In vitro effects of large and small glass fibers on rat alveolar macrophages.

The objective of this study was to explore the use of alveolar macrophage culture to evaluate the cytotoxicity of two glass fiber materials, a building insulation fiberglass (a relatively long and thick fiber) and a glass microfiber (a short and thin fiber). Alveolar macrophages were obtained from male Sprague-Dawley rats by bronchoalveolar lavage and were cultured with varying fiber concentrations for up to 3 d. Fiber toxicity was assessed by assaying cell viability, membrane integrity, and phagocyte function. The microfibers exhibited a concentration-dependent cytotoxicity shown by the loss of cell viability and function. The building insulation fiberglass had little effect on cell viability and did not change macrophage function in this assay system. The results of this study show that short and thin glass fibers are more toxic than long and thick fibers in vitro, supporting a role of fiber dimension in toxicity.