In vitro toxicity evaluation of new silane-modified clays and the migration extract from a derived polymer-clay nanocomposite intended to food packaging applications

- In vitro toxicity of modified clays with application in food industry was studied.
- Clay3, a silane modified clay with 3-APTES, did not show cytotoxicity.
- Clay4, a silane modified clay with VTMS, showed toxic effects.
- The aqueous migration extract of PP-Clay3 did not affect cell viability.
- The overall and specific migration levels were in accordance with the EU regulation.

The clay montmorillonite (Mt) is among the nanofillers more frequently used for food packaging applications. The organomodification of clays with different modifiers, such as silanes, is an important step in the preparation of improved polymer/clay materials known as nanocomposites. However, the toxicological data about these nanofillers is still scarce. In the present study, an in vitro toxicological evaluation in Caco-2 cells of two silane-modified clays based on Mt, Clay3 and Clay4 (0-250 μg/ml), was performed. The cytotoxicity, cell death, genotoxicity and oxidative stress produced by both organoclays were evaluated after 24 and 48 h of exposure. Moreover, the migration extracts obtained from nanocomposites of polypropylene (PP) + Clay3 and only PP were also investigated. Only Clay4 induced cytotoxicity, showing a reduction of cell viability to 63% of the control, as well as oxidative stress in a concentration-dependent manner. Regarding the PP-Clay3 migration extract, no cytotoxic effects were observed after exposure to the tested concentrations (0-100%). Moreover, significant differences in the presence of Ca, Mg and Si compared to the PP extract were obtained, although migration levels were in accordance with the food contact materials regulation. These findings indicate that a case-by-case toxicological assessment of organoclays should be performed.