Comparative Toxicity Responses of Thirdhand Smoke Derived from Conventional Cigarette and Heated Tobacco Products in Human Bronchial Epithelial Cells

Objective: Thirdhand Thirdhand smoke (THS) is described as the accumulated chemicals left on indoor surfaces after tobacco smoking. Individuals can be exposed to THS by dermal or oral contact with THS-embedded surfaces or by breathing in the off-gasses. In the present study, the cytotoxic, oxidative, and inflammatory responses of THS extracts yielded from conventional (THS-C) and heated-tobacco products (THS-H) were examined in BEAS-2B human bronchial epithelial cell line. Materials and Methods: The terrycloth samples were exposed to smoke in a closed polystyrene box and extracted in a complete cell culture medium for 24 hours at 37 degrees C. Following this, the cytotoxicity of THS was assessed by MTT assay. Malondialdehyde (MDA) and intracellular glutathione (GSH) levels were determined in BEAS-2B cell lysate to assess oxidative response. The aryl hydrocarbon receptor (AhR) and interleukine-6 (IL-6) levels were determined via an ELISA kit. Results: Both types of THS led to dose-dependent cytotoxicity in cells, which was remarkable with THS-C (50%, v/v). Moreover, GSH depletion and MDA increase were remarkable with both THS, particularly with THS-C. AhR activation was also slightly elevated with THS-C, whereas the increase in IL-6 was notable compared to THS-H. Conclusion: THS exposure might lead to potential health risks particularly for respiratory health and the results support the need for comprehensive regulations and public health initiatives to minimize the harmful effects of THS.