OSHA Releases Diacetyl Flavoring Bulletin

WASHINGTON, D.C.The U.S. Department of Labors Occupational Safety & Health Administration (OSHA) released a Safety Health Information Bulletin (SHIB) for employers and workers involved in the manufacture of flavorings in flavoring, food and beverage manufacturing about the potential health effects associated with exposure to diacetyl, a common component of butter flavoring, or its substitutes, and the techniques to limit exposure to flavoring chemicals.

According to the SHIB, diacetyl (butanedione, or 2,3-butanedione) is widely used in food and beverage flavorings, especially dairy flavors (e.g., butter, cheese, sour cream, egg, and yogurt flavors) and brown flavors (e.g., caramel, butterscotch, brown sugar, maple or coffee flavors). Certain fruit flavors (e.g., strawberry and banana) vanilla, tea, and other flavorings may also contain diacetyl. Industries that use these flavorings include candies, snack foods, prepared canned or frozen foods (especially sauces), some dairy products, bakeries, animal foods, soft drinks, and flavored cooking oils. Some foods (e.g., dairy products, such as butter, wine and beer) contain naturally occurring diacetyl.

In 2000, the Missouri Department of Health and Senior Services and the National Institute for Occupational Safety and Health (NIOSH) investigated a microwave popcorn processing plant in Jasper, MO. Nine former workers had been diagnosed with a severe lung disease called bronchiolitis obliterans. Diacetyl, a butter-flavoring chemical, was the predominant chemical isolated from air samples in the facility and the investigation concluded that there was a risk of occupational lung disease in workers who had inhalation exposure to butter flavoring Further investigations of additional microwave popcorn manufacturing facilities documented similar lung disease in workers leading NIOSH to conclude that workers exposed to butter flavorings were at risk of developing occupational lung disease, now often referred to as popcorn lung. Similar cases of occupational lung disease have been identified in workers in various flavoring manufacturing facilities in the United States, the Netherlands and the United Kingdom.

OSHA also cites a recently published study that found increased exposure to a reactive substance such as diacetyl alone or in combination with other butter flavorings likely increases the risk of obstructive lung diseases including bronchiolitis obliterans in susceptible individuals. Control of exposure to butter flavoring, including diacetyl and other airway reactive flavoring agents, for primary prevention is warranted both in regard to an eight-hour workday exposure and short-term peak exposure.

In addition to diacetyl, other volatile flavoring compounds were found in air samples during NIOSH investigations of microwave popcorn plants and flavoring manufacturing facilities. Researchers are currently investigating the role of flavoring substances, including diacetyl and its substitutes, in the development of fixed airways obstruction and bronchiolitis obliterans.

The occurrence of severe lung disease among workers exposed to diacetyl has led some manufacturers to reduce or eliminate the amount of diacetyl in some flavorings, foods, and beverages and use substitutes such as acetyl propionyl (2,3 pentanedione) and acetoin. These substitutes, some of which are structurally similar to diacetyl, have not been well-studied and OSHA has growing concern that they also pose health risks when inhaled, especially when used in combination with other flavoring chemicals.

OSHA has not established permissible exposure limits (PELs) for most flavoring substances, including diacetyl and acetoin. The SHIB provides recommendations for controlling exposure to diacetyl, diacetyl substitutes and other flavorings to protect employees from developing serious respiratory disease. According to OSHA, this SHIB is not a standard or regulation, and it creates no new legal obligations, but contains recommendations to protect workers and descriptions of relevant mandatory safety and health standards. The recommendations are advisory in nature, informational in content, and are intended to assist employers in providing a safe and healthful workplace. To accompany the publication of SHIB10-14-2010, OSHA also released a new single-page Worker Alert: Diacetyl and Substitutes to use as a workplace posting.