Inflammation in the mouse peritoneal cavity in the investigation of factors determining the biological activity of respirable industrial fibres.

Induction of peritoneal inflammation by respirable size mineral fibers was studied in mice. Amosite (12172735), crocidolite (12001284), a commercial glass microfiber, two types of commercial silicon-carbide (409212), four types of refractory ceramic fibers (RCFs), and four types of manmade vitreous fibers were instilled into the peritoneal cavity of male C57B16-mice at 8.2×10(7) fibers per milliliter of saline. Some of the glass microfibers had been treated with oxalic-acid, pH 1.4, for 14 days. Control mice were instilled with saline. Four days later the peritoneal cavity was lavaged. The extent of fiber induced inflammation was assessed from counts of the number of macrophages and granulocytes, defined as neutrophils plus eosinophils plus basophils, in the lavage fluid. All fibers produced an inflammatory response in the peritoneal cavity by increasing the number of macrophages and granulocytes. Eleven produced responses of similar magnitude, causing an influx of 2×10(6) to 6×10(6) granulocytes. Crocidolite induced a much stronger response, inducing an influx of 11×10(6) granulocytes. One of the RCFs which consisted of mostly short fibers induced a granulocyte influx of only 1×10(6) cells. The inflammatory responses showed no consistent relationship with fiber mass. Treatment of the glass microfibers with oxalic-acid significantly decreased their inflammatory potential. The authors conclude that across a wide range of fiber types, mineral fibers induce a similar degree of toxicity to mesothelial cells following instillation into the peritoneal cavity. Assessing peritoneal inflammation may be a useful assay for evaluating the ability of fibers to damage the mesothelium.