Overwhelmingly, research that’s relevant to human eating patterns shows us that E171 is safe when ingested normally through foods and drugs (1,2).

Although the evidence for general toxic effects was not conclusive, on the basis of the new data and strengthened methods we could not rule out a concern for genotoxicity and consequently we could not establish a safe level for daily intake of the food additive, commented Matthew Wright, member of the EFSA's Food Additives and Flavourings Panel in a press statement.

But in 2021, EFSA reevaluated titanium dioxide to consider the impacts of its nanoparticle. After considering more studies, EFSA concluded that nanoparticle-size titanium dioxide can accumulate in the body, break DNA strands and cause chromosomal damage.

Because of its unique pigment and fine-milled texture, titanium dioxide has become popular over the past century in a wide variety of different products. These include adhesives, paints, plastics, rubbers, textiles, inks, ceramics, and even some pharmaceuticals, foods, and hygiene products.

The chemical is also found in common household and industrial products such as paints, coatings, adhesives, paper, plastics and rubber, printing inks, coated fabrics and textiles, as well as ceramics.

The skin of an adult person is, in most places, covered with a relatively thick (∼10 μm) barrier of keratinised dead cells. One of the main questions is still whether TiO₂ NPs are able to penetrate into the deeper layers of the skin. The majority of studies suggest that TiO₂ NPs, neither uncoated nor coated (SiO₂, Al₂O₃ and SiO₂/Al₂O₃) of different crystalline structures, penetrate normal animal or human skin. However, in most of these studies the exposures were short term (up to 48 h); only few long-term or repeated exposure studies have been published. Wu et al.83 have shown that dermal application of nano-TiO₂ of different crystal structures and sizes (4–90 nm) to pig ears for 30 days did not result in penetration of NPs beyond deep epidermis. On the other hand, in the same study the authors reported dermal penetration of TiO₂ NPs with subsequent appearance of lesions in multiple organs in hairless mice, that were dermal exposed to nano-TiO₂ for 60 days. However, the relevance of this study for human exposure is not conclusive because hairless mice skin has abnormal hair follicles, and mice stratum corneum has higher lipid content than human stratum corneum, which may contribute to different penetration. Recently Sadrieh et al. performed a 4 week dermal exposure to three different TiO₂ particles (uncoated submicron-sized, uncoated nano-sized and coated nano-sized) in 5 % sunscreen formulation with minipigs. They found elevated titanium levels in epidermis, dermis and in inguinal lymph nodes, but not in precapsular and submandibular lymph nodes and in liver. With the energy dispersive X-ray spectrometry and transmission electron microscopy (TEM) analysis the authors confirmed presence of few TiO₂ particles in dermis and calculated that uncoated nano-sized TiO₂ particles observed in dermis represented only 0.00008 % of the total applied amount of TiO₂ particles. Based on the same assumptions used by the authors in their calculations it can be calculated that the total number of particles applied was 1.8 × 10¹³ /cm² and of these 1.4 x10⁷/cm² penetrated. The surface area of skin in humans is around 1.8 m²  and for sun protection the cream is applied over whole body, which would mean that 4 week usage of such cream with 5 % TiO₂ would result in penetration of totally 2.6 × 10¹⁰ particles. Although Sadrieh et al.concluded that there was no significant penetration of TiO₂ NPs through intact normal epidermis, the results are not completely confirmative.

That being said, titanium dioxide is particularly popular in concealers. ​​As one of the most naturally opaque and pearly-white materials on earth, titanium dioxide has the ability to provide excellent coverage while brightening the skin, whether you’re dealing with blemishes, dark spots, acne, or dark circles under the eye.

Titanium dioxide (TiO₂) is a naturally occurring mineral that is mined from the earth, processed and refined, and added to a variety of foods, as well as other consumer products. White in color, it is used to enhance the color and sheen of certain foods and is also key for food safety applications. In its natural state it exists in different bulk crystalline forms, such as anatase and rutile, but during processing it is ground into a very fine powder.