Breath Sampling As a Biomarker of Exposure. Yeh-Chung Chien, Panos Georgopoulos, and Clifford Weisel, Environmental & Occupational Health Sciences Institute, RWJMS-UMDNJ & Rutgers University, Piscataway, NJ 08855
Exhaled breath has been used as a biomarker of exposure and to evaluate physiologically based pharmacokinetic (PBPK) models. The present study was design to determine the amount of variation in breath concentrations for a single individual following tetrachloroethene exposures during visits to dry cleaning establishments and within a controlled environmental facility (CEF), thereby providing baseline information of the inherent uncertainty in these types of measurements. Tetrachloroethene breath concentrations were measured during and following repetitive exposures to the same individual during and after visits to dry cleaning stores and in the CEF for two different durations (30 and 90 minutes) and for a constant and varying exposure pattern. The PBPK model was able to predict the breath concentration during exposure when adequate exposure information was available. The model predictions of the breath concentration following exposure using an average exposure concentration as the input resulted in ~25% mean error compared to using a variable exposure value as the input to the model. Highly reproducible breath concentrations were measured post exposure for the same controlled exposures. The breath concentrations were used to optimize a PBPK model for the participant. The optimize model was then used to calculate breath concentrations for each of the exposure scenarios for comparison to the measured values, as well to examine differences in the amount that would enter different tissues in the body as a function of the exposure.