Maciej Goniewicz and a large team of collaborators published an extensive analysis of the biomarker data collected in the FDA/NIH PATH study. Their paper “Comparison on Nicotine and Toxicant Exposure in Users of Electronic Cigarettes and Combustible Cigarettes” reports on data collected in a large nationally-representative sample of 5105 people.

They measured a panel of 50 measures of exposure to nicotine as well carcinogens and heavy metals.

The point that e-cigarette enthusiasts will likely emphasize from the paper is that the measures of many of these toxins were lower in the e-cigarette users than the smokers. (They were also higher than in people who did not use any product, as expected.)

The most interesting and troubling finding is that the levels of 47 of the 50 chemicals were higher in the dual users (people who used both products at the same time) and 76% of the e-cigarette users were dual users (i.e., still smoking cigarettes). Of these 47, 28 were statistically significantly higher in the dual users than the people who just smoked cigarettes. (The levels of the other 3 chemicals were about the same in both groups.)

Contrary to what most people (including me) expected, the dual users and cigarette only smokers both smoked about the same number of cigarettes per day (about 15).

Thus, for most people using e-cigarettes (the dual users) unless they switch completely they would be better off if they just smoked the cigarettes.

Here are the Key Points and Abstract:

Key Points

Question Are electronic cigarette (e-cigarette) users exposed to known tobacco-related toxicants and, if so, how does the exposure compare with that of combusted tobacco cigarettes?

Findings In this population-based cohort study of 5105 participants, current exclusive e-cigarette users had greater concentrations of biomarkers of nicotine, tobacco-specific nitrosamines, volatile organic compounds, and metals compared with never tobacco users. However, these concentrations were lower than those observed in current exclusive cigarette smokers and dual users of both products.

Meaning Use of e-cigarettes appears to be associated with exposure to known tobacco-related toxicants, but the exposure is reduced compared with cigarette smoking.

Abstract

Importance Use of electronic cigarettes (e-cigarettes) is increasing. Measures of exposure to known tobacco-related toxicants among e-cigarette users will inform potential health risks to individual product users.

Objectives To estimate concentrations of tobacco-related toxicants among e-cigarette users and compare these biomarker concentrations with those observed in combustible cigarette users, dual users, and never tobacco users.

Design, Setting, and Participants A population-based, longitudinal cohort study was conducted in the United States in 2013-2014. Cross-sectional analysis was performed between November 4, 2016, and October 5, 2017, of biomarkers of exposure to tobacco-related toxicants collected by the Population Assessment of Tobacco and Health Study. Participants included adults who provided a urine sample and data on tobacco use (N = 5105).

Exposures The primary exposure was tobacco use, including current exclusive e-cigarette users (n = 247), current exclusive cigarette smokers (n = 2411), and users of both products (dual users) (n = 792) compared with never tobacco users (n = 1655).

Main Outcomes and Measures Geometric mean concentrations of 50 individual biomarkers from 5 major classes of tobacco product constituents were measured: nicotine, tobacco-specific nitrosamines (TSNAs), metals, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs).

Results Of the 5105 participants, most were aged 35 to 54 years (weighted percentage, 38%; 95% CI, 35%-40%), women (60%; 95% CI, 59%-62%), and non-Hispanic white (61%; 95% CI, 58%-64%). Compared with exclusive e-cigarette users, never users had 19% to 81% significantly lower concentrations of biomarkers of exposure to nicotine, TSNAs, some metals (eg, cadmium and lead), and some VOCs (including acrylonitrile). Exclusive e-cigarette users showed 10% to 98% significantly lower concentrations of biomarkers of exposure, including TSNAs, PAHs, most VOCs, and nicotine, compared with exclusive cigarette smokers; concentrations were comparable for metals and 3 VOCs. Exclusive cigarette users showed 10% to 36% lower concentrations of several biomarkers than dual users. Frequency of cigarette use among dual users was positively correlated with nicotine and toxicant exposure.

Conclusions and Relevance Exclusive use of e-cigarettes appears to result in measurable exposure to known tobacco-related toxicants, generally at lower levels than cigarette smoking. Toxicant exposure is greatest among dual users, and frequency of combustible cigarette use is positively correlated with tobacco toxicant concentration. These findings provide evidence that using combusted tobacco cigarettes alone or in combination with e-cigarettes is associated with higher concentrations of potentially harmful tobacco constituents in comparison with using e-cigarettes alone.

The full citation is:

Maciej L. Goniewicz, Danielle M. Smith, Kathryn C. Edwards, Benjamin C. Blount, Kathleen L. Caldwell, Jun Feng, Lanqing Wang, Carol Christensen, Bridget Ambrose, Nicolette Borek, Dana van Bemmel, Karen Konkel, Gladys Erives, Cassandra A. Stanton, Elizabeth Lambert, Heather L. Kimmel, Dorothy Hatsukami, Stephen S. Hecht, Raymond S. Niaura, Mark Travers, Charles Lawrence, Andrew J. Hyland. Comparison of Nicotine and Toxicant Exposure in Users of Electronic Cigarettes and Combustible Cigarettes. JAMA Netw Open. 2018;1(8):e185937. doi:10.1001/jamanetworkopen.2018.5937. It is available for free here.