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Sunscreen Technology – Nanoparticles on Trial

February 24, 2010

It was nearly one year ago since I took on the guise of my alter-ego  ‘lab rat’ to participate in a human study on the potential of the zinc oxide found in sunscreens to penetrate the skin.  The trial interested me on a number of levels. I have heard many a scary story about our skin and chemicals including those from camp 70% absorption to camp ‘only 10% get’s through if you REALLY try’.  I must admit that logic would lead me to the conclusion that our largest organ who’s main job is to keep what’s out out and what’s in in ‘could do better’ if it does indeed let 70% of stuff through (maybe we should just rub chocolate on our arms and give our mouths a break) but being a cosmetic chemist it seems too much of a ‘convenient truth’ to just blindly sit myself in the 10% camp. 

In addition to the skin penetration stuff I was also interested in the neat method that was proposed to track zinc through REAL people in REAL life situations using a stable isotope. That’s genius. Oh, and  last of all I just had to learn more about these nanoparticles.

So what does one do in such a situation? Well one finds some smart scientists with a laboratory,  a solar measuring machine and some rather sensible ideas and then follow them around, asking to be experimented on. That is what I did!

Lapping up the sun

And now the preliminary results are published :  ICONN2010 Abstract Gulson[1].

The trial looked at two sunscreen formulations which were identical except one that formulation contained nanoparticles of zinc oxide and the other contained the good old fashioned white stuff – big and chunky (sunscreen grade) zinc oxide.   Nano sized zinc oxide and titanium dioxide have been used in sunscreen formulations for a number of years now as they give all of the coverage of traditional physical sunscreens without the whiteness and heavy skin feel. However questions have been raised as to the general safety of nanoparticles which is not surprising for such a new and fast-developing area of technology. The questions are based on observations showing that when you blast a chemical down to such a small size (nano) you sometimes change not only its physical but also its chemical properties.   While safety tests have been carried out on nano zinc and titanium in order to pass them as cosmetic ingredients no compelling information has been found to doubt their safety. You can read more about my life on trial here.

So it is with great enthusiasm that I wish to share with you some preliminary conclusions (these results still stand but further analysis is being carried out in order to get a deeper understanding of the readings).

 The trial showed there to be no statistically significant difference in dermal absorption for the volunteers in the nanoparticle and the non-nano group.  Both groups absorbed some of the zinc showing that some of the Zinc Oxide found in sunscreens does penetrate healthy skin to a degree – a mean increase of 0.4% was recorded.  Urine and blood samples taken 6 days after the end of the trial showed a slight increase in the levels of  68 Zinc  (the rare isotope tracer) which is probably due to the way the zinc had been metabolised.

So what does that mean?

The most important conclusion that we can draw from this study is that the method of using a rare, stable isotope for tracking the fate of zinc oxide through the human body is scientifically sound.  That may not seem a very sexy conclusion but believe me, that is groundbreaking!

We can say much about the fact that the study only ran for a short time, only contained 20 people, wasn’t completely blinded and so on and that would all be right. However, the study did show that the method worked. We can apply a sunscreen onto the skin and quantitatively measure the passage of the key active through the body.  This trial wasn’t cheap and it wasn’t easy to carry out. The testing protocol was uncomfortable, time-consuming and costly.  Analysing the results has proven to be complex and we still don’t know if the Zinc present was particulate or soluble. 

Yes, this is real science and more often than not, real science created some really interesting questions. Sometimes you end up with more questions than answers.

So what’s next?

Well, there are a number of key questions that need answering and to do that we need to keep the research pedal to the metal. That will take time, money and vision.

Of key importance are the questions surrounding the passage of zinc through the skin and subsequently though the rest of our body.  We know that some zinc get’s through but we don’t know if that is physiologically significant and THAT is important.  After all, don’t many of us choose to ingest Zinc in the form of supplements every day?   Before we can jump to sensational conclusions and dire predictions we need to collect more evidence and be sure of our perspective.

