The Environmental Protection Agency has been withholding the results of a 2003 study that may indicate potential health risks from inhaling artificial butter flavor vapors from microwave popcorn, a group of scientists and former Occupational Safety and Health Administration officials say.
          Some workers at microwave popcorn factories have been diagnosed with a rare and fatal lung disease -- dubbed "popcorn workers' lung" -- and several of them are on lung transplant lists.
          The disease, bronchiolitis obliterans, is a serious and irreversible inflammation of the airways leading to the lungs. Studies in toxicology journals have linked diacetyl -- a common food flavoring and main ingredient of artificial butter flavoring -- to disease in laboratory animals.
The EPA will not release the study's findings until an internal review is completed, which may be submitted for publication in the fall, said EPA spokeswoman Suzanne Ackerman.