What Is Popcorn Lung

  • Harry White Master of Science - MS, Biology/Biological Sciences, General, University of Bristol, UK

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Bronchiolitis obliterans, also known as popcorn lung, is a rare, irreversible, chronic lung disease affecting your bronchioles, which are the small airways in the lungs. People with this condition have inflamed and damaged bronchioles, which eventually become scarred. 

Scarring occurs when your body tries to regenerate tissue after damage, this can impact the original anatomy and function of the tissue or organ. For this reason, scarring from popcorn lung can negatively affect your respiratory function, making it more difficult to breathe. Although the disease cannot be cured, it is important to treat it to prevent further damage and reduce the severity of any existing symptoms.1 

Why is it called popcorn lung disease?

In the year 2000, a group of eight former employees from a microwave popcorn factory experienced the onset of an uncommon and incapacitating lung condition, now known as bronchiolitis obliterans. Because of their incapacitating disease, four of these individuals were then placed on a waiting list for lung transplantation. 

In response to this alarming pattern, a thorough investigation was initiated to explore the connections among the affected patients. Researchers found that their respiratory affliction most likely originated from a molecule present in the vapours that emanated from butter flavourings, known as diacetyl, which was part of the popcorn production process.2 As a result, diacetyl has been removed by popcorn manufacturers from popcorn flavourings.3

What causes popcorn lung?

Popcorn lung can occur in patients for a variety of reasons. Some include:1,4

As mentioned above, diacetyl was used in the past to add a buttery flavour to microwaveable popcorn. Although diacetyl is no longer used in the popcorn industry, researchers at Harvard found that 39 out of 51 e-cigarette (vape) brands used this toxic substance in the United States.5 Nonetheless, this is different in Europe, as diacetyl was banned in Europe (including the UK) from both e-cigarettes and their liquid in 2016. It is however important to note that while e-cigarettes are harmful due to containing numerous toxic molecules, they may be beneficial for some users trying to quit smoking and that there have been no confirmed cases of popcorn lung as a result of e-cigarette use.6,7

Other chemicals may contribute to developing popcorn lung when inhaled:

  • Chlorine
  • Ammonia
  • Sulfur oxides
  • Hydrochloric acid
  • Nitrogen oxides
  • Nitrogen mustard
  • Phosgene

This is because these irritants may cause lung tissue damage therefore promoting scarring of the bronchioles.8

Symptoms and diagnosis

Sometimes people with popcorn lung don’t present any symptoms in the early stages of the disease. However, these symptoms will develop over time, within a few weeks or months, and may be exacerbated when exercising. As the disease progresses, symptoms get worse and can manifest in other body parts too, such as a skin rash.9

The most common symptoms of popcorn lung include:

  • A dry cough that sometimes brings up mucus
  • Shortness of breath
  • Wheezing
  • Tiredness
  • Night sweats

Because popcorn lung shares many symptoms with other lung diseases, it is often misdiagnosed as chronic obstructive pulmonary disease (COPD), asthma, emphysema, or bronchitis. For this reason, your doctor will need a medical history and will ask about your environmental exposure. In addition, your doctor may listen to your breathing during a non-invasive physical examination. Additional non-invasive tests are often used to measure your ability to inhale and exhale air, as well as a chest X-ray or CT scan. Sometimes, even after performing these tests, the diagnosis is unclear. In these cases, a surgical lung biopsy may be needed, which is the most definitive way to diagnose this condition.10

Current treatments for bronchiolitis obliterans

Unfortunately, there is no cure for popcorn lung. However, there are treatments available to slow down disease progression and reduce the severity of your symptoms. Some of the commonly used treatments for popcorn lung include:

  • Cough suppressants
  • Corticosteroids (e.g. prednisone) can be used to suppress immune function, reducing inflammation
  • Inhaled medications (e.g. albuterol) can dilate your bronchioles and facilitate breathing
  • Oxygen therapy to heighten your blood oxygen levels
  • Lung transplantation (used in severe cases)

If the disease is caused by a toxic agent, it is imperative to avoid further exposure to prevent further damage. Patients who do not respond to any medication and whose symptoms can be life-threatening may be offered lung transplantation, although this is not often recommended due to the implicated health risks.10 In fact, one of the risks of lung transplantation is the development of popcorn lung in the newly transplanted lung.1,10

How can popcorn lung develop after a lung transplant?

