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REVIEW ARTICLE

Composition of e-cigarette aerosols: A review and risk assessment of selected compounds

Jonathan Heywood

Corresponding Author

Jonathan Heywood

Paustenbach and Associates, Denver, Colorado, USA

Insight Exposure & Risk Sciences Group, Boulder, Colorado, USA

Correspondence

Jonathan Heywood, Insight Exposure & Risk Sciences Group, 1790 38th Street, Suite 201, Boulder, CO, USA.

Email: [email protected]

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Grayson Abele

Grayson Abele

Paustenbach and Associates, Denver, Colorado, USA

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Blake Langenbach

Blake Langenbach

Paustenbach and Associates, Denver, Colorado, USA

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Sydney Litvin

Sydney Litvin

Paustenbach and Associates, Denver, Colorado, USA

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Sarah Smallets

Sarah Smallets

Paustenbach and Associates, Denver, Colorado, USA

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Dennis Paustenbach

Dennis Paustenbach

Paustenbach and Associates, Jackson, Wyoming, USA

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First published: 15 August 2024

Jonathan Heywood and Dennis Paustenbach contributed equally.

Funding information: This work received no external funding.

Abstract

The potential harms and benefits of e-cigarettes, or electronic nicotine delivery systems (ENDS), have received significant attention from public health and regulatory communities. Such products may provide a reduced risk means of nicotine delivery for combustible cigarette smokers while being inappropriately appealing to nicotine naive youth. Numerous authors have examined the chemical complexity of aerosols from various open- and closed-system ENDS. This body of literature is reviewed here, with the risks of ENDS aerosol exposure among users evaluated with a margin of exposure (MoE) approach for two non-carcinogens (methylglyoxal, butyraldehyde) and a cancer risk analysis for the carcinogen N-nitrosonornicotine (NNN). We identified 96 relevant papers, including 17, 13, and 5 reporting data for methylglyoxal, butyraldehyde, and NNN, respectively. Using low-end (minimum aerosol concentration, low ENDS use) and high-end (maximum aerosol concentration, high ENDS use) assumptions, estimated doses for methylglyoxal (1.78 × 10−3–135 μg/kg-bw/day) and butyraldehyde (1.9 × 10−4–66.54 μg/kg-bw/day) corresponded to MoEs of 227–17,200,000 and 271–280,000,000, respectively, using identified points of departure (PoDs). Doses of 9.90 × 10−6–1.99 × 10−4 μg/kg-bw/day NNN corresponded to 1.4–28 surplus cancers per 100,000 ENDS users, relative to a NNN-attributable surplus of 7440 per 100,000 cigarette smokers. It was concluded that methylglyoxal and butyraldehyde in ENDS aerosols, while not innocuous, did not present a significant risk of irritant effects among ENDS users. The carcinogenic risks of NNN in ENDS aerosols were reduced, but not eliminated, relative to concentrations reported in combustible cigarette smoke.

CONFLICT OF INTEREST STATEMENT

At the time of submission, all authors were employed by Paustenbach and Associates, a consulting firm that provides scientific advice to the government, corporations, law firms, and various scientific/professional organizations. Paustenbach and Associates has been engaged by processors or distributors of ENDS products in various litigation matters and advisory roles. No outside financial support was provided to any of the authors or Paustenbach and Associates. Dennis Paustenbach has served as an expert in ENDS litigation and may, along with others, be called upon in the future to serve as an expert in ENDS litigation. The study design, execution, results, and interpretation of the current work are the sole responsibility of the authors, and this manuscript was prepared and written exclusively by the authors, who did not receive input from counsel or any other external interests during preparation of this text.

DATA AVAILABILITY STATEMENT

There is no data associated with this manuscript.