Oxidative stress may be a fundamental mode of injury associated with inspir
ed particles. To examine this, we determined the ability of three carbon bl
ack particles (CBPs; M120, M880, and R250) and two forms of silicon dioxide
, amorphous (Cabosil) and crystalline (DQ12) quartz, to deplete epithelium
lining fluid antioxidant defenses. Single and composite antioxidant solutio
ns of uric acid, ascorbic acid (AA), and reduced glutathione (GSH) were exa
mined in the presence of particle concentrations of 150 mu g/ml. Uric acid
was not depleted by any particle considered. AA was depleted in a near-line
ar fashion with time by the three different CBPs; however, AA depletion rat
es varied markedly with CBP type and decreased in the presence of metal che
lators. An initially high GSH depletion rate was noted with all CBPs, and t
his was always accompanied by the appearance of oxidized glutathione. Expos
ure to Cabosil or DQ12 did not result in the loss of GSH. Together, these d
ata demonstrate that particle type, size, and surface area are all importan
t factors when considering particle-antioxidant interactions in the airways
.