Cattle graze in a field near Sacramento, Calif. California Gov. Jerry Brown, along with many health advocacy groups, has called the overuse of antibiotics "an urgent public health problem." Rich Pedroncelli/AP hide caption

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Chipotle restaurant workers fill orders for customers. The company is now sourcing some of its pork from a British supplier that uses antibiotics to treat pigs when ill. Gail Hansen, a veterinarian and longtime critic of antibiotic overuse on farms, welcomes this shift in Chipotle's stance on the drugs. Joe Raedle/Getty Images hide caption

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Why Chipotle's Hard Line On Swine Antibiotics Is Now Blurry

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The European Union banned the use of antibiotics to boost animals' growth in 2006. At first, the ban had little effect on the amount of drugs given to pigs. Carsten Rehder/Corbis hide caption

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Piglets in a pen on a hog farm in Frankenstein, Mo. Jeff Roberson/AP hide caption

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Antibiotic Use On The Farm: Are We Flying Blind?

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Craig Rowles tends to his pigs in a barn near Carroll, Iowa. Dan Charles/NPR hide caption

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Are Antibiotics On The Farm Risky Business?

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Organic apples hang from trees in an orchard in Forest Range, Adelaide Hills, South Australia. donkeycart/via Flickr hide caption

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