April 2, 2026, 2:05 am | Read time: 8 minutes

Nicotine-Based E-Cigarettes “Probably Carcinogenic”

A team led by researcher Bernard W. Stewart published an extensive analysis in the journal “Carcinogenesis” at the end of March.¹ The scientists wanted to determine the actual cancer risk from e-cigarettes. To do this, they systematically evaluated all major studies since 2017. They examined not only human data but also results from lab and animal experiments.

The results are alarming: The researchers classify nicotine-containing e-cigarettes as “probably carcinogenic to humans.” In users’ bodies, they found clear traces of DNA damage caused by ingredients like nitrosamines or toxic metals. In mouse experiments, inhaled vapor even caused lung cancer. The experts’ conclusion is clear: Vaping triggers inflammation in the mouth and lungs and will lead to more cancers in these areas in the future.

How Strongly Is E-Cigarette Use Linked to Serious Cardiovascular Events?

Another review highlighted the acute and chronic dangers to the cardiovascular system. The researchers explicitly warn against considering e-cigarettes as a harmless alternative. Especially in combination with traditional tobacco, they can provoke massive heart damage. The study was published in February 2026 in the journal “BMC Public Health.”²

The international research team evaluated 26 studies with a total of over 900,000 e-cigarette users worldwide. The researchers wanted to know: How strongly is e-cigarette use linked to serious cardiovascular events?

Since previous data often only considered isolated aspects like heart attacks, the scientists aimed for a comprehensive picture that also includes strokes, coronary heart disease, and mortality. Particularly dangerous is the combined use of tobacco and e-cigarettes.

The results from Suraa N. Al-Rubaye and other scientists show a significantly increased risk for the cardiovascular system: The likelihood of major adverse cardiovascular events (MACE) was 1.57 times higher for vapers than for non-users.

Heart Attack Risk in Dual-Use Group Nearly Quadrupled

• The risk of stroke increased by 1.62 times
• The risk of coronary heart disease increased by 1.19 times
• In the dual-use group (those who used both tobacco and e-cigarettes), the MACE risk was 2.21 times higher.
• The likelihood of a heart attack was even 3.86 times higher in the dual-use group.

Study: Massive Heavy Metal Contamination in Popular Disposable Vapes

But what are the causes of these damages? In 2025, a team from the University of California examined popular brands of disposable e-cigarettes (dPODs) like Elf Bar, Esco Bar, and Flum Pebble. The study, published in “ACS Central Science,” clarified what exactly is in the devices and why they are so toxic.³

Massive Lead Problem in Esco Bar

The most shocking finding was lead in Esco Bar devices, specifically in the form of lead-containing bronze in components that had direct contact with the liquid. The lead levels were so high that a user inhaled four to 13 times more lead at the same nicotine dose as from a pack of cigarettes. In addition to lead, extremely high concentrations of nickel, chromium, copper, zinc, and antimony were found.

Nickel and Chromium in All Three Brands

The health-threatening amounts of nickel and chromium and the resulting cancer risk were found in all three brands (Esco Bar, Flum Pebble, and Elf Bar). These metals dissolve from the heating coils due to heat or enter the aerosol from other metal parts.

The researchers’ conclusion was damning. Disposable vapes release health-threatening amounts of heavy metals when vaping—sometimes significantly above toxic limits. “Toxic elements (e.g., lead, antimony, nickel) in the vapor from disposable e-cigarettes exceed acceptable thresholds for cancer risks and general toxicity due to release from heating coils and internal metallic components,” it states.

The manufacturer of Elf Bar, by the way, rejected the study results at FITBOOK at the time, claiming the tested devices were counterfeits and not produced by them. When confronted, study author Brett A. Poulin told FITBOOK: “We verified that all Elf Bar devices used in our study are genuine by using the manufacturer’s authentication tool and the security codes provided on the original packaging of each device.”

Heart Study: Vaping Significantly Increases Blood Pressure–Pulse Calmer Than with Tobacco Cigarettes

A team led by lead author Anasua Kundu from the University of Toronto examined the effects of e-cigarettes on the cardiovascular system. The researchers wanted to clarify whether vaping poses acute or long-term health risks and how these vary across different population groups. To do this, they reviewed 63 studies that included human data as well as results from animal and cell experiments.

