In vitro toxicity of respirable-size particles of diatomaceous earth and crystalline silica compared with asbestos and titanium dioxide

• Published in: Journal of occupational and environmental medicine Vol. 40; no. 1; p. 29
• Main Authors: Hart, G A, Hesterberg, T W
• Format: Journal Article
• Language: English
• Published: United States 01.01.1998
• Subjects: Animals; Asbestos - chemistry; Asbestos - toxicity; Cell Division - drug effects; Cell Nucleus - drug effects; Cell Survival - drug effects; Cells, Cultured; CHO Cells - drug effects; Cricetinae; Diatomaceous Earth - chemistry; Diatomaceous Earth - toxicity; In Vitro Techniques; Particle Size; Quartz - chemistry; Quartz - toxicity; Silicon Dioxide - chemistry; Silicon Dioxide - toxicity; Titanium - chemistry; Titanium - toxicity
• ISSN: 1076-2752
• DOI: 10.1097/00043764-199801000-00008

The relationship between particle characteristics and in vitro toxicity was investigated using Chinese hamster ovary cells. Test dusts included respirable natural (Nat) and flux-calcined (FC) diatomaceous earth (DE), quartz, cristobalite, TiO2, and chrysotile and crocidolite asbestos. All dusts elicited a qualitatively similar, concentration-dependent response: particle uptake, induction of micro- and polynuclei, and reduction in cell proliferation. However, similar mass concentrations of the dusts yielded a 35-fold range of toxicity: chrysotile > crocidolite > Nat DE > FC DE > quartz > Cristobalite > TiO2. In vitro toxicity did not correlate with crystalline silica content, surface area, composition, volume, particles/cm2, or fibrous geometry. Toxicity was closely associated with the number of particles/cm2 culture surface that had at least one dimension > 7.5 mu. Thus particle size but not shape could be a determinant of in vitro toxicity. Particle size might also impact in vivo pathogenesis.