PARTICLE ACTIVITY AND IN-VIVO PULMONARY RESPONSE TO FRESHLY MILLED AND AGED ALPHA-QUARTZ

This study examined the possibility of freshly fractured alpha-quartz being more toxic and inflammatory in vivo than aged quartz of the same composition and particle size. Fresh quartz was generated by a jet mi ll, and used immediately, while aged dust was stored for two months be fore use. Both the production of hydrogen peroxide and hydroxyl radica ls and the analysis of surface radicals verified the enhanced surface activity of fresh quartz. Male Fischer 344 rats were exposed to fresh or aged alpha-quartz by inhalation (20 mg . m(-3), 5 h per day, 5 d pe r week, for 2 weeks) and their pulmonary responses were determined 1-3 d postexposure. Exposure to aged quartz resulted in an increase in cy totoxic and inflammatory parameters. In comparison, the inhalation of freshly cleaved quartz resulted in dramatically greater increases in a ll of the pulmonary responses. This finding suggests that exposure to freshly machined quartz may result in a greater risk of pulmonary dise ase.