E-cigarettes could be a cancer risk and increase the risk of heart attack.

Two recent studies provide more evidence that e-cigarettes, which are widely considered to be safer than tobacco cigarettes, could be deadly.

A paper published in the Journal of Pediatrics by researchers at the University of California, San Francisco on Monday found five cancer causing chemicals in the urine of 16-year-olds who used e-cigarettes. Last week, another study based on 2014 and 2016 National Health Interview Surveys of nearly 70,000 Americans showed that daily e-cigarette usage doubled the risk of heart attack.

A number of studies also show that e-cigarettes do not contribute significantly to smoking cessation but may actually encourage consumers to become users of both e-cigarettes and tobacco cigarettes. In 2008, as evidence mounted about the risks of e-cigarettes, the World Health Organization encouraged marketers to stop promoting the product as a safe and effective means to quit smoking.

Teenagers who use e-cigarettes are three times more likely to be using tobacco cigarettes a year later, according to a study published in The BMJ (formerly the British Medical Journal) in September. Young children are also at risk. Data from the Centers for Disease Control and Prevention show that poison control centers received 215 calls a month in 2014 reporting poisoning by e-liquids, up from one call per month in 2010. More than half the calls concerned children younger than 5 ingesting e-liquids or getting the chemicals in their eyes or on their skin.

A team of Virginia Commonwealth University researchers also found that using e-cigarettes during pregnancy could result in craniofacial birth defects such as cleft palates.

VCU researchers have taken an interdisciplinary approach to discovering and learning about the risks posed by e-cigarettes. Antonio Abbate, M.D., Ph.D., vice chairman of cardiology at VCU Pauley Heart Center, has proven that e-cigarettes induce the same inflammatory response as tobacco cigarettes. S. Rutherfoord Rose, PharmD., professor of emergency medicine in the VCU School of Medicine, chair of the Division of Clinical Toxicology and director of the Virginia Poison Control Center, is concerned about e-liquid toxicity levels. Alison Breland, Ph.D., an assistant research professor in the Department of Psychology in the College of Humanities and Sciences — and a project director at the VCU Center for the Study of Tobacco Products — is an expert on the possible risks of long-term e-cigarette use.  

In interviews with VCU News, the researchers agreed that e-cigarettes pose varying degrees of cardiovascular and cancer risks.

Is it possible that e-cigarette liquid contains just as many, or more, carcinogens as tobacco cigarettes?

Alison Breland: Several studies have shown that the aerosol produced by e-cigarettes contains much lower levels of many of the potent carcinogens found in cigarette smoke, which are linked to a variety of cancers. However, e-cigarette aerosol does contain other toxicants, such as metals for example, and the effects of these toxicants are not yet well-characterized.

How does e-cigarette use negatively impact the heart?

Antonio Abbate: E-cigarettes, or smokeless tobacco, are certainly a trend worth addressing as they are used frequently by young adults. In 2014, the American Heart Association published a policy statement in which experts recommended that e-cigarettes be considered cigarettes for all intended purposes. Therefore, all laws and restrictions may be equally applied.

The statement cautioned, however, that knowledge regarding the risks of e-cigarettes compared with cigarettes was less established. It also said the American Heart Association would continue to follow the issue.

What is the level of toxicity of e-liquids used in e-cigarettes?

S. Rutherfoord Rose: Liquid nicotine refill cartridges/bottles may contain between 0.6 and 3.6 percent nicotine, or between 6 and 36 milligrams of nicotine per milliliter. Ingestion of only 2 to 5 milligrams can cause nausea and vomiting, and doses of 40 to 60 milligrams (or 0.8 to 1.0 milligrams in children) can be life-threatening. Therefore, one refill bottle can easily contain a lethal dose in a child and cause significant toxicity in an adult.

Are e-cigarettes linked to cancer, and what types?

