Currently nano Titanium Dioxide is considered to be safe as well as non nano Zinc Oxide.  Ultrasun products only use Titanium Dioxide (nano) in our products and non nano Zinc Oxide.   It's about getting a good balance between the feeling on the skin and vital Nano research, and we've achieved this. Ultrasun's use of Nanos is at a size that is independently recognised as unable to pass into bloodstream (the okotest) but small enough to leave a great result in the skin. We have to consider this as sun protection first and foremost, but also ensure the experience isn't sticky or one that leaves residue, resulting in a reluctance to use and protect