Impact of cigarette smoking on volatile organic compound (VOC) blood levels in the U.S. population: NHANES 2003-2004.

The impact of cigarette smoking on volatile organic compound (VOC) blood levels is studied using 2003-2004 National Health and Nutrition Examination Survey (NHANES) data. Cigarette smoke exposure is shown to be a predominant source of benzene, toluene, ethylbenzene, xylenes and styrene (BTEXS) measured in blood as determined by (1) differences in central tendency and interquartile VOC blood levels between daily smokers [≥1 cigarette per day (CPD)] and less-than-daily smokers, (2) correlation among BTEXS and the 2,5-dimethylfuran (2,5-DMF) smoking biomarker in the blood of daily smokers, and (3) regression modeling of BTEXS blood levels versus categorized CPD. Smoking status was determined by 2,5-DMF blood level using a cutpoint of 0.014 ng/ml estimated by regression modeling of the weighted data and confirmed with receiver operator curve (ROC) analysis. The BTEXS blood levels among daily smokers were moderately-to-strongly correlated with 2,5-DMF blood levels (correlation coefficient, r, ranging from 0.46 to 0.92). Linear regression of the geometric mean BTEXS blood levels versus categorized CPD showed clear dose-response relationship (correlation of determination, R(2), ranging from 0.81 to 0.98). Furthermore, the pattern of VOCs in blood of smokers is similar to that reported in mainstream cigarette smoke. These results show that cigarette smoking is a primary source of benzene, toluene and styrene and an important source of ethylbenzene and xylene exposure for the U.S. population, as well as the necessity of determining smoking status and factors affecting dose (e.g., CPD, time since last cigarette) in assessments involving BTEXS exposure.

Theoretical study of Ba(n+)-RG (RG = rare gas) complexes and transport of Ba(n+) through RG (n = 1,2; RG = He-Rn).

We present high-level ab initio potential energy curves for barium cations and dications interacting with RG atoms (RG = rare gas). These potentials are employed to derive spectroscopic parameters for the Ba(+)-RG and Ba(2+)-RG complexes, and also to derive the transport coefficients for Ba(+) and Ba(2+) moving through a bath of the rare gas. The results are compared to the limited experimental data, which generally show reasonable agreement. We identify a large change in binding energy going from Ba(+)-He and Ba(+)-Ne to Ba(+)-Ar, which is not present in Ba(2+)-RG, and show that this is due to significant dispersion interactions in Ba(+)-RG.