SMOKE from e-cigarettes could cause lung cancer – despite being tobacco free, experts have warned. Scientists found that exposure to nicotine vapour over a year caused mice to develop tumours in their lungs. They also discovered that e-cigarette smoke caused more than half of the mice to develop bladder hyperplasia – an increased number of […]
SMOKE from e-cigarettes could cause lung cancer – despite being tobacco free, experts have warned.
Scientists found that exposure to nicotine vapour over a year caused mice to develop tumours in their lungs.
They also discovered that e-cigarette smoke caused more than half of the mice to develop bladder hyperplasia – an increased number of cells lining the bladder, which could lead to cancer.
Study author Professor Moon-shong Tan, of NYU School of Medicine, said: “Tobacco smoke is among the most dangerous environmental agents to which humans are routinely exposed, but the potential of e-cig smoke as a threat to human health is not yet fully understood.
“Our study results in mice were not meant to be compared to human disease, but instead argue that e-cig smoke must be more thoroughly studied before it is deemed safe or marketed that way.”
The potential of e-cig smoke as a threat to human health is not yet fully understood
Prof Moon-shong Tan
His findings, published today in Proceedings of National Academy of Sciences (PNAS), showed that 22.5 per cent of the 40 mice exposed to e-cigarette smoke with nicotine over 54 weeks developed lung adenocarcinomas.
Prof Tan’s team also exposed 20 mice to e-cigarette smoke that didn’t contain nicotine – and found that none of them developed cancer and only one had signs of hyperplasia.
However, the study does have its limitations – including that it was conducted using a relatively small number of mice susceptible to developing cancer over their lifetime.
In the UK, e-cigarettes are tightly regulated for safety and quality.
They’re not completely risk free, but they carry a small fraction of the risk of cigarettes.
E-cigarettes do not produce tar or carbon monoxide, two of the most harmful elements in tobacco smoke.
The liquid and vapour contain some potentially harmful chemicals also found in cigarette smoke, but at much lower levels.
While nicotine is the addictive substance in cigarettes, it’s relatively harmless.
Almost all of the harm from smoking comes from the thousands of other chemicals in tobacco smoke, many of which are toxic.
Nicotine replacement therapy has been widely used for many years to help people stop smoking and is a safe treatment.
There’s no evidence so far that vaping causes harm to other people around you.
This is in contrast to secondhand smoke from smoking, which is known to be very harmful to health.
Source: NHS
The study mice also did not inhale smoke like a human would, but, instead were surrounded by it.
Co-author Herbert Lepor, the Martin Spatz Chair of Urology at NYU Langone Health, added: “Our next step in this line of work will be to expand the number of mice studied, to shorten and prolong e-cigarette exposure time, and to further investigate the genetic changes caused by e-cigarette smoke.”
Almost all researchers agree, however, that chemicals added during curing of tobacco – nitrate and nitrite – can cause a reaction called nitrosation, the authors say.
This is known to convert nicotine into nitrosamines such as NNN (N-nitrosonoricotine) and NNK (nicotine-derived nitrosamine ketone), proven carcinogens in mice and humans.
Prof Peter Hajek, Director of the Tobacco Dependence Research Unit, Queen Mary University of London (QMUL), said: “The study has unclear relevance for human vapers.
“Rodents were exposed to what are for them huge concentrations of chemicals that bear no resemblance to human exposure from vaping. Several animals in fact died during these exposures.
“The authors assigned the effects they observed to a carcinogen NNK – but NNK has been measured before in human vapers, and it is known that exposure from vaping is either negligible or none.”
The findings are based on very small numbers and need to be interpreted with extreme caution
Prof John Britton
Prof John Britton, a consultant in respiratory medicine at University of Nottingham, added: “The findings are based on very small numbers and need to be interpreted with extreme caution.
“The comparison between mice breathing vapour and mice breathing air is not statistically significant.
“There is no sample size justification and no power calculation. There is no message to the public here – I suspect these results are just noise.”
The research has been published at a time where the US is in the grips of a vaping epidemic.
At least 20 people have now been killed as a result of a mysterious lung disease which has been linked to e-cigarettes.
While, more than 1,000 people have also fallen ill – prompting health officials to warn people to stop using THC – the psychoactive element in cannabis – products immediately.
Last week, experts said that the devices could be causing by chemical burns similar to gas poisoning.
Researchers from the Mayo Clinic manged to review lung biopsies from e-cigarette users who were suspected to have the vaping lung injury.
They believe that the lung injuries were most likely caused by direct toxicity or tissue damage from noxious chemical fumes – similar to those seen in industrial accidents.
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