Center for Research on Ingredient Safety

What is titanium dioxide?

Titanium dioxide is a white, powdery substance that is widely used as a pigment, brightening agent, and protectant in various food, cosmetics, pharmaceuticals, and other industrial uses.

It is a naturally occurring oxide of the metal titanium. Titanium dioxide forms when titanium is exposed to oxygen, creating many differing titanium oxides found in minerals, dusts, sands, and soils. 

Titanium dioxide has excellent light-scattering properties, making it valuable in products that require a bright white color or opacity. It is commonly used in cosmetics, sunscreen, paints, coatings, plastics, food products, and many other applications where its brightening and reflective properties are desired.

Manufacturers source this mined mineral from rutile, brookite, and anatase. It is then processed and refined to meet stringent safety guidelines based on the end-use of the mineral.

Titanium dioxide added to foods and other ingestible products is commonly known as E 171, indicating its high food-grade purity.

What does titanium dioxide do?

Titanium dioxide amplifies and brightens white opacity because of its exceptional light-scattering properties. In food and drugs, these properties help to define colors clearly and can prevent products from UV degradation.

In cosmetics, titanium dioxide’s properties enhance coloration and can help protect skin from damaging UVA and UVB rays.

How are we typically exposed to titanium dioxide?

There are many ways we’re exposed to titanium dioxide in our everyday life. Below are the most common ways we come into contact with titanium dioxide.

Digestive System Exposure

We’re frequently exposed to E 171 through the foods we ingest. We find E 171 in many food products, like popsicles, ice cream, gum, and more. Another way we ingest E 171 is through pharmaceutical drugs. Many pills and capsules contain E 171 as an inactive ingredient.

Less frequently, we ingest E 171 through liquids such as salad dressing, dairy products, and some artificially colored drinks. However, since E 171 is insoluble, manufacturers must use other stabilizers to keep E 171 suspended in liquids as an emulsion; otherwise, it will settle to the bottom.

Topical Exposure

We apply titanium dioxide to our skin through sunscreens, makeup, lip balms, nail polish, and other cosmetic products.

We even use titanium dioxide when brushing our teeth, as it’s found in many toothpastes.

Respiratory Exposure

In industrial settings, people can be exposed to titanium dioxide through inhalation. Inhalation exposure to titanium dioxide is exceedingly rare for most people.

Why does the exposure route matter, and does titanium dioxide harm our health?

How we’re exposed to an ingredient matters significantly regarding our long-term health.

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 through sunscreens, makeup, and other topical products does not pose any health risks.

Overwhelmingly, research relevant to human eating patterns shows us that E 171 is safe when ingested typically through foods and drugs (1,2,3).

Other research suggests that E 171 could cause harm; however, those research processes did not consider how people are typically exposed to E 171. Research that adds E 171 to drinking water, utilizes direct injections, or gives research animals E 171 in drinking water through a feeding apparatus is not replicating typical human exposure. It's important to note that in these studies, when titanium dioxide is consumed in liquid form, it can settle if proper emulsification is not achieved. This can result in uneven and unpredictable titanium dioxide exposure to the research animals.

Let’s take a deeper look at titanium dioxide in foods.

E171 is not a singular ingredient; it’s always combined with other ingredients (e.g., proteins and fats) in the food product. Digesting food is a slow process for the body compared to drinking a beverage, which passes much more quickly through the body (1,2).

When E 171 is part of a food product, it passes through the digestive system without causing harm because E 171 combines with the other ingredients and absorption through the gastrointestinal tract is miniscule.

In some studies, researchers gave E 171 to animals in drinking water without the stabilizers that keep E 171 suspended in the liquid. Without stabilizers, E 171 can settle and prevent the ingredient from combining with surrounding ingredients. When E 171 isn’t combined with other ingredients, it can drastically alter the way it’s processed in the body, which could produce adverse health impacts.

However, humans are not exposed to E 171 in drinking water in any significant quantity over a long duration, so this potential effect is irrelevant to the human experience. It’s important to understand that a potential hazard is not the same as an actual risk.

Why does California want to ban titanium dioxide?

There are concerns that titanium dioxide may adversely impact our health. However, the studies linking titanium dioxide to adverse health outcomes didn’t reflect actual human exposure in real-life settings (1,2).

Additionally, some regulatory organizations have raised concerns about titanium dioxide particles used in food products. They worry because some particles can be smaller than 100 nanometers, which is considered "nano" size. However, it's important to note that most of these particles in food are larger, typically in the micron diameter range (1,000 nanometers).

Particles smaller than 100 nanometers tend to clump together, or agglomerate, when they come into contact with water or digestive fluids. As a result, their ability to pass through biological barriers becomes extremely limited. Similarly, particles larger than 100 nanometers struggle to move across these barriers because they are too big.

California has a unique relationship with ingredients and has legislation in place, such as Proposition 65, which requires warning labels on products made using any chemical known to cause adverse health impacts, even if adverse health events only occur in extremely high irrelevant doses or other outlying situations, that do not occur to the public. Proposition 65 labeling laws are in addition to the current federal regulations. 

The new bill, AB-418 Food product safety, goes above Proposition 65 warning labels to ban titanium dioxide and four additional ingredients (brominated vegetable oil, potassium bromate, propylparaben, and red dye 3) from foods sold in California. 

As of publication, the bill is currently under review and awaiting a final vote. 

What happens if titanium dioxide is banned in food products in California? 

If a ban on titanium dioxide is passed and upheld, companies will need to reformulate products or no longer sell products containing titanium dioxide in California.

Will a titanium dioxide ban in California impact drugs or cosmetics?

Per our understanding, the ban presently focuses on food products, not pharmaceutical medication or cosmetics. Therefore, we’d anticipate titanium dioxide would still be found in drugs and cosmetics, for the time being.  

The good news.

Current research continues to demonstrate that titanium dioxide exposure at levels within federal regulations is safe for humans. Federal regulatory agencies work to ensure the safety of the ingredients found in the products we use and consume. While California may choose a divergent path from the other states regarding ingredient regulation, our federal laws continue to provide recommendations and regulations for the products in our everyday lives.

If you have any questions about foods and ingredients, please reach out to us on Twitter, send us an email, or submit your idea to us at go.msu.edu/cris-idea