Sherman Packaged Walnuts is pictured in this undated handout photo courtesy of the U.S. Food and Drug Administration. Two U.S. food companies this week, Sherman Produce Co and Lansal Inc, issued ... more 
Sherman Packaged Walnuts is pictured in this undated handout photo courtesy of the U.S. Food and Drug Administration. Two U.S. food companies this week, Sherman Produce Co and Lansal Inc, issued voluntary recalls of walnuts and hummus dips sold at major retailers after listeria was detected in a sampling of the products, the Food and Drug Administration said on May 22, 2014. REUTERS/U.S. Food and Drug Administration/Handout via Reuters (UNITED STATES - Tags: FOOD HEALTH) ATTENTION EDITORS - FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS less 
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Reuters | Photo By HANDOUT / Reuters
Thu, May 22, 2014 2:12 PM EDT