Stung by lawsuits, consumer complaints and politicians' calls for action, many food producers have stopped using a flavoring additive that's been linked to a debilitating, irreversible lung condition found in workers at popcorn factories. It turns out, though, that some of the chemicals used in place of the additive, diacetyl, might be just as dangerous - if not more so. Diacetyl has long been used to give microwave popcorn and other foods a buttery flavor. Preliminary studies suggest that one popular substitute, 2,3-pentanedione, causes the same tissue damage, say researchers at the National Institute for Occupational Safety and Health, or...