In an article published on December 9, 2016 in the peer-reviewed journal Food Additives & Contaminants: Part A, scientists report on the possible release of titanium dioxide nanoparticles from non-stick coatings into food. Vivana Golja and colleagues from the National Institute of Public Health and Jozef Stefan Institute, Ljubljana, Slovenia, studied new and used frying pans with a quasi-ceramic non-stick coating, obtained on the Slovenian market. This type of coating consists of a silicone polymer matrix with embedded micro- and nanosized titanium dioxide particles and quartz silicium dioxide.
To estimate possible migration of titanium dioxide nanoparticles into foods, migration experiments (2 hours at 100 °C), repeated up to three times, were performed with deionized water, 3% acetic acid, and 5 g/L citric acid. Intact coating was found to release titanium in ionic form at up to 3,636 µg/L (citric acid simulant, third migration) and in nanoparticulate form at up to 861 µg/L (acetic acid simulant, third migration). In the experiments on thermal degradation, the first signs of changes in the polymer matrix were observed at 500 °C. Thus, at foreseeable conditions of use (up to 350 °C), thermal degradation of the coating matrix is expected to be negligible and will not affect the nanoparticle release. On the contrary, mechanical degradation studies showed that the surface wear due to scratches and other types of damage occurring during normal use may lead to significant release of titanium-containing particles, a large proportion of them nanosized.
A study published in January 2016 found that chronic oral exposure to titanium dioxide nanoparticles results in immune disruption and pre-cancer lesions in the gut (FPF reported). Food contact materials (FCMs) may contain not only titanium dioxide nanoparticles, but also other types of nanoparticles (FPF reported), and some studies have observed migration of nanosilver (FPF reported) and nanoclay (FPF reported) from FCMs. Many open questions remain regarding the migration and safety of nanomaterials in FCMs (FPF reported). The contribution of nanocomposite FCMs to the overall burden of human exposure to nanoparticles should be taken into consideration when examining the safety of nanotechnology applications in food.
Golja, V., et al. (2017). “Characterization of food contact non-stick coatings containing TiO2 nanoparticles and study of their possible release into food.” Food Additives & Contaminants: Part A (published December 9, 2016).
Bettini, S., et al. (2017). “Food-grade TiO2 impairs intestinal and systemic immune homeostasis, initiates preneoplastic lesions and promotes aberrant crypt development in the rat colon.” Scientific Reports 7: 40373 (published January 20, 2017).