As a component of out investigations into the pathophysiology of smoke inhalation, the present study characterizes the free radicals generated by combustion of Western bark (fir and pine), using the technique of electron spin resonance (ESR). Smoke was generated by heating the wood chips in a crucible furnace at a constant temperature of 400 degrees C and an air flow of 6 L/min. Smoke was filtered through Whatman I filters or bubbled through saline over a 1 min period beginning at O, 5, 10, 15 and 20 min after generation of the smoke. ESR analysis of the particles trapped by the filters revealed the generation of carbon-centered free radicals similar to those generated by coal or diesel particles. These radicals were observed at all time points and maybe associated with the surface or the core of the particles. Addition of H2O2 generated hydroxyl radicals (OH). There was no direct correlation between the generation of OH and the level of carbon-centered free radicals. In aqueous media, wood smoke particles also generated OH. Incubation of wood smoke particles with DNA, in vitro, caused DNA strand breaks as measured by gel electrophoresis. The H2O2 scavenger, catalase, the OH scavenger, formate, and the iron chelator, deferoxamine, inhibited the DNA strand breaks, white H2O2 enhanced them. These data suggest that free radical reactions mediated by wood smoke particles may play an important role in the cellular injury associated with smoke inhalation.
The Toxicologist. Society of Toxicology 38th Annual Meeting, March 14-18, 1999, New Orleans, Louisiana