Officially titanium dioxide is listed as a safe pigment, and according to the official study it presents no known adverse effects to humans and is not a carcinogen, although you can find this word in the descriptions given by some websites.
The only problem usually associated with T. dioxide is through breathing the powder or dust in which case lung tumors can be the result, however, a study titled the “Pulmonary Response of Rats Exposed to Titanium Dioxide by Inhalation for Two Years” was conducted several years ago. This study found that when rats are chronically exposed to excessive Titanium Dioxide dust at 250 mg/m for six hours per day, five days per week for two years, they can develop slight lung tumors.
The National Institute for Occupational Safety and Health (NIOSH) declared that the relevance of this research to lung problems in humans is negligible.
The Synergy Company makes a calcium supplement called “Bone Renewal” which is a titanium dioxide free supplement; however, it contains fermented soy gluten.