Some sunscreens contain simple nanomaterials: nanoparticles of zinc oxide or titanium dioxide. Sunscreens have had these for decades, but the particles used to be bigger, which is why lifeguards at the beach used to have white noses. Now the particles are smaller, so the sunscreens are transparent. Applying the “nanotechnology” label to these products is a far cry from what most of us would like to use the word for — atomically-precise systems, or at least devices — but it’s being used this way, so the field needs to deal with the PR consequences.
Nanowerk writes that Consumer Reports has done a test of sunscreens and that the ones with these particles don’t perform any better than the others which don’t. Based on this, and possible concerns about the nanoparticles, Consumer Reports is suggesting that users can choose other sunscreens.
With this in mind, I looked at my collection of sunscreen bottles, and found none with the particles. So that’s good, right?
Maybe not. It turns out that the FDA only requires sunscreens to last 3 to 5 years. I found only one bottle with an expiration date, on a new-looking bottle, of 2004. Which means the other bottles are probably older.
But it’s the organic sunscreens that break down with time. The zinc oxide and titanium dioxide should not change, I believe. (Correct me if I’m wrong here.)
So if I had taken a simple approach and thrown out any with the nanoparticles, I would be throwing out the only ones that still work. I’m sure many households are like mine — lots of bottles, not many new.
Conclusion: overall consumer safety is not a simple goal to achieve. There are tradeoffs to make. Discarding “nanotechnology” may not be the way to go. As the researchers say, we need more research. They’re right. —Christine
