Adding to the evidence that electronic cigarettes are anything but risk-free, a team of researchers from the University of Minnesota has discovered that tobacco vapor devices introduce three chemicals into the mouth that are known to damage DNA.
Their data, presented on August 20 at the 256th National Meeting & Exposition of the American Chemical Society, was drawn from analyses of saliva and oral tissue cells from 10 e-cigarette users and 10 non-users.
"It's clear that more carcinogens arise from the combustion of tobacco in regular cigarettes than from the vapor of e-cigarettes," lead investigator Silvia Balbo said in a statement. "However, we don't really know the impact of inhaling the combination of compounds produced by this device. Just because the threats are different doesn't mean that e-cigarettes are completely safe."
All e-cigarettes, also known as vape pens or vapes, rely on the same basic design: when a user presses a button or breathes through the tip, a small amount of the nicotine- (or other drug-) laden fluid in a refillable canister or replaceable cartridge is drawn into an internal chamber and atomized by a battery-powered heating coil. Air pulled into the chamber mixes with the condensed molecules, and the resulting aerosol is drawn into the user’s lungs.
Although this process avoids many of the toxic byproducts of smoking, vape fluids contain a myriad of solvents, preservatives, and flavoring agents that have dubious safety profiles when altered by high heat and consumed in this manner. A number of studies have shown that e-cigarette vapor carries dozens of irritants and possible or confirmed carcinogens.
However, most of the past research aimed at identifying DNA-altering molecules in e-cigarette vapor has used gas chromatography, and scientists hoping to assess how these substances build up in living tissue have looked at mice who were exposed to levels proportionate to a human smoker.
To assess real-world exposure in humans, Balbo and her colleagues examined the chemicals present in the mouth of five habitual users after a 15-minute vape session. Five healthy non-users served as controls. Though the levels of some chemicals varied across the group, all five showed high amounts of acrolein, methylglyoxal, and formaldehyde.
These three chemicals can form covalent bonds with DNA, creating what is called a DNA adduct. If the DNA adduct can’t be repaired by specialized housekeeping enzymes, normal DNA replication and gene translation will be interrupted, and a cancerous mutation may arise.
Subsequent analysis of cells taken from the mouth of five more users revealed that four of the five had increased levels of acrolein DNA adduction compared with controls.
The team hopes that follow-up studies can confirm these results in a larger group of people.
"Comparing e-cigarettes and tobacco cigarettes is really like comparing apples and oranges. The exposures are completely different," Balbo said. "We still don't know exactly what these e-cigarette devices are doing and what kinds of effects they may have on health, but our findings suggest that a closer look is warranted."
According to the Centers for Disease Control and Prevention (CDC), e-cigarettes have exploded in popularity since the first pocket-sized, mass-produced versions were introduced to the US in 2006. They are now the most commonly used tobacco product among adolescents, a trend that public officials attribute, at least in part, to the candy-like variety and novelty of fluid flavors.