The U.S. EPA yesterday approved for another seven years the use of a controversial bio-engineered corn that produces its own pesticide. Researchers concluded that Bt corn poses no environmental or human health risks, but environmentalists and consumer-advocacy groups have expressed fears that the long-term health effects are unknown and that the crop will lead to a new strain of resistant pests. Farmers are required to plant at least 20 percent of their corn fields with conventional varieties to discourage genetic mutations that could lead to resistance, but studies showed that nearly a third of all farmers using the corn violated that restriction last year. Elsewhere on the Frankenfood front, India is expected to approve commercial production of genetically modified foods by March.