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Florida’s outbreak of listeria has so far led to at least one death, 22 hospitalizations and an ice cream recall since January. Humans get sick with listeria infections, or listeriosis, from eating soil-contaminated food, undercooked meat or dairy products that are raw, or unpasteurized. Listeria can cause convulsions, coma, miscarriage and birth defects. And it’s the third leading cause of food poisoning deaths in the U.S.
Avoiding unseen food hazards is the reason people often check the dates on food packaging. And printed with the month and year is often one of a dizzying array of phrases: “best by,” “use by,” “best if used before,” “best if used by,” “guaranteed fresh until,” “freeze by,” and even a “born on” label applied to some beer.
People think of them as expiration dates, or the date at which a food should go in the trash. But the dates have little to do with when food expires, or becomes less safe to eat. I am a microbiologist and public health researcher, and I have used molecular epidemiology to study the spread of bacteria in food. A more science-based product dating system could make it easier for people to differentiate foods they can safely eat from those that could be hazardous.