Nanoparticles in Food - with a focus on the toxicity of titanium dioxide

The use of nanoparticles, in many different fields, is rapidly increasing. What substances, and to what extent they exist in food and supplements, and the prevalence of such products on the market, is of interest to the Swedish National Food Agency. Answering those questions, as well as providing information regarding their potential toxicity, was the intent of this thesis. To understand the difficulties, and possibilities, in analyzing nanoparticles in food, a methods-section was included, covering the most common techniques, the theory behind them and when they may be used. It became abundantly clear that analyzing nanoparticles in food, and investigating their potential toxicity, is anything but simple, and requires a combination of many techniques. Quite surprisingly, it seems the occurrence of nanoparticles in food, as today, are not added on purpose, since not one nanosubstance to be used in food has been approved by EU. Rather, studies have revealed they originate from a nanosized fraction of food additives, such as TiO2 (E171), which has attracted particular attention in this report. This nanofraction may be as large as 40%, and the estimated total intake of TiO2 (as stated by EFSA) is 1.28 mg/kg/person, resulting in quite an amount of nano TiO2, provided the numbers are correct. The toxicity of silver has also been reviewed, since the colloidal form, which includes nanoparticles, is quite common as a health supplement. Toxicity studies are not unambiguous though, some indicate geno-and–cytotoxicity and others do not. Importantly, the toxicity studies on TiO2 have not been done on E171, but on many other forms of TiO2, whose relevance is difficult to predict. TiO2 is, however, classified as a possible carcinogen by IARC. Several groups have taken an interest in a potential relation between particle intake and various chronic inflammatory diseases, also discussed in this report. In conclusion, the size, modifications of E171 and its toxicity, requires more attention in order for food authorities to confidently ascertain healthy food for the public.