Each year, billions of dollars are wasted in the united states because food, drink, and drugs grow too hot or too cold during transport. Researchers at Infratab in Oxnard, CA, have developed electronic tags that track time and temperature for such perishables as vaccines and meat. Ranging in size from a postage stamp to a credit card, the battery-powered tags are programmed with data on the relationship between temperature and shelf life for specific items. Measuring the temperature every 15 minutes, a tag shows the approach of an item’s expiration date by turning a liquid-crystal display from green to yellow to red. This method is more reliable than conventional date stamps, chemical-based labels, and temperature probes mounted in trucks, says Infratab CEO Terry Myers. And retailers can access the temperature history of any tag by scanning it with a computerized radio frequency reader. Companies that ship meat, beer, and pharmaceuticals are testing the tags, which cost from several cents to several dollars each and should be commercially available within a year.