NANOCLAYS IN FOOD PRODUCTS: BENEFITS AND POSSIBLE RISKS (LITERATURE REVIEW)
Nanoclays (NC) are aluminosilicates that consist of layers (nano-plates) being 1-2 nanometers thick and having a diameter over 1 µm, nanotubes, and nano-disks. Due to such structure and their ion-exchange and sorption properties as well as gas permeability NC are widely used in industries, agriculture, and medicine. Gas-barrier composite packages are made from hydrophobic NC modified with cation-active surface-active substances. A person can be orally exposed to NC due to their migration from packages into food products and drinks, when NC are applied in medicine as enteric sorbents and anti-bacterial preparations, they can be introduced with food additives and residual quantities of technological auxiliaries as well as in case when food products and agricultural raw materials are accidentally contaminated with clays. Multiple research works dwell on experiments with NC performed with model systems in vitro when NC turned out to be cytotoxic for various cell types, and it was more apparent for hydrophobic NC than for their non-modified analogues. Minimum effective NC dose varied from 0.001 to 1 mg/ml in various in vitro tests. In vitro research on NC toxicity yielded somewhat contradictory results. Though NC didn’t seem to have apparent acute toxicity (IV hazard category, LD50 > 5,000 mg/kg), results obtained via sub-acute and chronic experiments with their duration being up to 196 days and single clinical observations revealed a number of both toxic and non-toxic effects. Organic NC modifiers were highly toxic in vitro. Besides, NC produce anti-microbe effects and it may result in dysbiotic disorders when they are introduced orally. Model experiments revealed that NC and their organic modifiers could possibly migrate from packages into food products. NC are able to free silicon and aluminum that are partly biologically available. A contribution made by NC that are contained in packages into overall exposure to toxic aluminum should be examined profoundly given an adverse situation caused by clay minerals being introduced into a human body as components contained in food additives. Assessment of aluminum consumption with food rations in Russia and several foreign countries revealed it was necessary to exclude potassium and calcium aluminosilicates, bentonite, and kaolin (Е555, Е556, Е558, and Е559) from the list of additives that are permitted for use in food industry.