Rejecting entreaties from consumers and activists, Wal-Mart Stores Inc. says it has no objection to selling a new crop of genetically modified sweet corn created by biotech giant Monsanto. Environmental and health activists expressed surprise and disappointment at Wal-Mart's decision. Earlier this year, Whole Foods, Trader Joe's and General Mills said they would not carry or use the genetically modified sweet corn. A lot of people who were their customers explicitly said we don't want you to carry this product, and I think it's unfortunate that they chose not listen to that feedback," said Patty Lovera, assistant director of the consumer group Food and Water Watch. In March, the group presented Wal-Mart with a petition signed by 463,000 people asking it to boycott the product, she said. Monsanto's genetically modified sweet corn is resistant to a common herbicide, which allows farmers to kill weeds without killing the corn. It also contains a toxin that fends off certain pests. Critics say they would like the U.S. Food and Drug Administration to require some pre-market safety testing and labeling of genetically modified foods, saying the lack of study makes it impossible to know whether they pose health risks. "There has been a doubling of food allergies in this country since 1996," said Michael Hansen, a senior scientist at Consumers Union, the policy arm of Consumer Reports. "Is it connected to genetically engineered foods? Who knows when you have no labeling? That is the problem."