Titanium Dioxide (Ci 77891)
Titanium Dioxide (CI 77891) is an inorganic oxide sunscreen agent conforming generally to the formula TiO2 (CAS #13463-67-7). It functions as a UV absorber/filter, cosmetic colorant, and opacifying agent. It is available in both regular and nano-sized particle forms, with nanoparticles offering improved spreadability and reduced whitish tint. It works primarily through absorption of UV radiation rather than reflection, contrary to the traditional "physical sunscreen" narrative.
Titanium Dioxide provides broad-spectrum UV protection, with particularly strong coverage in the UVB and UVA II range (290–350 nm). It is highly photostable and has a well-established safety profile in its regular (non-nano) form, being non-irritating and free from hormonal/estrogenic concerns associated with some chemical filters. It is considered one of the best UV-filter agents currently available, especially in markets where newer-generation filters are not yet approved.
Regular-sized Titanium Dioxide has a good safety profile, but nano-sized particles raise concerns about potential skin absorption, possible protein complex formation, and free radical promotion — though studies as of the source date have not demonstrated significant percutaneous penetration. UVA I protection (350–400 nm) is less effective compared to UVB/UVA II coverage. Cosmetically, non-nano forms are difficult to spread and leave a notable white cast on skin.
