AMS No. 089-11

Soo Kim (202) 720-8998

Soo.kim@ams.usda.gov

WASHINGTON, May 5, 2011—The U.S. Department of Agriculture published today a proposed rule that would establish exemptions for use of two synthetic substances in organic livestock production: fenbendazole and moxidectin.

These substances are specifically proposed for use as parasiticides consistent with the recommendations of the National Organic Standards Board (NOSB).

Fenbendazole was petitioned for use in March 2007 to manage specific gastrointestinal worms and lungworms in organic livestock production. It functions by blocking the polymerization of tubulin into microtubules in gastrointestinal worms and lungworms, thereby disrupting the integrity and transport functions of the parasites’ cells. During deliberations on this petition, the NOSB concluded that fenbendazole had clear advantages over ivermectin, which is the only parasiticide currently allowed for use in organic production. The proposed rule would add fenbendazole, along with a restrictive annotation, to the National List of Allowed and Prohibited Substances, thereby allowing use of the applicable form of fenbendazole among breeder stock for beef and dairy cattle, goats, and swine, provided it is not administered during the last third of gestation and lactation for progeny that will be sold as organic. The action would also allow the use of the applicable form of fenbendzole for turkeys.

Moxidectin was petitioned in March 2003 for use as a topical medical treatment for controlling internal and external parasites in organic cattle production. It functions as an endectocide (a drug effective against both internal and external parasites) and activates glutamate-gated chloride channels and GABA-gated chloride channels, causing paralysis of certain arthropods and nematodes. It is effective against a wide range of adult and larval internal and external parasites including gastrointestinal roundworms, lungworms, cattle grubs, mites, lice and horn flies. The NOSB recommended the use of moxidectin for control of internal parasites only. Consistent with the recommendations from the NOSB, this proposed rule would add moxidectin, along with a restrictive annotation, to the National List.

The NOP invites comments on the proposed amendments to the National List, a subpart of the USDA’s organic standards that identifies the synthetic substances that may be used and the nonsynthetic (natural) substances that may not be used in organic production. The Organic Foods Production Act of 1990 and NOP regulations specifically prohibit the use of any synthetic substance in organic production and handling unless the synthetic substance is on the National List.

The NOP must receive comments by July 5, 2011 to be considered during final rulemaking. Parties can view the docket and submit comments by visiting http://www.regulations.gov (search for keyword/ID AMS-NOP-10-0078; NOP-09-03).

For further information, contact Melissa Bailey, Ph.D., Director, Standards Division, telephone (202) 720-3252; fax (202) 205-7808.