There are two primary forms of titanium dioxide commercially available: anatase and rutile. The rutile form is typically used in sunscreens due to its superior ability to handle UV rays and stability in the presence of UV light. The anatase form is typically used in other types of products, such as paint. Another plus of the rutile form is that its UVA protection extends past 400 nanometers, which is the upper limit of UVA.

However, since it’s photosensitive — meaning it can stimulate free radical production — it’s usually coated in silica or alumina to prevent potential cell damage without reducing its UV-protective properties (7Trusted Source).