What's the difference between non-nano zinc oxide and nano-sized zinc oxide in sunscreen?
The answer can be complex.
Non-Nano Zinc Oxide (not small)
Non-nano particles are much larger and more consistent in size than nano-sized particles. These large particles do not seep through skin pores and so do not enter the bloodstream. Non-nano sunscreens are generally “more white” in appearance on the skin.
Nano Zinc Oxide (small)
Nano particles have a diameter smaller than 100 nanometers or 0.1 micron. (A micron is one millionth of a meter.)
Nano particles may be hazardous for humans, since they’re tiny enough to enter the bloodstream through the skin. Most nano-particle sunscreens contain particles of only 15 nanometers, or about 85% SMALLER than the limit.
All mineral sunscreens on the market are either micron-sized (non-nano), micronized or nano. (Some companies use micronized particles but may still be using nano particles because nano particles are technically a finer version of the micronized form.)
Many mineral sunscreens use nano zinc oxide because it is less whitening, which some consider more aesthetically appealing than the classic whiteness from non-nano (larger) mineral compounds. Products marketed as “clear” or "shear" mineral sunscreens use nano-sized varieties of zinc oxide or titanium dioxide.
The only way to ensure non-nano is if the company explicitly states particle size average and standard deviation, as we do below.
The Risks and Dangers of Nano Zinc Oxide
Most importantly, nano particle sunscreens harm reefs and marine life, since the small particles readily enter and negatively affect marine biosystems. Any sunscreen that uses nano-sized zinc oxide or titanium dioxide is NOT reef safe.
Nano particles can also absorb through human skin and into the bloodstream, where they can affect human biosystems. There is yet no evidence to show this is harmful, but there hasn’t been a large amount of research, and so the issue remains undetermined. Our approach is to use caution until definitive scientific evidence is available, and since the use of nano particles does not increase sunscreen effectiveness, we avoid nano particles in our products because there’s little reason to accept possible increased risks without corresponding benefits.
“Reef safe” can be Misleading
Remember, the term "reef safe" is unregulated, and many sunscreen brands market their products as “reef-safe” simply because they don’t contain 2 specific petrochemical ingredients banned by a growing list of government jurisdictions. However, they contain several other petrochemical ingredients (or nano sized mineral compounds) that make them completely UNSAFE for reefs and other marine life, not to mention the humans using them.
Waxhead does not use nano particle zinc oxide — we use ONLY top quality non-nano zinc oxide. This particle size range has been used for decades and is considered completely safe.
The average individual particle size of the Zinc Oxide USP we use is 0.260 microns (260nm) with a standard deviation of 0.012 micron (12nm). Hence, there are statistically zero particles smaller than 100nm, the cutoff for the nano classification. Most nano sunscreens on the market have particle sizes in the range of 10-20nm.
1. Know your ingredients — Flip over your sunscreen and read the ingredients. We want everyone to know what good ingredients are, regardless of whether they use our products or not. Your health is worth it.
2. Buy safe sunscreen — Waxhead is dedicated to using only the healthiest, safest, most effective ingredients in our sunscreens. Shop Safe Sunscreen here.
3. Teach a friend — If you know someone who might still be buying sunscreen with questionable ingredients, please share this post with him/her.