In the small trial, five e-cigarette users gave saliva samples before and after a 15-minute vaping session using their own usual e-cigarette device and liquid. Their samples were compared with controls who did not vape.
The vapers had raised levels of three known carcinogenic compounds: formaldehyde, acrolein and methylglyoxal. Levels of formaldehyde were between two and six times higher among vapers than controls, and levels of acrolein and methylglyoxal were between 30 and 60 times higher, the study authors told a press conference at the annual conference of the American Chemical Society (ACS).
'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,' said study author Dr Silvia Balbo at the University of Minnesota in Minneapolis.
After identifying the compounds in the vapers' saliva, the researchers then went on to test whether they were having an effect on their DNA. After taking oral cells from the participants' mouths, the researchers isolated the DNA to assess for damage.
Four out of the five vapers' had higher levels of a type of damage called 'DNA adduct', caused by acrolein. If this DNA damage is not repaired in the cells, they have a higher likelihood of becoming cancerous.
Previous research has found potentially harmful compounds in e-cigarette vapour, however this study showed that such chemicals are reaching users' tissues and having a biological effect. In addition, it simulated realistic vaping situation, with participants using their own usual e-cigarette devices and vape fluids.
In addition to the three carcinogenic compounds found, which are also present in traditional cigarettes, the researchers discovered a range of unknown carbon compounds found in the vapers' saliva. The researchers plan to determine whether these have an effect on DNA in a larger follow-up study.
'Once these compounds are reaching the oral cavity and are getting into contact with the tissue and saliva, there are oral flora metabolic reactions that can occur, and different [carbon] species generated,' said Dr Balbo.
Due to the small number of participants, the study is being treated as a pilot for a larger research project with greater numbers of vapers and non-vaping controls. The researchers also plan to compare DNA damage from vaping to that caused by traditional cigarettes.
'E-cigarettes are a popular trend, but the long-term health effects are unknown,' said Dr Romel Dator, also of the University of Minnesota, who presented the work at the ACS meeting. 'We want to characterise the chemicals that vapers are exposed to, as well as any DNA damage they may cause.'