In addition to Skittles, other candies that contain titanium dioxide include Nice! mints, Trolli sour gummies and Ring Pops, according to Environmental Working Group. 

In food, titanium dioxide is often used as an artificial color additive. Tasha Stoiber, senior scientist at the consumer health nonprofit Environmental Working Group, says titanium dioxide can generally be thought of as a paint primer – it often goes on a hard-shelled candy like Skittles before the color is added to give it a uniform shine.