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.^[1]

Monosodium methyl arsonate

Names
IUPAC name Sodium hydrogen methylarsonate
Other names Monosodium methyl arsenate; sodium methylarsonate; monosodium methane arsonate; methyl arsonic acid monosodium salt; EPA Pesticide Chemical Code 013803
Identifiers
CAS Number	2163-80-6 Y
3D model (JSmol)	Interactive image
Abbreviations	MSMA
ChemSpider	15697 N
ECHA InfoCard	100.016.815
PubChem CID	23664719
UNII	600QCW45IV Y
CompTox Dashboard (EPA)	DTXSID2025686
InChI InChI=1S/CH5AsO3.Na/c1-2(3,4)5;/h1H3,(H2,3,4,5);/q;+1/p-1 N Key: JITOKQVGRJSHHA-UHFFFAOYSA-M N InChI=1/CH5AsO3.Na/c1-2(3,4)5;/h1H3,(H2,3,4,5);/q;+1/p-1 Key: JITOKQVGRJSHHA-REWHXWOFAY
SMILES C[As](=O)(O)[O-].[Na+]
Properties
Chemical formula	CH4AsNaO3
Molar mass	161.95 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Arsenic is classified as a Group-A carcinogen.^[1] The EPA states that:^[2]

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