Did you know that neither the FDA nor the cosmetic science industry have a formal definition for nano-size zinc oxide? Its interpretation varies widely within the industry. BASF’s Z-COTE®, a popular supplier of microfine zinc oxide powders for sunscreen and mineral makeup, considers 200 nanometers as the upper limit. Micronisers’s Microsun™ nanosized zinc oxide powders have average particle size of 30 nanometers. With the term ‘nano’ falling out of favor amongst consumers, more and more sunscreen manufacturers are now using the term ‘micronized’. Again, no regulations on that terminology. Micronized zinc oxide could very well be nano zinc oxide and in many instances, it is! Unless you know the average particle size, there’s no way of knowing whether the zinc oxide powder in your sunscreen is produced with nanotechnology or not. Particle size labeling is also not required and I do not know of any sunscreen that labels or publishes that information. But you can always get the specs directly from the zinc oxide manufacturers. Also, many sunscreens will advertise their zinc oxide brand, like SunSmart with Z-cote® or Dermatone with Z-cote®.
This and much more in my sunscreen e-report.