The announcement comes a day after a doctor at a leading lung research hospital said in a warning letter to federal regulators that consumers, not just factory workers, may be in danger from fumes from buttery flavoring in microwave popcorn.
ConAgra spokeswoman Stephanie Childs said the company decided in the past few months to remove the butter flavoring diacetyl from its popcorn because of the risk the chemical presents to workers who handle large quantities.
The chemical diacetyl has been linked to cases of bronchiolitis obliterans, a rare life-threatening disease often called popcorn lung.
ConAgra's announcement comes a week after another popcorn manufacturer, Weaver Popcorn Co. of Indianapolis, said it would replace the butter flavoring ingredient because of consumer concern.
ConAgra doesn't know how soon it will be able to replace diacetyl with a different butter flavoring, Childs said, but the change will be made sometime over the next year.
"We've made that decision based on the knowledge for the potential risk to our employees," Childs said.
The Omaha-based company has already been making changes at its popcorn plants over the past few years to reduce employee exposure to diacetyl, she said.
But the company doesn't believe diacetyl in popcorn represents a safety risk to consumers, Childs said.
"We're fully confident that microwave popcorn is safe for consumers in the home," she said.
It was reported Tuesday that a pulmonary specialist at Denver's National Jewish Medical and Research Center had written to federal agencies to say doctors there believe they have the first case of a consumer who developed lung disease from the fumes of microwaving popcorn several times a day for years.
Dr. Cecile Rose sent the letter to federal health officials in July.
The first government study to look at what fumes are produced by microwaving popcorn at home is due to be published as soon as this month, the U.S. Environmental Protection Agency said Wednesday.
The two-year study by EPA researchers was completed in late 2005 and has been under wraps since then, prompting critics to charge that the agency was protecting industry interests. But an EPA spokeswoman said the delay was due to a string of requirements including scientific review, submitting the report to industry and the time it took to get into a scientific journal.
EPA spokeswoman Suzanne Ackerman said the paper was recently accepted for publication as early as this month in a major scientific journal that she would not name.
The EPA denied a Freedom of Information request last fall from The Associated Press for the report, arguing it was a draft still under review. The agency has not yet answered an AP appeal of that rejection.
Ackerman confirmed that the study had been submitted to popcorn manufacturers ahead of its release. She said that was done to let companies make sure there were no competitive secrets in the report. EPA scientists signed nondisclosure agreements with industry in return for lists of ingredients the makers use in the popcorn and the packaging.
The report, titled "Emissions from Cooking Microwave Popcorn," is not a study of the health effects of diacetyl or any other fumes on consumers. Instead, it looks at exactly what gases including diacetyl are produced in what amount when consumers make microwave popcorn at home.
The Flavor and Extract Manufacturers Association said that Rose's finding does not suggest a risk from eating microwave popcorn. The concern instead focuses on workers inhaling it in manufacturing settings, either in making the flavoring or adding it to food products ranging from popcorn to pound cakes.
The Washington, D.C.-based association has said several flavor manufacturers are either researching alternatives to diacetyl or are already marketing butter flavors free of the chemical.
The trade group said the FDA has approved the use of diacetyl as a flavor ingredient, and diacetyl occurs naturally in foods such as butter, cheese and fruits.