Bronchiolitis obliterans

Bronchiolitis obliterans, or Constrictive bronchiolitis, one form of which is called Popcorn Workers' Lung or popcorn lung, is a rare and life-threatening form of fixed obstructive lung disease in which the bronchioles are plugged with granulation tissue.

Bronchiolitis means inflammation of the bronchioles and Obliterans refers to the fact that the inflammation of the bronchioles partially obliterates the airways.

There is no consensus classification scheme for bronchiolitis subtypes. One author describes four specific subtypes as follows:

• cellular bronchiolitis
• respiratory bronchiolitis
• bronchiolitis obliterans
• bronchiolitis obliterans with intraluminal polyps (proliferative bronchiolitis obliterans).

In addition, because of similar names, Bronchiolitis obliterans is sometimes confused in the public mind with bronchiolitis obliterans organizing pneumonia (BOOP), a completely different pulmonary disorder.

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Etiology

Bronchiolitis obliterans has many possible causes, including: collagen vascular disease, transplant rejection in organ transplant patients, viral infection (RSV, adenovirus, PCP, HIV, CMV), drug reaction, aspiration and complications of prematurity (bronchopulmonary dysplasia), and exposure to toxic fumes, including: diacetyl, sulfur dioxide, nitrogen dioxide, ammonia, chlorine, thionyl chloride, methyl isocyanate, hydrogen fluoride, hydrogen bromide, hydrogen chloride, hydrogen sulfide, phosgene, polyamide-amine dyes, and ozone. Additionally, the disorder may be idiopathic (without known cause). ^[1][2][5]

Presentation

Bronchiolitis obliterans is a lung disease characterized by fixed airway obstruction. Inflammation and scarring occur in the airways of the lung, resulting in severe shortness of breath and dry cough.

Standard lung capacity is normally around 80% lung usage. Bronchiolitis obliterans reduces this to 16% to 21%.

Symptoms include:

• dry cough
• shortness of breath
• wheezing

The symptoms can start gradually, or severe symptoms can occur suddenly. ^[3]

Diagnosis

Bronchiolitis obliterans is often misdiagnosed as asthma, bronchitis, emphysema, or pneumonia.

Diagnosis may include the following tests:

• Chest X-rays tests.
• Diffusing capacity of the lung (DLCO) tests are usually normal.
• Spirometry tests show fixed airway obstructions and sometimes restriction.
• Lung Volume tests may show hyperinflation (excessive air in lungs caused by air trapping).
• High-resolution computerized tomography scans of the chest at full inspiration and expiration may reveal heterogeneous air trapping on the expiratory view as well as haziness and thickened airway walls.
• Lung biopsies may reveal evidence of constrictive bronchiolitis obliterans (i.e., severe narrowing or complete obstruction of the small airways). An open lung biopsy, such as by thoracoscopy, is more likely to be diagnostic than a transbronchial biopsy. Special processing, staining, and review of multiple tissue sections may be necessary for a diagnosis]. ^[4]

Prognosis/treatment

This disease is irreversible and severe cases often require a lung transplant. Evaluation of interventions to prevent bronchiolitis obliterans relies on early detection of abnormal spirometry results or unusual decreases in repeated measurements.

Industrial inhalants

There are many industrial inhalants that are known to cause various types of bronchiolitis, including Bronchiolitis obliterans. ^[5]

Industrial workers who have presented with bronchiolitis:

• nylon-flock workers ^[6]
• workers who spray prints onto textiles with polyamide-amine dyes ^[6]
• battery workers who are exposed to thionyl chloride fumes
• workers at plants that use or manufacture flavorings, e.g. diacetyl butter-like flavoring ^[3][6][7]

