PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

This Public Health Statement is the summary 

chapter from the Toxicological Profile for 

Methoxychlor. 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 

methoxychlor 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. Methoxychlor 

has been found in at least 58 of the 1,613 current or 

former NPL sites. However, the total number of 

NPL sites evaluated for methoxychlor is not known. 

As more sites are evaluated, the sites at which 

methoxychlor is found may increase. This 

information is important because exposure to 

methoxychlor 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 methoxychlor, 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 METHOXYCHLOR? 

Methoxychlor, also known as DMDT, Marlate®, or 

Metox®, is a manufactured chemical now used in 

the United States for controlling insects. 

Methoxychlor is effective against flies, mosquitos, 

cockroaches, and a wide variety of other insects. 

This insecticide is used on agricultural crops and 

livestock, and in animal feed, barns, and grain 

storage bins. Some pesticide products that contain 

methoxychlor are used for controlling insects in 

gardens or on pets. 

Pure methoxychlor is a pale-yellow powder that has 

a slightly fruity or musty odor. It does not readily 

evaporate into air or dissolve in water. Pesticide 

workers usually dissolve methoxychlor in a 

petroleum-based liquid and apply it as a spray, or 

they mix it with other chemicals and apply it as a 

dust. Application of methoxychlor as an insect killer 

accounts for most of the methoxychlor that enters 

the environment. Since the use of methoxychlor is 

highly seasonal, the amount that is released to the 

environment tends to be greater during periods of 

insect control (spring and summer). Some 

methoxychlor is released to the environment from 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

chemical manufacturing plants that make 

methoxychlor or from manufacturing sites that 

formulate products containing methoxychlor. A 

small amount may also be released from hazardous 

waste sites where it has been disposed of. 

1.2 WHAT HAPPENS TO METHOXYCHLOR 

WHEN IT ENTERS THE 

ENVIRONMENT? 

Methoxychlor does not occur naturally in the 

environment. Most methoxychlor enters the 

environment when it is applied to forests, 

agricultural crops, and farm animals. Methoxychlor 

can be applied to forests and crops by aerial 

spraying. This process can contaminate nearby land 

and water. Methoxychlor that is released into the air 

will eventually settle to the ground, although some 

may travel long distances before settling. Rain and 

snow cause methoxychlor to settle to the ground 

more quickly. 

Once methoxychlor is deposited on the ground, it 

becomes bound to the soil. Because of this, 

methoxychlor does not tend to move rapidly from 

one place to another. However, soil particles that 

contain methoxychlor can be blown by the wind or 

be carried by rainwater or melted snow into rivers 

or lakes. Most methoxychlor stays in the very top 

layer of soil, but some of the products that it breaks 

down into may move deeper into the ground. 

Smaller amounts of methoxychlor in air may settle 

directly into rivers, lakes, and other surface waters. 

Once methoxychlor is in water, it usually binds to 

sediments or organic matter and settles to the 

bottom. 

Methoxychlor is broken down in the environment 

by several processes. However, these processes are 

slow and may take months. In soil, some 

methoxychlor is broken down by bacteria and other 

microorganisms, and some is broken down by a 

reaction with water or materials in soil. In air and 

water, some methoxychlor is broken down by 

sunlight. Methoxychlor is also broken down by 

reactive chemicals normally present in the air. Some 

of the breakdown products are capable of producing 

harmful effects similar to those caused by exposure 

to methoxychlor. 

Methoxychlor can accumulate in some living 

organisms, including algae, bacteria, snails, clams, 

and some fish. However, most fish and animals 

change methoxychlor into other substances that are 

rapidly released from their bodies, so methoxychlor 

does not usually build up in the food chain. 

1.3 HOW MIGHT I BE EXPOSED TO 

METHOXYCHLOR? 

Most people are not exposed to methoxychlor on a 

regular basis. Although methoxychlor is not usually 

detected in air, people can be exposed to low levels 

of methoxychlor by inhaling dusts and aerosols in 

air surrounding areas where methoxychlor is used. 

