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PUBLIC HEALTH STATEMENT 

MIREX AND CHLORDECONE 

CAS#: MIREX 2385-85-5 

CHLORDECONE 143-50-5 

Division of Toxicology August 1995 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for Mirex 

and Chlordecone. 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 statement was prepared to give you 

information about mirex and chlordecone and to 

emphasize the human health effects that may result 

from exposure to them. The Environmental 

Protection Agency (EPA) has identified 1,408 

hazardous waste sites as the most serious in the 

nation. These sites make up the National Priorities 

List (NPL) and are the sites targeted for long-term 

federal clean-up activities. Mirex has been found in 

at least 7 of the sites on the NPL. Chlordecone has 

been found at 2 of the sites on the NPL. However, 

neither mirex or chlordecone are on EPA's list of 

target chemicals and the number of NPL sites 

evaluated for mirex and chlordecone is not known. 

As EPA evaluates more sites, the number of sites at 

which mirex and chlordecone are found may 

increase. This information is important because 

exposure to mirex and chlordecone may cause 

harmful health effects and because these sites are 

potential or actual sources of human exposure to 

mirex and chlordecone. 

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 can 

be exposed to a substance only when you come in 

contact with it. You may be exposed by breathing, 

eating, or drinking substances containing the 

substance or by skin contact with it. 

If you are exposed to substances such as mirex and 

chlordecone, many factors will determine whether 

harmful health effects will occur and what the type 

and severity of those health effects will be. These 

factors include the dose (how much), the duration 

(how long), the route or pathway (breathing, eating, 

drinking, or skin contact) by which you are 

exposed, the other chemicals to which you are 

exposed, and your individual characteristics such as 

age, sex, nutritional status, family traits, lifestyle, 

and state of health. 

1.1 WHAT ARE MIREX AND CHOLORDECONE? 

Mirex and chlordecone are two separate synthetic 

insecticides that have similar chemical structures. 

They do not occur naturally in the environment. 

Mirex is a snow-white crystalline solid and 

chlordecone is a tan-white crystalline solid. Both 

compounds are odorless and neither burns easily. 

Mirex and chlordecone are no longer made or used 

in the United States. Mirex and chlordecone were 

most commonly used in the 1960s and 1970s. Mirex 

was used as a pesticide to control fire ants mostly in 

the southeastern part of the United States. It was 

also used extensively as a flame retardant additive 

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 

MIREX AND CHLORDECONE 

CAS#: MIREX 2385-85-5 

CHLORDECONE 143-50-5 

Division of Toxicology August 1995 

under the trade name Dechlorane in plastics, rubber, 

paint, paper, and electrical goods from 1959 to 1972 

because it does burn easily. Chlordecone was used 

to control insects that attacked bananas, citrus trees 

with no fruits, tobacco, and ornamental shrubs. It 

was also used in household products such as ant and 

roach traps. Chlordecone is also known by its trade 

name Kepone . All registered products containing 

mirex and chlordecone were canceled in the United 

States between 1977 and 1978. 

1.2 WHAT HAPPENS TO MIREX AND 

CHOLORDECONE WHEN THEY ENTER 

THE ENVIRONMENT? 

Mirex and chlordecone contaminated water and soil 

while they were being manufactured and used in the 

1960s and 1970s. These substances can still enter 

surface water through runoff of contaminated soil at 

facilities that once manufactured these chemicals or 

by seeping from waste disposal sites. Mirex and 

chlordecone do not evaporate to any great extent 

into the air. They also do not dissolve easily in 

water. Most of the mirex and chlordecone in water 

attaches to soil particles suspended in the water or 

to sediment. When they bind to soil particles in 

water, they can travel long distances. Both 

compounds bind strongly to soil. Because they are 

not likely to move through the soil, very little will 

get into underground water. Mirex and chlordecone 

can stay in soil, water, and sediment for years. Both 

compounds are slowly broken down in soil, water, 

and sediment. Mirex is broken down more quickly 

than chlordecone. Mirex is broken down to 

photomirex, which can also cause harmful health 

effects. Photomirex is even more poisonous than 

mirex. It is produced when sunlight reacts with 

mirex in water or in the air. Fish or animals that live 

in waters that contain mirex or chlordecone, or that 

eat other animals contaminated with mirex or 

chlordecone, can build up these substances in their 

bodies. The amounts of mirex and chlordecone in 

their bodies may be several times greater than the 

amount in their prey or in the surrounding water. 

