The agency's Animal and Plant Health Inspection Service (APHIS) yesterday announced the minute levels of regulated genetic material found in Clearfield 131 (CL131) rice seed has been identified as LLRICE604.
The findings come after the regulatory agency launched an investigation into the contamination of CL131, a long-grain rice seed from BASF, because it was suspected to contain genetic material not yet approved for commercialization.
Earlier this month, APHIS issued 'emergency action notifications' to inform distributors of the seed, which had been scheduled for planting this spring, that it must be held until the agency concludes its investigation.
Tests conducted at USDA laboratories as part of the investigation revealed that the rice had been contaminated by the PAT (phosphinothricin-N-acetyltransferase) protein, contained in the LLRICE 604 variety developed by Bayer Cropscience.
"The PAT protein has been repeatedly and thoroughly scientifically evaluated and is used safely in food and feed, cultivation and breeding in the United States as well as nearly a dozen other countries around the world. APHIS has previously deregulated similar genetically engineered herbicide-tolerant products such as corn, canola and soybean," said the agency in a statement.
The US Food and Drug Administration (FDA) has previously evaluated the PAT protein for safety on a number of occasions through the Agency's voluntary biotechnology consultation process. FDA therefore concluded that the presence of rice from the LLRICE 600 series at low levels in food would pose no food or feed safety concerns.
Based on this determination, APHIS said it will not prevent movement or processing of CL131 rice from previous years.
In 1999, APHIS deregulated - or approved for commercial use - two similar herbicide tolerant rice lines, LLRICE62 and LLRICE06. The agency extended this deregulation in November 2006 to include LLRICE601.
The USDA said an investigation continues to determine the circumstances surrounding the release and whether any USDA regulations were violated.
Another GM contamination involving the LLRICE 600 series last year caused a major disruption in the US rice industry.
The contamination - involving the GMO LL Rice 601 variety - sparked a flow of reactions against the firm and the US rice export market. Such limits on rice exports had an immediate impact on US farmers, who retaliated with a flood of lawsuits against Bayer. The variety has since been approved by USDA.
However, the agency says it has not as yet received a petition from Bayer to deregulate the variety in the latest contamination case. As a result, because LLRICE604 remains a regulated article, producers will not be able to plant any CL131 seed that currently remains on hold.