Extreme testing of undiluted e-cigarette aerosol in vitro using an Ames air-agar-interface technique

January 18, 2018


D. Thornea, M. Hollingsb, A. Seymourb, J. Adamsona, A. Dalrymplea, M. Ballantyneb, M. Gacaa

a British American Tobacco, R&D, Southampton, Hampshire, SO15 8TL, UK
b Covance Laboratories Ltd., Otley Road, Harrogate, North Yorkshire HG3 1PY, UK

This study investigated the in vitro mutagenicity of e-cigarettes and designed a study to deliver e-cigarette aerosol on an undiluted per puff basis under extreme testing conditions, using the Ames assay across a broader range of bacterial tester strains. The Vitrocell VC 10 smoking robot, previously used to generate and dilute cigarette smoke aerosols was modified to enable the testing of an undiluted e-cigarette aerosol.

There is a growing consensus that e-cigarettes hold the potential for reducing the harm associated with cigarette smoking. Recently published studies have reported in vitro testing of e-cigarettes, demonstrating reduced toxicological and biological effects. Few studies however have reported the use of e-cigarettes under extreme testing conditions. To assess the full mutagenic potential of a commercially available electronic-cigarette (Vype ePen), this study investigated the delivery of aerosol under extreme conditions, using a scaled-down 35mm plate Ames bacterial reverse mutagenicity assay. S. typhimurium strains TA98, TA100, TA97, TA104 and E. coli WP2 uvrA pKM101 with or without metabolic activation (S9), were employed. Using a modified Vitrocell VC 10 exposure system 0, 180, 360, 540, 720 or 900 puffs of undiluted e-cigarette aerosol was generated and delivered to bacterial cultures aligned to reported human consumption data. The results demonstrate that no mutagenic activity was observed in any strain under any test condition even when exposed to 900 puffs of undiluted ecigarette aerosols +/− S9. Positive control responses were observed in all strains +/− S9. Nicotine assessments demonstrated an increased and consistent aerosol delivery, with calculated maximum doses of∼1 mg/mL delivery of nicotine. These data demonstrate the validity of this unique testing approach and adds further information to the growing weight of evidence that e-cigarettes offer substantially reduced exposure when compared to conventional cigarette smoke. For future in vitro assessments of next generation tobacco and nicotine products, the generation, delivery and testing of undiluted aerosols can now be considered.

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