Since methoxychlor is not usually detected in 

surface or well water sources, exposure from 

drinking water is not likely to be significant for the 

general public. However, surface water that has 

been treated with methoxychlor for control of insect 

larvae should be avoided until methoxychlor residue 

has decreased below the level of concern. 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

Methoxychlor is not usually found in food. 

However, low levels are sometimes detected in 

foods obtained from areas where methoxychlor has 

been used. 

Fish usually do not contain detectable levels of 

methoxychlor, but people who eat fish caught in 

water contaminated with methoxychlor may 

occasionally have above-average intakes of 

methoxychlor. 

People who make or use methoxychlor may be 

exposed by breathing in the dust or aerosol, or by 

getting it on their skin. For example: 

• If you work in a factory that makes 

methoxychlor or products containing 

methoxychlor, you could be exposed to 

methoxychlor in air or on your skin during 

work hours. The government has estimated 

that approximately 3,400 people may be 

exposed to methoxychlor in this way. 

• Methoxychlor is present in some pesticides 

used for home gardening or for spraying 

pets (such as cats and dogs). If you use these 

products, you could be exposed to aboveaverage levels of methoxychlor in air and on 

your skin. 

• If you live or work on or near a farm where 

methoxychlor is used on crops or livestock, 

you could be exposed to above-average 

levels of methoxychlor in air, soil, and 

possibly in water. 

If you live near a hazardous waste site that contains 

methoxychlor, you could be exposed by breathing 

in methoxychlor from the air, by swallowing 

contaminated soil or water, or by getting 

contaminated soil or water on your skin. The 

amount of exposure you receive depends on 

conditions specific to where you live and can only 

be evaluated on a case-by-case basis. 

1.4 HOW CAN METHOXYCHLOR ENTER 

AND LEAVE MY BODY? 

Scientists do not know how much or how quickly 

methoxychlor is absorbed into your body if you 

breathe it in or if it contacts your skin. If you get 

methoxychlor-contaminated soil or water on your 

skin, some of it may pass through your skin and 

enter your bloodstream. If you breathe 

methoxychlor-containing dust into your lungs, some 

of the dust will deposit in your lungs. Dust that 

deposits in the upper part of your lungs is likely to 

be coughed up and swallowed. Dust that deposits 

deep in your lungs is likely to remain long enough 

for the methoxychlor to pass through the lining of 

your lungs and enter your bloodstream. If you 

swallow food, water, or soil containing 

methoxychlor, most of it will rapidly pass through 

the lining of your stomach and intestines and enter 

your bloodstream. 

Once methoxychlor enters your bloodstream, it is 

distributed to all parts of your body. Animal studies 

suggest that methoxychlor is changed into other 

substances called metabolites by your liver. Most of 

these metabolites leave your body within 24 hours, 

primarily in your feces, with lesser amounts in your 

urine. Some methoxychlor can enter the fat in your 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

body, but methoxychlor does not accumulate or 

build up in fat. 

1.5 HOW CAN METHOXYCHLOR 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. 

Very few reports exist on the health effects of 

methoxychlor in humans. In animals, exposure to 

high levels of methoxychlor caused effects on the 

nervous system. These effects included tremors, 

convulsions, and seizures. These effects are 

probably caused by methoxychlor itself and not by 

its metabolites. Because methoxychlor is quickly 

transformed into metabolites by the liver, you are 

not likely to experience nervous system effects 

unless you are exposed to very high levels. 

Some of the breakdown products of methoxychlor 

cause effects similar to those produced by estrogen. 

Estrogens are naturally occurring hormones that are 

important in women for the development and 

maintenance of their ovaries, uterus, and breasts, 

and also play a role in the development of the 

reproductive system in men. Studies in animals 

show that exposure to methoxychlor adversely 

affects the ovaries, uterus, and mating cycle in 

females, and the testes and prostate in males. 

