Titanium dioxide as used in sunscreens is commonly modified with other ingredients to ensure efficacy and stability. Examples of what are known as surface modifier ingredients used for titanium dioxide include stearic acid, isostearic acid, polyhydroxystearic acid, and dimethicone/methicone copolymer.

Numerous studies have linked titanium dioxide to genotoxicity and cytotoxicity. Genotoxicity refers to a chemical’s potential to cause DNA damage, which can, in turn, lead to cancer. Cytotoxicity is a general term that refers to a characteristic of being harmful to cells.  

FAQ – EFSA 2021 safety assessment of titanium dioxide (E171)

3.   The calcined product obtained by the ordinary zinc bismuth method is slurried into a slurry, which is sequentially treated with sodium silicate, aluminum sulfate or sodium aluminate and a surfactant, and then filtered, washed, dried and pulverized.

Lithopone is an inorganic white pigment, obtained from co-precipitation of Zinc sulfide (ZnS) and Barium sulfate (BaSO4). Titanium Dioxide (TiO2) has replaced Lithopone as a white pigment in majority applications as TiO2 is more durable. However, it is much cheaper than TiO2 and has advantages such as low binder requirement and good dispensability. As a white pigment, it can improve the substrate's weather resistance, and improve the fungicidal properties of paint formulations. Some of the major applications of Lithopone include manufacturing of paint pigments, plastic & rubber products, paper, printing inks, cosmetics, and leather & linoleum products. It is commercially available under names such as pigment white 5, Barium zinc sulfate sulfide, Becton White, C.I. 77115, Charlton White, Enamel White, and Zincolith. On the basis of content of ZnS, Lithopone is available at 28%-30% Lithopone and 60% Lithopone.

Titanium Dioxide Description

Fig. 6. AOPP measured on samples of MSSA with: A) 0.2 mg/mL P25TiO₂NPs; B) 0.02 mg/mL P25TiO₂NPs; C) 0.2 mg/mL VitaminB2@P25TiO₂NPs; D) 0.02 mg/mL VitaminB2@P25TiO₂NPs after 3 h of irradiation (red) and 6 h (blue). SD <1 (error bars too small to be seen) and p < 0.05 between C-D and A-B.

In a 2017 study published in Scientific Reports, researchers exposed rats to human-relevant levels of E171 to examine the effects of intestinal inflammation and carcinogenesis. They saw that “a 100-day E171 treatment promoted colon microinflammation and initiated preneoplastic lesions while also fostering the growth of aberrant crypt foci in a chemically induced carcinogenesis model.” They continued: “Stimulation of immune cells isolated from Peyer’s Patches [which are clusters of lymphoid follicles found in the intestine] showed a decrease in Thelper (Th)-1 IFN-γ secretion, while splenic Th1/Th17 inflammatory responses sharply increased,” researchers wrote. “A 100-day titanium dioxide treatment promoted colon microinflammation and initiated preneoplastic lesions.” The scientists concluded: “These data should be considered for risk assessments of the susceptibility to Th17-driven autoimmune diseases and to colorectal cancer in humans exposed to TiO2 from dietary sources.”

However, the market could not sustain these high prices and strived for equilibrium, causing the prices to fall. Further, after the complete removal of restrictions, the factories churned out products at a much faster pace than the market offtakes. Hence, the manufacturers reduced their quotations to maintain positive product movement in the market. The spot prices of titanium dioxide averaged around 2264 USD/MT in June’23 in the Chinese market.

Nowadays, the use of nanoparticles in pharmaceutical and cosmetic products has increased. In the last case, nano-sized components are used without proper characterization of their effects, leading to unwanted and dangerous consequences for the users [1,2].