Genotoxicity of clays with potential use in biopolymers for food packaging

Genotoxicity of clays with potential use in biopolymers for food packaging Plastics produced from biopolymers are of commercial interest as they are manufactured from renewable resources such as agricultural crop wastes and have the potential to meet environmental and health requirements. Biopolymers that are strengthened using reinforcing nano-scale fillers may improve the packaging quality by increasing barrier function and heat-resistance.

Toxicological data on clays containing a nano-fraction and organo-modified clays remain very limited. The aim of this study is to investigate the genotoxic potential of clays that can be used in biopolymers for food contact materials. Two clays were tested in the comet assay using Caco-2 cells (a human colon cancer cell line); a natural montmorillonite (Cloisite®Na+) and an organo-modified montmorillonite (Cloisite®30B).

Both clays were tested in crude suspensions (suspended in cell culture medium) and crude suspensions filtrated through a 0.2 µm pore size filter in order to investigate the potential effect of “nanoparticles” only. The two clays showed noticeable differences in genotoxicity; both crude and filtered suspensions of Cloisite®Na+ showed negative results, while crude and filtered suspensions of Cloisite®30B were genotoxic in a clear concentration related manner.

Analysis of inorganic elements and particle size distributions of filtered suspensions of Cloisite®30B indicated that no clay particle were present. However, the organo-modifier was detected in filtered suspensions of Cloisite®30B by HPLC-MS, thus indicating that the organo-modifier was at least partly responsible for the genotoxic effect.

As a follow up on the in vitro results the compounds will be tested in an in vivo comet assay experiment. Wistar rats will be exposed to Cloisite®30B and Cloisite®Na+ by oral gavage and the comet assay will be performed on cells from different organs including the liver, colon and kidney. A fully automated comet assay scoring system (Imstar) will be used to evaluate the genotoxic potential.