Microbiologist Mi Kang works to identify a strain of E. coli from a specimen in a lab at the Washington State Department of Health on Tuesday in Shoreline, Wash. Elaine Thompson/AP hide caption

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Chipotle restaurant workers fill orders for customers in Miami, Fla., on April 27, 2015, the day that the company announced it will only use non-GMO ingredients in its food. Joe Raedle/Getty Images hide caption

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Waiting in line for an exhibit at the Chipotle Cultivate Festival on factory farming. Festivalgoers had to visit four such exhibits to get a free burrito. Peggy Lowe/Harvest Public Media hide caption

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Chipotle's announcement that it has removed all GMOs from its menu items is part of a growing food industry trend. From left: Nestle chocolates, Chipotle tortillas, Diet Pepsi, Kraft Macaroni & Cheese Dinner, a Subway sandwich. All of these companies have dropped ingredients over the past year in response to consumer demands. Meredith Rizzo/NPR; iStockphoto; PepsiCo; iStockphoto; iStockphoto hide caption

toggle caption Meredith Rizzo/NPR; iStockphoto; PepsiCo; iStockphoto; iStockphoto

Workers prepare burritos at a Chipotle Mexican Grill in New York. The restaurant chain has stopped serving pork in about one-third of its U.S. locations. Richard Levine/Demotix/Corbis hide caption

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Chipotle Mexican Grill launched The Scarecrow, an arcade-style adventure game for iPhone, iPad and iPod touch. Business Wire hide caption

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The antibiotic-free pigs roam freely on Niman Ranch in Iowa. Sarah Willis/courtesy Niman Ranch hide caption

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