Detection of titanium dioxide particles in human, animal and infant formula milk

Titanium dioxide (TiO₂) nanoparticles (NPs) are manufactured massively for countless industrial applications. They are classified as potential carcinogens to humans by inhalation and banned from food applications in France and Europe due to their suspected toxicity. Whereas their release in ecosystems has been recently documented, their presence in mammals remains underexplored. Milk is a good proxy for livestock and human exposure to pollutants but has never been monitored for TiO₂-NPs. Here, we analyzed human, animal and infant formula milk samples by single particle inductively coupled plasma mass spectrometry (sp ICP-MS) and by synchrotron radiation-based X-ray fluorescence. We found that titanium microparticles and nanoparticles were present in all the samples tested and analyzed their size and concentration. Chemical speciation of Ti indicated predomination of rutile TiO₂, followed by anatase TiO₂ and to a lesser extent other Ti-bearing mineral (ilmenite FeTiO₃, titanite CaTiSiO₅ or pseudobrookite Fe₂TiO₅). Altogether, these findings demonstrate the presence of titanium-containing nanoparticles in milk and the inevitable exposure of newborns on a daily basis until weaning and of human consumers at all ages.