1.3 HOW MIGHT I BE EXPOSED TO MIREX AND 

CHOLORDECONE? 

Most people are exposed to very low levels of 

mirex and chlordecone. The most likely way for 

people in the general population to be exposed to 

mirex or chlordecone is by eating food, particularly 

fish, taken from contaminated areas. Currently, 

three states (Ohio, New York, and Pennsylvania) 

have issued a warning to the public that fish may 

contain mirex. This warning applies mostly to fish 

caught in Lake Ontario. The state of Virginia has 

also issued a warning to the public about possible 

chlordecone contamination in fish and shellfish 

caught in the lower 113 miles of the James River. 

This contamination was caused when chlordecone 

was manufactured in one factory in Hopewell, 

Virginia, polluting the James River. People who 

live in areas where these compounds were used or 

made have higher levels in their tissues. Mirex was 

found in the milk of women who live in these areas, 

so nursing infants could be exposed. People who 

live near hazardous waste sites may be exposed to 

mirex or chlordecone by touching or eating 

contaminated soil that is on unwashed hands, food 

containers, or food itself, since these compounds 

bind to soil particles. Because mirex and 

chlordecone do not dissolve easily in water or 

evaporate easily in air, people are not likely to be 

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 

MIREX AND CHLORDECONE 

CAS#: MIREX 2385-85-5 

CHLORDECONE 143-50-5 

Division of Toxicology August 1995 

exposed to them by drinking water or by inhaling 

air. Since mirex and chlordecone are no longer 

produced, the only people likely to be exposed 

through their work are those involved in the cleanup and removal of contaminated soils and 

sediments. 

Mirex and chlordecone do not occur naturally in the 

environment. Although mirex is not usually found 

in the air, it was detected at very low levels of up to 

10 parts of mirex per quadrillion 

(1,000,000,000,000,000) parts of air in air samples 

from southern Ontario, Canada. Surface water 

concentrations of mirex ranged from 0.06 to 2.6 

parts mirex per one trillion (1,000,000,000,000) 

parts of water in the Niagara River between 1981 

and 1983. More recent monitoring data from 1987 

show that mirex concentrations are decreasing in 

the surface waters of the Great Lakes to about 0.022 

parts per trillion (ppt). In the mid-1980s, mirex was 

found in sediments of Lake Ontario at levels 

ranging from 6.4 parts per billion (ppb) to 38 ppb. 

Nationwide, the average level of mirex in fish was 

less than 4 ppb in 1986. However, fish from Lake 

Ontario had levels as high as 225 ppb. Chlordecone 

was found in surface water samples from the James 

River estuary at levels less than 10 ppt in 1977. 

More recent data were not available. In 1978, 

chlordecone was detected in sediments from the 

James River below its production site at 

concentrations of less than one part chlordecone in 

one million parts of sediment. In 1981, chlordecone 

was found in clams from the James River at levels 

ranging from 60 to 140 ppb. 

1.4 HOW CAN MIREX AND CHOLORDECONE 

ENTER AND LEAVE MY BODY? 

Studies in animals show that mirex can be taken 

into your bloodstream when you breathe in cigarette 

smoke containing mirex or eat food contaminated 

with mirex. We do not know if mirex can pass 

through your skin and enter your body after you 

touch it. Mirex passes from the stomach and 

intestines of animals into their blood. We do not 

know how much passes from the stomach and 

intestines of people into the bloodstream. Once in 

the bloodstream, mirex is carried to many parts of 

the body where it is stored, mainly in fat. Mirex is 

not broken down in the body. Mirex that is not 

stored leaves the body unchanged mainly in the 

feces. Very little leaves the body in the urine. Most 

of the mirex that is swallowed leaves the body in 

feces within two days. However, the mirex that 

enters the bloodstream and is stored in fat leaves the 

body very slowly. This process can take from 

several weeks to months. Mirex can also enter 

breast milk from the bloodstream of nursing 

mothers who have been exposed. 

