Lynn McFadden, Ph.D., is the Senior Manager of Toxicology for Enthalpy Specialty Labs. Lynn earned a Bachelor of Science in Chemical Engineering from Trine University, a Master of Science in Chemical Engineering from the University of Michigan, and a Doctor of Philosophy in Chemical Engineering from Virginia Commonwealth University. Her dissertation work involved designing and prototyping the first portable device to measure aerosol exposure within the breathing zone and cellular response in real time – the Portable In Vitro Exposure Cassette (PIVEC). Through the Fulbright Program and as part of her dissertation work, she worked as a Fulbright Fellow at the Centre for Research & Technology Hellas – Aerosol and Particle Technology lab in Thessaloniki, Greece. Lynn served as a Postdoctoral Fellow at Rutgers University after graduation, expanding her research into bioaerosols. She joined Enthalpy in 2021 as a Group Leader and quickly progressed to Senior Manager. Lynn’s research interests currently include aerosol exposure, nicotine products, and the relationship between laboratory testing and real-world applicability.

OpenTox 2023 Virtual Conference 

In Vitro Characterization of a Heated Tobacco Product Collected Using a Novel Method 

Due to the reduced harm nature of Heated Tobacco Products (HTPs) in comparison to combustible cigarettes, the generation of concentrated extract is necessary. Condensate testing in vitro toxicology assays is limited by the maximum allowable solvent levels that can be used, as well as the concentration of the generated condensate. Here we present results from the development of two HTP aerosol collection methods and corresponding Bacterial Reverse Mutation (Ames) Assay and Neutral Red Uptake (NRU)  Assay results using commercially available IQOS devices (v2.4) and Marlboro Amber HeatSticks. Using our proprietary method for aerosol collection and extraction where multiple devices are activated sequentially and aerosol collected mass (ACM) is trapped on custom-sized 30 mm pads placed behind the  IQOS devices to minimize aerosol losses, we generated an aerosol condensate of ~200 mg/ml of ACM,  more than tripling the capabilities of our standard linear collection method while also reducing vaping time required. Based on our current in-house standard collection, the concentration of test articles is ~60 mg/ml, resulting in a maximum dose of 3 mg/plate for Ames and an upper end of the NRU dose range of ~300  mg/ml. With this improved collection method, we are able to extend the top of the NRU dose range to  ~1000 mg/ml and beyond the OECD recommended maximum of 5 mg/plate for Ames. In the present study,  both DMSO-extracted ACM and whole smoke (particulate and gas vapor phase components trapped together) were tested in five strains of S. typhimurium used in the Ames assay and 3T3 cells in the NRU  assay. For the Ames assay, extending the dosing range leads to an improved understanding of toxicity from the test article. For the NRU assay, EC50 values were calculated for both extract types, demonstrating that this novel method improves the ability to determine the EC50 of aerosol condensates by extending the dosing range. This aerosol generation method is highly flexible, having the ability to be extended to electronic nicotine delivery system devices.