Evaluation of flavourings potentially used in a heated tobacco product: Chemical analysis, in vitro mutagenicity, genotoxicity, cytotoxicity and in vitro tumour promoting activity

Introduction:
This article presents a study evaluating the impact of flavorings in a heated tobacco product (ThP) on the levels of toxicants in the emissions and in vitro responses. The study compares the chemical profile and toxicity of a ThP with and without flavorings to that of a reference cigarette (3R4F). The study aims to determine whether the inclusion of potential flavorings in the ThP would add to the levels of toxicants in the emissions or alter in vitro responses.

Key Points:

* The study used a ThP consisting of two parts: a hand-held device and a tobacco rod (Neostik) containing reconstituted Virginia blended tobacco and glycerol.
* The Neostiks were heated to a maximum temperature of 250 °C, and aerosol was generated, which delivered nicotine and flavoring components if present.
* The toxicant emissions were measured from both Neostiks and compared to those of 3R4F.
* The study used several in vitro toxicity assays, including the ames test, in vitro micronucleus test, mouse lymphoma assay (MLa), Neutral Red uptake assay (NRU), and Bhas 42 cell transformation assay.
* The results showed that the addition of flavorings to the Neostik did not alter the chemical profile of ThP emissions or change in vitro responses relative to the unflavored Neostik.
* The toxicant emissions were significantly lower in the ThP compared to 3R4F, and no mutagenicity was observed in the ames test or MLa.
* The in vitro micronucleus test showed weak genotoxic responses in both Neostiks, but these responses were less than 3R4F.
* The Bhas 42 cell transformation assay and NRU assay did not show tumor-promoting potential or cytotoxicity in either Neostik.

Main Message:
The study found that adding flavorings to the ThP did not alter the chemical profile of ThP emissions or change in vitro responses relative to the unflavored Neostik. The toxicant emissions were significantly lower in the ThP compared to 3R4F, and no mutagenicity was observed in the ames test or MLa. The weak genotoxic responses observed in the in vitro micronucleus test were less than 3R4F. Overall, the study suggests that the addition of flavorings to the ThP does not increase the toxicity of the emissions or alter in vitro responses.

Crooks, Ian, Louise Neilson, Ken Scott, Lorna Reynolds, Tobi Oke, Mark Forster, Clive Meredith, Kevin Mcadam, and Chris Proctor. “Evaluation of Flavourings Potentially Used in a heated Tobacco Product: Chemical analysis, in Vitro Mutagenicity, Genotoxicity, Cytotoxicity and in Vitro Tumour Promoting activity.” Food and Chemical Toxicology 118 (august 2018): 940–52. https://doi.org/10.1016/j.fct.2018.05.058.