Electronic cigarettes, commonly known as vapes, have become increasingly popular, particularly among younger generations. These devices offer an alternative to traditional cigarettes, raising questions about their long-term health implications. One area of growing scientific interest is the potential connection between vaping and bladder cancer. This article explores bladder cancer, the components of vaping, and what is known about any possible link.
Understanding Bladder Cancer
The bladder is a hollow, muscular organ in the lower abdomen that stores urine. Bladder cancer occurs when cells in the bladder lining grow abnormally and form a tumor. These cancerous cells can interfere with bladder function and may spread if untreated.
Many factors increase the risk of bladder cancer. Traditional cigarette smoking is the most significant risk factor, accounting for about half of all cases. Harmful chemicals in tobacco are absorbed into the bloodstream, filtered by the kidneys, and accumulate in the urine, exposing the bladder lining to carcinogens. Other established risk factors include exposure to certain industrial chemicals (e.g., aromatic amines, dyes) in occupations involving rubber, leather, textiles, or paint products. Chronic bladder irritation from recurrent infections or bladder stones, certain medications like cyclophosphamide, and parasitic infections such as schistosomiasis also contribute.
Vaping: Components and Exposure Routes
Vaping involves electronic cigarettes or vape pens, which heat a liquid (e-liquid or vape juice) to produce an aerosol for inhalation. The device typically contains a battery, a heating coil, and a cartridge holding the e-liquid.
E-liquids generally consist of main components: nicotine, flavorings, water, and carrier liquids. Propylene glycol and vegetable glycerin are the most common carrier liquids, which help create the visible aerosol. When heated, these carrier liquids can partially decompose, forming volatile carbonyls such as formaldehyde, acetaldehyde, and acrolein. Beyond these main ingredients, e-liquids and their aerosols can contain other substances, including trace amounts of metals (e.g., nickel, tin, lead, cadmium), tobacco-specific nitrosamines (TSNAs), polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). These components are inhaled and absorbed into the bloodstream, where they are processed by the body.
Current Scientific Understanding of Vaping and Bladder Cancer
The direct link between vaping and bladder cancer is an active area of ongoing scientific investigation. Long-term effects are not yet fully understood due to the relatively short history of widespread vaping compared to traditional smoking. However, research is shedding light on potential connections by examining biomarkers of exposure in e-cigarette users. One systematic review of 22 studies identified 40 different parent compounds and four metals in the urine of e-cigarette users, some of which are known carcinogens.
Further analysis within this review revealed 63 unique toxicant or carcinogenic metabolite biomarkers, with six strongly linked to bladder cancer, present in the urine of e-cigarette users. This suggests that while e-cigarettes may expose users to lower levels of some carcinogens compared to traditional tobacco, they still introduce harmful compounds into the body. For instance, certain aldehydes and aromatic amines, recognized bladder carcinogens, have been found at higher concentrations in the urine of e-cigarette users compared to non-smokers.
Specific compounds like tobacco-specific nitrosamines (TSNAs) and polycyclic aromatic hydrocarbons (PAHs), known to damage DNA in bladder cells, have been detected in the urine of e-cigarette users, though generally at lower levels than in traditional cigarette smokers. While urinary biomarkers related to bladder cancer are significantly lower in e-cigarette users than in traditional tobacco users, they are still significantly higher than in non-smokers. This indicates that despite being considered a less harmful alternative to traditional smoking, vaping carries carcinogenic risks to the bladder. The long-term implications of chronic exposure to these urinary carcinogens from e-cigarettes remain unknown and necessitate continued research.