Beyond sunscreens, pigment-grade titanium dioxide, listed as CI 77981, is found in almost all tinted products. But why is it used and found in this form in cosmetic formulas? Continue reading to learn more about this component.
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What is "CI 77891" and what is its purpose?
Summary
Published November 5, 2021,
updated on April 29, 2024,
by
Stéphanie, Doctorate in Life and Health Sciences
—
6 min read
Topics:
What is the benefit of adding CI 77891 to cosmetic formulas?
Listed on product labels under the INCI name "CI 77891", the pigmented titanium white has the chemical formula TiO2 and is the main odourless white inorganic compound, derived from a purification of ores, used commercially. It was intentionally produced for the first time in 1923 to be used as a white pigment.
Although titanium dioxide exists in three different crystalline forms (anatase, rutile, and brookite), the anatase and rutile forms are the primary ones used in cosmetics.
| Identification | Chemical and Physical Characteristics |
|---|---|
| Chemical Formula | TiO2 |
| Synonym | CI 77981, CI Pigment White 6, titanium white, titanium dioxide, titanium (IV) oxide |
| Appearance | Fine white crystalline powder |
| Method of Acquisition | Sulphate or Chlorine Process |
| Molar Mass | 76.87 g/mol |
| Granulometry | Diameter between 0.01 and 3,000 µm (micrometric form) |
| Solubility | Insoluble in water, organic acids, and weak inorganic acids; Soluble in sulphuric acid, oils, and alkalis |
| Stability | Photostable |
Although it has other functions, CI 77891 is also used in the formulation of a wide variety of coloured products, such as eyeshadows, foundations, blushes, loose powders or lipsticks, as a pigment of the Colour Index for its brilliant white colour due to its high refractive index, its ease of dispersion and its opacity. Used for aesthetic design purposes, it thus helps to define colours and create numerous different shades by mixing it with other colours in order to cater to all skin types.
Of mineral origin, CI 77891 is one of the most widely used pigments today. Lip oils, tinted serums, tinted concealers... it is present in all our tinted skincare products.
How is titanium dioxide extracted?
Titanium dioxide is the combination of the element titanium, commonly found in its natural state in ilmenite ore (ferrotitanium oxide) and rutile ore, with oxygen. It is extracted from the earth, then processed and purified. Two main methods are employed to obtain pure titanium oxide, which can be used in cosmetics.
Through a sulphate process, the oldest one (1930), in which impure ilmenite is dissolved in hot concentrated sulphuric acid (H2 SO4), followed by crystallisation and precipitation leading to the anatase form of titanium dioxide;
FeTiO3 + H2 O + H2 SO4 —> FeSO4 + TiO(OH)2
Through a chlorine process (1950) in the event where rutile, a mineral with a high titanium dioxide content, undergoes carbochlorination in the presence of chlorine to form titanium tetrachloride (TiCl4), followed by purification and an oxygen treatment at 1,400°C which leads to the rutile form of TiO2.
TiO2 + 2C + 2Cl2 —> TiCl4 + 2 CO
The surfaces of the particles are then treated with silica, alumina, or other organic compounds to facilitate and stabilise their dispersion.
CI 77891: Are there risks?
In cosmetics, CI 77891 is generally regarded as safe. However, its safety has been questioned, particularly when it is inhalable as it can be in powder form. Indeed, it is considered as a possible carcinogen in humans (category 2B) since 2006 by the International Agency for Research on Cancer (IARC), largely due to studies that have revealed an increase in lung cancers due to inhalation exposure in animals.
Indeed, in its 2011 report, the ANSM states that inhalation exposure to high doses of TiO2 promotes the development of lung cancer in rats, through an indirect effect of genotoxic oxidative stress. However, it notes that these results are not transferable to cosmetics, as in this case, the exposure is dermal. Nevertheless, it should be clarified that such a risk seems to primarily occur in a professional environment during the production of TiO2 powders and the manufacturing of products containing them.
On the other hand, other studies have evaluated the carcinogenic effect of TiO2 through intratracheal administration and the results showed no significant increase in the incidence of tumours in the various treated animal models (mice, rats, hamsters). Furthermore, the risk seems to exist only if a significant amount of titanium dioxide powder is inhaled. Moreover, KREYLING W. and his colleagues reported in a 2008 study that alveolar macrophages (phagocytes) effectively eliminate the particles of TiO2 of micrometric size (3 to 6 μm) in rats that were exposed to titanium dioxide powders by inhalation.
The evidence for the carcinogenicity of titanium dioxide is thus limited and not sufficient. Further experiments need to be conducted in order to provide relevant toxicological and human exposure data for a reliable hazard assessment.
Sources
KREYLING W. & al. The role of macrophages in the clearance of inhaled ultrafine titanium dioxide particles. American Journal of Respiratory Cell and Molecular Biology (2008).
Scientific Committee on Consumer Safety (SCCS). Opinion on Titanium dioxide (TiO2) used in cosmetic products that lead to exposure by inhalation (2020).
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