E.coli outbreak linked to romaine lettuce has revived concerns over a leafy green industry that has long grappled with how to produce safe food. The U.S. Food and Drug Administration said that it is still looking for the lettuce source. The FDA said it isnt clear at what point in the supply chain the whole-head lettuce was contaminated. Blockchain, which we have discussed in several recent posts, may be one answer to the problem of the multi-state E. coli outbreak.”]