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Nanoparticles in Sunscreens – What are they anyway?

February 6, 2009

It seems that Nano particles are everywhere these days. Almost all of us have heard about these things but how many people actually understand what they are and why are they in sunscreens. Realize Beauty aims to find out!

First, we need to work out what a nanoparticle is!

Nano – Very small ( 100 nanometres or smaller)  , Particle – stuff bound together (could be dust, soil, Zinc, water, anything really)

So a Nano Particle is some very small stuff that is bound together – 100 nanometres is very small.

A nanometer is one billionth of a metre 10,000,000,000’th of a metre!  For comparrison a human hair is 40,000 nano metres thick  or 400 times bigger than a nano particle.

So, you get the picture. These things are small!

Now we need to know why they are in our sun screens.

Well, in the old days when I was a kid (well, 1980’s) we spent our beach days clad in thick white paste. That was sunscreen back in the day. Yes, you could get the lovely light tanning milks but no, they wouldn’t do much for the health of your skin. If you wanted to be protected from the sun you had to see the cream all over you! By the time the year 2000 turned around we had two types of sunscreen on the market. Those with chemical filters and those with physical filters, I will explain.

Chemical filters are in the sunscreens with the ingredient listings as long as your arm, lots of complicated sounding names (common examples are ethyl hexyl methoxycinnamate, avobenzone,  benzophenone-3). Chemical filters are clever and can change the energy from the sun as it hits the sunscreen barrier on your skin.  The suns rays are left unable to get through the skin and damage it. People like these because they can be made cosmetically elegant. They  often run straight into your skin and leave no white marks – great for under make-up!  Some people avoid these as the chemical cocktail can occasionally induce allergies, others don’t like them because they involve a chemical change on the skin.

Physical filters are ingredients listed as Zinc Oxide and/or Titanium Dioxide. These are classed as physical filters because they act a bit like paint. They sit on top of your skin and deflect the suns rays so that they don’t penetrate. There is no chemical change involved in order to provide sun protection.  People like these as they are the most well tolerated ingredients of all sunscreen agents – fewer people have allergies to Titanium and still fewer to Zinc. People don’t like these because they are typically heavier on the skin and can leave while marks.

So where are the nano particles?

Zinc Oxide and Titanium Dioxide, in recent times have been engineered to make them more cosmetically acceptable. We (the consumer) wanted sun protection without the ghosting. The industry smashed the particles to pieces, creating particles so small that the human eye can’t see them. The result – nano particles and elegant Physical sunscreens.

Sounds OK but why all the drama then? Surely just making the zinc and titanium smaller wouldn’t change anything!

Well, nano technology has come a long way in a short time as far as consumer products are concerned. Lots of brands jumped at the chance to make physical sunscreens lighter and more appealing.  Suddenly nano was everywhere!  Nanotechnology is not new and is not entirely man made. Particles that spew out of volcano’s  can be nano, soot and some dust in the atmosphere is nano. Nano is somewhat natural…..

The fast take up of this new wonder technology caused some concern in scientific,  environmental  and health circles. The main reason is that when you blast things to such a small size it is not only their size that changes, the whole essence of the particle changes.  These small bits of zinc and titanium can start behaving very differently from their bigger and bulkier mothers and fathers. This may or may not cause problems in use but as with all scientific advancements more experimentation was needed. The main worry for zinc and titanium in sunscreens is that the particles get through the skin and start moving through the bloodstream.

Oh, so we now have sunscreens with millions of tiny spect that act erratically. Sounds scary, can they get in my skin?

Well. Now we get to the cosmetic science bit,  a nanoparticle is small, a few nanoparticles stuck together are small, a few hundred nanoparticles stuck together is still small.  In a sunscreen containing nano zinc and/or titanium, the nano particles are usually found in clumps. Too clumpy and the sunscreen would not work well but even the best formulation wouldn’t be able to make a sunscreen that keeps each nano-particle appart from it’s friends. They simply love each other!

That said, the zinc and titanium may be “nano” in as much as each particle has been blasted to a small size but once it is in a formulation (or recipe) the chances are, it will stick to a few hundred friends. The trick for the scientist is to get these “clumps” dispersed enough so that the sun cream is elegant to wear and still streak free. This can be achieved by mixing the zinc/titanium with other chemicals to make a stable and light emulsion – too much info for here but you get the picture. Sunscreen’s that contain nanoparticles, contain big ones!

Oh, so everything is fine then.

