Methoxychlor

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, and endocrine disruption activity.

The amount of methoxychlor in the environment 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 sediments. 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 was banned in the United States in 2003 and in the European Union in 2002.

Health and environmental impacts

The EPA lists methoxychlor as "a persistent, bioaccumulative, and toxic (PBT) chemical by the EPA Toxics Release Inventory (TRI) program",

Human exposure

Human exposure to methoxychlor occurs via air, soil, and water, 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. Such effects adversely affect both the male and female reproductive systems. It is expected that this "could occur in humans" but has not been proven.

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.

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

References

References

1. {{PGCH. 0388
2. {{IDLH. 72435. Methoxychlor
3. Karickhoff. (1979). "Sorption of Hyrdophobic Pollutants on Natural Sediments". Water Research.
4. U.S. Environmental Protection Agency. (June 30, 2004). "Methoxychlor Reregistration Eligibility Decision (RED) EPA Publication No. EPA 738-R-04-010".
5. European Union - DG SANCO. "EU Pesticides Database".
6. (May 15, 2023). "Governments accelerate action and take bold decisions to address pollution from chemicals and wastes". Secretariat of the Basel, Rotterdam and Stockholm Conventions.
7. ATSDR. (September 2002). "Public Health Statement about Methoxychlor".
8. (2000). "A Metabolite of Methoxychlor, 2,2-Bis(p-Hydroxyphenyl)-1,1,1-Trichloroethane, Reduces Testosterone Biosynthesis in Rat Leydig Cells Through Suppression of Steady-State Messenger Ribonucleic Acid Levels of the Cholesterol Side-Chain Cleavage Enzyme". Biology of Reproduction.
9. Cummings AW. (1997). "Methoxychlor as a model for environmental estrogens". Crit Rev Toxicol.