Detection of titanium particles in human liver and spleen and possible health implications

Titanium dioxide (TiO₂) is produced at high volumes and applied in many consumer and food products. Recent toxicokinetic modelling indicated the potential of TiO₂ to accumulate in human liver and spleen upon daily oral exposure, which is not routinely investigated in chronic animal studies. A health risk from nanosized TiO₂ particle consumption could not be excluded then.

Here we show the first quantification of both total titanium (Ti) and TiO₂ particles in 15 post-mortem human livers and spleens. These low-level analyses were enabled by the use of fully validated (single particle) inductively coupled plasma high resolution mass spectrometry ((sp)ICP-HRMS) detection methods for total Ti and TiO₂ particles. The presence of TiO₂ in the particles in tissues was confirmed by Scanning Electron Microscopy with energy dispersive X-ray spectrometry.

These results prove that TiO₂ particles are present in human liver and spleen, with ≥24% of nanosize (< 100 nm). The levels are below the doses regarded as safe in animals, but half are above the dose that is deemed safe for liver damage in humans when taking into account several commonly applied uncertainty factors. With these new and unique human data, we remain with the conclusion that health risks due to oral exposure to TiO₂ cannot be excluded.