There is no doubt that the fact that this study poses more questions than it offers up answers will irritate and sit uncomfortably with some people but all I can see is opportunity. Not the opportunity for making a quick buck, quite the opposite. The opportunity to engage the global cosmetics industry, the best academic minds and the brightest human guinea pigs to take skincare to a brave new level.   The only thing missing is the dollars – anyone got a few to spare?

Amanda Foxon-Hill

Response to the ICONN abstract published by Professor Brian Gulson et al in conversation with Gavin Greenoak.

Thanks  to Brian Gulson for his time in discussing these preliminary  findings.

Brian is presenting his findings at the International Conference on Nanoscience and Nanotechnology in Sydney later today.

9 Comments leave one →
  1. February 24, 2010 11:07 am

    Thanks for that. I had heard about the debate re ‘nano-zinc’ only recently and so it piqued my interest when I saw your tweet.

    Personally I prefer limiting sun exposure and using good old fashioned coconut oil (NOT reef oil….pure, unadulterated coconut oil). But if you are out in the sun for long periods that does not offer enough protection so I’ve been conscious of choosing products that will not have potential nasties and I have tended to go for the creams based on zinc and titanium.

    Cheers, Linda.

    • RealizeBeautyEd permalink
      February 24, 2010 11:54 am

      Dear Linda,
      Thanks for the feedback. At the end of the day we all make our own mind up and I agree that our minds are the best sunscreen that we have! Enjoy your time under the sun.

  2. February 26, 2010 12:22 am

    Very interesting study. I am a great believer of sunscreen use everyday- want to make sure it’s working but not harming.

  3. March 6, 2010 4:25 pm

    interesting take. I was actually at ICONN along with a representative from friends of the Earth – we agreed the results seemed to be presented to show that there was evidence that the traced Nanoparticle got through the skin and traveled around the body till excreted. Further, most experiments are done using synthetic skin or hairless mouse skin – and do not represent “real” skin ie the skin used is close to prefect – most adult skin isn’t. The inference wrt zic supplements was that we take bulk zinc at non-toxic levels and need it, but again, until we know more about the changes that may occur in the nano forms of any bulk chemical perhaps more prudent regaulation is required – at least labelling shoudl stipulate if ENPs are present so consumers can make their own mind up.

    But I’m glad you reported it as the public should be asking many more questions and demanding better labelling so they can make a informed choice about what they want to buy and use on them and their family

  4. March 3, 2012 12:37 pm

    May I simply say what a relief to uncover someone that truly knows what they are discussing over the internet. You actually realize how to bring a problem to light and make it important. More and more people should look at this and understand this side of your story. I was surprised you’re not more popular given that you definitely have the gift.

    • RealizeBeautyEd permalink
      March 3, 2012 3:03 pm

      LOL totally love the comment up to the part when you slid in a back handed compliment! I’m popular enough thank you, one thinking person is worth 1 million sheep 😉

  5. March 4, 2012 2:57 am

    Interesting…the debate continues. Thanks for sharing. What would your recommendations be for your readers and consumers based upon these findings? We’re left with the choices of slathering chemicals all over our bodies; using products with all nano- or a mixture of nano-sized particles; or looking like clowns with >30nm ZnO. What choice would you make? I wear facial sunscreen daily, and with rosacea, I absolutely cannot use chemicals, and I prefer uncoated ZnO due to its therapeutic properties, but alas I do draw attention when my face is completely white :-/

    • RealizeBeautyEd permalink
      March 4, 2012 12:45 pm

      My advice remains the same. Wear sunscreen, lots of it, re-apply, use your brain and behave in a sensible way, avoid sun if you’ve been drinking lots or are on medications that change the way your skin behaves in sun. At the moment for me, the issue of nanoparticles from a consumer perspective is not an issue. I am concerned about the effect that certain nanoparticles may have in the environment and what goes onto your skin does end up in the environment so I would like more time (and funding) to research that. However, for now the best advice I can give is nano/ non-nano, whatever just use sunscreen.


  1. Zinc and the Nano Sunscreen Revolution « Realize Beauty

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