Fertility is decreased in both female and male 

animals. These effects can occur both in adult 

animals and in developing animals exposed 

prenatally or shortly after birth. Effects of 

methoxychlor on reproduction have been studied 

mainly in animals given methoxychlor in food or 

water, but it is expected that these effects could 

occur following inhalation and skin exposures as 

well. Likewise, it is expected that reproductive 

effects seen in animals could occur in humans 

exposed to methoxychlor, but this has not been 

reported. 

There is not enough information available to 

definitely state whether methoxychlor causes 

cancer. However, most of the information that we 

have indicates that methoxychlor does not cause 

cancer. One very small study in humans indicated a 

possible link with increased incidence of leukemia. 

However, a definitive connection between a cause 

of leukemia and exposure to methoxychlor cannot 

be made with so little information. Most animal 

studies with methoxychlor have been negative for 

cancer. Therefore, the International Agency for 

Research on Cancer (IARC) has determined that 

methoxychlor is not classifiable as to its 

carcinogenicity to humans. Similarly, the EPA has 

determined that methoxychlor is not classifiable as 

to its human carcinogenicity. 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

1.6 HOW CAN METHOXYCHLOR AFFECT 

CHILDREN? 

This section discusses potential health effects from 

exposures during the period from conception to 

maturity at 18 years of age in humans. 

Children are likely to be exposed to methoxychlor 

in the same way as adults, primarily from low-level 

contamination of food. Other possible sources of 

methoxychlor exposure for children include 

swallowing soil, crawling on home carpets, 

breathing in house dust and residues from 

methoxychlor-containing pesticides used for home 

gardening or pet care, and touching work clothes or 

equipment used to apply products that contain 

methoxychlor. 

Little information is available regarding the effects 

of methoxychlor in children. Exposure to very high 

doses of methoxychlor may cause nervous system 

effects such as tremors or convulsions. The 

reproductive system is likely to be the most 

sensitive target of methoxychlor in both adults and 

children. Methoxychlor is metabolized in the liver 

to substances that act like estrogen in the body. This 

probably occurs similarly in children and adults. 

Estrogens are naturally occurring substances that 

are necessary for the proper development and 

function of the male and female reproductive 

system. Elevated levels of estrogen, or substances 

like methoxychlor that mimic estrogen, have been 

shown to disrupt reproductive development and 

function in animals. This has resulted in early 

puberty in females, delayed puberty in males, 

disruption of the reproductive cycle in females, 

decreased fertility in males and females, and altered 

hormone levels in the blood. These effects can 

happen when the exposure occurs before birth or 

between birth and sexual maturity. It is thought that 

similar effects could occur in humans, but this has 

not been reported. 

There is no evidence in humans that methoxychlor 

causes birth defects. Methoxychlor does not cause 

structural birth defects in animals, but exposure to 

high levels of methoxychlor during pregnancy 

caused reduced survival of fetuses. It is unclear 

whether or at what level of exposure this might 

occur in humans. 

Methoxychlor or its metabolites can probably be 

transferred from a pregnant mother to a developing 

fetus in animals, since abnormal reproductive 

development has been seen in the newborn animals 

born to mothers exposed during pregnancy. In 

animals, methoxychlor and metabolites of 

methoxychlor that are estrogenic can be transferred 

from a nursing mother to her newborn babies 

through breast milk. Methoxychlor and its 

metabolites can probably cross the placenta and 

have been detected in human breast milk. 

 

1.7 HOW CAN FAMILIES REDUCE THE 

RISK OF EXPOSURE TO 

METHOXYCHLOR? 

If your doctor finds that you have been exposed to 

significant amounts of methoxychlor, ask whether 

your children might also be exposed. Your doctor 

might need to ask your state health department to 

investigate. 

