Research and Developmer, Jane McKay, has written an article in collaboration with Healthy Child Healthy World. Understanding Sunscreen: Micronization and Nanoparticles
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 who use non-toxic sunscreens are accustomed to the ghostly pale residue left behind after a good slathering. This whitening, although cosmetically unacceptable to many people, is caused by zinc oxide and titanium dioxide, which create a powerful physical barrier to the sun’s rays. Historically, in order to avoid this undesirable result, chemical absorbers were developed to replace these ingredients.
Chemical absorbers are compounds absorbed through the skin, which 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 returned to the drawing board in order to create a product that uses physical, rather than chemical barriers, but doesn’t clog pores or leave a white residue. 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 have been done under real life conditions or even on the actual commercial formulations being used (because manufacturers won’t reveal their recipes).
Until more research has been done and some regulations are 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.