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Abstract
Introduction Electronic nicotine delivery systems (ENDS) are known to contain heavy metals such as lead (Pb), nickel (Ni) and chromium (Cr). The presence of heavy metals in ENDS may be due to contamination of e-liquids or leaching from elements of the ENDS device. This study investigates differences in ENDS metal concentrations between product type, year of purchase, country of purchase and e-liquid flavour.
Methods Various open-system (refill e-liquids; n=116) and closed-system (prefilled with e-liquid; n=120) products were purchased in 2017 and 2018 from the USA, England, Canada and Australia. Electrothermal atomic absorption spectroscopy was used to analyse each product for Pb, Ni and Cr. Multiple linear regression and Kruskal-Wallis non-parametric statistical tests were conducted using GraphPad.
Results Linear regression showed system type, year of purchase (not supported by Kruskal-Wallis), country of purchase and flavour type each had significant impacts on heavy metal concentrations. Open-system e-liquid samples showed no quantifiable levels of heavy metals. Closed-system samples contained concerningly high concentrations of Pb, Ni and Cr. Closed-system samples from the USA commonly displayed higher average heavy metal concentrations than those from England. Some fruit and mint-flavoured closed-system products showed higher heavy metal concentrations than tobacco-flavoured products.
Conclusion The presence of heavy metals only in closed-system products suggests that metals may be leaching from ENDS device parts. Highly variable heavy metal concentrations between ENDS products demonstrate that various product characteristics may affect the degree of leaching and that there is a need for further regulation of these products.
- Electronic nicotine delivery devices
- Heavy Metals
- Public policy
Data availability statement
Data are available upon reasonable request. Data contain replicate values for sample metal concentrations. Concentrations and product images are available upon request.
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Data availability statement
Data are available upon reasonable request. Data contain replicate values for sample metal concentrations. Concentrations and product images are available upon request.
Footnotes
Contributors MLG and RJO contributed to the conception of the work. ACB, LMS, NJL, MLG and RJO contributed to data analysis. ACB, LMS, NJL, JH, MLG and RJO drafted the manuscript. ACB ran all experiments. All authors approved the final version of the manuscript. RJO has full access to all study data and takes responsibility for the integrity of the data and accuracy of the data analysis.
Funding Research reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under award numbers P01 CA200512 and P30 CA016056.
Disclaimer The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Competing interests MLG reports grants from and served as an advisory board member to pharmaceutical companies that manufacture smoking cessation drugs. Other authors declare no conflict of interest.
Provenance and peer review Not commissioned; externally peer reviewed.
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