Validation of a Xenobiotic Vapor Generation and Exposure Chamber System for Quantification of Exposure Effect in 3-Dimensional Human Tissue Reconstructs

As the number of manufactured xenobiotics continues to increase, the need for accurate, reproducible methods for quantifying exposure and the related health effects becomes more imperative. My Master Thesis goal was twofold: (1) develop an exposure-chamber system capable of delivering a constant concentration of a xenobiotic vapor and (2) quantify the effect of benzene (as a model xenobiotic) vapor exposure using commercial in vitro 3-dimentional (3D) human skin and lung tissue reconstructs. These reconstructs were exposed to clean air, 30 ppm, 60 ppm, or 120 ppm of benzene for 6 h per day for 5 consecutive days. The concentration of benzene in the exposure-generation system was measured in real-time using gas chromatography-flame ionization detection. Cytotoxicity was determined in the tissue culture media using spectrophotometry. Morphological changes in the tissue reconstructs were observed through histological staining using both hematoxylin and eosin as well as Periodic acid-Schiff stains. The results demonstrate that the exposure-chamber system can deliver a constant concentration of benzene vapor for an extended period of time. The skin reconstructs showed no evidence of toxicity at the levels ≤120 ppm while the lung reconstructs indicated a potential dose-response to benzene exposure. The absence of toxicity in the skin reconstructs indicates that the stratum corneum serves as an effective protective barrier towards benzene vapor exposure. The observed responses in the lung reconstructs provide evidence that this model is amenable for biological assessment of toxic effects due to xenobiotic vapor exposure. This research provides a foundation to further develop methods using 3D human reconstruct models for evaluation of adverse effects due to xenobiotic exposure.Master of Science in Public Healt