Popcorn Lung (Bronchiolitis Obliterans)

Popcorn lung is a lung condition caused by exposure to the chemical diacetyl.

Popcorn lung is a serious and irreversible condition in which the tiny air sacs in the lungs become scarred and constricted, which results in no air movement or O2 - CO2 exchange in the lungs.

Other names for popcorn lung include:

• Bronchiolitis obliterans
• Obliterative bronchiolitis

In 2004, The US Centers for Disease Control and Prevention (CDC) reported several cases of bronchiolitis obliterans in workers in a microwave popcorn plant in Missouri in 2000. After an investigation by the NIOSH (National Institute of Occupation Safety and Health), it was discovered that a flavoring agent termed diacetyl (2,3-butanedione) was used to give the popcorn a buttery taste. Inhaling this chemical flavoring likely contributed to the development of this lung disease.

More recently, a legal case was settled in Colorado for over 7 million dollars. The award was granted to a consumer who developed bronchiolitis obliterans ("popcorn lung") after eating two bags of microwaved popcorn every day for 10 years. Since workers who manufacture microwaved popcorn were at risk, the judgment stated that the popcorn manufacturers and the supermarket corporations should have realized that consumers could also be at risk of this lung disease.

It appears e-cigarettes and vaping devices (often called vapes) may potentially cause popcorn lung or a similar condition. Canadian researchers reported a  single 2019 case of a lung injury fitting the popcorn lung profile linked to marijuana and nicotine vapes. This report came on the heels of a spate of dozens of U.S. injuries and deaths linked to vitamin E acetate in marijuana-based and nicotine-based vape fluid. The outbreak, dubbed vaping lung disease, fit the profile of a different kind of condition than the Canadian case, one with different kinds of lung damage than seen in popcorn lung.

A study published in 2015 in the Journal Environmental Health Perspectives showed that harmful chemicals associated with "popcorn lung" are present in many types of flavored e-cigarettes, particularly those with flavors like fruit and candy that may appeal to young smokers. Of the 51 flavored e-cigarettes tested, flavoring chemicals were found in 47 and diacetyl specifically in 39 samples. This suggests a potentially dangerous level of exposure via e-cigarettes to chemicals that can cause severe lung damage.

Another chemical similar to diacetyl called 2,3-pentanedione also is suspected as a cause of the disease. Both diacetyl and 2,3-pentanedione are released into the air during the grinding and packaging of coffee beans. These two chemicals are members of the chemical class alpha-diketones. Other members of this chemical class may cause similar lung damage according to the CDC, but they have not yet been studied.

Other causes of popcorn lung may be due to some of the following chemicals when inhaled:

• Acetaldehyde
• Formaldehyde
• Sulfur dioxide
• Nitrogen oxides
• Chlorine
• Hydrochloric acid
• Ammonia
• Metal oxides (formed during welding)
• Mustard gas (chemical weapon)

The symptoms of "popcorn lung" are primarily cough and shortness of breath. These symptoms can develop slowly and subtly, gradually progressing to more disabling symptoms over time.

Other symptoms of popcorn lung include:

• Fevers
• Cough (may be chronic)
• Shortness of breath (especially with exercise)
• Night sweats
• Weight loss

Severe exposure to these chemicals as seen in people who work at microwave popcorn plants may include inflammation of the skin and mucosal surfaces (eyes, nose, and/or throat). In general, however, because the symptoms are so similar to tobacco-related chronic obstructive pulmonary disease (COPD) as well as asthma, the diagnosis may be difficult to make without a high level of suspicion.

The diagnosis of bronchiolitis obliterans lung begins by taking a thorough history, and additional testing is required to confirm the diagnosis. Lung function testing (spirometry), chest X-rays, and CT scans usually are done to help determine a preliminary diagnosis. Lung tissue biopsy, which often requires an open lung surgical procedure, is necessary to confirm the diagnosis of bronchiolitis obliterans.

The disease can be randomly located in lung tissue, making it difficult at times for the pathologist to make an accurate diagnosis.

The primary treatment of popcorn lung is the removal of any exposure to the diacetyl agent. Special facial coverings and respirator masks are required for workers exposed to this chemical. In some cases, the person must be removed from diacetyl exposure and the environment.

For consumers, avoiding exposure to diacetyl is essential. In some people, this will result in a gradual decrease in symptoms if the process was diagnosed early enough. Steroids, antibiotics, and oxygen may be used to treat symptoms. In others, however, the disease can progress and may even require lung transplantation.

According to the CDC, most individuals show little or no response to medical treatments for popcorn lung. However, if a person is diagnosed early and exposure to the chemicals is stopped, he or she may note a decrease or discontinuation of symptoms such as chronic cough.

Generally, people with popcorn lung have a lower life expectancy than the rest of the population. Life expectancy for bronchiolitis obliterans varies widely and depends on the severity and cause of the condition.