Sunscreen and nanoparticles

Could your sunscreen be doing you more harm than good?
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  • Updated:26 Jul 2012
  • Author:Karina Bray  Karina Bray Google Plus
  • rateraterateraterate: Member rating

01 .Sunscreens and nanoparticles





How do sunscreens work?


What are nanoparticles?


Why the concern about nanoparticles in sunscreen?





In order for nanoparticles in sunscreens to be considered dangerous, they have to firstly penetrate the skin, then go somewhere they can do significant damage. For now, there is no solid proof this can happen. 

How it works

To get through the skin, the particles have to be small enough. Zinc oxide and titanium dioxide are often manufactured in nano-size particles, but they tend to clump together. These “clumps” are known as “aggregates”, which can in turn clump together to form "agglomerates". While agglomerates break up fairly easily, aggregates require enormous amounts of energy to break up, and wouldn’t do so in the normal use of sunscreens. Sunscreen maker Hamilton Laboratories commissioned testing of their own sunscreens, which contained primary particles in the nano range, but in the finished products found no nanoparticles, suggesting the primary particles had formed larger aggregates. Our testing found few nano-size particles present in sunscreens, suggesting either the primary particles were mostly aggregating or that the primary particle size used was larger than the nano-range. 

What manufacturers say

Manufacturers argue that aggregates over 100nm don’t qualify as nanoparticles because they’re too big; however, critics argue the aggregates still have similar properties to nano-particles – one of which is high reactivity due to a large surface area – which could be an issue if they penetrate the skin.

Some manufacturers prefer to keep the particles from aggregating because it improves the transparency of the product. Nanoparticles can be coated so they don't aggregate. However, these coated nanoparticles are less reactive than uncoated particles, so even if they do penetrate the skin, they may not do much damage.

What scientists say

Can nanoparticles really penetrate the skin? 

The key to the safety debate is whether the nanoparticles can penetrate the outer “dead” layer of skin into underlying live tissue where they can penetrate living cells and cause damage. Under laboratory conditions with pieces of skin tissue, scientists have been able to get nanoparticles to pass through the tissue. However, research to date has not found this to be true in 'live' healthy, intact skin, although there’s some suggestion they may penetrate mechanically stressed skin (when exercising, for example) or broken skin (caused by acne, psoriasis or wounds). An Australian study found that when zinc nano-compounds were applied to skin, tiny amounts of zinc had penetrated. But it was unclear whether it was actually the nanoparticles themselves, or zinc ions from the nanoparticles which had dissolved and diffused through the skin. Ions are not the same as nanoparticles - and zinc itself is an essential nutrient. If they penetrate, the nanoparticles have to be sufficient in quantity to have a measurable or noticeable impact.

How much gets through?

In studies where researchers successfully get metal oxide ions to penetrate skin, the amount getting through appears to be tiny.

Do metal pigment nanoparticles cause DNA damage in living cells?

If the nanoparticle makes its way to living tissue, it has to enter the cell and access cellular components such as mitochondria and DNA. Studies using cultured human or mammalian cells, bacteria or naked DNA to test the effect of nanoparticles of all kinds have found damage to DNA. However, in almost all cases the nanoparticles tested were not directly comparable with nano metal oxides: they were different forms of particle or different substances (and the substances tested were often more hazardous than zinc or titanium). As such, results cannot be generalised between different forms of nanoparticles and different substances.

Living cells have all sorts of protective mechanisms against oxidative damage that aren’t necessarily present in the laboratory cells, and certainly not present in naked bacterial DNA. Some scientists have been confident that these protective mechanisms will kick into action against nano-sunscreens. However, a recent study of mice who'd been given titanium dioxide nanoparticles in their drinking water found significant DNA and chromosomal damage occurred. So, no protective effect evident.