The result: Compared to non-use, e-cigarette consumption acutely leads to an increase in heart rate and blood pressure. However, this increase in heart rate was lower than with conventional cigarettes. The study was published in 2025 in “BMJ Journals Heart.”⁴

E-Cigarettes May Offer Small Benefits for Smokers

Despite the alarming findings on cancer, cardiovascular risks, and toxins, there is also data showing why e-cigarettes may be beneficial for a certain group. A study published in 2025 in “BMJ Open” by Sitasnu Dahal and his team examined 520 smokers trying to reduce their tobacco consumption.⁵

The team found that those who switched to e-cigarettes with high nicotine content (36 milligrams per milliliter) were able to reduce their cigarette consumption the most. As a positive side effect, blood lipid levels improved in these participants after six months. The ‘good’ HDL cholesterol increased, while the ‘bad’ LDL cholesterol decreased. However, the researchers emphasize that this is mainly due to the massively reduced tobacco consumption—and not because the vapor itself is health-promoting.”

However, when interpreting the results, it must be considered that only smokers who wanted to reduce their consumption were included. So, not those who necessarily wanted to quit completely. The study is also based on self-reporting, making it prone to recall errors. Additionally, the study had a significant dropout rate (36 percent).

An important aspect for switchers was also contributed by the aforementioned blood pressure study. It showed that the short- to medium-term switch from tobacco to e-cigarettes can even improve blood flow and blood pressure, which was particularly observed in women and younger individuals.

Scientific Controversy: Are E-Cigarettes as Dangerous for Heart and Lungs as Regular Cigarettes?

In the scientific community, there is a faction (prominently represented by U.S. scientist Stanton Glantz) that claims e-cigarettes are nearly as dangerous for the heart and lungs as traditional cigarettes. Glantz and other researchers published a comprehensive meta-analysis in 2024 in the journal “NEJM Evidence.” They evaluated a total of 107 studies and investigated how high the health risks of e-cigarettes are compared to traditional tobacco cigarettes in the general population.

Essentially, the researchers conclude that the risk of cardiovascular diseases, strokes, and metabolic disorders is similar for e-cigarette users as for smokers of traditional cigarettes. The focus was on cardiovascular diseases, strokes, metabolic disorders, asthma, COPD (Chronic Obstructive Pulmonary Disease), and oral diseases. Particularly highlighted (as in the study on cardiovascular events) is the significantly higher risk for all examined diseases with the combined use of e-cigarettes and regular cigarettes compared to “just” smoking.

Glantz calls for a fundamental reassessment of the assumption that e-cigarettes offer substantial harm reduction across all disease-relevant areas—especially considering the widespread combined use (dual use).

This study is criticized by other researchers. Brad Rodu, a professor at the University of Louisville in Kentucky with a research focus on “tobacco harm reduction,” accuses Glantz and colleagues of methodological errors in a 2025 published analysis.⁶ For example, the researchers included cases of erectile dysfunction in the “cardiovascular diseases” category, which had a very high risk ratio and thus skewed the overall average for severe heart diseases upward. Additionally, Glantz included studies on flu illnesses in the COPD category, which critics say is scientifically untenable.

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Renowned Physician: E-Cigarettes Not Safe at All

According to Michael Blaha, a renowned professor of cardiology and epidemiology at the Johns Hopkins University School of Medicine, e-cigarettes contain fewer toxic chemicals than traditional tobacco, but still cannot be considered safe.⁷ Even if vaping may be less harmful than smoking, it is still dangerous for the heart and lungs. Blaha emphasizes that one is exposed to a variety of chemicals that are not yet fully understood and are likely not safe. The physician also points to the massive addiction potential: Users can even receive a higher nicotine dose by increasing the device’s voltage or using “extra-strength” cartridges.

He is particularly concerned that a new generation of teenagers, who otherwise would never have smoked, is becoming addicted to nicotine through vaping. Studies, such as those reported by the “Guardian,” show that teenagers who vape are significantly more likely to turn to cigarettes.⁸ The rise in the use of disposable products (Puff Bars) among students is also highlighted as particularly alarming by the Federal Institute for Public Health (BIÖG).⁹

The 2023 demand by the German government’s drug commissioner for a vape flavor ban has stalled politically.

Conclusion–This Question Should Be Asked by Smokers

E-cigarettes are not a harmless alternative but a risk in themselves, with indications of cancer, cardiovascular damage, and toxic metals. For smokers, they may help reduce tobacco consumption in the short term. But what matters is what comes next: a real exit or just a switch—or worse, both in parallel.
The crucial question is: Do I really want to break free from addiction—or am I just looking for the more convenient way to stay in it?