In the context of a lung transplant, bronchiolitis obliterans can be a way of chronic rejection. Chronic rejection occurs when the recipient’s immune system recognises the transplanted organ as foreign and mounts an immune response against it. This immune response can lead to inflammation and scarring in the bronchioles, eventually leading to bronchiolitis obliterans. To minimise the risk of the recipient’s body rejecting the lungs, transplant recipients are normally prescribed immunosuppressants. As the name suggests, immunosuppressants suppress the immune system to prevent it from attacking the healthy transplanted lung. However, rejection can still occur in some cases.

It's important to note that the development of bronchiolitis obliterans is just one potential complication after a lung transplant, and not all transplant recipients will develop the disease.1

Can popcorn lung be prevented?

Popcorn lung can develop for a variety of reasons, including respiratory viral infections. For this reason, there is no way to fully prevent popcorn lung disease. However, the risk of developing this condition can be reduced by following several practices. Some ways in which you can do this are:

  • Using protective measures and appropriate equipment at work if your job involves exposure to any of the chemicals associated with popcorn lung disease
  • Ensuring proper ventilation of the workplace to help reduce the concentration of airborne particles and lower the risk of inhalation
  • Avoiding e-cigarettes and vaping products which may contain diacetyl, especially if you live in the U.S
  • Staying informed about the potential risks associated with certain chemicals and substances, since education can empower you to make informed choices and avoid unnecessary exposure

What to expect if you have popcorn lung

The development and progression of bronchiolitis obliterans varies on a case-by-case basis. Some patients achieve significant improvement after receiving medication, while treatment only slows down the progression of symptoms in others. However, this needs to be further investigated, since not enough research has been conducted. 

As the disease progresses, you may have an increased risk of developing other respiratory infections, such as bronchitis and pneumonia. You may also require further tests to monitor the deterioration of your lung function, as well as supplemental oxygen therapy and mechanical ventilation if symptoms are very severe and significantly affect your ability to breathe. You may be offered a lung transplant if your symptoms become life-threatening.1

FAQs

Can you live a normal life with popcorn lung?

While there is no cure for popcorn lung, there are many treatments available which help alleviate the symptoms. However, living a ‘’normal’’ life with popcorn lung can vary from person to person. The severity of symptoms and the impact on daily life can differ, depending on factors such as the disease stage, the patient’s response to treatments, and the presence of other health conditions.

How long does popcorn lung take to kick in?

The development of the disease is not immediate and varies from person to person as it depends on its causes as well as the individual’s susceptibility. In people exposed to chemicals associated with the disease (e.g. diacetyl), symptoms may appear after months or years of exposure.

Can you fully recover from popcorn lung?

While available treatments can help manage the symptoms and slow down disease progression, the scarring on the bronchioles is not reversible. For this reason, with the available treatments, it is unlikely to fully recover from this condition.

Is diacetyl safe to eat?

According to the U.S. Food and Drug Administration (FDA), diacetyl is generally considered safe to eat in the amounts commonly found in food. The levels of diacetyl found in food are much lower than those that were encountered in occupational settings which led to health concerns in the 2000s.11

Is Popcorn Lung associated with the consumption of microwave popcorn?

No, you can’t get popcorn lung from consuming microwave popcorn. 

Summary

Bronchiolitis obliterans, commonly known as popcorn lung, is a rare and irreversible chronic lung disease affecting the bronchioles. The disease is characterised by inflammation, scarring, and impaired lung function. Initially identified in former microwave popcorn factory workers in the 2000s, researchers linked the condition to exposure to diacetyl, a molecule present in butter flavouring. Although diacetyl is no longer used in popcorn, some e-cigarettes in the U.S. still contain it.

