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September 2002

Methoxychlor ToxFAQs™ PDF PDF Version, 33 KB

CAS#: 72-43-5

This fact sheet answers the most frequently asked health questions about methoxychlor. For more information, you may call the ATSDR Information Center at 1-888-422-8737. This fact sheet is one in a series of summaries about hazardous substances and their health effects. 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.


Exposure to methoxychlor occurs mainly when workers, farmers, and gardeners use this pesticide. Most people are not exposed to this chemical on a regular basis. In animals, high levels of methoxychlor caused tremors and convulsions, and affected fertility. Little is known about the effects of methoxychlor on human health. Methoxychlor has been found in at least 58 of the 1,613 National Priorities List sites identified by the Environmental Protection Agency (EPA).

What is methoxychlor?

Methoxychlor is a manufactured chemical that does not occur naturally in the environment. Pure methoxychlor is a pale-yellow powder with a slight fruity or musty odor.

Methoxychlor is used as an insecticide against flies, mosquitoes, cockroaches, chiggers, and a wide variety of other insects. It is used on agricultural crops and livestock, and in animal feed, barns, grain storage bins, home garden, and on pets.

Methoxychlor is also known as DMDT, Marlate®, or Metox®.

What happens to methoxychlor when it enters the environment?

How might I be exposed to methoxychlor?

How can methoxychlor affect my health?

There is very little information on how methoxychlor can affect people's health. Animals exposed to very high amounts of methoxychlor suffered tremors and convulsions and seizures. Because methoxychlor is broken down quickly in the body, you are not likely to experience these effects unless you are exposed to very high levels.

Animal studies show that exposure to methoxychlor in food or water harms the ovaries, uterus, and mating cycle in females, and the testes and prostate in males. Fertility is decreased in both male and female animals. These effects can occur both in adult and in developing animals and could also occur following inhalation or skin contact. These effects are caused by a breakdown product of methoxychlor which acts as a natural sex hormone. These effects have not been reported in humans, but they could happen

How likely is methoxychlor to cause cancer?

Most of the information available from human and animal studies suggests that methoxychlor does not cause cancer. The International Agency for Research on Cancer (IARC) and the EPA have determined that methoxychlor is not classifiable as to its carcinogenicity to humans.

How can methoxychlor affect children?

Little information is available on the health effects of children exposed to methoxychlor. Children exposed to large amounts of methoxychlor may suffer tremors and convulsions, as would probably occur in adults. However, we do not know whether children differ from adults in their susceptibility to methoxychlor. The process of sexual maturation may be altered in children born to women exposed to methoxychlor during pregnancy or in children exposed shortly after birth. This possibility is based on what we know from studies in animals. There are no studies that examined whether methoxychlor causes birth defects in humans.

How can families reduce the risk of exposure to methoxychlor?

Is there a medical test to show whether I've been exposed to methoxychlor?

There are laboratory tests that can detect methoxychlor in fat, blood, semen, and breast milk. These tests can only detect exposure within 24 hours because methoxychlor leaves your body quickly. These tests do not tell how much methoxychlor you were exposed to or whether harmful health effects will occur. The tests are not routinely available at the doctor's office because they require special equipment.

Has the federal government made recommendations to protect human health?

The EPA also 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). The EPA also limits the amount of methoxychlor present in agricultural products to 1-100 ppm.

The Occupational Safety and Health Administration (OSHA) sets a Permissible Exposure Limit (PEL) of 15 milligrams of methoxychlor per cubic meter of air (15 mg/m3) in the workplace during an 8-hour shift.

The Food and Drug Administration (FDA) limits the amount of methoxychlor in bottled water to 0.04 ppm.


Agency for Toxic Substances and Disease Registry (ATSDR). 2002. Toxicological Profile for Methoxychlor. Update. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.

Where can I get more information?

ATSDR can tell you where to find occupational and environmental health clinics. Their specialists can recognize, evaluate, and treat illnesses resulting from exposure to hazardous substances. You can also contact your community or state health or environmental quality department if you have any more questions or concerns.

For more information, contact:

Agency for Toxic Substances and Disease Registry
Division of Toxicology and Environmental Medicine
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Phone: 1- 800-232-4636 / TTY: 888-232-6348  
FAX: 770-488-4178

This page was updated on 09/11/2007