Rice farmers in Arkansas, Missouri, Mississippi, Louisiana, Texas and California have sued Bayer CropScience, alleging its genetically modified rice has contaminated the crop. The farmers alleged that the unit of Germany's Bayer AG failed to prevent its genetically modified rice, which has not been approved for human consumption, from entering the food chain. As a result, they said, Japan and the European Union have placed strict limits on U.S. rice imports and U.S. rice prices have dropped dramatically. U.S. agriculture and food safety authorities learned on July 31 that Bayer's unapproved rice had been found in commercial bins in Arkansas and Missouri. While the United States is a small rice grower, it is one of the world's largest exporters, sending half of its crop to foreign buyers. Japan, the largest importer of U.S. rice, suspended imports of U.S. long-grain rice a week ago. U.S. rice growers are responsible for about 12 percent of world rice trade.