The mutagenic assessment of an electronic-cigarette and reference cigarette smoke using the ames assay in strains Ta98 and Ta100

Introduction:
This text describes a study that compares the mutagenic potential of an electronic cigarette (e-cigarette) and a reference cigarette using the ames assay in strains Ta98 and Ta100. The study assessed two different test matrices: e-cigarette aerosol collected matter (aCM) and freshly generated e-cigarette aerosol. The results were compared to those obtained for cigarette smoke total particulate matter (TPM) and whole aerosol.

Key points:

* The study found that e-cigarette aCM was non-mutagenic in the 85 mm plate incorporation ames assay in strains Ta98 and Ta100, while cigarette smoke TPM and aerosol from 3R4F reference cigarettes were mutagenic in both tester strains.
* Freshly generated e-cigarette aerosol was also found to be negative in both strains after an aaI aerosol exposure, while positive control responses were observed in both strains using benzo[a]pyrene, 2-nitrofluorene, sodium azide, and 2-aminoanthracene in Ta98 and Ta100 in the presence and absence of metabolic activation.
* The study highlights the importance of using a comprehensive ames package of data, including the standard OECD-five, Ta98, Ta100, Ta1535, Ta1537 (or Ta97) and E. coli (or Ta102), to assess e-cigarettes properly.
* The study also suggests that Ta104, which is more sensitive to carbonyl-based compounds found in e-cigarette aerosols, may be a useful addition to the testing battery.
* Regulatory standard product testing approaches will become important in determining whether e-cigarette aerosols are less biologically active than cigarette smoke.
* Future studies should be supported by in vitro dosimetry approaches to draw more accurate comparisons between cigarette smoke, e-cigarette aerosol exposure, and human use.

Main message:
The study suggests that e-cigarettes have a reduced mutagenic potential compared to cigarette smoke in tester strains Ta98 and Ta100 in both particulate and aerosol test matrices. however, the study emphasizes the importance of using a comprehensive ames package of data and in vitro dosimetry approaches to draw more accurate comparisons between cigarette smoke, e-cigarette aerosol exposure, and human use. The study's findings support the growing evidence that e-cigarettes are significantly less harmful than cigarettes, but further investigations are required before a clear understanding of the mutagenic potential of e-cigarettes can be established.

Thorne, D., I. Crooks, M. hollings, a. Seymour, C. Meredith, and M. Gaca. “The Mutagenic assessment of an Electronic-Cigarette and Reference Cigarette Smoke Using the ames assay in Strains Ta98 and Ta100.” Mutation Research/Genetic Toxicology and Environmental Mutagenesis 812 (December 2016): 29–38. https://doi.org/10.1016/j.mrgentox.2016.10.005.