Researchers find titanium dioxide provides superior SPF when combined with mesoporous silica

09 Mar 2023 --- Amid an ongoing debate on the safety of Titanium dioxide (TiO2), recent research has found that TiO2 incorporated into mesoporous silica (SBA-15) can be considered a broad-spectrum ingredient for innovative sunscreens, particularly for the photoprotection of lips.

“Since the lips are sensitive to the adversities of the environment, including UV radiation, the application of lipstick sunscreens is of great importance and expected to provide protection for this particular area against sunburn and photoaging, among other unfavorable responses to unprotected UV exposure,” the researchers state.

“During recent years, there has been growing interest in the development of safer and more effective sunscreens using several strategies. In our experimental conditions, we obtained acceptable lipsticks in terms of aspect and organoleptic properties.”

The researchers developed a lipstick sample containing TiO2 and found that its incorporation into the SBA-15 achieved superior performance and photostability compared to isolated compounds and the lipstick base.

SBA-15 alone could not generate satisfactory values of SPF and critical wavelength. There has been growing interest in the development of safer and more effective sunscreens using several strategies.

TiO2 lipstick’s photoprotective efficacy
The research funded by the National Council for Scientific and Technological Development and Coordination for the Improvement of Higher Education Personnel investigated the in vitro photoprotective efficacy and photostability of lipstick formulations containing TiO2 incorporated into SBA-15. 

“For our lipstick prototype samples, the efficacy parameters (sun protection factor and critical wavelength) were determined by diffuse reflectance spectrophotometry with an integration sphere, with the functional photostability observed after the samples were exposed to an artificial UV irradiation source in a Suntest CPS+ solar simulator,” the researchers detail.

The study found that the sample containing TiO2 incorporated into SBA-15 presented greater absorption in the UVA and UVB regions compared to the sample containing 10% TiO2 free state. However, in its free state, TiO2 was not able to offer broad-spectrum protection but had better absorption in the UVB than in the UVA region.

Overall, the highest SPF value was found for the sample containing 10% TiO2 incorporated into the SBA-15.

“Improving sunscreen formulations to provide a photostable profile associated with a broad-spectrum protection has become an utmost relevant issue in the cosmetic science and dermocosmetics in general,” the researchers assert.

“The development of safe, effective and innovative active ingredients elevates the competitiveness of the related industries, to offer the consumers more alternatives to be adopted as sun care protection strategies.”

They highlight that photostability to UV radiation is an important parameter since a sensitive UV-filtering molecule could degrade and induce photoallergy and phototoxicity. The research investigated the in vitro photoprotective efficacy and photostability of lipstick formulations containing TiO2 incorporated into SBA-15.

TiO2 safety
EU political authorities imposed an EU-wide TiO2 ban that came into full force on August 7, 2022, forcing companies to innovate alternatives for the ingredient, which has applications in sunscreens, pressed powders, loose powders, UV filters and whitening agents.

However, the EU General Court had annulled the TiO2 classification in November 2022 deeming the ban a “manifest error in its assessment.”

According to the Scientific Committee on Consumer Safety (SCCS), “the safety assessment has shown that using pigmentary TiO2 in loose powder up to a maximum concentration of 25% in a typical face makeup application is safe for the general consumer.”

“Without more information, it may not be clear whether these conclusions would apply to the use of pigmentary TiO2 materials in other similar types of cosmetic applications on the market.”

Meanwhile, France states that the court decision “is a setback” to protecting the health of EU citizens and workers involved in TiO2’s use. The nation defends its stance, saying that the regulation of TiO2 is essential and needs a reaffirmation of its hazardous properties.

The introduction of France’s appeal is reported to have a suspensive effect on the General Court’s judgment. Therefore, the harmonized classification will continue to apply until the outcome of the new procedure.

By Radhika Sikaria