...

However, it is important to note that while mica and titanium dioxide can be beneficial in shampoo, they may not be suitable for everyone. Some individuals may experience allergic reactions or irritation when using products containing these minerals, especially if they have sensitive skin or hair. Therefore, it is always advisable to conduct a patch test before using any new product, especially if you have never used mica or titanium dioxide before.

...

A few non-dietary studies have reported adverse effects in the gastrointestinal tract of laboratory animals given food-grade TiO2. However, these same effects were not seen when the same or higher doses of food-grade TiO2 were administered in the animals' diet. Dietary studies best reflect how humans are exposed to TiO2 from food. Thus, the Food Directorate placed the most emphasis on the results of these studies in the state of the science report.

...