About Flavoring-related Lung Disease

Overview

Diacetyl and its substitute, 2,3-pentanedione (acetyl propionyl), are flavoring chemicals used in food flavoring and production industries. These include microwave popcorn, bakery mix, and flavored coffee industries.

Workplace exposure to diacetyl has been associated with severe respiratory impairment and a lung disease called obliterative bronchiolitis. The disease is also called constrictive bronchiolitis and bronchiolitis obliterans. This serious lung disease causes scarring and constriction in the smallest airways of the lung called bronchioles, blocking air movement. Obliterative bronchiolitis cannot be cured. The chemical 2,3-pentanedione is chemically similar and has had similar respiratory effects in animal studies.

The U.S. Food and Drug Administration has evaluated flavoring chemicals and determined they are "generally recognized as safe" to eat. However, workers can be exposed to flavoring chemicals in different ways and quantities than the general consumer. They can be harmful for food and chemical industry workers who breath air contaminated with these chemicals.

Much remains unknown about flavoring-related chemicals. Identifying which specific substances contribute to flavorings-related lung disease is challenging. Flavoring mixtures are complex and health data for many chemicals are unavailable. The flavorings industry has estimated over a thousand flavoring chemicals can potentially be respiratory hazards.

Employers, safety professionals, and workers should take steps to prevent working conditions and practices that place workers at risk.

Research

NIOSH has led research on the occupational impacts of flavorings and recommendations. The first observation of obliterative bronchiolitis in a food production employee may have occurred in 1985. It was in a facility where diacetyl was listed among ingredients used in making flavorings for the baking industry.

In August 2000, a health department requested NIOSH assistance to investigate obliterative bronchiolitis in former workers of a microwave popcorn plant. This led to further NIOSH research that found artificial butter flavorings added to the popcorn caused disease. Findings from NIOSH investigations in microwave popcorn and flavorings manufacturing industries provided a basis for the 2004 NIOSH Alert: Preventing Lung Disease in Workers Who Use or Make Flavorings. A Summary Sheet is also available in Spanish.

In 2016, NIOSH published a criteria document that provides critical review of scientific and technical information on:

• Prevalence or frequency of hazards
• Existence of health risks
• Methods to identify and control exposure

The document also provides recommended exposure limits for diacetyl and 2,3-pentanedione.