Nano particles as food additives: improving risk assessment

The anticaking agent E551 silicon dioxide, or silica, has been used widely in the food industry over the past 50 years, and was long thought to be quite safe. Now, however, researchers working on the National Research Programme 'Opportunities and Risks of Nanomaterials' have discovered that these nanoparticles can affect the immune system of the digestive tract. It ensures that dry foods such as instant soup, instant coffee and spice powder retain good flow properties. 'Synthetic amorphous silica', the ultrafine powder which is obtained from quartz and bears the E number E551, has been used for around a century with no apparent cause for concern. 'Previously it was assumed that these nanoparticles are completely inert,' explains Hanspeter Nägeli from the Institute for Pharmacology and Toxicology at the University of Zurich. Awakening the self-defence mechanism. Now, however, Nägeli and his colleagues working on the National Research Programme 'Opportunities and Risks of Nanomaterials' (NRP 64) have found out that these particles are capable of activating certain immune cells.