Vaping linked to bronchiolitis in Canadian youth, implicating the flavoring diacetyl

The recent paper “Life-threatening bronchiolitis related to electronic cigarette use in a Canadian youth” provides a very well documented case report of a 17 year old youth who developed serious lung disease, likely from vaping.

Unlike the cases of EVALI that have been attracting a lot of attention in the US, the authors make a good case that this young man developed bronchiolitis obliterans, a rare form of serious lung disease also known as “popcorn lung” because it was first identified among workers in a factory making microwave popcorn. 

What’s the connection?  Microwave popcorn is often flavored using diacetyl to give it a buttery flavor.  While fine to eat, it seriously damages lungs.  Diacetyl is a widely used flavoring agent in e-cigarettes.

Diacetyl causes different problems that vitamin E acetate, which has been identified as one likely casue of EVALI.

This case adds to the evidence that FDA and other regulators need to regulate the actual flavoring agents in e-cigarettes and other tobacco products.  The whole discussion to date has been about what the law calls characterizing flavors, namely whether a product is marketed as flavored.  For example, the law bans characterizing flavors like licorice in cigarettes – so you can’t sell a cigarette as a licorice cigarette – but licorice remains a widely used ingredient in cigarettes.

Simon Landman and his coauthors also have an excellent summary of 46 case studies of vaping-related lung illness dating back to 2012.  They detail 18 different kinds of lung disease patterns in these cases, pointing to the fact that e-cigarettes damage the lungs in many different ways, a finding consistent with the biological evidence that e-cigarettes adversely affect many aspects of lung function.

This issue is especially important because of the Trump Administration’s capitulation to the tobacco companies over flavors.

Here is the abstract:

BACKGROUND: Although electronic cigarettes (e-cigarettes) were initially marketed as a potential smoking-cessation aid and a safer alternative to smoking, the long-term health effect of e-cigarette use ("vaping") is unknown. Vaping e-liquids expose the user to several potentially harmful chemicals, including diacetyl, a flavouring compound known to cause bronchiolitis obliterans with inhalational exposure ("popcorn worker's lung").

CASE DESCRIPTION:  We report the case of a 17-year-old male who presented with intractable cough, progressive dyspnea and malaise after vaping flavoured e-liquids and tetrahydrocannabinol intensively. Initial physical examination showed fever, tachycardia, hypoxemia, and bibasilar inspiratory crackles on lung auscultation. Computed tomography of the chest showed diffuse centrilobular "tree-inbud" nodularity, consistent with acute bronchiolitis. Multiple cultures, including from 2 bronchoalveolar lavage samples, and biopsy stains, were negative for infection. He required intubation, invasive mechanical ventilation and venovenous extracorporeal membrane oxygenation (ECMO) for refractory hypercapnia. The patient's condition improved with high-dose corticosteroids. He was weaned off ECMO and mechanical ventilation, and discharged home after 47 days in hospital. Several months after hospital discharge, his exercise tolerance remained limited and pulmonary function tests showed persistent, fixed airflow obstruction with gas trapping. The patient's clinical picture was suggestive of possible bronchiolitis obliterans, thought to be secondary to inhalation of flavouring agents in the e-liquids, although the exact mechanism of injury and causative agent are unknown.

INTERPRETATION: This case of severe acute bronchiolitis, causing near-fatal hypercapnic respiratory failure and chronic airflow obstruction in a previously healthy Canadian youth, may represent vaping-associated bronchiolitis obliterans. This novel pattern of pulmonary disease associated with vaping appears distinct from the type of alveolar injury predominantly reported in the recent outbreak of cases of vaping-associated pulmonary illness in the United States, underscoring the need for further research into all potentially toxic components of e-liquids and tighter regulation of e-cigarettes.

The full citation is: Landman ST, Dhaliwal I, Mackenzie CA, Martinu T, Steele A, Bosma KJ.   Life-threatening bronchiolitis related to electronic cigarette use in a Canadian youth.  CMAJ. 2019 Dec 2;191(48):E1321-E1331. doi: 10.1503/cmaj.191402. Epub 2019 Nov 20.  It is available here.