CI 77891 is titanium dioxide, a white mineral pigment used in cosmetics, sunscreens, and personal care products. You’ve likely spotted it on an ingredient label for foundation, sunscreen, toothpaste, or nail polish. The “CI” stands for Colour Index, an international system for identifying colorants, and 77891 is the specific number assigned to titanium dioxide. It also goes by its CAS registry number 13463-67-7, and when used in food, the same compound is labeled E171.
What CI 77891 Does in Products
Titanium dioxide serves three main roles in cosmetics and skincare. First, it’s a white pigment. Its naturally high refractive index (meaning it bends light very effectively) makes it exceptionally good at creating opacity and bright white color. This is why it shows up in foundations, concealers, and any product that needs coverage or a lighter shade.
Second, it works as a physical UV filter. Unlike chemical sunscreens that absorb UV radiation, titanium dioxide sits on the skin’s surface and reflects both UVA and UVB rays. This broad-spectrum protection makes it a staple in mineral sunscreens, particularly those marketed for sensitive skin.
Third, it acts as an opacifying agent, giving products a smooth, creamy, non-transparent appearance. Even products where sun protection isn’t the goal, like lip balms or tinted moisturizers, often include CI 77891 for its ability to create an even, blendable texture.
Where You’ll Find It
CI 77891 appears across a wide range of product categories. It has been used for decades in makeup, sun care, hair products, skin care, and oral care cosmetics. Specific examples include foundations, concealers, face powders, eye shadows, nail polishes, toothpaste, hair styling sprays, and sunscreens. If a product is white, tinted, or offers sun protection, there’s a good chance titanium dioxide is in the formula.
Does It Absorb Through Skin?
One of the reasons CI 77891 remains widely used is that it doesn’t meaningfully penetrate the skin. Titanium dioxide particles are insoluble, and dermal penetration studies on both regular and nano-sized particles show they do not reach viable skin cells. Multiple safety bodies, including Australia’s industrial chemicals agency and the EU’s Scientific Committee on Consumer Safety (SCCS), have confirmed this. The particles stay on or near the skin’s surface, which is exactly where you want a physical sunscreen to sit.
The Inhalation Question
The safety picture shifts when titanium dioxide becomes airborne and can be breathed in. The International Agency for Research on Cancer (IARC) classifies titanium dioxide as a Group 2B substance, meaning “possibly carcinogenic to humans.” That classification is based on animal studies where rats developed elevated lung cancer rates after chronic inhalation exposure, though the evidence from human studies remains limited.
This distinction matters for specific product types. The EU’s SCCS evaluated the risk and concluded that CI 77891 in loose face powder at concentrations up to 25% is safe for consumers. Hair styling aerosol sprays are a different story: the SCCS found that concentrations up to 25% in aerosol sprays are not safe for consumers or hairdressers. Safe limits for aerosol sprays were set much lower, at 1.4% for general consumers and 1.1% for hairdressers who face repeated daily exposure.
Products that don’t become airborne, like nail polishes, eye shadows in pressed form, and liquid foundations, don’t raise these inhalation concerns.
Nano vs. Non-Nano Forms
CI 77891 comes in two particle sizes. The standard (pigmentary) form uses larger particles that create the classic white, opaque look. The nano form uses much smaller particles, typically under 100 nanometers, which appear more transparent on the skin. Nano titanium dioxide is popular in sunscreens because it provides UV protection without the visible white cast.
In the EU, cosmetic products containing the nano form must label it with “[nano]” after the ingredient name. The European Food Safety Authority (EFSA) noted in 2021 that while nano titanium dioxide showed no general organ toxicity or reproductive effects, it could not rule out potential DNA damage based on tests with nanomaterials. The U.S. FDA reviewed the same data and did not identify genotoxicity concerns, pointing out that some of the concerning test results involved administration methods not relevant to how people actually encounter the ingredient. The regulatory conversation is ongoing: as of September 2025, the European Commission has requested a new scientific opinion covering both nano and non-nano forms in cosmetics.
CI 77891 vs. E171
These are the same chemical compound with different regulatory labels. CI 77891 is the cosmetic designation, while E171 is the food additive code used in the EU. The EU banned E171 in food in 2022 after EFSA concluded it could not confirm safety due to the unresolved genotoxicity question with nanoparticles. This ban applies only to food. CI 77891 remains permitted in cosmetics throughout the EU, the U.S., and most other markets, though with the aerosol and spray restrictions noted above. In the U.S., the FDA still permits titanium dioxide in food, noting that its own review of the data did not identify cancer concerns and that National Toxicology Program studies found no carcinogenic effects from dietary exposure.