PMID- 37932763 OWN - NLM STAT- MEDLINE DCOM- 20231108 LR - 20231110 IS - 1743-8977 (Electronic) IS - 1743-8977 (Linking) VI - 20 IP - 1 DP - 2023 Nov 6 TI - Heterogeneous deposition of regular and mentholated little cigar smoke in the lungs of Sprague-Dawley rats. PG - 42 LID - 10.1186/s12989-023-00554-6 [doi] LID - 42 AB - BACKGROUND: Quantifying the dose and distribution of tobacco smoke in the respiratory system is critical for understanding its toxicity, addiction potential, and health impacts. Epidemiologic studies indicate that the incidence of lung tumors varies across different lung regions, suggesting there may be a heterogeneous deposition of smoke particles leading to greater health risks in specific regions. Despite this, few studies have examined the lobar spatial distribution of inhaled particles from tobacco smoke. This gap in knowledge, coupled with the growing popularity of little cigars among youth, underscores the need for additional research with little cigars. RESULTS: In our study, we analyzed the lobar deposition in rat lungs of smoke particles from combusted regular and mentholated Swisher Sweets little cigars. Twelve-week-old male and female Sprague-Dawley rats were exposed to smoke particles at a concentration of 84 +/- 5 mg/m(3) for 2 h, after which individual lung lobes were examined. We utilized Inductively Coupled Plasma Mass Spectrometry to quantify lobar chromium concentrations, serving as a smoke particle tracer. Our findings demonstrated an overall higher particle deposition from regular little cigars than from the mentholated ones. Higher particle deposition fraction was observed in the left and caudal lobes than other lobes. We also observed sex-based differences in the normalized deposition fractions among lobes. Animal study results were compared with the multi-path particle dosimetry (MPPD) model predictions, which showed that the model overestimated particle deposition in certain lung regions. CONCLUSIONS: Our findings revealed that the particle deposition varied between different little cigar products. The results demonstrated a heterogenous deposition pattern, with higher particle deposition observed in the left and caudal lobes, especially with the mentholated little cigars. Additionally, we identified disparities between our measurements and the MPPD model. This discrepancy highlights the need to enhance the accuracy of models before extrapolating animal study results to human lung deposition. Overall, our study provides valuable insights for estimating the dose of little cigars during smoking for toxicity research. CI - (c) 2023. The Author(s). FAU - Lin, Kaisen AU - Lin K AD - Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, 48824, USA. kaisen@msu.edu. AD - Air Quality Research Center, University of California, Davis, Davis, CA, 95616, USA. kaisen@msu.edu. FAU - Wallis, Christopher AU - Wallis C AD - Air Quality Research Center, University of California, Davis, Davis, CA, 95616, USA. FAU - Wong, Emily M AU - Wong EM AD - Air Quality Research Center, University of California, Davis, Davis, CA, 95616, USA. FAU - Edwards, Patricia AU - Edwards P AD - Center for Health and the Environment, University of California, Davis, Davis, CA, 95616, USA. FAU - Cole, Austin AU - Cole A AD - UC Davis Interdisciplinary Center for Plasma Mass Spectrometry, University of California, Davis, Davis, CA, 95616, USA. FAU - Van Winkle, Laura AU - Van Winkle L AD - Department of Anatomy, Physiology and Cell Biology, University of California, Davis, Davis, CA, 95616, USA. AD - Center for Health and the Environment, University of California, Davis, Davis, CA, 95616, USA. FAU - Wexler, Anthony S AU - Wexler AS AD - Air Quality Research Center, University of California, Davis, Davis, CA, 95616, USA. AD - Department of Mechanical and Aerospace Engineering, University of California, Davis, Davis, CA, 95616, USA. AD - Department of Civil and Environmental Engineering, University of California, Davis, Davis, CA, 95616, USA. AD - Department of Land, Air, and Water Resources, University of California, Davis, Davis, CA, 95616, USA. LA - eng GR - T30IR0955/Tobacco-Related Disease Research Program/ GR - T30IR0955/Tobacco-Related Disease Research Program/ GR - T30IR0955/Tobacco-Related Disease Research Program/ GR - T30IR0955/Tobacco-Related Disease Research Program/ PT - Journal Article DEP - 20231106 PL - England TA - Part Fibre Toxicol JT - Particle and fibre toxicology JID - 101236354 RN - 0 (Tobacco Smoke Pollution) RN - 0R0008Q3JB (Chromium) SB - IM MH - Humans MH - Rats MH - Animals MH - Adolescent MH - Male MH - Female MH - Rats, Sprague-Dawley MH - *Tobacco Smoke Pollution MH - Lung MH - *Tobacco Products/analysis MH - Chromium PMC - PMC10626780 OTO - NOTNLM OT - Heterogeneous deposition OT - Little cigar smoke particles OT - Lung lobar deposition OT - MPPD model OT - Sprague-Dawley rats COIS- The authors declare that they have no competing interests. EDAT- 2023/11/07 00:42 MHDA- 2023/11/08 06:43 PMCR- 2023/11/06 CRDT- 2023/11/06 23:59 PHST- 2023/08/14 00:00 [received] PHST- 2023/10/31 00:00 [accepted] PHST- 2023/11/08 06:43 [medline] PHST- 2023/11/07 00:42 [pubmed] PHST- 2023/11/06 23:59 [entrez] PHST- 2023/11/06 00:00 [pmc-release] AID - 10.1186/s12989-023-00554-6 [pii] AID - 554 [pii] AID - 10.1186/s12989-023-00554-6 [doi] PST - epublish SO - Part Fibre Toxicol. 2023 Nov 6;20(1):42. doi: 10.1186/s12989-023-00554-6.