E-Cigarette Vapor—Even when Nicotine-Free—Found to Damage Lung Cells

This study is more or less useless without several data points they left out. There is no mention of what devices are used to gather the e-cigarette vapor into a concentrate, so we have no idea at what temperature the vapor was created, which is hugely relevant to the chemical composition of the e-cig concentrate they made. Since the concentrate is what was used for the animal studies, they provide no useful information whatsoever - humans do not vape e-cig extract nebulized in saline, so the methods used in gathering that extract are hugely relevant.

They also do not mention what e-liquid they used, which is similarly relevant. An e-liquid is typically comprised of nicotine, propylene glycol, vegetable glycerine, and flavoring. food and pharmaceutical grades of the PG & VG and similarly pure nicotine don't contain acrolein, so it's reasonable to assume it was present in the flavoring or created during the vaporization of the liquid. We could get some valuable data regarding a particular flavoring component used in the juice they used, or a particular vaporization pattern to avoid, but they don't provide that data either.

The bias or perhaps ignorance of the researchers is made somewhat clearer in a small aside they include in the paper:

In addition, NMR detected the 254 propylene glycol (antifreeze) and glycerol in e-Cig solutions

Propylene Glycol is only an antifreeze in the sense that it's freezing point is lower than water. It carries virtually none of the high toxicity of Ethylene Glycol, which is much more typically a constituent of antifreeze than PG. When PG is used in antifreeze, it is used to drop the toxicity rather than to raise it. It has thousands of other uses, including being a common component of inhaled pharmaceutical formulations. To simply and unnecessarily note it as "antifreeze" as if a single uncommon use of a versatile chemical renders it toxic is silly and has no relevance here except to attempt to excite the confirmation bias of the uneducated.

/r/science Thread Link - the-aps.org