Association of Vaping-Related Lung Injuries with Rates of E-Cigarette and Cannabis Use Across U.S. States

Summary of Study

Bottom line: In the US, states with higher rates of e-cigarette and cannabis use prior to the 2019 "e-cigarette or vaping product use-associated lung injury" (EVALI) outbreak had lower EVALI prevalence. These results suggest that EVALI cases did not arise from e-cigarette or cannabis use per se, but rather from locally distributed e-liquids or additives most prevalent in the affected areas.

This is the first study to assess how geographic variation in EVALI case prevalence relates to rates of vaping and cannabis use. Neither higher adult vaping rates nor higher rates of recent cannabis use predicted increased EVALI prevalence across US states. Indeed, for both variables, an increase in these behaviors was associated with a significant decrease in EVALI prevalence.

The US nicotine e-cigarette market is dominated by products from five brands. There should be a positive association between states’ rates of vaping and EVALI if major brands’ products are implicated. If cannabis per se drives the outbreak, one might expect a positive association between rates of recent cannabis use and EVALI. However, these relationships may not hold if additives in black market nicotine or THC e-liquids are responsible, as the composition of such products varies between local markets.

Mapping state EVALI cases per capita suggests a geographically concentrated cluster of high prevalence states as well as several lower prevalence areas. This variation is less consistent with use of a common, nationally available product driving the outbreak than consumption of black market or locally modified e-liquids. In fact, a half percentage point increase in the vaping rate is associated with an 11% reduction in EVALI cases per capita.

These findings are consistent with evidence linking the EVALI outbreak to vitamin E acetate and informally purchased or modified THC e-liquids, as opposed to use of well-established nicotine e-cigarettes.

Policymakers should proceed with caution when considering bans on flavored e-liquids because restricting legal sales may push some vapers towards illicit sources, user-modified e-liquids (e.g., to add flavoring), or even conventional cigarette use. Given EVALI’s potential lethality and a myriad of work suggesting that conventional cigarette use is far more dangerous than vaping nicotine, these outcomes could be disastrous for public health.

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