Diacetyl – It Smells Like Butter, But It’s Bad for the Lungs

Diacetyl is an artificial flavoring that smells like butter. It is used to give food products such as popcorn, chips, candies, and pastries a buttery taste. Workers in facilities that use or produce food flavorings may breathe vapors, dusts, or mists containing diacetyl. This puts them at risk of developing bronchiolitis obliterans, a serious and irreversible lung disease that can lead to lung transplants and death.

Bronchiolitis obliterans is characterized by inflammation and scarring in the smallest airways of the lungs. Symptoms of the disease include a persistent cough, shortness of breath upon exertion, and wheezing. Symptoms are typically mild at first and gradually become worse. Sometimes, however, severe symptoms can occur suddenly.

Other health effects associated with diacetyl exposure include irritation of the eyes, nose, and throat from breathing the vapors. These vapors can even cause chemical burns to the eyes. Skin contact with diaceytl can cause irritation and dermatitis, an inflammation of the skin characterized by redness, flaking, and cracking.

Cal/OSHA has instituted a special emphasis program to monitor workers and provide information to employers on how to minimize diacetyl exposure. There are approximately 30 flavoring manufacturers in the state who have been identified by Cal/OSHA as using diacetyl as an ingredient in their products. Many more food manufacturers use these flavorings. Currently, there are no exposure standards for diacetyl, but some unions, with the support of physicians and scientists, have petitioned Cal/OSHA and Federal OSHA for emergency regulations.

To reduce exposure to diacetyl, recommendations by the National Institute for Occupational Safety and Health (NIOSH) and the California Department of Health Services include:

• Substitution. Use flavorings known to be less hazardous, if possible. Alternatively, use flavoring formulations designed to release less vapors or respirable powders into the air during handling.
• Engineering Controls. Use closed processes to transfer flavorings. Isolate the mixing room and other areas where flavorings are handled, and maintain these areas under negative pressure relative to the rest of the facility. Use local exhaust ventilation at sources of potential exposure. If flavorings are heated, keep the temperature as low as possible to minimize emission of chemical vapors.
• Administrative Controls. Restrict access to areas where flavorings are openly handled. Use work practices that limit the release of vapors and dusts. Keep containers tightly sealed when not in use. Maintain good housekeeping. Clean up spills promptly. Do not use compressed air for cleaning up flavorings. Use caution when cleaning tanks or containers with steam or hot water, as the heat may release more chemical vapors.
• Respiratory Protection. For routine operations, respirators may be needed until other control measures can be implemented or to supplement them. They may also be needed during maintenance activities and emergencies. At a minimum, use half-mask respirators equipped with organic vapor cartridges and particulate filters. However, in some situations, more protective respirators may be appropriate.
• Personal Protective Equipment. Chemically resistant gloves, protective clothing, and tight-fitting goggles should be worn if skin and eye protection are needed.

Medical monitoring of workers can help in early detection of the disease. This should include spirometry, a test that can measure how well a person’s lungs are functioning. Employees should have lung function testing before working with diacetyl and on a regular basis while working with the chemical.

Worker education is also important. Employees must be informed if they are working with diacetyl or other hazardous chemicals. They must be trained in the control measures that have been put in place, appropriate work practices, emergency procedures, and personal protective equipment to be used.

Review Material Safety Data Sheets (MSDS) to see if flavorings contain diacetyl. Other names for diacetyl include biacetyl, 2,3-butanedione, and 2,3-butadione. Look for its Chemical Abstract Service (CAS) number, 431-03-8. Although diacetyl may have many names, its CAS number is unique.

For more information go to www.dhs.ca.gov/ohb/hesis/hesispubs.htm and www.cdc.gov/niosh/topics/flavorings/. If you need help identifying or controlling health hazards, request an industrial hygiene consultation through State Fund’s Loss Control Department or your broker/agent.

The above evaluations and/or recommendations are for general guidance only and should not be relied upon for legal compliance purposes. They are based solely on the information provided to us and relate only to those conditions specifically discussed. We do not make any warranty, expressed or implied, that your workplace is safe or healthful or that it complies with all laws, regulations or standards.