"If you think those shopper loyalty cards weighing down your wallet or key chain are only good for special discounts, you've overlooked a completely different sort of potential benefit
Those colorful bits of bar-coded plastic also give stores a way to track your purchases that can help federal investigators hunt down the source of foodborne illness. And they can be used by the retailers to quickly let you know if food you bought has been recalled.
But there are broad differences among stores on how they use the cards to shore up food safety. And two consumers, backed by the Center for Science in the Public Interest, are putting Safeway's Club Card to the test..."