Cancer Research UK has joined other public health experts in criticizing a study on the effects of e-cigarette vapor on mice and human cells tested in a lab. Despite the clear limitations of the study and the shaky (at best) history of conclusions of mouse and cell studies actually matching up with impacts on humans, various media outlets were happy to incredulously report the story.
Below is a portion of Cancer Research UK’s response.
What did the study show?
They found that e-cig vapour raised levels of DNA damage in the lungs, bladders and hearts of mice.
They also found that the molecular machinery cells use to repair this DNA damage was less effective in the lungs of mice exposed to e-cig vapour.
Then they looked at how nicotine, the chemical that e-cigs vaporise, affects human lung and bladder cells 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-cigs 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?
The researchers described their results with an interesting line:
“It is therefore possible that e-cigarette smoke may contribute to lung and bladder cancer, as well as heart disease, in humans.”
While this is technically possible, the study didn’t look at humans, and so didn’t show any effect on the health of humans.
Different e-cigs devices deliver different amounts of vapour, and people use them in different ways. So the levels of e-cig vapour and nicotine used in the study might not match the levels that people are exposed to through normal use.
And other research didn’t show a link between nicotine products and cancer.
Finally and crucially, the study didn’t compare vaping to tobacco smoke.