Named after the mythological first sons of the world, titanium was discovered in 1791. It is found abundantly in the earth’s crust and is heat-resistant, lightweight, and resists corrosive acids, making it a valuable additive in a variety of products. Titanium is added to sunscreens, because it can also absorb UV rays.
To make titanium into a pure, white pigment, it is processed into titanium dioxide. This makes it valuable in cosmetics. No studies have found it to be toxic in this form either, including by ingestion.
Sounds great so far, but wait. The problem with titanium dioxide occurs when its particles are ground into micro-sized, or nanoparticles such as technology now makes possible. Unfortunately, this is what is increasingly being used in the cosmetic and sunscreen industries. These particles are so fine that they can easily penetrate the cell walls in your body, instead of staying on the surface of the skin. Remember how they absorb UV rays? In some studies, subjects used micronized titanium dioxide for 2-4 weeks on their skin. Scientists then viewed their skin under UV light and could clearly see the particles in the percutaneous (deeper) layers of skin.
So, in answer to the question, titanium dioxide is not dangerous except in nanoparticle form. It may take a little research to find cosmetics and sunscreens that do not use nanoparticles, but they are out there.