Development and Application of a Novel Aerosol Respiratory Deposition Method to Assess Health Risks of Metals in E-Cigarette Aerosol

WEI-CHUNG SU, Jinho Lee, University of Texas Health Science Center at Houston

     Abstract Number: 10
     Working Group: Health-Related Aerosols

Abstract
This study improved the performance of the Mobile Aerosol Lung Deposition Apparatus (MALDA) and utilized it to investigate the respiratory deposited mass of e-cigarette aerosol. The enhanced MALDA broadens its applicability in aerosol respiratory deposition studies by covering a wider particle size range, from nanometers to micrometers, making it ideal for various aerosol exposure research. By integrating MALDA with the Micro-Orifice Uniform Deposit Impactor (MOUDI), the resulting MALDA-MOUDI tandem system enables an effective estimation of the size-dependent deposited mass of inhaled aerosol in major airway regions, providing crucial data for assessing health risks caused by aerosol exposure. To study e-cigarette aerosol respiratory deposition using the MALDA-MOUDI tandem system, a series of laboratory experiments were conducted to obtain the deposited mass of e-cigarette aerosol in human airways. Three different types of e-cigarettes (JUUL, disposable, and IQOS) were used to generate test e-cigarette aerosol. Respiratory deposition experiments were carried out under both active (mainstream) and passive (secondhand) vaping conditions. Metal-induced health risks were systematically evaluated based on the measured respiratory deposited mass according to presumed active and passive vaping scenarios. The acquired results indicated that non-cancer and cancer risks associated with metals released from the tested e-cigarettes fell within acceptable levels for both active and passive vaping. The MALDA-MOUDI approach developed in this study can be applied to other environmental and occupational aerosol exposure research to assess health risks associated with toxic substances present in the aerosol particles.