MSMA: Status Report

In the summer of last year, the EPA communicated that “all uses for MSMA, SMA, CAMA and cacodylic acid (organic arsenical herbicides) are ineligible for reregistration.” EPA’s main cause for concern is the possibility that applied organic organic arsenical herbicides may change to more toxic inorganic forms of arsenic in soil, and that these substances may be carried to drinking water. Arsenic levels left in MSMA’s wake raise a concern for cancer risk, according to the EPA.

There are about 90 end-use products that contain MSMA. It is most commonly used on turf and cotton crops.

The evaluation of the chemical was mandated as part of the Federal Insecticide, Fungicide and Rodenticide Act. The Act requires all products with active ingredients registered before 11/1/84 to be studied. MSMA, which originated in the 1960’s, meets the criteria for evaluation. The evaluation process us called regregistration.

If this decision prevails, these herbicides will no longer be available for use with cotton and turfgrasses. The cancellation of MSMA and other organic arsenicals is expected to have the greatest negative impact on the sod industry. The organic arsenicals have been the mainstay of treatment for post emergence grass weed in bermudagrasses, zoysiagrasses and tall fescue. Some substitutes have become available in recent years, except for bermudagrass, for which there is no equivalent alternative. Also, for a number of weeds, like dallisgrass, vaseygrass and others, no post emergent control is available. Organic arsenicals also address many sedges, some broadleaf weeds, and other weeds.

The reregistration process provides a 60-day public comment period before final decisions are made. EPA’s original comment period for the organic arsenical herbicides was extended in the Fall of 2006; then re-opened in December for an additional 30 days.

Some turfgrass, golf, and chemical industry advocates have highlighted the negative effects that could result from the reversal of registration: weed control costs could rapidly increase to unacceptable levels for many segments of the turf industry; significant difficulties would be caused for turfgrass managers attempting to control weeds; adverse economic impact for chemical manufacturers and providers; and the potential for decreases in the rate that some turfgrasses (bermudagrass) can be harvested.

Others emphasize the possible risks associated with the herbicides, and maintain that health risks outweigh the benefits; and that acceptable substitutes are now available.

To read about the EPA’s report on MSMA and other organic arsenicals, visit www.epa.gov/oppsrrd1/reregistration/methanearsonic_acid

At the time of this writing, the EPA’s decision on reregistration is pending.

This report was compiled from information published by Golf Course News, the Georgia Sod Producers Association, the US Environmental Protection Agency, and www.beyondpesticides.org.