Although food-grade titanium dioxide must be 99 percent pure, there’s still a risk of it containing potential contaminants, such as mercury, lead and arsenic. Additionally, inhaling the mineral over time can possibly cause it to build up in your body, leading to adverse effects.

From studies deemed relevant, the experts found that titanium dioxide as a food additive is poorly absorbed by the gastrointestinal tract of mice and rats, with no adverse effects observed in short-term studies in rodents receiving titanium dioxide in their diets. No observed adverse effect levels (NOAELs) of 15,000 milligrams per kilogram of bodyweight (mg/kg BW) per day and 5,000 mg/kg BW per day—the highest doses tested—were established for mice and rats, respectively.

For research published in Archives of Toxicology in 2020, scientists fed one group of mice a solution containing titanium dioxide for one month, and compared it to those that did not receive the additive. They found “the richness and evenness of gut microbiota were remarkably decreased and the gut microbial community compositions were significantly changed” in the titanium dioxide group when compared with the control group. The tests also revealed that the titanium dioxide exposure could cause locomotor dysfunction, or mobility issues “by elevating the excitement of enteric neurons, which might spread to the brain via gut-brain communication by vagal pathway.” The researchers concluded: “These findings provide valuable insights into the novel mechanism of TiO2NP-induced neurotoxicity. Understanding the microbiota-gut-brain axis will provide the foundation for potential therapeutic or prevention approaches against TiO2NP-induced gut and brain-related disorders.”

Titanium dioxide particles help light scatter and reflect, Kelly Johnson-Arbor, MD, a medical toxicology physician at the National Capital Poison Center, told Health. Because of that, we often use it as a whitening agent.

In 2022, a year after the EFSA recommended against the use of E171, the Food Standards Australia New Zealand (FSANZ) conducted its own reassessment of titanium dioxide as a food additive. The agency concluded that titanium dioxide was indeed safe to use as a food additive. The United Kingdom and Canada came to similar conclusions.

Certificate of Analysis (Lithopone B301, Lithopone B311 powder TDS)

Analyst Insight

Over the last several years, nanoparticles have come under scrutiny for adverse health effects. Nanoparticles are ultrafine particles between 1 to 100 nanometers in diameter. (To put this in perspective, the average human hair is around 80,000 nanometers thick.) Because of their size, which can be engineered and manipulated at the atomic or molecular level, nanoparticles exhibit unique physical, chemical, and biological properties. Titanium dioxide is one of the most commonly produced nanoparticles in the world.