Pigment grade titanium dioxide is produced at a much larger particle size than nano grade. It is used as a colourant to whiten and brighten product formulations. Nano grade titanium dioxide is manufactured into very fine (nano) particles and is transparent and colourless. It is commonly used in sunscreens to provide effective protection from potentially harmful UV rays.

Abstract

In a small study published in the European Journal of Nutrition in 2020, researchers examined the effects of several food additives, including titanium dioxide, along with artificial sweeteners and cleaning products by testing the fecal samples of 13 people. Titanium dioxide was among the samples that “induced significant shifts in microbiome community structure.”  The growth of the bacterium species belonging to C. leptum, which has been shown to decrease in patients with inflammatory bowel disease, “significantly decreased in the presence of … titanium dioxide” among other additives and sweeteners tested.

Because of its ability to absorb UV light, it's particularly useful as an ingredient in sunscreens — while its light-scattering properties are great for applications that require white opacity and brightness, such as in paint and paper.

Les pouvoirs couvrant et éclaircissant du lithopone normal sont supérieurs à ceux de la céruse et de l'oxyde de zinc, mais inférieurs au Dioxyde de Titane pur, étant le meilleur blanc sous tout rapport. C'est le sulfure de zinc qui, avec son indice de réfraction de 2,37, est l’élément opaque ; le 2nd composé, le sulfate de baryum, joue un rôle de diluant minéral et favorise l'efficacité de la diffusion du premier.

As of August 7, the use of titanium dioxide in food is banned in the European Union. Europe is taking a precautionary principle approach based on findings from the European Food Safety Authority (EFSA).

“Unlike some other chemicals used in food, titanium dioxide has no nutritive, preservative, or food safety function—its use is purely cosmetic,” said CSPI principal scientist for additives and supplements, Thomas Galligan. “The prospect of titanium dioxide nanoparticles damaging DNA is concerning enough for us to recommend consumers avoid foods that have it.” 

An inorganic chemical, titanium dioxide is used as a dye to help products achieve a certain appearance, including whitening a product. Some experts and publications have described it as being akin to a paint primer that's used before the color is added to food in order to give products a uniform shine. Its presence is common in many items beyond Skittles including coffee creamers, cake mixes, and chewing gum. It's also used for pigment and in cosmetics manufacturing.

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.