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Dear god, please stop this deluge of junk

13, Sep, 2016

By Tom Pruen

This past month has seen a deluge of ‘scientific’ publications that have strong, bold, conclusions that are pitifully supported by the actual tests performed (e.g. this and this).

We now have another candidate for the most overblown overextension of results award.

A poster presented at a conference states :

“This study shows, for the first time, that ECV upregulates adhesion of S. pneumoniae to lung cells. Nicotine appears partly responsible, but most of the increased adhesion is due to other compounds.”

This is interesting, and supported by the data. So far, so good.

However, the statements that were given to the press fare less well under any kind of critical examination.

“Professor Jonathan Grigg, a leading respiratory scientist, found that the propellant and the nicotine in e-cigarettes ​make airway cells more prone to bacterial infection, especially with pneumonia.”

There’s a tiny little problem here.

Firstly, in vitro tests (i.e. tests conducted ‘in glass’) on isolated cells do not accurately reflect the system from which they are taken, making extrapolation to systemic responses speculative.

Secondly, both nicotine and propylene glycol exhibit anti-bacterial effects, but these were removed from the cells before culturing bacteria, so it’s impossible to know if the increased adhesion is offset by these effects. Nicotine in particular is noted for its effectiveness against gram positive bacteria, which includes the bacteria which was used in this test. Washing makes a great deal of sense from a methodology perspective, but means that the modelling of real world exposures is extremely poor.

Thirdly, smoking is a risk factor for lung infections of all kinds, so a person who switches from smoking to vaping will reduce their risk (something demonstrated by survey data, which finds self-reported cough, colds, and other similar illnesses reduced in people who have switched).

So, does the increase in adhesion found in this study increase the risk of infection?

Probably not.

Does the data in this study demonstrate that vapers have an increased risk of pneumonia?

No. It not only doesn’t, it can’t.

A broad consideration of the likely effects of vaping on respiratory infections has been done, and can be found here.

Sadly, since it doesn’t support scary clickbait headlines, it didn’t get much publicity, and probably never will.

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