OMAHA, Neb. (AP) - The nation's largest microwave popcorn maker says it will change the recipe for its Orville Redenbacher and Act II brands over the next year to remove a flavoring chemical linked to a lung ailment in popcorn plant workers.

The decision by ConAgra Foods comes after it was revealed that a leading lung research hospital had written federal regulators to warn that consumers may also be in danger from fumes from the buttery flavoring.

A ConAgra spokeswoman says the company decided to remove the butter flavoring from its popcorn because of the risk the chemical presents to workers who handle large quantities. The chemical has been linked to cases of a rare life-threatening disease often called popcorn lung.

Last week, Weaver Popcorn said it would replace the butter flavoring ingredient because of consumer concern.