Reactivity of surface nicotine towards indoor ozone
Initial Award Abstract
In spite of the relatively long residence time of sorbed nicotine in indoor environments, its chemical reactions with atmospheric oxidants have not been systematically investigated, and the degree to which such reactions occur in indoor environments has not been determined. Atmospheric ozone was recently recognized as a major driver of indoor chemistry, and was shown to react with tobacco smoke components, yielding aldehydes that are toxic and mucous membrane irritants. The proposed investigations will evaluate nicotine's reactivity towards atmospheric ozone, to provide a more accurate description of two important aspects of secondhand tobacco smoke exposure: the identification of toxic irritants byproducts generated by indoor oxidation of nicotine, and the influence of those reactions in the overall nicotine indoor dynamics. Since nicotine is predominantly sorbed to indoor surfaces, its reactivity towards ozone will be experimentally evaluated in the presence of materials commonly found indoors, such as carpet, gypsum board and polyurethane foam, among others. This study will also analyze the effect of surface moisture content and acid-base interactions between the alkaloid and surface sites on nicotine sorption and reactivity. Oxidation byproducts present in the gas-phase and sorbed to surfaces will be analyzed by derivatization methods which improve the sensitivity of conventional chromatographic analysis, in order to provide a more complete description of stable byproducts and postulate possible reaction mechanisms.
The indoor dynamics of nicotine has been the subject of various recent studies aimed at evaluating the limitations and applicability of the use of the alkaloid and its metabolites as ETS biomarkers. Significant biases between non-smokers exposures to nicotine and to other ETS components (volatile components, particulate matter) were estimated, based on the observed lack of correlation of their indoor dynamics, which has been mainly attributed to the strong sorption and slow re-emission of nicotine from indoor surfaces. Knowledge of the reactivity of nicotine towards ozone and related radicals may lead to improved models of its indoor fate, and to better assessments of the power and limitations of nicotine-related tracers (such as urinary cotinine) as ETS biomarker. One of the main hypothesis to be tested by the proposed research is that ozone can effectively reduce the amount of nicotine sorbed to indoor sufaces and its re-emission levels, as compared with values determined in the absence of atmospheric oxidants.
The present proposal involves: 1) the design and development of a 1-m3 Teflon test chamber to study nicotine sorption and reactivity towards O3 on selected materials that are predominant in indoor environments, with precise control of the relative humidity; 2) the identification of stable nicotine oxidation byproducts and elucidation of reaction mechanisms involving O3 and OH radicals generated by its decomposition; and 3) the evaluation of the effect of ozone concentration, relative humidity and surface pH on the observed nicotine dynamics and chemistry. |
|Effect of Ozone on Nicotine Desorption from Model Surface Evidence for Heterogeneoues chemistry
|Periodical: Environmental Science and Technology
|Authors: Hugo Destaillats Brett C. Singer Sharon K. Lee and Lara A Gundel