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Inhalation Study of the In Vivo Toxicity of Essential Oils

Inhalation Study of the In Vivo Toxicity of Essential Oils

Principal Investigators: Narayanan Rajendran and Lynn Crosby

Funding Mechanism: Research Contract

ID number: HHSF223201510033I

Award Date: 9/14/2017

Institution: Illinois Institute of Technology Research Institute


Some essential oils used in tobacco products – including cinnamon bark oil, cinnamon leaf oil, and sage oil -- have been shown in in vitro studies to be toxic or are believed to possess toxic properties based on scientific literature. The aim of this study is to determine the inhalation toxicity of these three essential oils in rats and use these data to estimate potential inhalation toxicity in humans. In three 14-day dose-ranging studies (one per oil), researchers will expose rats to aerosol generated from the oil and determine the threshold concentration that can cause non-lethal/non-painful/non-stressful effects and the maximum tolerable dose (or maximum feasible dose). In three sub-acute 28-day studies (one per oil), researchers will characterize the dose response of each oil and determine the no observed adverse effect level (NOAEL), no observed effect level (NOEL), lowest observed adverse effect level (LOAEL), and lowest observed effect level (LOEL). The objective of the 14-day studies is to determine the starting dosages for the 28-day studies based on clinical signs, whereas the objective of the sub-acute studies is to observe and quantify toxicity in all organs, especially the nasopharyngeal tissue, respiratory tract and lungs. Study findings will help determine the potential for human health effects from exposure to inhaled essential oils and may inform regulatory activities related to tobacco product additives/ingredients.