Yeah, this title for the article is really terrible. The "why" that scientists are investigating is not why many lung cancers aren't in nonsmokers. The "why" they are investigating is "why are these non smokers getting cancer?". Once smoking stops being such a dominant cause, you put more energy into the other cases.
I can’t find any complete numbers (most prevalent factors after smoking would be environmental, and therefore underreported, especially when as hard to detect as radon), but national health agencies tend to put the Radon section second, after Smoking [1,2]. An uncited figure on a Hopkins webpage suggests 30% of non-smoking lung cancer cases are caused by Radon [3]. Among the well-known environmental factors (asbestos, secondhand smoke), it seems to be about equal for risk increase [4]. Given that asbestos and secondhand smoke are on the decline, it stands to reason that radon will tend toward being the top cause, barring a rise in prevalence of one of the disease risk factors (asthma, pneumonia, HIV, tuberculosis).
Of course this is all moot because vaping will be revealed to be the current #1 cause of lung cancer in the coming decades, by a long shot. No citation necessary.
> Of course this is all moot because vaping will be revealed to be the current #1 cause of lung cancer in the coming decades, by a long shot. No citation necessary.
That isn't obvious or apparent to me at all so I do think a citation would be good to see. Nicotine is definitely a culprit in a lot of cardio-related issues for sure. I think some flavoring agents are the more questionable thing and would be curious to hear about those specifically in relation to lung cancers.
Fair enough. Cancer causation is just so weird, I'm going off the heuristic that stuff in your lungs that your lungs aren't prepared for is probably not great, especially with chronic exposure. And your lungs are really only prepared for air (which includes many things within certain tolerances [0]). The "not great" => "cancer" pipeline is really where the hand-waving comes in, and mostly far too early to tell whether the parts of vaping that are "not great" for your lungs will in fact be carcinogenic for your lungs.
So that being said, I'm mostly going to offer citations for "vaping is not great for your lungs." And that being said, I'm just going to offer citations for "specific parts of vaping are not good for your lungs." But my broader argument is that putting stuff in your lungs is going to be bad for your lungs, and these are just the most obvious ones we've found so far. Unfortunately I won't be able to find a citation for that argument.
So, first, the most recent: a study showing disposable vapes had incredibly high level of toxic metal emissions [1]. The non-disposable Juul et al variously have some concerning levels, but the insane numbers are on disposables, which are largely (entirely?) illegal in the US, at least. Still, they're not illegal everywhere, they were used heavily for several years in the US, and several of the top Google results were redditors complaining about the stupid ban and talking about how to get around it. All of this combines to lung damage down the line, and several of the toxic metals are outright carcinogenic, so lung cancer as well.
A more particular example: popcorn lung is a terrifying name, but pretty restricted risk, given the causing chemical is only in certain flavors, and those have supposedly stopped using it [2]. But again, an example of weird chemicals in your lungs cause weird things, and it'll be decades til we figure out all of them.
And finally, a study showing that vaping plus smoking leads to a four-fold higher risk of lung cancer over smoking alone (yes, they adjusted for age, gender, race, location of residence, prevalent comorbidities, and pack-years of smoking) [3].
[0] I was hoping to make a glib point about even high enough pollen concentration being bad for your lungs, but in fact a recent study suggests that allergies reduce risk of lung cancer! I'm chalking that up to allergies being your body's way of keeping non-air particulates from your lungs, but who knows. https://www.frontiersin.org/journals/medicine/articles/10.33...
