Food grade Titanium dioxide E171 contains microparticles and a fraction of nanoparticles (NPs). As concern about the use of NPs in food products grew, research about the impact of oral exposure to E171 from dietary and non-dietary sources on human health has recently increased.

It is a hardly known fact that beside the approved uses E171 powder (mixed with other particles like Zinc-Stearate and Zirconium Oxide) is used as Medical Device in the dental field as matting agents (powders and sprays), sprayed in high quantities into the open oral cavity as moisture free aerosols (CAD / CAM methods "Chairside"). Any proper use of the aerosols consisting of respirable free particles is associated with inhalation exposure. Concern applies in particular to the professional user (dentist) because of the frequency of recurrent applications with inhalation exposure day after day for years and centuries. But concern applies as well to risk patients.

I could not find any publication with inhalation exposure to E 171 alone or mixed with other metals. Is there any experience?