USDA can't pinpoint how biotech rice taint occurred

WASHINGTON (Reuters) - A lengthy U.S. investigation failed to pinpoint how trace amounts of a biotech rice under development at a research facility made their way into two widely grown varieties of long-grain rice, Agriculture Department officials said on Friday.

The biotech rice and the commercial varieties, Cheniere and Clearfield, were grown from 1999 to 2001 at a research station in Louisiana. They were not intended to be mixed.

U.S. rice exports suffered a serious disruption at harvest time in 2006 when Bayer CropScience reported that trace amounts of its biotech rice were found in Cheniere rice. It was found in Clearfield 131 rice on February 16.

"We were not able to determine the exact mechanism" that introduced the Bayer CropScience biorice material into Clearfield and Cheniere, said Cindy Smith, head of the USDA's Animal and Plant Health Inspection Service.

No enforcement action will be taken against Bayer CropScience, she said.

During a telephone news conference, Smith said APHIS was considering stronger regulations, such as specifying how long researchers must keep records and the kinds of documents that must be kept. APHIS said it also may require greater separation of seed breeding beds and genetically engineered varieties "to reduce the likelihood of pollen flow."

A proposed regulation may be unveiled in spring 2008.

Agriculture Undersecretary Bruce Knight told reporters separately the review found "no smoking guns."

Cheniere and LLRICE601 were grown at the same time at the Rice Research Station in Crowley, Louisiana. Clearfield 131 and LLRICE604, also developed by Bayer CropScience, were grown at the station but not planted at the same time.