Dosimetric Analysis of Aerosol Generated by a Vitrocell® VC10® Smoking Robot – Investigations on Dose Dependency and Consistency of Application

November 30, 2019

Adam Seymour, Michael Hollings, Joanne Larner and Julie Clements;

Covance Laboratories Ltd, Harrogate, UK

QCMs were used to assess the deposition of cigarette aerosol from a Vitrocell® VC10® in Vitrocell® Ames, 6/4, 12/4 and 24/4 exposure modules. The power to resolve difference between 8 and 1 SLPM is statistically significant in all module types assessed. Uniformity within each module was confirmed (P >0.98) in all module types, at all airflows. Repeatability was assessed and found to be consistent (no significant difference) in all module types at airflows of 10, 8 and 4 SLPM, however, at 1 SLPM a significant difference was noted in 9 out of 12 experiments – likely an artifact of high deposition.
These results show that exposures utilizing the Vitrocell® VC10® and associated modules are robust; but indicate the necessity of dosimetry measures to aid in the quantification of delivered dose.

Quartz Crystal Microbalances (QCMs) were used to assess the suitability of the Vitrocell® VC10® exposure system. The main objective of the study was to deliver smoke aerosol in a consistent and dose dependent manner across a range of module formats.
Dose resolving power, uniformity of deposition within the module, and repeatability across experiments were all assessed by the application of the 3R4F aerosol after dilution with clean air at flow rates of 10, 8, 4 and 1 SLPM (n=3). Twelve 3R4F were smoked per experiment according to the HCI Smoking regimen (Health Canada Test method T-115). Exposure duration in the system was 66 minutes. Vitrocell® Ames 4, 6/4, 12/4 and 24/4 exposure modules were assessed. The ability to resolve statistically significant differences between   the 8, 4 and 1 SLPM dilution levels was observed across all modules in the test, however none of the module formats were able to detect a significant difference between dilution rates between
10 and 8 SLPM. Uniformity of deposition within the module was assessed on a per experiment basis and found to have no significant differences and high reproducibility (adjusted P >0.98) in all module formats tested and across the full range of airflows. Repeatability was assessed per airflow over three experiments and showed no significant difference at airflows of 10, 8 and 4 SLPM, however a significant difference between experiments was found in 9 out of 12 cases at 1 SLPM airflow.
Our assessments show that the Vitrocell® VC10® is capable of delivering cigarette aerosol in consistent and dose dependent manner. However, it was found that resolution of small differences in dose (particularly at higher dilution rates) is critical and therefore at low dilution rates variability of deposition should be expected on a per experiment basis.

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