Are Nanoparticles in Sunscreen Safe?

Americans have finally gotten the message about wearing sunscreen. Okay, okay, we collectively moaned, We’ll wear it.

That’s great! Because we will avoid getting burned from the sun’s UVB rays, and will shun the wrinkles caused by UVA rays. Now we can just sit back and... Wait, what’s this new anxiety? Sunscreens are not good for us?

The latest concern about sunscreen revolves around nanoparticles. Nanotechnology isn’t one product or industry—it’s a broad technique that focuses on creating and using very small particles. How small? You can’t see them with the human eye; they are no bigger than 100 nanometers. For comparison, a small fleck of dust is 3,000 nanometers. These teensy particles have many applications, and are used in pigments and inks, vitamins, cosmetics, batteries, ceramics and sunscreens.

Remember those 1960’s pictures, where the lifeguards have thick white stripes on their noses? That’s because they were using a sunscreen containing a physical blocker, like zinc oxide and titanium oxide. Nanotechnology has allowed the invention of transparent physical sunblock, so we can use zinc oxide without looking quite so crazy. But the concern is that these teeny, tiny particles might be absorbed into the skin and enter our bodies.

When I heard this, I thought, ‘well, rats!’ I’m avoiding chemical-based sunscreens because they come with a slew of their own issues, and can irritate skin. Was I going to have to stop using sunscreen altogether and move into the basement? To put my fears to rest, I read a pool-ful of scientific articles, and wanted to share the gist of what I found:

• “Nanotechnology has been used in sunscreens for many years. To date, our assessment, drawing on the best available evidence, is that nanoparticles used in sunscreens do not pose a risk.” --the Cancer Council of Australia.
• The Therapeutic Goods Administration, also from Australia, concluded, “the current weight of evidence suggests that titanium dioxide and zinc oxide nanoparticles do not reach viable skin cells; rather, they remain on the surface of the skin and in the outer layer of the skin that is composed of non-viable cells.” Click to read the whole report.
• In their meta-analysis, “Sunscreen controversies: A critical review,” by Mark E. Burnett and Steven Q. Wang, the authors stated, “Considerable data assessing the potential toxicity of these materials in sunscreens has been published to date, and the studies referenced above were performed in controlled environments on healthy, undamaged skin. It has been established that the stratum corneum [the five outermost layers of the skin] is an effective barrier preventing the entry of nano-ZnO and -TiO₂ into deeper layers of the skin. Nonetheless, it remains to be determined whether a greater degree of penetration occurs through skin that is damaged, diseased or otherwise compromised.”
• According to the consumer advocate group CHOICE, there is more risk from not using sunscreen than there is from using it, regardless of whether or not it contains nanoparticles.

So what’s the bottom line? While research is ongoing, so far it seems safe to use sunscreen with nanoparticles. But, if you have compromised skin, you should talk to your doctor about what sunscreen is best for you.