Are iQOS Aerosols Cytotoxic
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: iQOS cigarettes are a new heat-not-burn tobacco product that is being sold in 20 countries where they have been well received. In early markets, such as Japan, the manufacturer has had difficulty meeting demand for the product. iQOS will likely be introduced into the USA this year, and it has been projected that heat-not-burn products may become a dominate product that could eventually replace conventional cigarettes. Because iQOS heat tobacco rather than burning it, they emit fewer chemicals than conventional cigarettes, and as a result, they are being sold as a harm reduction product. Reports published by their manufacturer indicate that iQOS aerosol is less harmful than smoke from a conventional research cigarette. However, because they are a new entry into the tobacco market, there is very little published information on them, and their effects on human health are not well characterized. This project, which focuses the performance and toxicity of iQOS aerosol, directly addresses the TRDRP research priority 'Environmental Exposure and Toxicology'. We propose two goals: (1) to collect data on iQOS performance using a smoking machine and (2) to evaluate the toxicity of iQOS aerosol using cultured cells exposed to different concentrations of aerosol. We are currently collecting data on the performance properties of iQOS, such as how strong a puff is needed to produce aerosol and the number of puffs per cigarette. Our first proposed goal is to complete collecting performance data and prepare a manuscript on performance that would contain data that could be used by other investigators in future studies. Our second goal is to test the toxicity of aerosol from tobacco flavored iQOS and compare this to smoke from a conventional commercial cigarette and a research cigarette. Because iQOS cigarettes require cleaning, we also propose to compare the toxicity of aerosol from cigarettes that have not been cleaned to those that are properly cleaned. Some of the iQOS kits we have purchased have come without cleaning tools, suggesting that these products will be used without cleaning in some cases. Buildup of tobacco residues in uncleaned iQOS cigarettes could increase the toxicity of the aerosol, and this factor has not yet been examined in any published study. To accomplish this goal, we will use three cell-based assays for toxicity. The MTT assay measures cell metabolism. The neutral red assay measures uptake of a dye from solution, and the trypan blue assay measures rupture or leakiness of the cell's surface membrane. These assays will be used in conjunction with four cell types. Cells from mice (3T3 cells) that were used in the tobacco company study will be included in our project for comparison. The other three cell types are from the human lung and are primary targets of inhaled iQOS aerosol. These include cells that line the lung and cells that support the lining. Aerosols and smoke will be collected in the cell culture medium. Experiments will be done using serial dilutions of each test solution over eight different doses. Endpoints will be evaluated after 48 hours of exposure to test solutions. Dose response curves will be analyzed to determine the doses that inhibit survival of 50% of the cells versus the control. The lowest dose that produces an effect will also be analyzed and the potency of each treatment will be determined. From these data, we will be able to determine which products are the most cytotoxic and which cell types are the most sensitive to these products. We will also determine if cleaning iQOS products between uses affects the toxicity of the aerosol. These data will provide new information on the performance and cytotoxicity of iQOS products and will help guide future research with heat-not-burn products. The data will also provide baseline information that can be used by regulatory agencies when creating policies for heat-not-burn products and will help health care workers advise smokers and patients adopting iQOS products.