Well, yes and no. So far studies on nano-sunscreens and the skin have given encouraging results. Professor Brian Gulson from the Macquarie  Universities Graduate School of the Environment ran a small study last year looking at the fate of nano-particles on the skin. He studied specially taged Zinc particles through the body from application and found very little absorption through the skin.  He was interviewed for the ABC, the interview is linked to here:  Dr Brian Gulson’s work on nanoparticles.

The second part of this study is due to start in March and I am going to be part of it!  Dr Brian Gulson’s work is part of a global study of nanoparticles. Australia has the honor of testing out nano sunscreens. Other countries are looking at carbon nano tubes, nano medicines and nano foods.  I will be donating part of my back to find out where these little particles end up! My journey as a “lab rat” and an more insights into nanoparticles in sunscreens will be posted over the course of the trial which goes for a week.  I hope that you will join me and the Realize Beauty team.

So, should you be worried about nano particles?  Well,  the balance of scientific evidence is in favour of continuing on with this technology in sunscreens.  You are much more likely to get skin cancer from wearing no sunscreen than  you are from nano sunscreen particles. However, science being as it is I am sure we still have a lot to learn.

If in doubt stay out (of the sun!) Cover up with a hat, glasses and long sleeves and you’ll be right! When you need to wear sunscreen wear an SPF 30 plus, broad spectrum and don’t stress.

Only one month to go until the trial – join me then!


9 Comments leave one →
  1. February 8, 2009 1:22 pm

    Reapply sunscreen every two hours and after swimming or sweating. Cosmetic

  2. March 13, 2009 2:03 pm

    The unknown risk is that nanoparticles do absorbed through the skin and get into the bloodstreem. The initial research already noticed their toxicity to the immune cells. The question is what may be the long term effect on the body? How are they assimilated, can they accumulate in different tissues? Can they change blood rheology etc?

  3. RealizeBeautyEd permalink
    March 14, 2009 6:41 pm

    There is still much to learn about nanoparticles which is why the government is funding research into their fate both directly into the environment and through the skin. So far the evidence points to nanoparticles not being able to penetrate the skin when applied as a sun cream. However, results of the study that I am a part of will help to clarify this further. We are only just starting to find out what nanoparticles can and can’t do but everything being looked at is aimed at keeping the public safe and protected. There are many potential benefits to be had through nanotechnology so this research is very worthwhile

  4. March 16, 2009 11:40 am

    Good luck with your adventure on Thursday, Amanda. Hope everything will good for you and your crew. Do you think that penetrability of nanoparticles is also depend on the base of the cream? I think the base is also important because it will assist carrying nanoparticles transepidermaly and deliver them into the blood stream. If its possible to create a base which will stay as a film on the skin and hold nanoparticles on the surface it may reduce the risks. What do you think?
    Austraroma P/L

  5. RealizeBeautyEd permalink
    March 16, 2009 7:52 pm

    Hi Tatiana,
    The base formulation that contains the nanoparticles will play a part in where the particles end up. This is also true for other cosmetics actives. Sunscreen manufacturers do use special ingredients such as film formers and emulsifiers to make sure that sunscreen actives stay in contact with the skin’s surface as that is where they are needed. However, when it comes to anti-aging creams that contain sunscreen actives they have a much harder job. They contain actives that may need to enter the epidermis and sunscreens that need to stay on top! That would have to be looked at in another study!

  6. March 18, 2009 9:35 pm

    Thanks Amanda, it would be interesting if you could provide more details about research you participating now. I recon the base should be an important variable there.
    Re anti-aging creams, it may be another interesting discussion… Frankly i don’t understand why do we need sunscreen in anti-aging cream which is mostly used at night, why?

  7. March 25, 2009 5:14 pm

    Hi Tatjana and Amanda,

    I would like to respond to your deliberations on a base formulation that could stop particles from penetrating but allow anti-aging molecules to get into the skin. This happens almost automatically because to penetrate into the skin, a chemical needs to be solubilized and as Amanda is rightly describing, nanoPARTICLES are not. As a rule of thumb, a particle penetrates 10,000 less than the same substance solubilized. Particles can then still penetrate into to hole around the hair, but it stays there as in a reservoir and comes out over a period of 10 days together with our sebum.
    So as long as the anti-aging chemical has the right characteristics to penetrate the skin and the formulation the right characteristics and the nanoparticle says a nanoparticle, this (i.e., the active going in and the sunscreen staying out) will happen.


  1. Agidoo Press » Blog Archive » Nanoparticles in Sunscreens - What are they anyway?
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