Particle activity and in vivo pulmonary response to freshly milled and aged alpha-quartz.
Shoemaker-DA; Pretty-JR; Ramsey-DM; McLaurin-JL; Khan-A; Teass-AW; Castranova-V; Pailes-WH; Dalal-NS; Miles-PR; Bowman-L; Leonard-S; Shumaker-J; Vallyathan-V; Pack-D
Scand J Work, Environ & Health 1995 Sep; 21(Suppl 2):15-18
The in-vivo toxicities of freshly fractured and aged alpha quartz (14808607) were compared to determine if freshly milled quartz is more toxic and inflammatory. Freshly fractured quartz was produced in a jet mill for immediate use and milled quartz, stored for 2 months, served as aged quartz dust. The increased surface activity of fresh quartz was verified by analysis of surface radicals, through electron spin resonance spectroscopy and of production of hydroxyl radicals and hydrogen-peroxide. Pulmonary responses of male Fischer-344-rats were measured from 1 to 3 days after exposure to fresh or aged quartz by inhalation. Rats were exposed to quartz dust at 20mg/m3, 5 hours per day, 5 days each week, for 2 weeks. Control animals were exposed to filtered air. One to 3 days postexposure, pulmonary responses were determined. Aged alpha quartz inhalation produced pulmonary inflammation and cytotoxicity as indicated by increased levels of albumin, protein, phospholipid, red blood cells and N-acetyl-beta-D-glucosaminidase in bronchoalveolar lavage fluid and increased lipid peroxidation in lung tissue. Increased lavage leukocytes and alveolar macrophage activity were also detected. All these parameters were significantly higher following exposure to freshly milled quartz than they were in rats exposed to aged quartz. The authors conclude that the increased activity of fresh cleavage surfaces in fractured alpha quartz might produce increased risk of disease. They suggest that this is a common factor behind the increased incidence of silicosis in rock drillers, sandblasters and silica flour millers.
NIOSH-Author; Fibrogenicity; Physical-properties; Inhalation-studies; Laboratory-animals; Mineral-dusts; Pathogenicity; Quartz-dust; Toxic-effects;
Author Keywords: aged; freshly fractured silica; inhalation; pulmonary inflammation; silicosis; surface activity
Dr DA Shoemaker, Division of Biomedical and Behavioral Science, NIOSH, 4676 Columbia Parkway, Cincinnati, OH 45226, USA
Scandinavian Journal of Work, Environment and Health