Electronic cigarettes, commonly known as e-cigarettes, vapes, or “carts” when referring to the liquid-filled cartridges, have rapidly grown into a public health phenomenon. These devices heat a liquid to create an aerosol, which users inhale, simulating the act of smoking without burning tobacco. The widespread adoption of vaping, particularly among younger people, has raised a fundamental question: does inhaling the aerosol from these cartridges carry a cancer risk? The answer lies in the complex chemistry of the liquids and the devices themselves. Examining the components before and after they are heated reveals the potential for the formation of cancer-causing substances.
Composition of Vape Cartridges
The core of any vape cartridge is the e-liquid, typically composed of solvent carriers such as propylene glycol (PG) and vegetable glycerin (VG). These compounds make up the majority of the liquid volume and are responsible for producing the visible aerosol when heated. While generally recognized as safe for ingestion, their safety profile changes significantly when they are aerosolized and inhaled repeatedly over time.
A wide array of flavor additives are also mixed into the e-liquid. Certain flavoring compounds, such as diacetyl, have been linked to serious respiratory illnesses like bronchiolitis obliterans, a condition that scars the small airways of the lungs. Although the direct carcinogenicity of many flavorings is still under investigation, they contribute to the overall chemical cocktail inhaled by the user.
Beyond the liquid, the device hardware itself introduces another layer of potential toxicity. The heating element, or coil, is often made from metals like nickel, lead, chromium, and tin. As the coil is repeatedly heated, tiny particles of these heavy metals can leach into the e-liquid and subsequently be inhaled. Inhaling heavy metals such as cadmium and arsenic is concerning because they are recognized as carcinogens that can accumulate in the body.
Chemical Transformation from Heating
The process of heating the e-liquid is where the most significant chemical transformations occur, leading to the creation of toxic compounds not present in the original liquid. The high temperatures reached by the heating coil cause the thermal decomposition of the PG and VG base. This thermal breakdown generates a range of volatile organic compounds and carbonyls that pose a health risk.
Among the most concerning of these newly formed chemicals are formaldehyde, acetaldehyde, and acrolein. Formaldehyde is classified as a Group 1 human carcinogen, meaning there is sufficient evidence that it causes cancer in humans. Acetaldehyde is classified as a Group 2B carcinogen, meaning it is possibly carcinogenic to humans. The formation of these aldehydes depends on the power setting of the device, with higher wattage leading to exponentially greater production of these harmful substances.
Acrolein, another major product of this thermal decomposition, is highly reactive and has been implicated in vascular toxicity and cellular damage. The amount of these toxic aldehydes produced by some vaping devices can, in certain conditions, even exceed the levels found in the smoke from traditional combustible cigarettes. This chemical process fundamentally changes the inhaled substance into an aerosol containing known and suspected carcinogens.
Current Data on Cancer Risk
Determining a definitive, long-term cancer rate from vaping remains challenging because e-cigarettes have only been widely available for about two decades. Consequently, there is no large-scale epidemiological data yet to confirm a direct causal link between vaping and a specific cancer diagnosis, as most cancers take many years to develop. The scientific focus has instead shifted to identifying biological markers of risk.
Current toxicological and cellular studies provide evidence that the risk is not zero, even for non-smokers who exclusively vape. Research has demonstrated that vapers exhibit similar damaging changes to the DNA of cells in their mouth and airways as traditional smokers. These changes, known as DNA adducts and epigenetic modifications, are considered early indicators associated with an increased risk for future cancer development.
Studies have also identified biomarkers of harm, including oxidative stress, cellular apoptosis, and genotoxicity, in cells exposed to e-cigarette aerosol. While the overall exposure to carcinogens is generally lower for vapers compared to smokers, the presence of known cancer-causing chemicals created during the heating process confirms a substantial, non-zero risk. The scientific consensus suggests that while vaping is less harmful than smoking tobacco, it introduces a unique and serious health risk compared to not using either product.