When E171 is part of a food product, it passes through the digestive system without causing harm because E171 combines with the other ingredients. 

Nano-sized P25TiO₂NPs were kindly donated by Dr. Scaiano, Ottawa University (Canada). Riboflavin (vitamin B2) was from Sigma and ascorbic acid (vitamin C) and KBr (for IR pills) were from Cicarelli. Base cream for the animal experiments was purchased from Todo Droga and the LED panel was built ad hoc.

JECFA also evaluated estimates of dietary exposure to titanium dioxide, estimating the maximum 95^th percentile of exposure to be 10 mg/kg BW per day. Overall, considering the low oral absorption of titanium dioxide as a food additive, the committee reaffirmed the ADI “not specified” that was established at the 13^th meeting.

It doesn’t take much to imagine what they must be doing to our poor skin each day as we layer on our sunscreen, foundation, concealers, eyeshadows & lip sticks which all contain large doses of titanium dioxide.