A report from the FDA indicates that a chemical coating used in microwave popcorn bags breaks down when heated into a substance called perfluorooctanoic (PFOA). The Environmental Protection Agency has identified PFOA as a “likely carcinogen.” Another study has found an acid that can be extracted from the chemical causes cancer in animals and is “likely to cause cancer in humans.”
A second potential danger in microwave popcorn is diacetyl, an FDA-approved chemical found in the fake butter flavoring. There’s even a debilitating respiratory disease called “popcorn workers lung,” (the medical name of the condition is bronchiolitis obliterans) suffered by microwave popcorn factory workers caused by extended inhalation of the chemical’s fumes. The National Institute for Occupational Safety and Health, (NIOSH) concluded that diacetyl needs further study so that workers in the flavorings and snack industry are no longer at risk
The Food and Drug Administration continues to study whether consumers can develop lung disease from inhaling diacetyl. In response to the concerns regarding the risks of diacetyl exposure, a number of microwave popcorn manufacturers have discontinued using it in their products.