The Environmental Protection Agency is studying chemicals released into the air when a bag of microwave popcorn is popped or opened.
Exposure to vapors from butter flavoring in microwave popcorn has been linked to a rare lung disease contracted by factory workers in Missouri, Illinois, Iowa and Nebraska.
The National Institute for Occupational Safety and Health has said it suspects the chemicals insist people who microwave popcorn and eat it at home are not in danger.
In the first direct study of chemicals contained in one of the nation's most popular snack foods, the EPA's Indoor Environment Management Branch is examining the type and amount of chemicals emitted from microwave popcorn bags.
A scientist says further research would be needed to determine any health effects of those chemicals and whether consumers are at risk.