Nicotine, Carcinogen, and Toxin Exposure in Long-Term E-Cigarette and Nicotine Replacement Therapy Users: A Cross-sectional Study.
BACKGROUND
Given the rapid increase in the popularity of e-cigarettes and the paucity of associated longitudinal health-related data, the need to assess the potential risks of long-term use is essential.


OBJECTIVE
To compare exposure to nicotine, tobacco-related carcinogens, and toxins among smokers of combustible cigarettes only, former smokers with long-term e-cigarette use only, former smokers with long-term nicotine replacement therapy (NRT) use only, long-term dual users of both combustible cigarettes and e-cigarettes, and long-term users of both combustible cigarettes and NRT.


METHODS
Cross-sectional study.


METHODS
United Kingdom.


METHODS
The following 5 groups were purposively recruited: combustible cigarette-only users, former smokers with long-term (≥6 months) e-cigarette-only or NRT-only use, and long-term dual combustible cigarette-e-cigarette or combustible cigarette-NRT users (n = 36 to 37 per group; total n = 181).


METHODS
Sociodemographic and smoking characteristics were assessed. Participants provided urine and saliva samples and were analyzed for biomarkers of nicotine, tobacco-specific N-nitrosamines (TSNAs), and volatile organic compounds (VOCs).


RESULTS
After confounders were controlled for, no clear between-group differences in salivary or urinary biomarkers of nicotine intake were found. The e-cigarette-only and NRT-only users had significantly lower metabolite levels for TSNAs (including the carcinogenic metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol [NNAL]) and VOCs (including metabolites of the toxins acrolein; acrylamide; acrylonitrile; 1,3-butadiene; and ethylene oxide) than combustible cigarette-only, dual combustible cigarette-e-cigarette, or dual combustible cigarette-NRT users. The e-cigarette-only users had significantly lower NNAL levels than all other groups. Combustible cigarette-only, dual combustible cigarette-NRT, and dual combustible cigarette-e-cigarette users had largely similar levels of TSNA and VOC metabolites.


CONCLUSIONS
Cross-sectional design with self-selected sample.


CONCLUSIONS
Former smokers with long-term e-cigarette-only or NRT-only use may obtain roughly similar levels of nicotine compared with smokers of combustible cigarettes only, but results varied. Long-term NRT-only and e-cigarette-only use, but not dual use of NRTs or e-cigarettes with combustible cigarettes, is associated with substantially reduced levels of measured carcinogens and toxins relative to smoking only combustible cigarettes.


BACKGROUND
Cancer Research UK.
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Lion
L
Shahab
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Maciej L
ML
Goniewicz
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Benjamin C
BC
Blount
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Jamie
J
Brown
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Ann
A
McNeill
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
K Udeni
KU
Alwis
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
June
J
Feng
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Lanqing
L
Wang
From University College London and King's College, London, United Kingdom; Roswell Park Cancer Institute, Buffalo, New York; and Centers for Disease Control and Prevention, Atlanta, Georgia.
Robert
R
West
D000328:Adult; D015415:Biomarkers / Q000032:analysis / Q000652:urine; D002273:Carcinogens / Q000032:analysis*; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D009538:Nicotine / Q000032:analysis* / Q000652:urine; D009602:Nitrosamines / Q000032:analysis / Q000652:urine; D027544:Salvia / Q000737:chemistry; D016540:Smoking Cessation / Q000379:methods; D013997:Time Factors; D061485:Tobacco Use Cessation Devices / Q000009:adverse effects*; D055549:Volatile Organic Compounds / Q000032:analysis / Q000652:urine
D015415:Biomarkers; D002273:Carcinogens; D009602:Nitrosamines; D055549:Volatile Organic Compounds; D009538:Nicotine