Alison Breland: I am not aware of e-cigarettes being linked to any type of cancer at this point. A recent report by the National Academy of Sciences on e-cigarettes states, “there are no epidemiological studies on the potential association between e-cigarettes and cancer in humans to make any conclusions.” However, it is possible that users have not been using e-cigarettes long enough for cancers to develop. E-cigarettes have only been on the U.S. market since 2007.

Based on what we know right now, I think that e-cigarettes will be associated with less risk for cancer than tobacco cigarettes. With that said, e-cigarettes may carry some risk for cancer, as the aerosol produced does contain some carcinogens. In other words, e-cigarettes are not risk-free.\

Are there any findings to suggest that e-cigarette use impacts the heart in different ways than smoking tobacco cigarettes?

Antonio Abbate: E-cigarettes do not have carbon dioxide or carbon monoxide but still have plenty of inhaled irritants that induce injury and have nicotine — the main ingredient that has the action on the blood pressure and the heart. In relation to nicotine, most of the impact is going to be the same, despite the absence of smoke. There are products that when heated create chemicals such as acrolein, which induces oxidative injury to the lungs and the endothelium, the cell layer in the vasculature.

Reports of young children getting e-liquid in their eyes and on their skin have increased. What are some of the associated risks?

S. Rutherfoord Rose: Liquid nicotine is very irritating to the eye and can cause burns. Exposure to skin would be less concerning, and severity would depend on the nicotine concentration (strength) and duration of exposure (before it is washed off).

Liquid nicotine is more concerning in unintentional pediatric ingestions because of its potency. Children have been known to get sick after ingesting one entire tobacco cigarette, most of which contain between 13 and 30 milligrams of nicotine. E-cigarettes are less likely to result in inadvertent poisoning since the nicotine is inside the device, though the devices differ in how easy it may be to access the liquid.  

Could e-cigarettes be linked to health risks to which tobacco cigarettes are unrelated?

Alison Breland: E-cigarettes may be linked to health risks. There are concerns about the effects of e-cigarette flavors and other chemicals (especially when they are heated to high temperatures) on lung function. This is particularly concerning in individuals who use e-cigarettes but have never used cigarettes. More specifically, for cigarette smokers, switching to exclusive e-cigarette use might improve lung function. Users who never smoked tobacco cigarettes who initiate with e-cigarettes may have a reduction in lung function.

It’s hard to say for sure though, because few studies have been done. There are also concerns about the effects of e-cigarette chemicals, in particular nicotine, on the developing adolescent brain, as well as the effects of e-cigarette chemicals on fetuses.

Middle and high school students are known to use e-cigarettes. Are there additional cardiovascular risks posed to young users?

Antonio Abbate: Individuals younger than 18 using e-cigarettes is not only illegal but irresponsible. The long-term consequences are unknown. There are also additional injuries that we have witnessed with these e-cigarettes that are related to severe burns due to device malfunctions, which are really tragic.

Do you think future studies, perhaps as far as 10 to 15 years out, will indicate that cancer rates have increased due to e-cigarette use? Why or why not?

Alison Breland: This is a difficult question to answer. Based on what we know right now, I do not think that exclusive e-cigarette use will be linked to increased rates of cancer 10 to 15 years from now when compared to rates for tobacco cigarettes. However, that is a prediction for exclusive e-cigarette use. Most users of e-cigarettes use both e-cigarettes and tobacco cigarettes concurrently. If e-cigarettes users maintain their tobacco cigarette use, they are at increased risk for cancer as opposed to their risk if they quit all tobacco products.

You researched the link between e-cigarette use and inflammation. How are e-cigarettes linked to inflammation?

Antonio Abbate: My research is about inflammation and how it promotes heart disease. I collaborated with researchers from the [Sapienza University of Rome] in Italy, who found that e-cigarettes induce the same inflammatory response standard cigarettes do. It is thought that the inflammation is not caused by the actual smoke but rather by the nicotine and other chemical irritants.