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Understanding Sunscreen: Micronization And Nanoparticles

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Tuesday, May 10, 2011

Healthy Child:

When choosing the safest sunscreen, it’s not only important to know which offer the best protection without relying on toxic ingredients, it is also important to understand what terms like “micronization,” “nanosized,” and “nanoparticles” refer to.

Most of us are familiar with the white noses of lifeguards and parents using non-toxic sunscreens are used to the ghostly pale residue left behind after a good slathering. This whitening is caused by zinc oxide and titanium dioxide, which create a powerful physical barrier to the sun’s rays, but it is cosmetically unacceptable to many people. Historically, in order to sidestep this undesirable result, chemical absorbers were developed to replace these ingredients.

Chemical absorbers are compounds that penetrate the skin and then absorb UV irradiation. These compounds (like PABA, oxybenzone, and benzophenones) have been used for many years primarily because they do not create a whitening effect. But, many chemical filters degrade after prolonged sun exposure, can irritate sensitive skin, and cause other long-term environmental and health impacts.

Coming full circle, manufacturers have been back at the drawing board trying to create a product that uses physical instead of chemical barriers, but doesn’t clog pores and leave a white residue. What they have found is that by shrinking the zinc oxide or titanium dioxide through a process called “micronization,” they can achieve these goals.

Micronization is the process of reducing the average diameter of a solid material's particles. Usually, the term micronization is used when the particles that are produced are only a few micrometers in diameter. But, the word is used ambiguously and a particle can actually be micronized until it becomes nano-sized.

Nano-sized means having a size measured in nanometers and a nano-sized material is not necessarily a nanoparticle. According to Kim Walls, M.S., of Episencial, "a nanoparticle is any particle less than 100 nanometers in diameter. So, a material that has been reduced to 500 nanometers is NOT a nanoparticle because it is 5 times larger than 100 nanometers. (As a point of reference, a particle must be less than 50 nanometers to enter skin cells; less than 70 nanometers to enter the lungs.)"

This brings us to the question of safety. While the larger sized micronized particles appear to be both safe and effective, some questions still linger about the safety of nanoparticles. Preliminary studies seem reassuring for topical use, but there is still concern regarding inhalation or ingestion.

What should you do?

● If you use a sunscreen that contains nanoparticles, use a lotion formulation not spray (we don’t recommend spray of any kind) and monitor children to keep hands out of mouths.

● If you’re researching different kinds of sunscreens that use micronized particles, you might need to call manufacturers to ask about their ingredients. In particular, ask them specifically if they are using nanoparticles. If you want leave nothing to chance: ask for the particle size.

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Posted by Erin  on  06/06/2011  at  11:42 AM

SafeMama.com has an awesome cheatsheet on this subject with specific brand recommendations: http://safemama.com/cheatsheets/sunscreen/

Her top overall recommendation this year is Purple Prairie (rated 1 in EWG’s Skin Deep Database), which you can buy from Healthy Child Healthy World Trusted Partner Lullaby Organics here: http://lullabyorganics.com/. The sun stick version is better for swimming than the lotion.

Also available from Lullaby Organics is BienElla suncare, rated “0” (safest) by EWG. BienElla will leave you with a white sheen because the zinc particle size is quite large, but the incredible safety of the ingredients makes this one of the best options available if your top priority is safety from toxins and you’re ok with the white.

Posted by Erin Ely  on  05/15/2011  at  11:14 AM

Thanks this article is really helpful for understanding more about the differences between micronized and nano sized particles.

Miessence Reflect Outdoor Balm is a company that uses micronized Zinc Oxide.
DISCLAIMER: I sell Miessence

The “mean” is the “average” you’re used to, where you add up all the numbers and then divide by the number of numbers.
The “median” is the “middle” value in the list of numbers
the zinc oxide in Miessence Reflect Outdoor Balm

mean - 105nm
median - 150nm
range - 30-180nm
the definition of a nanoparticle is where the mean particle size is smaller than 100nm.
Micronized sized particles do not pass through your skin.
Micronization is achieved through mechanical grinding not nano engineering.

Miessence was also rated as one of the Top Sunscreens in the EWG 2010 Sunscreen report: http://www.ewg.org/2010sunscreen/best-beach-sport-sunscreens/

You can view info on Miessence Reflect Outdoor Balm on my website:
http://elyorganics.com/miessence-products/13430/

Posted by Betsy (Eco-novice)  on  05/13/2011  at  02:47 PM

I’m good with the physical barrier that leaves a white film on my and my kids’ skin.  Then I know the particles are nice and big and that the sunscreen is forming a physical barrier.  But I’m not trying to pick up anyone when I go to the beach. . . I can see that those sunscreens lack some cosmetic appeal.

Posted by Lori  on  05/13/2011  at  12:33 PM

I would love it if readers would post some brands that have this safe form of sunscreen.  We go through bottles of the stuff each summer and I need to stock up!  Preferably something that stays on fairly well in the pool.

Posted by Kerry  on  05/10/2011  at  05:40 PM

I also like California Baby and Blue Lizard Sunscreen.  It’s great on my fair kids skin.

Posted by greta keller  on  06/18/2010  at  04:14 PM

my 3 years old baby child has photodermatosis and is very difficult to her because she has to use a sunscreen theres terrible for her in the school , but i now thanx to u i know is the best option to my health child! thnax again

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