Heated Tobacco Products (HTPs) and vaping devices (Electronic Nicotine Delivery Systems or ENDS) provide inhaled nicotine without the burning of traditional cigarettes. Both systems heat a substance to create an inhalable aerosol, but they differ significantly in the materials used and the chemical composition of their output. Understanding these differences, from the core mechanisms to the resulting health impacts, is necessary for evaluating the relative risks each product poses.
Core Mechanisms of Delivery
Heated Tobacco Products (HTPs) rely on the direct heating of processed tobacco leaf, often formed into small sticks or plugs. The device uses an internal electronic heating element, such as a ceramic blade, to heat the tobacco to a controlled range (typically 250°C to 350°C). This temperature vaporizes nicotine and flavor compounds without causing combustion, which occurs above 900°C in a conventional cigarette. The user then inhales this tobacco-derived aerosol.
The mechanism of a vaping device is fundamentally different, as it heats a liquid solution rather than tobacco leaf. This e-liquid, often called vape juice, is primarily composed of humectants like propylene glycol (PG) and vegetable glycerin (VG), nicotine, and flavor additives. An atomizer, containing a metallic heating coil and a wick, rapidly heats the liquid, converting the solution into a fine particle aerosol. The operational temperature varies widely depending on the device’s power setting, which influences the aerosol output.
Aerosol and Vapor Composition
The output inhaled from HTPs still contains tobacco-derived compounds and harmful substances, though levels are generally reduced compared to cigarette smoke. Tobacco-Specific Nitrosamines (TSNAs), potent carcinogens, are found in HTP aerosols, but their concentrations are reported to be 7 to 17 times lower than in conventional cigarette smoke. The heating process generates a lower overall content of carbonyls and polycyclic aromatic hydrocarbons (PAHs) than combustion. However, some specific harmful compounds, such as the PAH acenaphthene, can be present in higher concentrations in HTP aerosol than in traditional cigarette smoke.
Vaping aerosol is chemically simpler than both cigarette smoke and HTP aerosol, lacking combustion byproducts and the broader range of tobacco-derived toxins. The primary constituents are the carrier chemicals (propylene glycol and vegetable glycerin), nicotine, and various flavorants. A concern for vaping involves heavy metals (nickel, tin, and lead) leaching into the aerosol from the metallic heating coil. Furthermore, certain flavorants, like diacetyl, have been linked to severe respiratory disease when inhaled.
Comparative Health Impacts
Both HTPs and vaping devices expose users to fewer toxicants than combustible cigarettes. However, neither product is without biological consequence, and both induce acute physiological changes upon use. Studies indicate that using HTPs and e-cigarettes can cause a short-term increase in heart rate and blood pressure, reflecting immediate cardiovascular strain. This effect is comparable to that observed after smoking a traditional cigarette, suggesting that inhaled substances impact the circulatory system.
Research shows that HTP aerosol can elicit a biological response in lung cells similar to cigarette smoke, including oxidative stress and genetic lesions. While this response occurs at higher exposure levels than traditional smoking, it suggests the risks from HTPs should not be minimized. Vaping has been linked to severe, acute respiratory conditions, such as E-cigarette or Vaping Product Use-Associated Lung Injury (EVALI). Concerns remain regarding the long-term effects of inhaling glycols and complex flavor chemicals deep into the lungs.
The addiction potential of both product types is high due to nicotine content. Modern high-power vaping devices and those using nicotine salts can deliver nicotine to the bloodstream rapidly and at concentrations comparable to a combustible cigarette. Although some HTPs may deliver lower nicotine levels, this can lead to compensatory puffing behaviors, where users take longer draws to satisfy cravings. For former smokers, switching completely to either HTPs or vaping has been associated with a reduction in respiratory symptoms compared to continued smoking.
Current Regulatory Oversight
In the United States, the Food and Drug Administration (FDA) regulates both HTPs and vaping devices as “tobacco products.” This classification subjects both categories to rigorous requirements for pre-market authorization. Manufacturers must submit a Pre-Market Tobacco Product Application (PMTA) to demonstrate that marketing their product is appropriate for public health protection. This review considers the risks and benefits to the population as a whole, including both users and non-users.
Both HTPs and vaping products must carry specific health warnings on packaging and advertising, stating that nicotine is an addictive chemical. Internationally, regulatory approaches vary widely, impacting product availability and design. Some countries ban the sale of all vaping products, while others treat them as consumer electronic goods or strictly regulated tobacco products. The regulatory classification often dictates restrictions on flavorings, nicotine concentration limits, and taxation levels.