SAFETY AND TOXICITY OF FOOD NPs EMPLOYED IN FOOD PRODUCTS
The physiological pathways of NPs entry into the body include skin permeation, inhalation, and oral consumption. As a matter of fact, the characteristics of the NPs as well as their extent directly affect the ADME profile in human and other living systems (Katouzian & Jafari, 2016). As NPs enter the GIT via the oral route, they remain isolated from blood by epithelial cells. NPs may translocate to the other organs through the connective tissues located beneath the epithelial layer. Moreover, the absorption of the NPs seems to be different in different parts of the GIT, as it is high in the small intestine and relatively low in the buccal cavity (Roblegg et al., 2012). Deleterious effects have been observed as a result of NPs accumulation in the intestinal cells, such as inflammatory bowel disease (Tetley, 2007), besides other studies revealed that some metal NPs can be aggregated in rats’ (Jani, McCarthy, & Florence, 1994) and fish (Zhang et al., 2007) intestine and transferred to other organs causing inflammation responses. The aftermath of inflammation and lacerations could be the high rate of NPs’ uptake within the intestine. Moreover, food NPs present in the intraepithelial zone can compete in absorbance with normal food due to their high surface area and extra reactivity (Frohlich & Roblegg, 2012).
The safety of produced nanocapsules plus their physicochemical and functional properties are of utmost importance in the production process and their health outcomes. Monitoring of the safety of nanocapsules is also essential during their fabrication. Thus, the identification and implementation of safety analysis techniques by precise and correct instruments are necessary for the development of nanoencapsulation technologies for the food and nutraceutical industries.
Concerning the possible toxicity and risks of digested NPs, it should be considered their physicochemical alterations triggered by pH, ionic strength, carbohydrate, lipid, and the protein content of the body fluids (Frohlich & Roblegg, 2012). When the NPs enter the blood stream, they react with blood cells as well as proteins of plasma; afterward, they enter the cells and can modify DNA of the cells, therefore changing their performance. In spite of the low rate of NPs absorption in the body, they can be accumulated in organs in long term and cause cytotoxicity and immunological responses. Currently, not many studies have been performed regarding the toxicity and absorption profile of food-relevant NPs. Therefore, clinical studies and in vitro tests should be carried out to fill the gap existing in safety of these edible engineered NPs (Bellmann et al., 2015). In this chapter, mostly the safety and toxicity potential of food-relevant and edible nanostructures are discussed and chiefly the recent investigations are sought. Moreover, the characterization methods and instruments are explored in detail.