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E-cigarette users are exposed to potentially harmful levels of metal linked to DNA damage

Zinc excess in the body correlates with oxidative stress–eua022020.php

RIVERSIDE, Calif. — Researchers at the University of California, Riverside, have completed a cross-sectional human study that compares biomarkers and metal concentrations in the urine of e-cigarette users, nonsmokers, and cigarette smokers.

They found that the biomarkers, which reflect exposure, effect, and potential harm, are both elevated in e-cigarette users compared to the other groups and linked to metal exposure and oxidative DNA damage.

“Our study found e-cigarette users are exposed to increased concentrations of potentially harmful levels of metals — especially zinc — that are correlated to elevated oxidative DNA damage,” said Prue Talbot, a professor of cell biology, who led the research team.

Zinc, a dietary nutrient, plays key roles in growth, immune function, and wound healing. Too little of this essential trace element can cause death; too much of it can cause disease. Its deficiency, as well as its excess, cause cellular oxidative stress, which, if unchecked, can lead to diseases such as atherosclerosis, coronary heart disease, pulmonary fibrosis, acute lymphoblastic leukemia, and lung cancer.

Electronic cigarettes consist of a battery, atomizing unit, and refill fluid. Metals in e-cigarette aerosols come mainly from the metal components in the atomizer– nichrome wire, tin solder joints, brass clamps, insulating sheaths, and wicks — as well as the e-fluids that the atomizers heat.

The study, which appears in BMJ Open Respiratory Research, marks the first time researchers have examined and quantified urinary biomarkers of effect and potential harm in relation to metals in e-cigarette users.

A biomarker is a quantifiable characteristic of a biological process. Biomarkers allow researchers and physicians to measure a biological or chemical substance that is indicative of a person’s physiological state. Previous e-cigarette studies with humans have examined biomarkers of exposure — for example, nicotine or nicotine metabolites — but none have studied biomarkers of potential harm or shown how this harm correlates with metal exposure.

The biomarkers studied by the UC Riverside researchers were 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage; 8-isoprostane, an indicator of the oxidative degradation of lipids; and metallothionein, a metal response protein. All three biomarkers were significantly elevated in e-cigarette users compared to the concentrations in cigarette smokers.

“Our findings reaffirm that e-cigarette use is not harm free,” said Shane Sakamaki-Ching, a graduate student in the Cell, Molecular and Developmental Biology Graduate Program and the research paper’s first author. “Indeed, prolonged use may lead to disease progression.”

The researchers advise physicians to exercise caution when recommending e-cigarettes to their patients. Electronic cigarette aerosols contain potentially harmful chemicals, cytotoxic flavor chemicals, metals, ultrafine particles, and reaction products. E-cigarette use has been linked to adverse health effects such as respiratory diseases, increased risk for cardiovascular disease, and impaired wound healing following surgery.

“Pregnant women, especially, should not be encouraged to use e-cigarettes,” Talbot said. “Excess of zinc in their bodies can lead to nausea and diarrhea. Given the recent deaths and pulmonary illnesses related to e-cigarette usage, everyone should be made aware of the potential health risks linked to e-cigarette usage.”

The study involved 53 participants from the Buffalo, New York, area. Talbot and Sakamaki-Ching were joined in the study by Monique Williams, My Hua, Jun Li, Steve M. Bates, Andrew N. Robinson, and Timothy W. Lyons of UCR; and Maciej L. Goniewicz of the Roswell Park Comprehensive Cancer Center, Buffalo, New York.

The study was supported by grants from the National Institutes of Health.

Examining the relationship between impulsivity-related personality traits and e-cigarette use in adults


•Trait impulsivity did not differentiate e-cigarette users from non-smokers.

•Lack of perseverance and negative urgency differentiated e-cigarette users from cigarette smokers.

•Negative and positive urgency differentiated e-cigarette users from dual users.

•Trait impulsivity was unrelated to measures of frequency and intensity of e-cigarette use.



The present study aimed to investigate the relationship between impulsivity-related personality traits based on the UPPS-P model and e-cigarette use. The study used a sample of mainly European adults and compared e-cigarette users with non-smokers, cigarette smokers and dual users (those who currently smoke cigarettes and use e-cigarettes). Additionally, the relationship between impulsivity-related traits and frequency and intensity of e-cigarette use was examined, while the main reasons for e-cigarette use were also assessed.


Participants were 720 adults (234 non-smokers, 164 smokers, 150 e-cigarette users, 172 dual users), who completed online questionnaires regarding sociodemographics, smoking/e-cigarette use behaviour, and impulsivity (UPPS-P scale).


Impulsivity-related traits did not significantly differentiate e-cigarette users from non-smokers. E-cigarette users showed lower levels of lack of perseverance than cigarette smokers, and they exhibited lower levels of negative and positive urgency than dual users. Negative urgency also significantly differentiated smokers and non-smokers, with smokers having higher levels of the trait. No significant results were found examining the relationship between the impulsivity-related traits and e-cigarette behaviour (number of days vaping per month, number of times vaping per day, and millilitres of e-liquid used per day). The main reason given for e-cigarette use was the perception that it is less harmful than cigarettes.


The present study found that trait impulsivity differentiated e-cigarette users from cigarette smokers and dual users, but did not differentiate e-cigarette users from non-smokers. Such findings are important to not only help us identify factors associated with e-cigarette use, but also to potentially inform treatment plans and decisions.

Psychological well-being and dual-use of cigarettes and e-cigarettes among high school students in Canada


•6.3% of Canadian middle and high school students were dual users of cigarettes and e-cigarettes.

•Three times more Canadian youth used e-cigarettes exclusively than used cigarettes exclusively.

•High-frequency dual-users had lower psychological well-being than low-frequency dual-users.

•High-frequency cigarette dual-users had higher autonomy scores than low-frequency dual-users.



Cigarette and e-cigarette use are prevalent among Canadian adolescents. Evidence shows psychiatric comorbidity with adolescent cigarette smoking, but little is known about psychological well-being among dual users of e-cigarettes and cigarettes. This study examined the association between dual-use status and psychological well-being among high school students.


We used the 2016–2017 Canadian Student Tobacco, Alcohol, and Drugs Survey. Scales of psychological well-being (relatedness, autonomy, competency, prosocial behavior, and social responsiveness) were derived from self-reported data. Dual-use status was categorized into non-users, cigarette-only smokers, e-cigarette-only users, and four types of dual-users. Multivariable linear regression models examined the association between dual-use and psychological well-being.


Among the participants, 6.3% were current dual-users, 4.1% were cigarette-only smokers, 12.6% were e-cigarette-only users, and 77.0% were non-users. Compared to non-users, relatedness and social responsiveness were lower for all users. When compared to e-cigarette users, most other users had lower relatedness (high-frequency dual-users [β=-6.05], high-frequency cigarette dual-users [β=-2.27], high-frequency e-cigarette dual-users: [β=-1.32], low-frequency dual-users [β=-1.91], and cigarette-only smokers [β=-1.66]) and social responsiveness. High-frequency dual-users had lower scores for relatedness and social responsiveness, while high-frequency cigarette dual-users had higher autonomy, compared to low-frequency dual-users.


Dual-users had poorer psychological well-being, which differed among dual-user sub-groups. This study highlights an opportunity for specialized programs to promote psychological well-being and reduce tobacco product use among adolescents.


The study is based on respondent self-report, and the use of cross-sectional data precludes us from determining the temporal order between dual-use and psychological well-being.

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