Pulmonary Effect of Nickel Oxide, Crystalline Silica, and Titanium Dioxide—Relationship between Particle Size and Biological Effect—

Abstract

Pulmonary effects of titanium dioxide, crystalline silica, and nickel oxide were reviewed focusing on the relevance of the particle size. For titanium dioxide and nickel oxide, ultrafine particles administered to the lung causes greater inflammatory response than larger particles on the basis of unit mass. Surface properties (surface chemistry) appear to play an important role in ultrafine toxicity of titanium dioxide. There are few reports that show the submicron-sized (ultrafine) crystalline silica administered to the lung has a greater toxic potential than larger silica, however, further study is needed to confirm the cytotoxicity.