E-cigarettes (ECIGs) may be safer than their tobacco-laden counterparts, but they might not be any less addictive, according to a recent study published in Chemical Research in Toxicology.

Over the past few years, those products, which electronically heat up liquid nicotine and other chemicals to form an inhalable vapor, have been a hit for those looking to either wean off their sin stick habit or as a legal alternative to smoking for minors. According to the Centers for Disease Control, as many as 2.5 million teenagers have used these products in the past month, as of 2014 — even eclipsing the popularity of conventional cigarettes.  But research into how safe the process of vaping truly is for our bodies has been somewhat slow and inclusive.

At this point, it’s believed that the inhaled chemicals produced from an e-ciggie are less dangerous than the some-300 carcinogens that are released from a regular cigarette. However, what chemicals are exactly being taken into our lungs when we vape has been more of an unanswered question.

For this latest study, the researchers were interested in understanding what form of nicotine is produced and inhaled by the heating of the liquid preparation found in ECIGs. Nicotine, when found in smoke, can come into one of two forms, free-base (Nic) and protonated (NicH+). Free-base nicotine can be absorbed by the body and thus is the form that’s truly addictive to our brains. While it may be no surprise, the majority of the nicotine inhaled from a tobacco cigarette is free-base.

Noting that previous studies of ECIGs have only examined the amount of total nicotine released and not accounted for these varying forms, the authors utilized a “convenient solvent extraction method” to test the composition of the vapor released from a number of ECIG liquids commercially available. Not only did the free-base form make up the majority of the nicotine found in ECIGs, it was by a greater proportion when it was burned than when in its liquid form; indicating the very process of vaping produces more addictive nicotine.

This mismatching was also seen in the amount of nicotine advertised by the products. “Finally, labeled ECIG liquid nicotine concentration in commercial products was often inconsistent with measured nicotine,” they concluded.

Because of its addictive nature, the popularity of ECIGs may increase the chance that teens turn to the real deal once they grow older, health experts worry. This possibility would echo the same trend that occurs when people begin cigarette smoking at an early age.

“In today’s rapidly evolving tobacco marketplace, the surge in youth use of novel products like e-cigarettes forces us to confront the reality that the progress we have made in reducing youth cigarette smoking rates is being threatened,” said Mitch Zeller, director of the FDA’s Center for Tobacco Products, in a statement released by the CDC this past April 15. “These staggering increases in such a short time underscore why FDA intends to regulate these additional products to protect public health.”

For now, studies such as this should remind us that no form of smoking comes without its dangers.

Source: El-Hellani A, El-Hage R, Baalbaki R, et al. Free-Base and Protonated Nicotine in Electronic Cigarette Liquids and Aerosols. Chemical Research in Toxicology. 2015.