Monosodium methyl arsonate

Monosodium methyl arsenate (MSMA) is an arsenic-based herbicide. It is an organo-arsenate; less toxic than the inorganic form of arsenates. However, the EPA states that all forms of arsenic are a serious risk to human health and the United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites.

Arsenic is classified as a Group-A carcinogen. The EPA states that: "Arsenate (AsV) is the oxidized form and occurs in well-aerated soils, whereas in chemically-reduced soil environments, arsenite (AsIII) is the prevalent As form. Although arsenite is more toxic than arsenate, arsenate can also have deleterious effects on humans, plants, and microorganisms. Arsenic-contaminated soils pose serious risk to human health. The EPA also states that, while contaminated soil poses a serious risk to health, arsenic frequently mobilizes from soils and other sources, ending up in water where it is even more of a toxicity issue."

Trade names include:


 * Target 6 Plus
 * Target 6.6
 * MSMA 6 Plus
 * MSMA 6.6