The Food and Drug Administration upgraded a recall of frozen blueberries and mixed berries sold at Publix grocery stores across the U.S. to the highest health risk level on Tuesday, according to an enforcement report. Publix on July 29 announced a recall of four varieties of frozen GreenWise organic blueberries and mixed berries sold at stores across eight states over potential E. coli contamination. The FDA is now categorizing it as a "Class 1" recall, which the agency assigns to product recalls "in which there is a reasonable probability that the use of or exposure to a violative product will cause serious adverse health consequences or death."