Methoxychlor is a synthetic organochloride

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed t ...

, now obsolete.

Usage

Methoxychlor was used to protect crops, ornamentals, livestock, and pets against fleas, mosquitoes, cockroaches, and other insects. It was intended to be a replacement for DDT, but has since been banned for use as a pesticide based on its acute toxicity,

bioaccumulation Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...

, and endocrine disruption activity. The amount of methoxychlor in the

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

changes seasonally due to its use in farming and foresting. It does not dissolve readily in water, so it is mixed with a petroleum-based fluid and sprayed, or used as a dust. Sprayed methoxychlor settles on the ground or in aquatic ecosystems, where it can be detected in

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

s. Its degradation may take many months. Methoxychlor is ingested and absorbed by living organisms, and it accumulates in the food chain. Some metabolites may have unwanted side effects.

Banned

The use of methoxychlor as a

pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...

was banned in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

in 2003 and in the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...

in 2002.

Human exposure

Human exposure to methoxychlor occurs via air, soil, and water,, accessed 08-22-2008 primarily in people who work with the substance or who are exposed to air, soil, or water that has been contaminated. It is unknown how quickly and efficiently the substance is absorbed by humans who have been exposed to contaminated air or via skin contact. In animal models, high doses can lead to neurotoxicity. Some methoxychlor's metabolites have

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

ic effects in adult and developing animals before and after birth. One studied metabolite is 2,2-bis(''p''-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) which shows reproductive toxicity in an animal model by reducing testosterone biosynthesis. Such effects adversely affect both the male and female

reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are ...

s. It is expected that this "could occur in humans" but has not been proven. While one study has linked methoxychlor to the development of

leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ...

in humans, most studies in animals and humans have been negative, thus the EPA has determined that it is not classifiable as a

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...

. The EPA indicates that levels above the Maximum Contaminant Level of 40 ppb "cause" central nervous depression, diarrhea, damage to liver, kidney, and heart, and - by chronic exposure - growth retardation. Little information is available regarding effects on human pregnancy and children, but it is assumed from animals studies that methoxychlor crosses the placenta, and it has been detected in human milk Exposure to children may be different than in adults because they tend to play on the ground, further, their reproductive system may be more sensitive to the effects of methoxychlor as an

endocrine disruptor Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine (or hormonal) systems. These disruptions can cause ...

. Food contamination may occur at low levels and it is recommended to wash all foods. A number of

hazardous waste Hazardous waste is waste that has substantial or potential threats to public health or the environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits: ignitability, reactivity, cor ...

sites are known to contain methoxychlor. Maximum pesticide residue limits for the EU/UK are set at 0.01 mg/kg for oranges and 0.01 mg/kg for apples.

Labeling

The EPA lists methoxychlor as "a persistent, bioaccumulative, and toxic (PBT) chemical by the EPA Toxics Release Inventory (TRI) program", and as such it is a waste minimization priority chemical. Tradenames for methoxychlor include ''Chemform'', ''Maralate'', ''Methoxo'', ''Methoxcide'', ''Metox'', and ''Moxie''.

References

External links

*
CDC ReportPubertal Toxicity Study, 2003
{{Xenobiotic-sensing receptor modulators Endocrine disruptors Obsolete pesticides Organochloride insecticides Phenol ethers Trichloromethyl compounds Xenoestrogens Bis(4-hydroxyphenyl)methanes