On 2017 Feb 27, Zvi Herzig commented:

Prolonged exposures of oropharyngeal tissue submerged in refill liquids are a poor comparison to brief exposures from accidents.

The constituents of EC liquids other than nicotine (glycerol, propylene glycol and food flavorings) are GRAS approved in relation to oral consumption. It's therefore unlikely that these would pose a particular hazard in relation to oral cancer.

Likewise, with regards to nicotine, epidemiology of prolonged oral exposure in relation to snus is not linked to oral cancer either Lee PN, 2011.

Thus none of the known e-liquid constituents are plausibly related to oral cancer. Which supports the above conclusion that the study's results unrelated to normal exposures.

On 2017 Jan 03, Christian Welz commented:

we discussed that issue in the publication: "Because most EC users refill their cartridges by themselves, and incidental or accidental contact is logical and described (Varelt et al., 2015; Vakkalanka et al., 2014) we intentionally used unvapored liquids for our experiments...."

On 2016 Dec 20, Zvi Herzig commented:

This study directly exposes cells to liquids, despite that fact that users are exposed to the vapor, not the liquid. This issue has been noted previously Hajek P, 2014, Farsalinos KE, 2014. The ~3 ml of liquid which EC users consume daily Farsalinos KE, 2014 is diluted by much air over hundreds of puffs. This is incomparable to the direct exposures to liquids in the present study.

On 2016 Dec 20, Zvi Herzig commented:

This study directly exposes cells to liquids, despite that fact that users are exposed to the vapor, not the liquid. This issue has been noted previously Hajek P, 2014, Farsalinos KE, 2014. The ~3 ml of liquid which EC users consume daily Farsalinos KE, 2014 is diluted by much air over hundreds of puffs. This is incomparable to the direct exposures to liquids in the present study.

On 2017 Jan 03, Christian Welz commented:

we discussed that issue in the publication: "Because most EC users refill their cartridges by themselves, and incidental or accidental contact is logical and described (Varelt et al., 2015; Vakkalanka et al., 2014) we intentionally used unvapored liquids for our experiments...."