What is the difference between nanoparticles, micronized and micron-sized sunscreen forms?

Unfortunately the answer to this question is complex. Nanoparticles are particles defined as less than 100 nanometers in diameter, or 0.1 micron. Most nanoparticle sunscreens in the marketplace have particle sizes of 15 nanometers or 0.015 micron. Micronized sunscreens are created by grinding larger particle sizes into smaller ones. Typically micronized particles are between 0.1 micron and 100 microns, however the griding process may result in nanoparticles called ‘fines’ which are smaller. Kabana uses neither nanoparticle (size) zinc oxide, nor micronized (manufacturing process) zinc oxide. Instead Kabana uses micron-sized particles, created by a clean gas phase process that involves no griding and maintains a tight particle size distribution in the micron range, average size 0.260 +/- standard deviation of 0.012 microns, which is 20x larger than most nanoparticle sunscreens. Given this tight size distribution, there are statistically zero nanoparticles in our zinc oxide. This particle size range has been used in products for decades and is considered safe.

For reference, 100 microns is 0.1 millimeter, which is the size of a fine grain of sand and as a sunscreen, would be useless because it would be impossible to evenly apply (and gritty!). All mineral sunscreens on the market are micron-sized, micronized or nano. Some companies advertise they are using micronized particles, but may still be using nanoparticles because nanoparticles are technically also a finer version of the micronized form. The only way for you to know that a sunscreen active ingredient is not nano is if the company provides you a particle size number. Zinc oxide in Kabana products are in the micron range (0.26 micron = 260nm) and are non-nano.

Nanoparticles have received some bad press recently by the media, largely based on some publications about other nanotechnology based compounds (Buckminsterfullerene, otherwise known as buckyballs or C-60) that are, however, entirely unrelated to sunscreen active ingredients. The primary question regarding nanoparticle sunscreen ingredients is whether or not they have an increased capacity to cross the skin and get absorbed into the blood. Kabana has not encountered any well controlled scientific experiments or publications that state this to be the case, however there hasn’t been a large amount of research. The answer to the nanoparticle question therefore remains somewhat uncertain. It’s Kabana’s ethical policy to always use common sense. The use of nanoparticles does not increase sunscreen effectiveness significantly, so Kabana avoids nanoparticle zinc oxide in all of our products because there’s no reason to expose our customers to increased risk.

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