Cytotoxicity of Native-and Surface-Modified Asbestos

The increased risk of developing pneumoconiosis and/or lung cancer from occupational exposure to asbestos is a major health concern (Craighead et al. 1983). Because of its heat and fire resistant properties, asbestos is extensively used in industrial and commercial applications. Substitutes for this versatile mineral that possess its desirable properties, but devoid of harmful health effects, have not been readily available. Several chemical processes were attempted to commercially detoxify asbestos and retain its physical properties. It is not known whether this chemically modified asbestos is less toxic in biologic test systems (Flowers 1880). This report provides an in vitro comparative evaluation of amosite, crocidolite and chrysotile asbestos in native- and surface-modified forms with regard to their biologic toxicity. Lactate dehydrogenase (LDH), a cytoplasmic enzyme, and (s-glucuronidase (s-GLUC) and s-N acetyl glucuronidase (s-NAG), two lysosomal enzymes, were measured as markers of cellular toxicity after exposure of alveolar macrophages to native- and surface-modified asbestos. Hemolytic activity of both types of asbestos was measured as an index of cell membrane damage. The effect of native- and surface-modified asbestos on the induction of viral interferon system was monitored as a biologic marker of potential adverse effect on cellular defense mechanisms.