Titanium Dioxide in Makeup

Titanium dioxide occurs in nature in several crystal forms; only two are relevant to makeup and color cosmetic applications. Rutile TiO₂ (CAS No. 1317-80-2) is the thermodynamically more stable polymorph, with a density of approximately 4.23 g/cm³. As detailed in the function section above, rutile's higher refractive index translates directly into greater hiding power, making it the preferred opacifier in foundations, face powders, and concealers. Anatase TiO₂ (CAS No. 1317-70-0) has a lower density of approximately 3.78 g/cm³ and somewhat less hiding power per unit weight; it appears more frequently in certain UV-filter contexts.

Rutile is generally preferred in cosmetic formulations over anatase. Neither the CRC Handbook of Chemistry and Physics nor Cotton & Wilkinson's Advanced Inorganic Chemistry (6th ed.) attribute that preference to photocatalytic considerations within the scope of the regulatory sources governing finished cosmetic products; the operative preference is grounded in rutile's superior optical performance as documented in those references.

A regulatory consequence of the rutile-versus-anatase distinction that is directly relevant to consumers is this: neither 21 CFR 73.2575 nor SCCS/1617/20 differentiates between rutile and anatase. The FDA color additive regulation authorizes "titanium dioxide" without specifying a crystal form, meaning both polymorphs fall within its scope. The SCCS opinion similarly evaluates pigmentary TiO₂ on the basis of particle size — the pigmentary versus nano boundary — rather than crystal structure. The practical implication is that the crystal form present in a finished makeup product is not a regulatory disclosure requirement under either US or EU law, and it cannot be identified from the ingredient list. A label entry reading "Titanium Dioxide" or "CI 77891" is consistent with either polymorph, or a mixture of both, and no marking distinguishes one from the other at the point of sale.

When someone applies a mineral foundation or an SPF-containing makeup and notices a whitish, ashy film on the skin, they are observing an optical phenomenon that follows directly from the physics of light scattering. The key variables are particle size and the contrast in refractive index between the TiO₂ particle and the surrounding medium in the formulation. Pigment-grade TiO₂ particles typically fall in the range of approximately 200 to 400 nm — dimensions that place them squarely within the wavelength range of visible light (roughly 400–700 nm). At those sizes, the particles scatter not only UV radiation but also visible light efficiently, and the high refractive-index contrast established in the function section amplifies that scattering into the perceptible brightening of the skin surface known as white cast.

When TiO₂ is micronized to the range of approximately 10 to 50 nm, the dominant scattering behavior shifts: at those smaller dimensions, Mie scattering preferentially affects UV wavelengths, and visible light is transmitted with far less interference, substantially reducing the white cast visible to the eye. This particle-size boundary is directly relevant to the regulatory framework: the EU definition of a nanomaterial under Article 2(1)(k) of Regulation (EC) No. 1223/2009 places the threshold at primary particles smaller than 100 nm, meaning that micronizing TiO₂ sufficiently to minimize white cast can bring a formulation into the nano category — with the labeling and safety-assessment consequences described in the ingredient list section. The SCCS/1617/20 opinion's safety conclusions for pigmentary TiO₂, including the 25% concentration limit for face makeup and loose powder, apply specifically above that 100 nm boundary and are not automatically transferable to micronized forms below it.

The white cast effect is not equally visible across all skin tones. Because the effect is produced by scattered white light superimposed on the skin surface, the perceptible contrast between that scattered light and the underlying skin tone is greater on deeper and darker complexions than on lighter ones — making the phenomenon more noticeable and practically significant for consumers with medium-to-deep skin tones. This is a consequence of luminance contrast physics, not of any differential interaction between TiO₂ and skin chemistry.

In the United States, titanium dioxide is explicitly authorized as a color additive in cosmetics under a federal regulation that has been in place for decades. 21 CFR 73.2575 — the relevant provision within Title 21 of the Code of Federal Regulations — lists titanium dioxide among color additives that are exempt from batch certification. The regulation permits TiO₂ as a color additive in cosmetics generally, and its scope includes a provision that carries particular significance for consumers and formulators alike:

"[Titanium dioxide may be used as a color additive in cosmetics generally,] including cosmetics intended for use in the area of the eye."

This explicit inclusion of eye-area cosmetics matters because the FDA maintains a separate, stricter category for color additives used near the eyes — and the fact that 21 CFR 73.2575 affirmatively extends permission to that category means titanium dioxide is authorized not only in foundations, face powders, and concealers but also in eyeshadows, eyeliners, and similar products. No other qualification is added beyond conformity with good manufacturing practice (GMP): unlike some other color additive regulations, 21 CFR 73.2575 does not set a numerical maximum concentration. The operative standard is GMP-compliant use, which means manufacturers are responsible for ensuring that the quantity used is consistent with recognized manufacturing standards. For U.S. consumers, this means that titanium dioxide in any of these product formats sits within a clearly defined federal legal framework that binds manufacturers to established quality and safety standards.

The principal EU reference document for the safety assessment of titanium dioxide in cosmetics is the Scientific Committee on Consumer Safety opinion SCCS/1617/20, whose final version was adopted by written procedure on 6 October 2020. A preliminary version had been published on 7 August 2020, with a public commenting period running from 10 August to 7 September 2020. The assessment was conducted explicitly against the background of a potential classification of TiO₂ as a Category 2 carcinogen by inhalation under Annex VI of Regulation (EC) No. 1272/2008 — a classification context the SCCS addressed directly in its conclusions.

