ABSTRACT

48With the rapid development of nanotechnologies, a number of engineered nanomaterials (NMs), particularly solid NMs like TiO2, ZnO, Ag, and SiO2 NMs, are increasingly used in food science as food additives or in food packaging. This raises the health concern about the adverse health effects of engineered NMs after oral exposure. The present book chapter discusses the potential toxicity of ingested NMs based on the most recent studies. It has been shown that following oral exposure, ZnO NMs, and Ag NMs to a lesser extent could be absorbed into gastrointestinal tract and accumulated into various organs such as liver, kidney, and spleen, whereas TiO2 and SiO2 NMs are hardly absorbed. A number of studies showed that ZnO NMs were the most toxic NMs, followed by Ag NMs to a lesser extent, whereas TiO2 and SiO2 NMs generally showed little to no toxic effects both in vitro and in vivo. This could be explained by the relatively high bioavailability and activity of ZnO and Ag NMs, whereas oral exposure to TiO2 and SiO2 NMs generally showed negligible bioavailability. In the future, it is necessary and urgent to further assess the toxicity of engineered NMs used in food, especially in the case of long-time exposure, to ensure the safe use of them. There is also a need to further study the mechanisms.