An inspection conducted by the Food and Drug Administration on 1,102 e-liquids a year ago showed that 80.9 percent contained nicotine, which should be controlled and registered as medicine according to regulations.
The study is the most recent addition to a proliferation of research aiming to measure the impact of e-cigarettes on the heart, blood vessels, lungs and brain.
In the new study, the authors used magnetic resonance imaging (MRI) to take several measurements of blood vessel function in 31 healthy adults who had never smoked, before and after they took 16 three-second puffs of an e-cigarette containing propylene glycol, glycerol and flavouring but no nicotine.
E-cigarettes have become the most commonly used tobacco product among USA adolescents, it added. Felix W. Wehrli, PhD, the study's principal investigator, explained, 'While e-cigarette liquid may be relatively harmless, the vaporization process can transform the molecules - primarily propylene glycol and glycerol - into toxic substances'.
The group then performed a statistical analysis to determine group differences in vascular function before and after vaping.
The researchers applied a cuff to the participants' thighs to constrict the blood vessels, measuring how quickly blood flowed following its release and using an MRI procedure to observe changes in vascular function.
They observed an average reduction in the femoral artery's dilation by about 34 percent, a 17.5 percent decrease in peak blood flow, a 20 percent decrease in venous oxygen and a 28.5 percent decrease in blood acceleration after cuff removal (the speed at which blood returns to its normal flow after being constricted). "But the solvents, flavorings and additives in the liquid base, after vaporization, expose users to multiple insults to the respiratory tract and blood vessels".
More research is needed to address the potential long-term adverse effects of vaping on vascular health, but he predicts that e-cigarettes are potentially much more hazardous than previously assumed. "We will find out, years from now, the results."Wehrli warns that the safest course of action in the face of uncertain long-term health affects is to simply avoid e-cigarette use altogether". More than a decade after e-cigarettes were first marketed in the United States, it still looks like they are a substitute for the conventional kind, drawing people away from smoking rather than toward it.
Reference Acute Effects of Electronic Cigarette Aerosol Inhalation on Vascular Function Detected at Quantitative MRI. Until then, one health advocate says, "E-cigarettes are guilty until proven innocent".