Popcorn lung can develop from a variety of causes, including exposure to toxic substances, viral infections, autoimmune disorders, and having received a lung transplant. Common symptoms include a dry cough, shortness of breath, wheezing, tiredness, and night sweats. Because this condition shares symptoms with other respiratory illnesses, diagnosis can be challenging, requiring different tests.

While there is no cure for popcorn lung, treatments aim to slow disease progression and alleviate symptoms. Options include cough suppressants, corticosteroids, inhaled medication, oxygen therapy, and, in severe cases, lung transplantation.

Although this condition cannot be fully prevented, some preventative measures include workplace safety practices, proper ventilation, and avoiding exposure to harmful chemicals. It is imperative that if you have popcorn lung you take the medication prescribed by your doctor, and have your lung function monitored as your disease advances.

References

  • Krishna R, Anjum F, Oliver TI. Bronchiolitis Obliterans. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Nov 15]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK441865/
  • ‘We Were There’ - Diacetyl and Popcorn Lung Disease [Internet]. 2019 [cited 2023 Nov 15]. Available from: https://www.cdc.gov/os/wewerethere/diacetyl/index.html
  • Association AL. Popcorn Lung: A Dangerous Risk of Flavored E-Cigarettes [Internet]. [cited 2023 Nov 15]. Available from: https://www.lung.org/blog/popcorn-lung-risk-ecigs
  • Cui Z, Zhou X, Luo F, Wang J, Diao J, Pan Y. Worldwide Bronchiolitis obliterans research: A bibliometric analysis of the published literature between 2002 and 2022. Medicine (Baltimore). 2023 Jul 14;102(28):e34263.
  • Avenue 677 Huntington, Boston, Ma 02115. News. 2015 [cited 2023 Nov 15]. Chemicals linked with severe respiratory disease found in common e-cigarette flavors. Available from: https://www.hsph.harvard.edu/news/press-releases/e-cigarette-flavoring-chemicals-linked-to-respiratory-disease/
  • Ebersole J, Samburova V, Son Y, Cappelli D, Demopoulos C, Capurro A, et al. Harmful chemicals emitted from electronic cigarettes and potential deleterious effects in the oral cavity. Tob Induc Dis. 2020 May 8;18:41.
  • Cancer Research UK [Internet]. 2018 [cited 2023 Nov 15]. Does vaping cause popcorn lung? Available from: https://www.cancerresearchuk.org/about-cancer/causes-of-cancer/does-vaping-cause-popcorn-lung
  • Kerger BD, Fedoruk MJ. Pathology, toxicology, and latency of irritant gases known to cause bronchiolitis obliterans disease: Does diacetyl fit the pattern? Toxicol Rep. 2015 Nov 2;2:1463–72.
  • Cleveland Clinic [Internet]. [cited 2023 Nov 15]. Popcorn Lung: Causes, Symptoms, Treatment & Is It Real. Available from: https://my.clevelandclinic.org/health/diseases/22590-popcorn-lung-bronchiolitis-obliterans
  • Association AL. Bronchiolitis Obliterans (Popcorn Lung) Symptoms, Diagnosis and Treatment [Internet]. [cited 2023 Nov 15]. Available from: https://www.lung.org/lung-health-diseases/lung-disease-lookup/popcorn-lung/symptoms-diagnosis-treatment
  • CFR - Code of Federal Regulations Title 21 [Internet]. [cited 2023 Nov 16]. Available from: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1278&SearchTerm=diacetyl

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Gabriel Aurelio Ortega Toledo

Immunology degree - Bsc (Hons), Immunology, Biology, The University of Edinburgh

Gabriel is a recent graduate with a BSc in Immunology from the University of Edinburgh. While his academic foundation lies in immunology, his professional focus has expanded into the domains of education, media, and science communications. Gabriel has actively participated in various facets of medical research, contributes to a biology podcast, and collaborates with an autoimmune disease charity as a patient interviewer. His enthusiasm for medical writing stems from a profound interest in healthcare science, a commitment to simplifying complex data, and a genuine passion for connecting with people.

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