Animal studies show that chlordecone can pass into 

your blood when you eat food contaminated with it. 

Animal data show that only a small amount of 

chlordecone can pass through the skin into the 

bloodstream. We do not know if or how much 

chlordecone can pass from your lungs into your 

blood when you breathe it in. Like mirex, once 

chlordecone is taken up by your body, it is carried 

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 

MIREX AND CHLORDECONE 

CAS#: MIREX 2385-85-5 

CHLORDECONE 143-50-5 

Division of Toxicology August 1995 

by the blood throughout the body and is stored for a 

long time. Unlike mirex, chlordecone is found 

mainly in the liver. Chlordecone is broken down to 

chlordecone alcohol, which is a less harmful 

product. Chlordecone and its breakdown product 

slowly leave the body through the feces. This 

process can take from several weeks to months. 

Very little chlordecone leaves the body in the urine. 

Chlordecone has also been found in saliva and 

human milk. 

1.5 HOW CAN MIREX AND CHOLORDECONE 

AFFECT MY HEALTH? 

We do not know how mirex directly affects the 

health of people. However, animal studies have 

shown that eating mirex can cause harmful effects 

on the stomach, intestines, liver, and kidneys. 

Eating mirex can also cause harmful effects on the 

eyes, thyroid, nervous system, and reproductive 

system. Since these effects occur in animals, they 

may also occur in people. Animals that eat large 

amounts of mirex for a relatively short time can 

develop diarrhea. In animals, short-term exposure 

(14 days or less) to low and high levels of mirex 

and intermediate exposure (15–364 days) to low 

levels can harm the liver. Trembling, tiredness, and 

weakness can also occur after short-term exposure 

to large amounts of mirex. Younger animals are 

more sensitive to these effects on the nervous 

system. Intermediate exposures to low levels of 

mirex caused tiredness, and exposure to higher 

levels caused extreme excitability. Long-term (365 

days or more) exposure to low levels of mirex 

caused harm to the kidneys. Short-term and 

intermediate exposures to moderately low levels of 

mirex did not harm kidneys. Exposure to sufficient 

amounts of mirex may cause cataracts in animals if 

they are exposed before or soon after birth. We do 

not know whether human infants may also develop 

cataracts; it is not likely that mirex will cause 

cataracts in adults. Short-term, low-level exposure 

to mirex may harm reproduction and development 

in rodents. High-level exposures may result in 

miscarriage. 

Studies in workers exposed (intermediate- or longterm) to chlordecone have shown harmful effects on 

the liver, the nervous system, and reproductive 

systems. Workers exposed to high levels of 

chlordecone during its manufacture experienced 

trembling, irritability, blurry vision, and headaches. 

Studies in rats have shown that pretreatment with 

some anticonvulsants or antidepressants increases 

the seriousness of the tremors associated with 

chlordecone exposure. Therefore, people being 

treated with these drugs for epilepsy or depression 

may also experience more serious tremors if they 

are exposed to chlordecone. Male workers 

experienced some harmful reproductive effects. 

However, there was no evidence that the ability to 

father children was affected. Some workers exposed 

to high levels of chlordecone developed skin rashes 

and enlarged livers. Animal studies show effects 

similar to those seen in humans. In addition, longterm exposure to small amounts of chlordecone 

caused kidney effects in animals. It is possible 

exposure to high concentrations of chlordecone for 

a long time may also hurt people's kidneys. Animal 

studies show harmful effects on the ability of 

female animals to reproduce. We do not know if 

similar effects occur in exposed women. Animal 

studies show that chlordecone harms the offspring 

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 

MIREX AND CHLORDECONE 

CAS#: MIREX 2385-85-5 

CHLORDECONE 143-50-5 

Division of Toxicology August 1995 

of exposed animals. We do not know if similar 

harmful developmental effects will occur in people. 

