Titanium Dioxide (Nano)
Titanium Dioxide is an inorganic (physical) sunscreen agent conforming to the formula of titanium oxide (CAS #13463-67-7). It functions as a UV absorber and UV filter, providing broad-spectrum coverage primarily in the UVB and UVA II range (290–350 nm), with less efficacy in the UVA I range (350–400 nm). It also acts as a cosmetic colorant and opacifying agent, contributing a white tint to formulations. Nano-sized particles are used to improve spreadability and reduce the characteristic white cast, though this introduces additional safety considerations under ongoing investigation.
Titanium Dioxide provides broad-spectrum UV protection (strongest in UVB and UVA II ranges) and is highly photostable. Regular-sized particles have a strong safety profile, being non-irritating and largely free from hormonal/estrogenic concerns associated with some chemical filters. It is considered one of the best UV-filter agents currently available, particularly in markets where newer-generation filters are not yet approved.
Nano-sized particles raise concerns about potential deeper skin penetration, possible protein complex formation, and free radical promotion, though studies as of the source's cited literature have not demonstrated significant percutaneous penetration in sunscreen use. Cosmetically, regular (non-nano) particles are difficult to spread and leave a notable white cast. Subject to cosmetic restrictions (IV 143, VI 27, VI 27a for nano form).
