In an article published on April 30, 2016 in the peer-reviewed journal Food and Chemical Toxicology, Isabelle Severin and colleagues from the Derttech « Packtox », Univeristy of Bourgogne-Franche-Comté, Dijon, France, assessed the migration and in vitro toxicity of sol-gel coatings for polycarbonate (PC) plastics. Protective barrier films such as sol-gel coatings may be deposited on the surface of PCs in order to improve mechanical properties, but also to prevent the migration of bisphenol A (BPA, CAS 80-05-7). BPA, a chemical with endocrine disrupting properties, has been classified as a reproductive toxicant by the European Commission (EC) and EU Member States (FPF reported). Its use in FCMs is currently being reviewed by the European Food Safety Authority (FPF reported), and the EC is planning new regulation restricting migration of BPA from certain FCMs (FPF reported).
The two coatings investigated by the study’s authors were based on organically modified silica (ORMOSIL). One coating formulation included methyltriethoxysilane (MTES, CAS 2031-67-6), and another one 3-glycidyloxypropyltriethoxysilane (GPTES, CAS 2602-34-8) and tetraethylorthosilicate (TEOS, CAS 78-10-4). Migration tests were carried out with 3% acetic acid and 10% ethanol for 1 hour at 100°C, with 95% ethanol for 3 hours at 60°C, and with isooctane for 1 hour at 60°C. In all conditions, overall migration from both coatings was below the 10 mg/dm2 limit set up by the regulation on plastics materials for food contact. This shows that these coatings have good cohesion and adhesion to PC.
In vitro tests for genotoxicity included bacterial reverse mutation test (Ames test) and micronucleus test in human cell line HepG2. In vitro test for estrogenicity assessed the activation of transiently transfected estrogen receptor in the same cell line. The results of all in vitro tests were negative for both sol-gel coatings tested.
The authors note that the acceptable levels of overall migration, along with the absence of genotoxicity and estrogenicity, lend support to further development of ORMOSIL-based coatings for food contact applications.
Severin, I. et al. (2016). “In vitro toxicity assessment of extracts derived from sol-gel coatings on polycarbonate intended to be used in food contact applications.” Food and Chemical Toxicology 93:51-57.