However, it is possible that if parents are exposed to 

enough chlordecone, their children's development 

may be harmed. Very young and very old people 

may be especially sensitive to chlordecone. 

We do not know for sure whether either mirex or 

chlordecone causes cancer in humans. The 

Department of Health and Human Services (DHHS) 

has determined that mirex and chlordecone may 

reasonably be expected to be carcinogens. The 

International Agency for Research on Cancer 

(IARC) has determined that mirex and chlordecone 

are possibly carcinogenic to humans. The EPA has 

not classified mirex or chlordecone as to 

carcinogenicity. In rodents, mirex causes liver, 

adrenal, and blood cancer. Chlordecone also causes 

liver cancer in rodents, but because of problems 

with these animal studies, more information is 

necessary to be sure. 

1.6 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO MIREX AND 

CHOLORDECONE? 

There are medical tests to determine whether you 

have been exposed to mirex. Levels of mirex can be 

measured in blood, feces, fat, or milk. The tests are 

not done in routine medical examinations. However, 

doctors can collect tissue and body fluid samples 

and send them to university medical centers or 

medical laboratories where the tests can be 

performed. The tests are specific for mirex 

exposure. Since mirex is stored in your body for a 

long time and slowly excreted, the tests can detect 

mirex for a long time after exposure has stopped. 

However, the tests are unsatisfactory indicators of 

the amount of mirex to which you have been 

exposed. This is because a long time may have 

passed since you were exposed and you cannot be 

sure how much mirex may have left your body by 

the time the test is performed. The tests also cannot 

be used to predict whether you will experience any 

potential health effects or harmful changes 

following exposure. 

There are medical tests to determine whether you 

have been exposed to chlordecone and/or its 

breakdown product, chlordecone alcohol. Levels of 

chlordecone and/or chlordecone alcohol can be 

measured in blood, saliva, feces, or bile. 

Chlordecone levels in blood are the best indicator of 

exposure to chlordecone. Since chlordecone 

remains in the blood for a long time, the test is 

useful for a long time after exposure has stopped. 

Chlordecone can be detected in saliva only within 

the first 24 hours after exposure; therefore, this test 

has limited use. Blood levels of chlordecone are a 

good reflection of total body content of 

chlordecone. However, the test is an unsatisfactory 

indicator of the amount of chlordecone to which 

you have been exposed because you cannot be sure 

how much chlordecone left your body between the 

time you were exposed and the time the test is 

performed. These tests cannot predict how your 

health may be affected after exposure. The tests are 

not done in routine medical examinations, but 

doctors can collect body fluid samples and send 

them to a university medical center or a medical 

laboratory for analysis. 

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 

MIREX AND CHLORDECONE 

CAS#: MIREX 2385-85-5 

CHLORDECONE 143-50-5 

Division of Toxicology August 1995 

1.7 WHAT RECOMMENDATIONS HAS THE 

FEDERAL GOVERNMENT MADE TO 

PROTECT HUMAN HEALTH? 

The federal government has made regulations to 

protect individuals from the possible health effects 

of mirex and chlordecone. The National Institute for 

Occupational Safety and Health (NIOSH) 

recommends that the average workroom air levels 

of chlordecone should not exceed 50 parts per 

trillion (ppt) over an 8-hour period. EPA suggests 

that taking into your body each day an amount 

equal to 200 picograms (pg) of mirex per kilogram 

(kg) of your body weight is not likely to cause any 

significant (noncancer) harmful health effects. The 

Food and Drug Administration (FDA) has 

determined that concentrations of mirex below 100 

ppt in fish and other foods are not likely to harm 

people who eat these foods. EPA has set a limit of 1 

ppt in surface waters to protect aquatic life from the 

harmful effects of mirex. FDA has determined that 

concentrations of chlordecone below 400 ppt in 

fish, crabs, and shellfish are not likely to harm 

people who eat these foods. 

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). 1995. Toxicological profile for mirex 

and cholordecone. 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