Popcorn Workers Lung

In rare instances, bronchiolitis obliterans may be caused by inhalation of airborne diacetyl — a chemical used to produce the butter-like flavoring in many foods such as candy, microwave popcorn and wines. This first came to public attention when eight former employees of the Gilster-Mary Lee popcorn plant in Jasper, Missouri, developed bronchiolitis obliterans. In 2000, the Missouri Department of Health called in NIOSH to make a determination of the cause, and to recommend safety measures. After surveying the plant and each patient's medical history, NIOSH recommended respiratory protection for all workers in microwave popcorn production. Due to this event, bronchiolitis obliterans began to be referred to in the popular media as "Popcorn Lung" or "Popcorn Workers Lung". ^[4][8][9]

One heavy consumer of microwaved popcorn has been diagnosed with this disease, which is the first known case involving a consumer. ^[13]

On August 27, 2007, Weaver Popcorn Company of Indianapolis promised to replace the diacetyl butter flavor ingredient in Pop Weaver popcorn with another flavoring.^[14].

In September 2007, Dr. Cecile Rose, pulmonary specialist at Denver's National Jewish Medical and Research Center, warned federal agencies that consumers, not just flavoring or food factory workers, may be in danger of contracting bronchiolitis obliterans. David Michaels, of the George Washington University School of Public Health, first published Rose's warning letter on his blog. ^[10][11][12]

On September 4, 2007, the Flavor and Extract Manufacturers recommended reduction of diacetyl in butter-like flavorings. The next day ConAgra Foods announced that it would soon remove diacetyl from its popcorn products.^[15]

See also

• Diacetyl
• Bronchiolitis obliterans organizing pneumonia

Notes

1. ^{^} Brant & Helms (1999). Fundamentals of Diagnostic Radiology. 
2. ^{^} Webb, et al (2000). High Resolution CT of the Lung, 3rd Edition. 
3. ^{^} Center for Disease Control (2002). Fixed obstructive lung disease in workers at a microwave popcorn factory, 7th Edition. 
4. ^{^} National Institute for Occupational Safety and Health. Preventing lung disease in workers who make or use flavorings, 2004
5. ^{^}  Colby, T.V. "Bronchiolitis, Pathologic Considerations". Am J Clin Pathology 1998;109:101-9
6. ^{^} National Institutes of Health. Haz-Map; Information on Hazardous Chemicals and Occupational Diseases by Jay A. Brown, M.D., M.P.H.
7. ^{^} California Department of Health Services
8. ^{^} E. Neil Schachter. "Popcorn Workers' Lung". New England Journal of Medicine 2002;347(5):360-1.
9. ^{^} David Egilman (2007). "Popcorn Workers Lung"
10. ^{^}  "Doctor warns consumers of popcorn fumes", Marcus Kabel, Associated Press, September 5, 2007, hosted by Yahoo! News, retrieved 2007-09-10.
11. ^{^}  Letter from Cecile Rose to U.S. Food and Drug Administration, from www.defendingscience.org
12. ^{^}  David Michaels (2007). Popcorn Lung Coming to Your Kitchen? The FDA Doesn’t Want to Know, a blog post at thepumphandle.wordpress.com
13. ^{^} Reuters New Report: FDA to probe popcorn link in man's lung disease.
14. ^{^}  Weaver Popcorn Company Press Release: "Pop Weaver Introduces First Microwave Popcorn With Flavoring Containing No Diacetyl", 2007-08-27, hosted at PRNewswire.com. "Pop Weaver introduces first microwave popcorn with flavoring containing no diacetyl"PDF (216 KiB).
15. ^{^}  USA Today. ConAgra to drop popcorn chemical linked to lung ailment
16. ^{^} Popcorn Lung linked to Mesothelioma

References

• Brant & Helms. Fundamentals of Diagnostic Radiology LWW, 1999.
• Webb, et al. High Resolution CT of the Lung. 3rd edition. LWW, 2000.
• Harber, Philip; Saechao, Kaochoy; & Boomus, Catherine. Diacetyl-induced lung Toxicological Reviews 2006;vol 25(4):261-72.