The opinion evaluates TiO₂ in two regulatory contexts under EU cosmetics law: as a colorant (Annex IV, entry 143 of Regulation (EC) No. 1223/2009) and as a UV filter (Annex VI, entry 27 of the same Regulation). For both uses, the SCCS assessment focuses on pigmentary (non-nano) TiO₂ — the larger-particle form that is distinct from nanomaterial TiO₂, a distinction addressed in the ingredient list section below. For a typical face makeup application using loose powder, the Committee concluded that pigmentary TiO₂ is safe for consumers at concentrations up to 25% both when used as a colorant under Annex IV, entry 143, and when used as a UV filter under Annex VI, entry 27. The same 25% ceiling therefore applies across both regulatory functions in these non-spray face makeup and loose powder formats.

This conclusion does not extend to aerosol spray products. For a typical hair-styling aerosol spray, the SCCS assessed 25% as not safe — neither for general consumers nor for professional hairdressers. Instead, the Committee derived substantially lower safe concentrations for those formats: 1.4% for consumers and 1.1% for hairdressers. The reason for this divergence is the exposure route: in aerosol formats, TiO₂ particles are actively propelled into the air by a propellant, creating a dense, finely distributed particle cloud that can be inhaled deep into the respiratory tract. The inhalation exposure in spray scenarios is of a fundamentally different order of magnitude than the limited airborne release that occurs when loose powder is applied with a brush or sponge. For all product formats where an inhalation route is relevant, SCCS/1617/20 requires that a calculated Margin of Safety exceed 25 — a methodological threshold discussed further in the following section.

Headlines that describe titanium dioxide as a "carcinogen" draw on a classification that, without its essential context, is essentially meaningless for consumers applying makeup. The International Agency for Research on Cancer (IARC) classifies TiO₂ in Group 2B — "possibly carcinogenic to humans". This classification was first documented in IARC Monographs Volume 47 (1989) and was reviewed again in Volume 93 (2010). Importantly, IARC Volume 93 confirmed and retained the Group 2B classification — it did not revise it upward or downward. Consumers encountering references to either volume should understand they reflect the same regulatory conclusion, not two separate or evolving assessments.

What Group 2B means — and does not mean — requires careful reading. As the International Chemical Safety Card ICSC 0338 (ILO/WHO) makes plain, the classification concerns long-term or repeated inhalation of airborne TiO₂ dust, primarily in occupational settings such as TiO₂ manufacturing or industrial processing, where workers may be exposed to high concentrations of fine or ultrafine airborne particles over sustained periods. "Possibly carcinogenic" in this context means that there is limited evidence from animal inhalation studies — not that TiO₂ has been shown to cause cancer through skin contact or topical application. The occupational relevance of this dust-exposure concern is also reflected in established workplace air limits: the U.S. OSHA permissible exposure limit (PEL) for titanium dioxide is 15 mg/m³ as an 8-hour time-weighted average, the ACGIH threshold limit value (TLV) is 10 mg/m³ over the same period, and NIOSH has set recommended exposure limits (RELs) of 2.4 mg/m³ for fine TiO₂ and 0.3 mg/m³ for ultrafine TiO₂, both as 10-hour time-weighted averages — limits that reflect the inhalation hazard framework for workers, not consumers using finished cosmetics.

Consumers who apply foundation, press powder onto their skin, or blend concealer are exposed topically and dermally — not through the sustained occupational inhalation that forms the evidentiary basis for the IARC assessment. ICSC 0338 does not indicate a dermal carcinogenicity concern. Applying the IARC Group 2B classification to finished makeup products therefore means applying a finding about one specific exposure route — inhalation in industrial contexts — to a fundamentally different exposure scenario. For the exposure conditions that actually characterize cosmetic use, the directly relevant safety assessment is SCCS/1617/20, as discussed above.

Titanium dioxide is also assigned a Right to Know (RTK) Substance Number of 1861 under the New Jersey Department of Health hazard substance list, which records health, flammability, and reactivity ratings of 2, 0, and 0, respectively. These designations are occupational and industrial safety classifications tied to dust-inhalation and handling hazards — they describe the substance in bulk or airborne form in workplace contexts, not the risk profile of TiO₂ as an ingredient in a finished cosmetic product applied to skin.

The safety conclusions in SCCS/1617/20 — including the concentration limits discussed in the EU safety section — apply specifically to pigmentary (non-nano) TiO₂. The dividing line is primary particle size: nanomaterial TiO₂ consists of primary particles smaller than 100 nm by definition, while pigmentary TiO₂ has larger particles. The SCCS opinion explicitly leaves open whether its conclusions can be extended to nanomaterial forms of TiO₂ without further assessment. The scope of that opinion is therefore a boundary on what is currently known from a formal EU regulatory safety evaluation, not a statement that nano TiO₂ has been found unsafe — only that it has not been assessed to the same standard within this opinion.

This distinction between pigmentary and nano TiO₂ also determines which regulatory concentration thresholds apply and which labeling obligations are triggered. For labeling implications of this distinction — including how to identify nano TiO₂ on an EU ingredient list and what the absence of a comparable U.S. requirement means for American consumers — see the ingredient list section below.