Artificial Butter Flavoring Diacetyl Does Harm Lung

The delicious flavor of microwave popcorn... who isn't enticed to take a deep breath to inhale it? But the sweet buttery aroma is a result of an additive, an artificial butter flavoring called diacetyl. It has long been understood that diacetyl can cause what is more commonly known as "popcorn lung," a particular type of lung disease primarily affecting popcorn factory workers. More recently, the disease has also been diagnosed in a long-term high-volume consumer of microwave popcorn (AC reported). This led medical experts to believe consumers could be at risk as well. Still, the actual scientific proof was missing. Now scientists at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health, have conducted a study that found proof: Diacetyl is a toxin and indeed harmful to the lungs and respiratory system.

"Popcorn lung" is known in the medical community as "bronchiolitis obliterans." It is a severe and irreversible lung disease. Patients experience inflammation and scarring due to granulation tissue that plugs the bronchioles in the lung. If the disease has progressed to critical levels, only a lung transplant can save the patient.

The use of diacetyl is approved by the Federal Food and Drug Administration (FDA) as an artificial food additive. However, since a link between the exposure of the diacetyl fumes and the development of bronchiolitis obliterans in popcorn factory workers has become known, consumers have become concerned. Even though the scientific proof was missing that officially links diacetyl to "popcorn lung", microwave popcorn manufacturers have made an effort to reduce their workers' exposure to this substance and to reduce the amount of diacetyl used in flavoring the popcorn. Some microwave popcorn manufacturers are looking for alternatives to flavor their popcorn products.

As it turns out, these measures should be taken quickly as scientists have now found evidence that diacetyl is indeed harmful to the lungs and respiratory system. The NIEHS study was conducted on laboratory mice, but the results are deemed relevant to human health as well.

The scientists determined that the mice, after a three months exposure to diacetyl vapors, developed lymphocytic bronchiolitis. While lymphocytic bronchiolitis can develop into "popcorn lung," the mice were never diagnosed with bronchiolitis obliterans. The scientists point out this might be due to the fact that anatomical differences between human and mice make it more difficult for the toxic vapors to reach deep into the lungs of mice. However, lesions were found, when a method was used to develop the vapors further inside the mice's lungs.

Further studies are needed to exactly determine how the toxic vapors cause the disease and to see whether a less concentrated exposure to the diacetyl vapors will lead to similar results. The original study only exposed the mice to levels of the diacetyl vapors comparable to those found in popcorn factories.

Plans are being made for a larger set of studies to compile inhalation toxicity data on artificial butter flavoring. The studies will not only focus on diacetyl, but also on acetoin, another major flavoring component. Ideally, the toxic components will be identified. The NIEHS want to be able to set safe exposure levels for consumption as well as at the production level.