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Correspondence to Author: Ji Hyun Lee¹, , Mi Seong Jo², Hoi Pin Kim³, Youngshang Han⁴,Yong Taek Kwon⁵,Kangho Ahn^6,7,, Il Je Yu^1,8*. 

1. HCT Seattle, USA; toxin1130@gmail.com.
2. HCT, Icheon, Korea; whaltjd@hctm.co.kr.
3. H&H Bio, Asan, Korea; ghlqls93@hnhbio.com.
4. Department of Mechanical Engineering, University of Washington, Seattle, USA; visual94@uw.edu
5. H&H Bio, Asan, Korea; ytkwon@hnhbio.com
6. Art Plus, Seoul, Korea
7. Hanyang University, Ansan, Korea; khahn@hanyang.ac.kr
8. Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, USA; a62370867@gmail.com

DOI: 10.52338/jotr.2025.4468

Abstract:

Recently, new approach methods (NAM) have been utilized to reduce animal experimentation and housing and care costs. The use of NAM to assess safety is paramount, underscoring the need for the method to be established for validity and reliability. NAM for inhalation toxicity is now developing to replace traditional animal inhalation toxicity tests. To align with animal inhalation toxicity studies, dosimetry and dose metrics for in vitro inhalation must be consistent with those of animal studies. In this study, we present a novel approach to address key elements of dosimetry and dose metric characterization for in vitro inhalation toxicity testing using an air-liquid interface (ALI) system. By generating nanosized NaCl aerosols and exposing a 6-transwell ALI system for two hours, we quantitatively determined deposited doses for each transwell. Our study further identifies critical dose metrics for in vitro inhalation studies, including particle size, number concentration, concentration stability, and deposition variability during exposure. Importantly, when comparing the deposition outcomes of in vitro and in vivo systems, our results demonstrate that the in vitro deposition variability closely mirrors that observed in vivo lung deposition. This finding underscores the potential of our in vitro methodology to align with regulatory inhalation guidelines, offering a robust framework for transitioning from animal-based inhalation studies to NAM-based approaches. Our work contributes to the growing body of evidence supporting the scientific and regulatory feasibility of NAMs in inhalation toxicology, highlighting their capability to deliver accurate and reproducible results.

Keywords: In vitro inhalation, New approach methods, Air-liquid interphase, Dosimetry, Dose metric.

Citation:

Dr.Il Je Yu, Dosimetry And Dose Metric Considerations On In Vitro Inhalation Toxicity Testing Of Nano- Aerosols. Journal of Toxicological Research 2025.