In short, no, research demonstrates that E171 is safe when consumed in normal situations.

Moreover, how we're exposed to an ingredient matters significantly in terms of our health and potential toxicity.   

Research shows that inhaling titanium dioxide particles in significant quantities over time can cause adverse health outcomes. Unless you work in an industrial setting, inhaling substantial amounts of titanium dioxide is highly unlikely. 

Research supports that applying titanium dioxide to the skin in the form of sunscreens, makeup, and other topical products does not pose a health risk. 

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

Again, other research suggests that E171 could cause harm; however, those research processes did not design their studies to model how people are exposed to E171. Research that adds E171 to drinking water, utilizes direct injections, or gives research animals E171 through a feeding apparatus is not replicating typical human exposure, which occurs through food and medicine consumption.

Read more in-depth about the titanium dioxide risk at go.msu.edu/8Dp5. 

As a widely used substance with multiple applications, research is being carried out to improve the production process to reduce the levels of chemicals used and waste produced, and to recycle any by-products.

The Journal of the American Institute for Conservation (JAIC) is an international peer-reviewed periodical for the art conservation profession. The Journal publishes articles on treatment case studies, current issues, materials research, and technical analyses relating to the conservation and preservation of historic and cultural works. The topics encompass a broad range of specialties including architectural materials, archeological objects, books and paper, ethnographic materials, objects, paintings, photographic materials, sculpture, and wooden artifacts. Started as the Bulletin of the International Institute for Conservation-American Group (IIC-AG), in April 1961, the Journal matured into its current form in 1977. Since that time JAIC has become a repository for the core body of conservation information through its documentation of new materials, changing methods, and developing standards in the conservation profession. The four-color publication is distributed three times a year to AIC members and museum, library, and university subscribers.

Scientists analyzed research that examined how titanium dioxide nanoparticles interact with the brain for a 2015 review published in Nanoscale Research Letters. The researchers wrote: “Once the TiO2 NPs are translocated into the central nervous system through [certain] pathways, they may accumulate in the brain regions. For their slow elimination rates, those NPs could remain in the brain zones for a long period, and the Ti contents would gradually increase with repeated exposure.” After reviewing dozens of studies, the scientists concluded: “Long-term or chronic exposure to TiO2 nanoparticles could potentially lead to the gradually increased Ti contents in the brain, which may eventually induce impairments on the neurons and glial cells and lead to CNS dysfunction as a consequence.”

For a mini-review published in the journal Particle and Fibre Technology in 2021, scientists wanted to evaluate whether Ti02 particles contributed to the development and/or exacerbation of irritable bowel disease, and whether they altered the four elements of intestinal barrier function: the intestinal microbiota, the immune system, the mucus layer, and the epithelium. The breakdown of these four elements can contribute to autoimmune, neurological, inflammatory, infectious, and metabolic diseases. Following their review, the researchers concluded: “Data indicate that TiO2 is able to alter the four compartments of IBF and to induce a low-grade intestinal inflammation associated or not with pre-neoplastic lesions.” 

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.  

North America

But before titanium dioxide is made into sunscreens, it is first micronized. This is a process that takes ingredients that are normally quite heavy (like titanium dioxide) and makes them both stabler and easier to spread. And when micronized, titanium dioxide doesn’t penetrate the skin. That means that you’re getting all the sun protection benefits without the risk of harming yourself.

The European Commission banned titanium dioxide as a food additive in the EU in 2022 after the European Food Safety Authority (EFSA) conducted an updated safety assessment of E171 and concluded the panel could not eliminate concerns about its genotoxicity. 

There are two primary forms of titanium dioxide commercially available: anatase and rutile. The rutile form is typically used in sunscreens due to its superior ability to handle UV rays and stability in the presence of UV light. The anatase form is typically used in other types of products, such as paint. Another plus of the rutile form is that its UVA protection extends past 400 nanometers, which is the upper limit of UVA.

The EU expert panel did not identify an immediate health concern linked to TiO₂ when used as a food additive. However, due mainly to uncertainties concerning the safety of TiO₂ nanoparticles, the panel concluded that TiO₂ as a food additive (E171) could no longer be considered safe.