To use or not to use: Nanotechnology in sunscreens

To use or not to use: Nanotechnology in sunscreens

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

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  1. Pearl Chin June 14, 2007 at 8:51 pm - Reply

    Just my two cents. My peers who are interested in nanoparticle sunscreens are not interested in these because they work any better than current sunscreens. They buy them because they are allergic to chemical sunscreens and because they are transparent so they look natural. Purely for cosmetic and not functional reasons. And yes, zinc oxide and titanium dioxide should not break down over time so it can be hypoallergenic. The major concern is the particles may be so small they may get absorbed into the skin, how deep if they do and if it is toxic if it is and accumulates and can it be “washed” off/out easily. Yes, more research. Thanks and glad to be on board, Everyone. – Pearl

  2. Chris Hamilton June 19, 2007 at 12:18 pm - Reply

    I’ve just been working with the W.S. Badger company who makes natural skin care products including a sunblock with micronized zinc oxide (mean partcle size >100nm). They have been confonted with customer concerns regarding the use of ‘nanoparticles’ and our review of current research concluded that micronized mineral sunblocks are indeed safe as the particles do not absorb deeper than the surface dead layer of the skin and they are in fact better than most sunblocks in that they block both UVA and UVB and do not contain sunblock chemical with known health risks.

    Read the one page statement at:

  3. Christine Peterson June 19, 2007 at 2:08 pm - Reply

    Thanks, Pearl and Chris.

    There is a good link from Chris’s URL to the National Geographic “Green Guide,” which recommends the mineral sunscreens over the organic ones. Supposedly some of the latter can interfere with hormones or damage DNA. Not a simple issue here. —Christine

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