City Research Online

Abstract

This study investigates the potential adverse effects of flavoured e-liquids on the cellular components of the respiratory system, addressing a critical gap in understanding the adverse health consequences associated with electronic cigarette (EC) use. While ECs are deemed less hazardous than conventional tobacco smoking, concerns persist, especially regarding the inhalation of flavouring chemicals. Though these flavourings are generally recognised as safe for ingestion, their impacts upon inhalation, particularly when heated, remain ambiguous.

We evaluated 53 nicotine-free flavoured e-liquids, focusing on their direct and aerosolized impacts on submerged cultures and air-liquid interface (ALI) exposures. Employing in vitro endpoint assays, including cell count, cell viability, and cytotoxicity tests facilitated via a high-throughput 96-well plate system, we identified adverse effects associated with four specific flavours: cinnamon, hazelnut, vanilla tobacco, and menthol. These e-liquids demonstrated decreased mitochondrial membrane potential and increased reactive oxygen species (ROS) production, surpassing the effects of PG/VG vehicle control.

Gas Chromatography-Mass Spectrometry (GC-MS) analysis unveiled the presence of potentially toxic volatile organic compounds, including estragole, biphenyls, and 1,3-dioxane in these e-liquids. Aerosol exposure studies in ALI-differentiated HBEC-3KT cells illustrated a unique toxicological profile for each of the four flavours, with cinnamon emerging as the most toxic. Notably, all flavours and, more markedly,
cinnamon elicited a heightened genetic response in oxidative stress, marked by the significant stimulation of ddit3 and hmox1 genes. However, morphological changes to the lung epithelium were less pronounced than the 3R4F cigarette control. These findings contribute valuable insights to the ongoing discourse on EC safety. They provide empirical data that can inform regulatory decisions concerning restricting or banning specific e-liquid flavours due to their toxicological profiles. The nuanced understanding of flavour-specific adverse effects underscores the need for comprehensive evaluations of all e-liquid constituents to ensure public health safety amidst the growing popularity of ECs.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QH Natural history > QH301 Biology R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine R Medicine > RM Therapeutics. Pharmacology
Departments:	School of Health & Medical Sciences > Institute of Medical, Biomedical and Allied Health Education School of Health & Medical Sciences > School of Health & Medical Sciences Doctoral Theses Doctoral Theses

Export

Downloads