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CORESTA Meeting, Smoke Science/Product Technology, 2023, Cancun, STPOST 08

Aerosol generation and exposure atmosphere characterization of VITROCELL Air Liquid Interface (ALI) exposure system using ENDS products

Battelle Memorial Institute, Columbus, OH, U.S.A.

Electronic nicotine delivery systems (ENDS) are frequently tested to evaluate their potential as reduced-risk alternatives to combustible cigarettes. This involves a variety of tests including in vivo and in vitro inhalation toxicity evaluations. A major challenge in comparing in vitro to in vivo models is the difference in properties of aerosol atmosphere to which the test system is exposed during these assessments. Here, we produced and characterized ENDS aerosol for in vitro air-liquid-interface (ALI) cell culture exposures to establish that the aerosol properties were stable and consistent with in vivo exposures.

CORESTA CRM 81 puffing regimen (55 ml puff volume, 3 seconds puff duration and a 30 second puffing interval) was used to produce aerosol from a commercially available ENDS product. Twelve ENDS were loaded simultaneously on the puff ports of the top bar of a linear smoking machine (LM24E). The master controller automatically adjusts the sequence of puffing to produce continuous exhaust from the machine, thus enabling generation of consistent and stable aerosol atmosphere. A mixing bulb installed at the output of smoking machine enabled proper mixing of the aerosol and addition of dilution air flow. The aerosol was then introduced to a VITROCELL 24/48 exposure system. The VITROCELL dilution manifold was set to achieve three target concentrations – Maximum-Achievable-Concentration (MAC) based on gravimetric measurements, mid dose of ~50 % of MAC and a low dose of ~20 % of MAC.

Aerosol characterization showed a MAC of 3.9 mg/L was achievable in the exposure system. The mid and low doses were ~56 % and ~23 % of MAC. Aerosol particle size measurements showed a MMAD of ~1.0 µm with a GSD of ~1.6 across all groups. The temporal variability of aerosol concentration was <10 %.

In summary, methods were developed to generate stable and consistent ENDS aerosol in the ALI exposure system.