinfected with chlorine (chlorinated drinking 

water). Chlorophenols have been measured in 

chlorinated drinking water at parts per trillion (ppt) 

concentrations (that is, the amount [weight] of 

chlorophenols per trillion parts [volume] of water). 

In lakes, rivers, and streams, chlorophenols were 

found in less than 1 percent of the water that was 

tested. Chlorophenols have been measured in city 

air at concentrations of less than a part per trillion 

(the amount of chlorophenols [volume] per trillion 

parts [volume] of air). 

It has been estimated during the National 

Occupational Exposure Survey (NOES) from 1981– 

1983 that about 5,000 people in the United States 

are exposed to 4-chlorophenol, 2,4,5-

trichlorophenol, or 2,4,6-trichlorophenol at work 

(NOES 1990). It has not been estimated how many 

people are exposed at work to the other 

chlorophenols. People who make chlorophenols or 

use them as pesticides are most likely to have high 

exposure to these chemicals. For example, mixtures 

of tetrachlorophenols are used at sawmills as wood 

preservatives. Skin contact while treating wood 

with the tetrachlorophenols is the most likely route 

of exposure. Another likely route of exposure is 

breathing air contaminated by mono- and 

dichlorophenols. 

1.4 HOW CAN CHLOROPHENOLS ENTER 

AND LEAVE MY BODY? 

When chlorophenols are eaten, almost all of the 

compounds quickly enter the body. Chlorophenols 

also rapidly enter the body through the skin. Little 

is known about how much of the chlorophenols 

enter the body if one breathes air containing them. 

The monochlorophenols do not stay inside the body 

very long. They are changed to less harmful 

products, and most leave through the urine within 

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 

CHLOROPHENOLS 

Division of Toxicology July 1999 

24 hours. The other chlorophenols (dichlorophenol, 

trichlorophenols, tetrachlorophenols), which also 

leave through the urine as less harmful chemicals, 

can stay in the body for several days. 

1.5 HOW CAN CHLOROPHENOLS 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. 

One man who splashed pure 2,4-dichlorophenol on 

his arm and leg died shortly after the accident. 

Workers who made pesticides from chlorophenols 

and were exposed to chlorophenols as well as other 

chemicals through breathing and through the skin 

developed acne and mild injury to their livers. 

According to some studies, the risk of cancer was 

also slightly higher among workers who had made 

pesticides for a long time. These workers were 

exposed to very high levels of other chemicals as 

well as chlorophenols, so it is not certain whether 

the effects were caused by the chlorophenols or the 

other chemicals. 

Animals that were given food or drinking water 

containing chlorophenols at high levels developed 

adverse or negative health effects. The major 

effects with exposure to high levels of 

chlorophenols were on the liver and the immune 

system. Also, the animals that ate or drank 

chlorophenols did not gain as much weight as the 

animals that ate food and drank water not 

containing chlorophenols. 

Feeding rats and mice high doses of 2,4-

dichlorophenol for a long time did not cause cancer. 

However, long-term treatment of rats and mice with 

high doses of 2,4,6-trichlorophenol in food caused 

leukemia in rats and liver cancer in mice, 

suggesting that 2,4,6-trichlorophenol may be a 

carcinogen. The Department of Health and Human 

Services has determined that 2,4,6-trichlorophenol 

may reasonably be anticipated to be a carcinogen. 

The International Agency for Research on Cancer 

(IARC) has determined that the chlorophenols as a 

group, are possibly carcinogenic to man. The 

Environmental Protection Agency (EPA) has 

determined that 2,4,6-trichlorophenol is a probable 

carcinogen. 

Putting chlorophenols on the skin or eyes of animals 

causes severe injuries. Injury is greatest with 

exposure to the mono- and dichlorophenols. The 

signs of severe skin injury include redness, 

swelling, scabbing, and scar formation. The cornea 

was damaged when monochlorophenols were 

placed directly onto the eyes of rabbits. 

1.6 HOW CAN CHLOROPHENOLS AFFECT 

CHILDREN? 

This section discusses potential health effects from 

exposures during the period from conception to 

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 

CHLOROPHENOLS 

Division of Toxicology July 1999 

maturity at 18 years of age in humans. Potential 

effects on children resulting from exposures of the 

parents are also considered. 

The most likely source from which children could 

be exposed to chlorophenols is water that has been 

disinfected with chlorine. Children could receive 

larger doses because they consume more fluids per 

bodyweight than adults. Children may also be 

exposed in areas where chlorophenols have been 

sprayed as pesticides or herbicides. Children 

playing outdoors in areas with contaminated soil 

could be at risk for exposure because they often put 

objects or hands in their mouths. 

Monochlorophenols are used as household 

antiseptics, and 2,4-DCP is used for mothproofing. 

More complex chlorophenols are used as biocides. 

Biocides are substances used to kill organisms. 

We do not know whether chlorophenols cause birth 

defects in humans; chlorophenols have not been 

shown to cause birth defects in animals, even at 

high doses. High levels of chlorophenols given to 

pregnant female rats in the drinking water have 

tended to reduce the number of their newborn 

animals and to decrease the weights of the newborn. 

