Myth: Microwave bags leave toxic chemicals on popcorn.

Reality: A 2004 report from the National Institute for Occupational Safety and Health linked diacetyl, a chemical used in butter flavorings in microwave popcorn, to respiratory illnesses found in factory workers who mixed them. Researchers suspected that when inhaled over extended periods, the butter-flavoring vapors become hazardous. According to the EPA, however, the flavorings pose no threat to consumers. Microwave popcorn was in the press again in 2005, when the FDA looked at the PFOA in microwave-popcorn packaging and found that it migrates from the bag into the oil during heating. Later that year, though, the FDA declared that exposure negligible and not a safety hazard.

Bottom Line: It’s probably fine to nuke popcorn, but if you need more certainty, pop your corn in a covered pot on the stove or with an air popper.