Review

The nanosilica hazard: another variable entity

Dorota Napierska^1†, Leen CJ Thomassen^2†, Dominique Lison³, Johan A Martens² and Peter H Hoet^1*

• * Corresponding author: Peter H Hoet peter.hoet@med.kuleuven.be

• † Equal contributors

Author Affiliations

¹ Unit of Lung Toxicology, Katholieke Universiteit Leuven, Herestraat 49, 3000 Leuven, Belgium

² Center for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, 3001 Heverlee, Belgium

³ Louvain centre for Toxicology and Applied Pharmacology (LTAP), Université Catholique de Louvain, Avenue E. Mounier, 53.02, 1200 Brussels, Belgium

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Particle and Fibre Toxicology 2010, 7:39 doi:10.1186/1743-8977-7-39

Published: 3 December 2010

Abstract

Silica nanoparticles (SNPs) are produced on an industrial scale and are an addition to a growing number of commercial products. SNPs also have great potential for a variety of diagnostic and therapeutic applications in medicine. Contrary to the well-studied crystalline micron-sized silica, relatively little information exists on the toxicity of its amorphous and nano-size forms. Because nanoparticles possess novel properties, kinetics and unusual bioactivity, their potential biological effects may differ greatly from those of micron-size bulk materials. In this review, we summarize the physico-chemical properties of the different nano-sized silica materials that can affect their interaction with biological systems, with a specific emphasis on inhalation exposure. We discuss recent in vitro and in vivo investigations into the toxicity of nanosilica, both crystalline and amorphous. Most of the in vitro studies of SNPs report results of cellular uptake, size- and dose-dependent cytotoxicity, increased reactive oxygen species levels and pro-inflammatory stimulation. Evidence from a limited number of in vivo studies demonstrates largely reversible lung inflammation, granuloma formation and focal emphysema, with no progressive lung fibrosis. Clearly, more research with standardized materials is needed to enable comparison of experimental data for the different forms of nanosilicas and to establish which physico-chemical properties are responsible for the observed toxicity of SNPs.