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. 2025 Aug 22;27(9):1591-1599.
doi: 10.1093/ntr/ntaf053.

Nicotine and Toxicant Exposure among Individuals using both Combustible Cigarettes and E-cigarettes Based on Level of Product Use

Zheng Xue  1 , Eva Orr-Souza  1 , Nigar Nargis  1 , Minal Patel  1 , Tyler Nighbor  1
Affiliations

Nicotine and Toxicant Exposure among Individuals using both Combustible Cigarettes and E-cigarettes Based on Level of Product Use

Zheng Xue et al. Nicotine Tob Res. .

Abstract

Introduction: Dual use of combustible cigarettes and e-cigarettes is the most common multiple tobacco-use behavior in the United States, but its long-term health impact remains unclear. Biomarkers of exposure (BOE) can help identify potential health risks of dual use.

Methods: We analyzed data from 2,679 adult participants from Wave 5 of the Population Assessment on Tobacco and Health Study, a U.S. nationally representative study, including individuals reporting current exclusive cigarette use (n = 1,913), exclusive e-cigarette use (n = 316), and dual use (n = 450). Eight subgroups were created based on self-reported high/low (above/below mean) cigarettes per day (CPD) and days of e-cigarette use in past the 30 days (ECIG). Adjusted geometric mean concentrations were compared for total nicotine equivalents, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), three volatile organic compounds (VOCs), and heavy metals (lead and cadmium).

Results: Individuals reporting dual use did not differ from those reporting exclusive cigarette use on CPD (13.1 vs. 11.8, respectively). Dual-use groups with high CPD had higher levels of NNAL and VOCs compared to those with low CPD (eg, NNAL for high CPD/high ECIG: 257.07 ng/mg creatinine vs. low CPD/high ECIG: 64.57 ng/mg creatinine, p < .001; high CPD/low ECIG: 312.02 ng/mg creatinine vs. low CPD/low ECIG: 144.11 ng/mg creatinine, p < .001). Cigarette use (dual or exclusive use) was generally associated with higher BOE than exclusive e-cigarette use, though metal exposure did not differ between groups.

Conclusions: Dual use and exclusive cigarette use are associated with higher toxicant exposure compared to exclusive e-cigarette use.

Implications: In this population-based cross-sectional study, individuals reporting dual use appear to have nicotine and toxicant exposure at least at the same level as those using cigarettes alone and higher than exclusive e-cigarette use (except for metals). Given the adverse health consequences of dual use, including potential cancer risk, our findings highlight the need for clinicians and public health practitioners to increase awareness of the potential risks associated with dual use.

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Conflict of interest statement

All authors are employed by the American Cancer Society, Inc. at the time of the study, which receives grants from private and corporate foundations, including foundations associated with companies in the health sector for research outside of the submitted work. The authors are not funded by or key personnel for any of these grants. NN has received subawards from the University of Illinois Chicago through a grant from the Bloomberg Philanthropies, outside of the submitted work. The remaining salaries of NN and the salaries of ZX, EO, MP, and TN were funded solely through American Cancer Society funds. There are no other financial disclosures to report.

Figures

Figure 1.
Figure 1.
Exposure to nicotine equivalents-2 (TNE-2) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) among individuals reporting exclusive cigarette use (high/low CPD), exclusive e-cigarette use (high/low ECIG), and dual use of combustible cigarettes and e-cigarettes (e.g, High CPD/High ECIG), PATH Wave 5, 2018-2019 (N = 2,679). Notes: The bars represent adjusted geometric means and boxes represent the 95% confidence intervals of biomarkers of exposure based on weighted multivariate regression analysis. Shared letters indicate no statistically significant difference between groups (e.g., groups sharing “a” denotes no significant difference between groups; groups with different letters, “a” and “b,” denotes a significant difference between groups). nmol/mL = nanomole per milliliter, normalized for creatinine. pg/mg creatinine = picograms per milligram, normalized for creatinine
Figure 2.
Figure 2.
Exposure to N-Acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA), N-Acetyl-S-(2-cyanoethyl)-L-cysteine (CYMA), and N-Acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA) among individuals reporting exclusive cigarette use (High/Low CPD), exclusive e-cigarette use (High/Low ECIG), and dual use of combustible cigarettes and e-cigarettes (eg, High CPD/High ECIG), PATH Wave 5, 2018-2019 (N = 2,679). Notes: The bars represent adjusted geometric means and boxes represent the 95% confidence intervals of biomarkers of exposure based on weighted multivariate regression analysis. Shared letters indicate no statistically significant difference between groups (eg, groups sharing “a” denotes no significant difference between groups; groups with different letters, “a” and “b,” denotes a significant difference between groups). ng/mg creatinine = nanograms per milligram, normalized for creatinine.
Figure 3.
Figure 3.
Exposure to urinary Cadmium (UCD) and Lead (UPB) among individuals reporting exclusive cigarette use (High/Low CPD), exclusive e-cigarette use (High/Low ECIG), and dual use of combustible cigarettes and e-cigarettes (eg, High CPD/High ECIG), PATH Wave 5, 2018-2019 (N = 2,679). Notes: The bars represent adjusted geometric means and boxes represent the 95% confidence intervals of biomarkers of exposure based on weighted multivariate regression analysis. Shared letters indicate no statistically significant difference between groups (e.g., groups sharing “a” denotes no significant difference between groups; groups with different letters, “a” and “b,” denotes a significant difference between groups). ng/mg creatinine = nanograms per milligram, normalized for creatinine.
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