In one study animals exposed to chlorophenols 

showed delayed hardening of some bones. We do 

not know whether chlorophenols can cross the 

placenta or get into breast milk. 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO 

CHLOROPHENOLS? 

If your doctor finds that you have been exposed to 

significant amounts of chlorophenols, ask if 

children may also be exposed. When necessary 

your doctor may need to ask your state department 

of public health to investigate. 

The chlorophenols presented in this profile exist in 

eight different forms, each one having different 

properties and uses. Therefore, different routes 

exist in which a family may be exposed to 

chlorophenols. Chlorophenols are primarily used as 

antiseptics, disinfectants, herbicides, pesticides, and 

wood preservatives. People are at greater risk of 

exposure if they live near industrial facilities that 

use or manufacture chlorophenols or waste sites that 

could be releasing it into the environment. Most 

released chlorophenols are found in surface water or 

have become adsorbed in soil near the release point. 

Children should be kept from coming in contact 

with water or dirt in an area that could be 

contaminated. You should prevent your children 

from eating dirt. Make sure they wash their hands 

frequently and before eating. Discourage your 

children from putting their hands in their mouths or 

other hand-to-mouth activity. 

People who do not live near production or waste 

sites can still be exposed to chlorophenols through 

other routes. Chlorophenols can be present in 

drinking water when chlorine is used to disinfect it. 

The safe drinking water standard for 2-chlorophenol 

is 39 mg/L (monthly average). At low 

concentrations, chlorophenols give water an 

unpleasant, medicinal taste. 

Chlorophenols and other related chemicals are often 

used as herbicides and pesticides. 2,4-D and 2,4,5-

T, the latter of which has been banned, are 

herbicides often used on food crops that can break 

down to form 2,4-DCP. Children should be 

deterred from playing in areas where 2,4-D or other 

chlorophenol based herbicides or pesticides have 

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 

CHLOROPHENOLS 

Division of Toxicology July 1999 

been sprayed. Children are lower to the ground 

than adults and may be exposed because they often 

get dirt, grass, and other outdoor material on their 

skin and in their mouths. Also, your children may 

be exposed to chlorophenols if an unqualified 

person applies pesticides containing them around 

your home. In some cases, the improper use of 

pesticides banned for use in homes has turned 

homes into hazardous waste sites. Make sure that 

any person you hire is licensed and, if appropriate, 

certified to apply pesticides. Your state licenses 

each person who is qualified to apply pesticides 

according to EPA standards and further certifies 

each person who is qualified to apply "restricted 

use" pesticides. Ask to see the license and 

certification. Also ask for the brand name of the 

pesticide, a Material Safety Data Sheet (MSDS), the 

name of the product's active ingredient, and the 

EPA registration number. Ask whether EPA has 

designated the pesticide "for restricted use" and 

what the approved uses are. This information is 

important if you or your family react to the product. 

If you buy over-the-counter pesticide products to 

apply yourself, be sure the products are in unopened 

pesticide containers that are labeled and contain an 

EPA registration number. Carefully follow the 

instructions on the label. If you plan to spray 

inside, make sure the pesticide is intended for 

indoor use. 

If you feel sick after a pesticide has been used in 

your home, consult your doctor or local poison 

control center. 

Chlorophenols may also be present in many 

household products. 2,4-DCP is commonly used 

for mothproofing. 4-CP is used as a disinfectant in 

homes, farms, hospitals, and as an antiseptic for 

root canal treatment. Monochlorophenols have 

been used as antiseptics, although they have largely 

been replaced by other chemicals. Pesticides and 

household chemicals should be stored out of reach 

of young children to prevent unintentional 

poisonings. Always store pesticides and household 

chemicals in their original labeled containers. 

Never store pesticides or household chemicals in 

containers children would find attractive to eat or 

drink from, such as old soda bottles. 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO CHLOROPHENOLS? 

There is no medical test that is specific for 

chlorophenols to determine whether you have been 

exposed to these chemicals. Compounds that have 

been made by your body from chlorophenols can be 

measured in the urine. However, these compounds 

can also be found in the urine when you are exposed 

to other chemicals such as lindane (an insecticide) 

or to 2,4-dichlorophenoxyacetic acid (a chemical 

that kills weeds). 

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. Federal 

agencies that develop regulations for toxic 

substances include the Environmental Protection 

Agency (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 

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 

CHLOROPHENOLS 

Division of Toxicology July 1999 

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, 

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 chlorophenols include the 

following: 

The EPA recommends that drinking water 

concentrations of 2-chlorophenol should not be 

more than 0.04 part per million (ppm), and 

concentrations of 2,4-dichlorophenol should not be 

more than 0.02 ppm; these are levels that can be 

tasted. In order for chlorophenols to be lower than 

levels that can be tasted, the EPA recommends 

levels of 0.1 part per billion (ppb; the amount of 

chlorophenols per billion parts of water) for 

monochlorophenols, 0.3 ppb for 2,4-

dichlorophenols, and 1 ppb for 2,4,5-

trichlorophenol and 2,3,4,6-tetrachlorophenol. 

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: 

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). 1999. Toxicological profile for 

chlorophenols. 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