Many people have read the recent headlines in National Newspapers saying e-cigarettes are no different to conventional cigarettes in that they contain nicotine and that this can cause cancer. But the study that the stories are based on, published in the journal PNAS, does not actually show this.

What was the purpose of the study?

Researchers from the New York University School of Medicine looked at how e-cigarette vapour affected the DNA of mice and human cells in a Petri dish. They didn’t look at how it affected people. And they didn’t directly compare it to smoking. The research focused on how components of vapour from e-cigarettes damage cells’ DNA. And DNA damage may increase the risk of cancer. But they didn’t look directly at whether e-cigarettes cause cancer, either in mice or in people.

What did the study show?

The study showed that e-cig vapour raised levels of DNA damage in the lungs, bladders and hearts of mice. That the molecular machinery cells use to repair this DNA damage was less effective in the lungs of mice exposed to e-cigarette vapour.

They then looked at how nicotine, the chemical that e-cigarettes vaporises, affects the human lung and bladder cells were grown in a lab dish. Nicotine is what makes cigarettes addictive but isn’t what causes the damage from smoking. Both e-cigarettes and conventional cigarettes contain nicotine, but e-cigarettes have much lower levels of the harmful components of tobacco smoke.

The researchers found that nicotine damages the DNA inside those lab-grown human lung and bladder cells. And they found that these cells were less able to repair this damage. These cells were then more susceptible to further genetic faults that could give them properties like those of cancer cells.

What do the results mean?

In essence, the results gave no credible evidence that nicotine or e-cigarettes actually cause cancer. The researchers reach a rather ambiguous conclusion “It is, therefore, possible that e-cigarette smoke may contribute to lung and bladder cancer, as well as heart disease, in humans.” Technically everything is possible (much like crossing the road and falling under a bus scenario), but the fact is the study didn’t look at humans and so didn’t show any effect on the health of humans.

In a laboratory setting, much of the testing and experimentation is far different from that of e-cigarette users’ habits and the devices used. Different vaping devices deliver different amounts of vapour, and people use them in different ways. So the levels of vapour and nicotine used in the study could not match the levels that people are exposed to through normal use. Crucially before this study, previously documented research has demonstrated that there is no link between nicotine products and cancer.1

“In animal studies, however, nicotine itself has repeatedly failed to show carcinogenic effects (Levy & Martin, 1989). In one animal study, rats breathed in a chamber with nicotine at a concentration twice that found in the plasma concentration of heavy smokers (Waldum et al., 1996). Nicotine was given for 20 hr a day, 5 days a week, over a 2-year period. The authors found no increase in mortality or frequency of tumours in these rats compared with controls. Specifically, there were neither microscopic nor macroscopic lung tumours nor any increase in pulmonary neuroendocrine cells. Thus, even long-term exposure to inhaled nicotine at relatively high doses does not appear to have a carcinogenic effect.” 1 

Finally and crucially, the study failed to compare vaping to tobacco smoke.

So why the ‘Fake News’?

The evidence provided so far shows that e-cigarettes are far less harmful than smoking as much as 95%, as announced by Public Health England and further endorsed as recently as February 2018. That and the fact that for many people vaping is a more useful aide to stop smoking, and as we know all to well, good news does not sell – but bad news grabs attention – hence the ‘fake news’ and the media’s misleading attention-grabbing headlines. For them, it is not about saving lives but of making money

Be Informed – do not be deceived

¹ Does nicotine replacement therapy cause cancer? Evidence from the Lung Health Study