Tests on mice find e-cigs, promoted as a safer alternative to cigarettes contain nicotine which is far from harmless.
According to a new study, vapers have higher risk of cancer and heart disease, when compared to non-smokers.
The New York University School of Medicine team, led by Dr Moon-shong Tang, pointed out e-cigs were rapidly gaining popularity, especially among young people who regard them as harmless.
Battery-powered e-cigs have been widely promoted as a safer alternative to cigarettes because they do not burn tobacco — but scientists now warn the nicotine in them is far from harmless.
According to researchers, laboratory tests showed that when mice were to e-cig vapour they had higher levels of DNA damage in the heart, lungs and bladder than those just breathing clean air.
DNA repair systems which protect against cancer were also impaired in the cells of the animals, the US researchers discovered.
While tobacco smoke contains a host of dangerous chemicals, e-cig liquid consists only of nicotine and relatively harmless solvents. Recent studies have shown that e-cig users have 97 per cent less of a lung cancer-causing component known as NNAL in their bodies than tobacco smokers.
That is similar to the level in those on nicotine-replacement therapy.
However, NNAL levels for vapers are still significantly higher than for non-smokers, the team found.
According to the researchers e-cigarette smoke is carcinogenic and smokers have a higher risk than non-smokers to develop lung and bladder cancer and heart diseases.”
Similar results were seen in cultured human lung and bladder cells exposed to nicotine.