Metam sodium

 ( Pesticides ) 

Metam sodium is an organosulfur compound with the formula . The compound is a sodium salt of a dithiocarbamate. The compound exists as a colorless dihydrate, but most commonly it is encountered as an aqueous solution.

It is used as a soil fumigant, pesticide, herbicide, and fungicide. It is one of the most widely used pesticides in the United States, with approximately 60 million pounds used in 2001. 2000-2001 Pesticide Market Estimates , U.S. Environmental Protection Agency

Metam-sodium belongs to two , so it is designated Group A/C (Aus), Group A/C1 (global) and Group 1/5 (numeric).

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Preparation and properties Metam sodium is prepared by combining methylamine, carbon disulfide, and sodium hydroxide:

It also arises from the reaction of methyl isothiocyanate and sodium thiolate.

Upon exposure to the environment, metam sodium decomposes to methyl isothiocyanate and other sulfur compounds.

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Safety and environmental considerations

Metam sodium is nonpersistent in the environment since it decomposes rather quickly to toxic methyl isothiocyanate and carbon disulfide. In 1991 a tank car with 19,000 gallons of a metam sodium based pesticide spilled into Sacramento River above Lake Shasta. This killed all fish in a 41-mile stretch of the river. 20 years later the rainbow trout population had recovered.

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See also

• Zineb - A related dithiocarbamate salt which is also used as a fungicide

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External links

Categories: Pesticides, Herbicides, Fungicides, Dithiocarbamates, Organic Sodium Salts, Group 1 Herbicides, Group 5 Herbicides

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