Monosodium Salt of  Methanearsonic Acid

What is the regulatory status of MSMA?

Regulatory Information


In January 2009, the technical registrants of the organic arsenicals manufacturing-use products reached agreement with the U.S. Environmental Protection Agency (EPA) according to which MSMA has been allowed to be used on cotton, as well as some other use applications, including golf courses, sod farms and highway rights-of-way.  The registrants agreedto eliminate and phase out products of disodium methanearsonate (DSMA), calcium acid methanearsonate (CAMA), and cacodylic acid and its sodium salt, and modify certain uses of MSMA, including use on residential lawns, forestry, non-bearing fruit and nut trees, and citrus orchards. That phase out has begun, and no sales or distribution of MSMA for these particular uses is allowed, although use of existing stocks of MSMA is acceptable.


In September 2012, EPA informed the Organic Arsenical Products Task Force (OAPTF) that the sale of MSMA for golf course, sod farms and highway rights-of-way uses will NOT be terminated on December 31, 2012 as originally called for in the 2009 agreement between the Task Force and EPA. See September 14, 2012, letter from the Environmental Protection Agency (EPA) to the Organic Arsenical Products Task Force (Task Force) that confirms the sale, distribution, and use of MSMA products labeled for golf course, sod farms, and highway rights-of-way will continue for at least three years. The Federal Register notice that clarifies these conflicting provisions in the 2009 cancellation order, and allows continued use of those existing stocks of MSMA products labeled for the Group 3 uses beyond the December 31, 2013, deadline is available here.


In 2011, hundreds of user groups submitted letters to EPA regarding the benefits of MSMA and its importance in responsible and effective weed control for golf courses, sod farms, and highway rights-of-way.  The letters are now posted in the "comments" section of the EPA docket "Organic Arsenicals; Amendment to Reregistration Eligibility Decision."  A link to the docket is available here.


The following use restrictions continue to apply for golf courses:


  • Spot treatments only (100 sq feet per spot), not to exceed 25 percent of the total golf course acreage per year
  • One broadcast treatment for newly constructed courses only


For sod farms:


  • 1-2 broadcast applications
  • 25 foot buffer around permanent water bodies


For highway rights-of-way:


  • Two broadcast applications ONLY on highway rights-of-way
  • 100 foot buffer around permanent water bodies


Frequently Asked Questions Regarding Changes in EPA Agreement on MSMA - October 2012


Agreement with U.S. EPA For Continued Use of MSMA, January 27, 2009 (click here for the full Agreement)

Organic Arsenical Products Task Force (OAPTF)  ·  P.O. Box 33856  ·  Washington, D.C.  ·  20033-0856  ·  1-8877-221-2442


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