A comparison of cytotoxicity elicited in animals receiving doses of UFTiO
normalized to surface area of particle administered per surface area of alveolar epithelium. A comparison of cytotoxicity elicited in animals receiving doses (0.0313, 0.0625 and 0.125 cm2/cm2) of UFTiO2 and FTiO2 normalized to surface area of particles administered per surface area of alveolar epithelium at 1 day (Panel A), 7 days (Panel B), and 42 days (Panel C) post-exposure. Animals were exposed to various doses of UFTiO2 and FTiO2 by intratracheal instillation. Animals were euthanized at 1 day, 7 days, and 42 days post-exposure and bronchoalveolar lavage was performed. Cytotoxicity was assessed by measuring LDH activity. Values are increase in LDH activity above the BALF control and are given as means ± SE of 8 experiments. Control values of LDH activity were 46.375 ± 2.24, 39.5 ± 1.35, and 37.25 ± 2.63 U/l for 1, 7 and 42 days, respectively. Linear regression analysis with 95% confidence internal reveals that, when dose is normalized to surface area of particles administered, responses to UFTiO2 and FTiO2 are not significantly different.