Assessing Toxicant Properties and Health Effects of Cigarillo and Hookah Tobacco Aerosols in Rats

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Project Summary Nearly 16% of US young adults ages 18–24 report smoking cigars and a recent review documents growing evidence linking this product to lung cancer, coronary heart disease, aortic aneurysm and COPD. Similarly, epidemiological studies link waterpipe tobacco to these same diseases. To date, there are few studies characterizing health effects of these tobacco aerosols in animal models. The specific aims and research strategy derive from these research gaps and address two of the scientific domains in the RFA, toxicity and health effects. As mandated by the FDA, the studies are not mechanistic, but are designed to compare responses and effects across tobacco products (cigarettes, cigarillos, and hookah). The central hypothesis of this application is that cigarillo and hookah tobacco products will show significantly greater differences across one or more of the five health outcomes (cancer, transcriptional reprogramming, lung function and inflammation, cardiovascular effects and serum circulatory inflammation) being studied when compared to cigarettes. Building on more than two decades of experience in characterizing the physical and chemical properties of complex aerosols, aim 1 will use a recently developed 14-day rat nose only exposure system to provide comprehensive dose response characterization of hazardous chemicals in the exposure atmosphere linked to cancer and cardiopulmonary diseases between cigarettes, cigarillos, and hookah products. Quantitation of carboxyhemoglobin levels in response to increasing dose of the tobacco aerosols will be correlated with cardiovascular health effects biomarkers assessed under Aim 2, while plethysmography will evaluate exposure effects on pulmonary function. Aim 2 will use biospecimens collected following the 14-day exposures to assess effects across the five health outcomes described above. Sensitive and quantitative readouts of these cardiopulmonary biomarkers will be obtained to enable comparisons across products and to evaluate the effect of dose for informing differences in potency. A comprehensive set of biomarkers has been selected to enable identification of the most sensitive readouts for predicting long-term health effects. These biomarkers include specific DNA adducts, lipid peroxidation, cytokine panels, global assessment of lung transcriptional reprogramming, specific gene expression changes in heart and aorta and expression changes predictive for circulatory inflammation. Findings from these studies will support the establishment of new evidence-based regulatory policies for these products that in turn, will inform the public of their hazardous properties.