Removing the smoking confounder from blood volatile organic compounds measurements.

Because smoking is a major contributor to the internal dose levels of many volatile organic compounds (VOCs), it is difficult to assess other VOC exposures among smokers. Purge and trap/gas chromatography/isotope-dilution mass spectrometry was used to determine the internal dose of VOCs of smokers and nonsmokers. Median whole blood concentrations of benzene, styrene, and toluene were shown to be approximately two times higher among smokers than among nonsmokers. In addition, smoking elevated the blood levels of ethylbenzene, m-/p-xylene, and o-xylene when the log-transformed data were compared. Smoking also led to greatly increased levels of 2,5-dimethylfuran. These results indicate that blood levels of many VOCs are highly correlated with blood levels of 2,5-dimethylfuran and that this effect is primarily a result of smoking. The smoking confounder to blood levels of VOCs can be removed by including the concentration of blood 2,5-dimethylfuran concentration when evaluating results from a health and exposure evaluation. Determining the blood 2,5-dimethylfuran concentration appears to be an effective means of correcting the confounding influence of smoking and supplies a way of determining lower-level exposures that previously could not have been distinguished from the effects of smoking.