[Nanomaterials in foodstuffs - toxicological properties and risk assessment]

Nanomaterials measure below 100 nm in size in at least one dimension. In general, organic and inorganic nanoparticles can be distinguished. In addition, nanosized structures may differ substantially with regard to their shape, chemical composition and physical properties. They may originate either from natural processes or can be manufactured intentionally. The possible specific toxicological properties of nanoparticles that might be based on their enhanced reactivity due to an increased surface-to-volume ratio, as compared to larger particles, or which might result from preferential uptake in cells and tissues, are the subject of current toxicological research. Consumers are exposed to nanomaterials via the oral route by foodstuffs containing naturally formed, unknowingly incorporated or intentionally added nanoparticles. In the course of this work, an overview of the occurrence of nanomaterials in foodstuffs, including the legal definition and labeling requirements, will be given. Furthermore, specific characteristics of the oral uptake of nanomaterials will be presented alongside challenges for experimental investigation of gastrointestinal uptake and the effects of nanoscaled particles. These will be discussed in relation to potentially relevant toxicological properties and modes of action. Despite a plethora of available experimental studies, there are still knowledge gaps with regard to the exposure against orally ingested nanoparticles and with regard to possible toxicological consequences of such particles in order to allow for accurate risk assessment of the materials in foodstuffs and food packaging.