USE OF THE SHORT-TERM INFLAMMATORY RESPONSE IN THE MOUSE PERITONEAL-CAVITY TO ASSESS THE BIOLOGICAL-ACTIVITY OF LEACHED VITREOUS FIBERS

We used a special-purpose glass microfiber sample, Johns-Manville Code 100/475, to study the effects of various acid and alkali treatments o n biological activity as assessed by inflammation in the mouse periton eal cavity, the leaching of Si, and the phase contrast optical microsc opy (PCOM) fiber number. We used mild and medium treatments with oxali c acid and Tris buffer and harsh treatment with concentrated HCl and N aOH. Mild oxalic acid and Tris treatment for 2 weeks had no effect on any of the end-points, but prolonging the mild oxalic acid treatment t ime to 2 months reduced the biological activity and the fiber number. Medium oxalic acid treatment reduced the biological activity and the f iber number and caused a loss of Si. Medium Tris alkali treatment redu ced the PCOM-countable fibers and the biological activity but did not cause a substantial loss of Si. Harsh treatment with strong HCl did no t affect the fiber number or cause leaching but the biological activit y was reduced; strong NaOH reduced the fiber number and biological act ivity, and caused marked teaching of Si. The medium oxalic acid condit ions (pH 1.4) were more acid than those found in lung cells but produc ed the same effects (reduction in fiber number and biological activity ) as the more physiological mild treatment (pH 4.0), when prolonged. T his study suggests that medium oxalic acid treatment can be used as a short-term assay to compare loss of Si, reduction in fiber number, and change in biological activity of vitreous fibers. Such a combination of in vitro and in vivo assays is likely to provide the best approach to assessing the complex factors involved in changes in the toxicity o f vitreous fibers caused by residence in the lung.