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Ross Campbell
The Centers for Disease Control and Prevention in the U.S. just announced an investigation of a multistate outbreak of e-cigarette, or vaping, product use associated lung injury (EVALI). By November there were over 1,800 confirmed and probable cases and 37 deaths.1 This opens the safety of Electronic nicotine delivery systems (ENDS) to scrutiny once more.
ENDS promise to lower the risk of smoking-related disease, yet the WHO earlier this year warned against their use.2 Before rushing to judgment, let’s recap. Cancer Research UK and Public Health England both support vaping as less harmful than smoking. Thousands of smokers have used ENDS to help them quit tobacco.3 Are they all wrong?
While the pathology of vaping-associated lung injury is unknown, we do know the lungs are meant only for air. Occupational and environmental exposure to inhaled toxic compounds is known to cause lung damage. In some dramatic examples, lasting respiratory impairment has resulted from a single-event exposure.4, 5 By contrast, smokers and vapers flood their lungs continually with substances for which these delicate structures are not designed.
Findings published in 2018 linked exposure to the ENDS vapour to cancer in mice.6 Regardless of the precise initiation of the inflammatory response, consumers using ENDS might expect these devices not to be causing cancer at all. There is also evidence that e-liquids can contain potentially toxic compounds in addition to nicotine.7, 8
The WHO suggest that ENDS carry warnings to flag their potential to cause cardiorespiratory health problems, in part due to the diversity of products. Today all major tobacco firms sell ENDS, but plentiful alternatives exist with many consumers favouring e-liquids of uncertain origin and content. Of those affected in the U.S. outbreak, almost 80% reported vaping nicotine with tetrahydrocannabinol (THC) or cannabidiol (CBD) products and this link must be examined. No similar outbreak has yet been reported, which may be due to differences in regulation.9
Based on pure risk assessment principles, inhaling possibly toxic substances to the lungs must be contra-indicated. The lungs are intricate organs with a purpose that bridges pure cardiopulmonary function with a systemic one. What we put into our lungs, whether toxic or therapeutic, affects every aspect of our bodies and health. Yet as an alternative to the known harm of inhaling tobacco smoke ENDS likely represent a lesser of two evils. Since an estimated one in every two cigarette smokers die as a direct result of their habit, any form of harm reduction is to be welcomed.
Significant short-term health risks are associated with spikes in air pollution, especially toxic nitrogen oxides in diesel engine emissions. The urgent need to reduce exposure to diesel particulates forced a dramatic U-turn in transport policies worldwide.10 We haven’t yet seen research that shows similar significant short-term health risks from e-cigarettes, but care is needed to properly classify users of e-cigarettes.
The widespread concurrent use of ENDS among cigarette smokers is of concern for insurers seeking to differentiate smokers from non-smokers.11 Few never-smokers bother with e-cigarettes, but dual use compromises any health benefit and may not be associated with reduced exposure to tobacco-related health risks.12 While ENDS may be causing less harm so far, they are not harmless, and the emerging EVALI outbreak raises questions that cast serious doubt over their long-term safety.
