RESUMEN
For a tobacco heating product (THP), which heats rather than burns tobacco, the emissions of toxicants in the aerosol were compared with those in cigarette smoke under a machine-puffing regimen of puff volume 55 ml, puff duration 2 s and puff interval 30 s. The list of toxicants included those proposed by Health Canada, the World Health Organization Study Group on Tobacco Product Regulation (TobReg), the US Food and Drug Administration and possible thermal breakdown products. In comparison to the University of Kentucky 3R4F reference cigarette the toxicant levels in the THP1.0 emissions were significantly reduced across all chemical classes. For the nine toxicants proposed by TobReg for mandated reduction in cigarette emissions, the mean reductions in THP1.0 aerosol were 90.6-99.9% per consumable with an overall average reduction of 97.1%. For the abbreviated list of harmful and potentially harmful constituents of smoke specified by the US Food and Drug Administration Tobacco Products Scientific Advisory Committee for reporting in cigarette smoke (excluding nicotine), reductions in the aerosol of THP1.0 were 84.6-99.9% per consumable with an overall average reduction of 97.5%.
Asunto(s)
Aerosoles/análisis , Aerosoles/química , Sistemas Electrónicos de Liberación de Nicotina/métodos , Calefacción/métodos , Humo/análisis , Productos de Tabaco/análisis , Sustancias Peligrosas/análisis , Sustancias Peligrosas/química , Calefacción/efectos adversosRESUMEN
Inhalation of cigarette smoke particles (CSP) leads to adverse health effects in smokers. Determination of the localized dose to the lung of the inhaled smoke aids in determining vulnerable sites, and identifying components of the smoke that may be responsible for the adverse effects; thus providing a roadmap for harm reduction of cigarette smoking. A particle deposition model specific to CSP was developed for the oral cavity and the lung by accounting for cigarette particle size growth by hygroscopicity, phase change and coagulation. In addition, since the cigarette puff enters the respiratory tract as a dense cloud, the cloud effect on particle drag and deposition was accounted for in the deposition model. Models of particle losses in the oral cavities were developed during puff drawing and subsequent mouth-hold. Cigarette particles were found to grow by hygroscopicity and coagulation, but to shrink as a result of nicotine evaporation. The particle size reached a plateau beyond which any disturbances in the environmental conditions caused the various mechanisms to balance each other out and the particle size remain stable. Predicted particle deposition considering the cloud effects was greater than when treated as a collection of non-interacting particles (i.e. no cloud effects). Accounting for cloud movement provided the necessary physical mechanism to explain the greater than expected, experimentally observed and particle deposition. The deposition model for CSP can provide the necessary input to determine the fate of inhaled CSP in the lung. The knowledge of deposition will be helpful for health assessment and identification and reduction of harmful components of CSP.
Asunto(s)
Modelos Biológicos , Nicotiana , Sistema Respiratorio/metabolismo , Humo/análisis , Floculación , Humanos , Boca/química , Tamaño de la Partícula , Fumar/metabolismo , Agua/químicaRESUMEN
Single event electrospraying (SEE) is a method for on-demand deposition of femtoliter to picoliter volumes of fluids. To determine the influence of the size of the meniscus on the characteristics of the single event electrospraying process, glass capillaries were used with and without an antiwetting coating comprising a self-assembled 1H,1H,2H,2H-perfluorodecyltrichlorosilane-based monolayer to control the meniscus size. A large difference was found in driving single event electrospraying from a small meniscus compared to what is needed to generate a single event electrospraying from a large meniscus. Furthermore, after studying the different time constants related to the electrical and the hydrodynamic phenomena, we are able to explain the timing limitations of the deposition process from both a small and a large meniscus. The hydrodynamic relaxation time is significantly reduced in the case of the modified capillary, and the timing of SEE, which determines the deposition time, is limited by the resistor-capacitor RC time of the electrical circuit needed to drive the SEE. We have built a model that describes the almost one-dimensional motion of the liquid in the capillary during pulsing. The model has been used to estimate the hydrodynamic relaxation times related to the meniscus-to-cone and cone-to-meniscus transitions during SEE. By confining the meniscus to the inner diameter of the nozzle, we are able to deposit a volume smaller than 5 pL per SEE.