Understanding Suncscreen: Micronization and Nanoparticles

by Healthy Child

baby at the beachOur friend Jane McKay from TruKid, an all natural skin care line for kids, explains the difference between traditional sunscreens and their newer, safer counterparts.

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 the terms "micronization" and "nanoparticles" mean.

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. Increasingly, scientists have come to realize that they provide incomplete protection against UV-A rays. In addition, some 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 we have found is that by shrinking the zinc oxide or titanium dioxide through a process called "micronization" we can have the best of both worlds: superior non-toxic protection and cosmetic acceptability.

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. Some newer manufacturers are decreasing the size of the particles even more, into "nanoparticles" that essentially disappear immediately when rubbed onto skin.

A micrometer is one millionth of a meter. A nanometer is one billionth of a meter. (One thousand times smaller! It's difficult to fathom, but in comparison, a human hair's diameter is 800,000 nanometers). While the larger sized micronized particles appear to be both safe and effective, many questions still linger about the safety of nanoparticles. Preliminary studies seem reassuring, but only a few have been done and none under real life conditions or even on the actual commercial formulations being used (because manufacturers won’t reveal their recipes).

Until more research is conducted and some regulations put in place (right now manufacturers don't even have to tell you if their product contains nanoparticles), you can rely on watchdog organizations like Healthy Child Healthy World and the Environmental Working Group to let you know your safest options.

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