Heat-not-burn tobacco products may be 'not so hot' at protecting blood vessel function

Heat-not-burn products are not new, but have been recently updated and test marketed in several countries outside the United States with greater success. Despite tobacco industry claims of heat-not-burn products being less harmful than regular cigarettes, the health effects of the devices are still unproven, according to researchers.

Heat-not-burn devices raise the temperature of tobacco enough to release nicotine-containing vapor but not enough to burn, avoiding smoke exposure. To test the devices' ability to reduce harm, researchers assessed whether exposure to the vapor affects the ability of rats' blood vessels to widen when there is increased blood flow -- a measure of blood vessel health that is impaired with exposure to smoke from cigarettes, small cigars and marijuana.

Researchers found:

• After ten 15-second exposures over five minutes to the vapor from iQOS, a heat-not-burn device that has been test-marketed in several countries, blood vessel function decreased by 58 percent.
• Similarly, after ten 5-second exposures over five minutes to iQOS vapor, blood vessel function decreased by a similar amount, 60 percent.
• The reduction was comparable to that induced by cigarette smoke (57 percent for the 15-second exposures, 62 percent for the 5-second exposures).
• Exposure to clean air had no impact on blood vessel dilation.
• The amount of nicotine in the rats' blood after exposure to cigarette smoke was similar to the amount in blood after humans have smoked one cigarette, confirming that the exposure conditions were relevant to the real world. However, the amount of nicotine in the blood after exposure to iQOS vapor was substantially higher (70.3 nanogram/milliliter for iQOS, 15.0 nanogram/milliliter for cigarettes).

Using heat-not-burn products may not avoid the adverse cardiovascular effects of smoking cigarettes.