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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


February 20, 2020

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.


Disparities by income, age persist in tobacco use among Ohio adults


The Ohio Health Issues Poll is conducted every year to learn more about the health opinions, behaviors and status of Ohio adults. In 2019, OHIP asked Ohio adults several questions about tobacco use and their opinion on tobacco policies.


Ohio adults with lower incomes more likely to be current smokers

More than 2 in 10 Ohio adults (24%) reported being current smokers. This has remained relatively stable since OHIP began asking about smoking status in 2006. However, Ohio adults have consistently been more likely to smoke than adults across the nation. In 2018, the most recent year for which national data are available, 14% of adults nationwide reported being current smokers.1

Responses varied by household income. Ohio adults whose household income was 200% of the Federal Poverty Guidelines2 or less (42%) were nearly three times more likely to report being current smokers than those with household incomes greater than 200% FPG (15%). Since 2006, the percentage of current smokers has declined among Ohio adults with higher income but not among those living in or just above poverty.

Younger adults more likely to have tried e-cigarettes

Electronic cigarettes or e-cigarettes are also known as vapes, vape pens or e-hookahs and many are known by their brand names.3 The majority of
e-cigarettes contain nicotine and are not safe for children, young adults, pregnant women or anyone who is not a current smoker.4

Ohio adults ages 18 to 45 (44%) are about twice as likely as older adults (17%) to have ever tried an e-cigarette. This trend has continued since OHIP began asking about e-cigarette use in 2015. (See graph.)

About 1 in 10 Ohio adults (11%) reported using e-cigarettes some days, every day or rarely. The Behavioral Risk Factor Surveillance System asks a similar question and found that 5% of adults in the nation used e-cigarettes some days or every day in 2017, the most recent year for which data are available.5 While these questions are similar, it is important to recognize that OHIP allowed the response “rarely” in addition to “every day” and “some days.” Therefore it is not possible to make a direct comparison between the state and national percentages.

Ohio adults’ opinions about tobacco policies

OHIP asked Ohio adults whether they favored or opposed other policies that affect tobacco use:

  • An excise tax on the sale of e-cigarettes: 67% favor, 28% oppose. Support has increased since 2018 when 56% favored a tax.
  • A law that raises the age of sale from 18 to 21 on all tobacco products including e-cigarettes: 53% favor, 43% oppose. (See What’s Happening Now below.)
  • A $1 per pack increase in the cost of cigarettes: 43% favor, 54% oppose.

Why we ask these questions

Tobacco use is the leading cause of preventable death in the United States. It is responsible for about 20% of all deaths annually.6 Although cigarette use has declined in recent decades, the percentage of adults in Ohio who are current cigarette smokers continues to be higher than the nation. In addition, some people have not experienced this decline in smoking. These include adults living in or just above poverty. These smokers experience more tobacco-related health issues and often lack access to health care that could help treat these issues.7

Assessing public opinion about policies that reduce access to tobacco products is key to understanding the tobacco landscape. E-cigarettes are a newer product that have garnered much media attention in recent months. OHIP aims to understand who is using the products while monitoring the policy landscape across the state.

What’s Happening Now

In October 2019, Ohio’s Tobacco 21 law went into effect, making it illegal to give, sell or distribute all tobacco products – including e-cigarettes – to anyone under the age of 21. As of January 2020, Ohio is one of 19 states with such a law, along with more than 500 cities and municipalities.8 However, Ohio’s law does not include enforcement strategies. Many local jurisdictions, including Cincinnati, are implementing effective enforcement strategies such as compliance checks with retailers and tobacco retailer licensing programs. For more information about the Tobacco 21 legislation visit

1. Centers for Disease Control and Prevention. (2019). BRFSS Prevalence & Trends Data – Current Smoker Status. Retrieved from
2. In 2018, 200% of the Federal Poverty Guidelines for a family of four was $50,200.
3. Centers for Disease Control and Prevention. (2020). About Electronic Cigarettes (E-Cigarettes). Retrieved from
4. Centers for Disease Control and Prevention. (n.d.). Electronic Cigarettes: What’s the Bottom Line? Retrieved from
5.  Centers for Disease Control and Prevention. (2019). BRFSS Prevalence & Trends Data – E-Cigarette Use. Retrieved from
6. Centers for Disease Control and Prevention. (2019). Smoking and Tobacco Use. Retrieved from
7. Campaign for Tobacco-Free Kids. (2015). Tobacco and Socioeconomic Status. Retrieved from
8. Tobacco 21. (2019). State by State. Retrieved from