You can purchase products containing 

methoxychlor as an over-the-counter pesticide 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

product to apply yourself. If you do purchase such a 

product, be sure that the product is in an unopened 

pesticide container that is labeled and contains an 

EPA registration number. If you plan to apply the 

pesticide indoors, make sure that the pesticide is 

approved for indoor use. Be sure to carefully follow 

the instructions on the label and follow any warning 

statements. Children can be exposed to pesticides 

by entering a room or playing on a lawn too soon 

after a pesticide has been applied. Carefully read 

and follow the directions on the pesticide label 

about how long to wait before re-entering the 

treated area. If you or any member of your family 

feels sick after a pesticide has been applied, consult 

your doctor or local poison control center. 

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 that children would find 

attractive to eat or drink from, such as old soda 

bottles. Your children may be exposed to 

methoxychlor if an unqualified person applies 

pesticides containing it around your home. Make 

sure that any person you hire is licensed. Your state 

licenses each person who is qualified to apply 

pesticides according to EPA standards. Ask to see 

the license. 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 what are the EPA 

approved uses. This information is important if you 

or your family react to the product. 

Children may be exposed to methoxychlor if they 

come in contact with family pets or farm animals 

that have been treated with the pesticide. Exposure 

may occur through skin contact with the animal or 

application devices, or by breathing vapor from 

animal-dipping solutions and baths. Dipping 

solution that contains methoxychlor should be 

disposed of according to the directions on the 

product label. Waste methoxychlor should never be 

discarded in any area where children might play. 

Although methoxychlor has been found in some 

foods, it occurs at very low levels. To reduce your 

family's risk of exposure, you should thoroughly 

wash all fruits and vegetables before preparing them 

for consumption. 

Methoxychlor may be released to soil and water, 

especially near hazardous waste sites. Hazardous 

waste sites are often clearly marked, but children 

have a tendency to ignore signs that are designed to 

alert us to dangers. Your children should be 

encouraged not to play at or near hazardous waste 

sites. Low levels of methoxychlor have also been 

found in carpet and house dust. 

 

1.8 IS THERE A MEDICAL TEST TO 

DETERMINE WHETHER I HAVE BEEN 

EXPOSED TO METHOXYCHLOR? 

Specific and sensitive tests have been developed to 

detect methoxychlor in blood, fat, semen, and breast 

milk of exposed individuals. Because methoxychlor 

is removed from the body relatively quickly, these 

tests are only useful in detecting recent exposures 

(within 24 hours) and are not useful for detecting 

past exposures to methoxychlor. These tests 

currently cannot be used to estimate how much 

methoxychlor you have been exposed to or whether 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

adverse health effects will occur. These tests are not 

usually performed in a doctor's office because 

special equipment is required and samples must be 

sent to a laboratory for testing. 

 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 

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 methoxychlor include the following: 

The federal government has taken several actions to 

help protect humans from excess exposure to 

methoxychlor. EPA limits the amount of 

methoxychlor that may be present in drinking water 

to 0.04 parts of methoxychlor per million parts of 

water (0.04 ppm). EPA has also set limits of 1-100 

ppm on the amount of methoxychlor that may be 

present in various agricultural products (crops, 

fruits, vegetables, grains, meats, milk, and food for 

livestock). FDA limits the amount of methoxychlor 

in bottled water to 0.04 ppm. EPA restricts the 

amount of methoxychlor that may be released to the 

environment during burning or by disposal in 

landfills. OSHA has set a Permissible Exposure 

Limit (PEL) of 15 milligrams per cubic meter of air 

(mg/m3) for the average amount of methoxychlor 

that may be present in air during an 8-hour 

workday. A court decision struck down a proposed 

PEL of 10 mg/m3. The American Conference of 

Governmental Industrial Hygienists (ACGIH) 

recommends a Threshold Limit Value (TLV) of 10 

mg/m3. 

1.10 WHERE CAN I GET MORE 

INFORMATION? 

If you have any more questions or concerns, please 

contact your community or state health or 
 PUBLIC HEALTH STATEMENT 

 METHOXYCHLOR 

 CAS#: 72-43-5 

Division of Toxicology September 2002 

__________________________________________________________________________________________

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 

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). 2002. Toxicological profile for 

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

Health and Human Services, Public Health Service.