What the regulators say

At present, the Therapeutic Goods Administration (TGA), which has jurisdiction over sunscreens, does not distinguish between nano- and non-nano variants of a particular ingredient. However, it hasn’t been completely oblivious to their emergence in the market, and conducted two large research reviews in 2006 and 2009.
It concludes “there is evidence from isolated cell experiments that zinc oxide and titanium dioxide can induce free radical formation in the presence of light and this may damage these cells. However, this would only be of concern in people using sunscreens if the zinc oxide and titanium dioxide penetrated into viable skin cells. The weight of current evidence is that they remain on the surface of the skin and in the outer dead layer of the skin.”
Regulators in most other countries also tend to focus on “new chemicals” and existing chemicals produced at the nanoscale are not considered to be “new” for regulatory purposes, despite their differing properties. In Europe, however, cosmetics will soon be required to indicate the presence of nanoparticles in their ingredients labelling. The TGA, in cooperation with international agencies, is continuing to monitor scientific research.

CHOICE verdict

The weight of evidence shows that not using sunscreen is more dangerous than using sunscreen, given there is no firm evidence that nanoparticles found in sunscreens can penetrate the skin and make their way to living cells. But a lack of evidence doesn’t mean it can’t happen; more research is needed, preferably using real people and relevant products. This is reason enough to invoke the precautionary principle, and nanoparticles should be proven to be safe before they hit the market. Some companies have found ways to make larger, non-nanoparticle forms of zinc oxide transparent, and there are also ways of treating nanoparticles so they’re less reactive. We would prefer to see these technologies be used. We want nanoparticles to be labelled on products so consumers can choose to avoid them if they’re concerned.

03.2010 results - Sunscreens tested for nanos


Please note: These are test results from 2010.
For more information about this test, email us at

Which sunscreens contain nanoparticles?

CHOICE purchased 12 widely available SPF 30+ sunscreens from top-selling brands. All contained zinc oxide or titanium dioxide; some also contained chemical sunscreens. Where there was more than one product from a particular brand that met purchase criteria, only one from each brand was purchased. The samples we bought were repackaged and sent to a laboratory experienced in this sort of testing. Dynamic light scattering was used to measure the size of the metal particles. 

The testing showed that most sunscreens had some particles of about 100nm or less (which qualifies as a nanoparticle). We didn't test for aggregates or agglomerates of nanoparticles.

No nanoparticles grroup-of-4-2

Four sunscreens tested had no particles of this size. They were:

  • Cancer Council Classic Sunscreen * 
  • Nivea Sun Moisturising Sunscreen Lotion
  • Hamilton Everyday Face Sunscreen
  • Banana Boat Sensitive Sunscreen

It is worth noting that both the Cancer Council and Banana Boat claim on their websites that all their sunscreens are free of nanoparticles. If you’re concerned about nanoparticles, Cancer Council Classic is particularly recommended because it’s nano-free and doesn’t contain chemical absorbers, which have their own concerns.


Some nanoparticles group-of-7

Most of the sunscreens we tested contained low levels of nanoparticles. These were:

  • Woolworths Select Clear Zinc *
  • UV Tripleguard Summer Skin Sunscreen Lotion*
  • Coles Sports Clear Zinc
  • Ego Sun Sense Toddler Milk
  • Chemmart Clear Zinc *
  • Le Tan Sheer Daily Mineral Moisturising Sunscreen *
  • Invisible Zinc *
These sunscreens would all qualify as 'nano-free' according to proposed industry criteria which allow for up to 10% accidental contamination by nanoparticles, though Friends of the Earth would prefer the cut-off to be 5%. These criteria allow for difficulties in the pigment manufacturing process, which is not always very precise. However, some companies (including the four with no nanoparticles above) don't appear to have an issue with contamination, suggesting it's possible to avoid it.

     L'oreal UV

    Lots of nanoparticles  

    L’Oréal UV Perfect contained by far the most nanoparticles under 100nm. L’Oréal defends the use of nanoparticles, pointing out they’re widely found in nature and that “nanopigments do not cross the skin barrier, and public health agencies worldwide acknowledge their innocuity ”. 


    Products marked with an asterisk (*) contain no chemical sunscreens. 

    More information

    Friends of the Earth (FoE) is the most vocal opponent of nanotechnology being used in cosmetics and sunscreens, and recommends people use chemical-free, non-nano sunscreens. You can read more in its Nano-ingredients in sunscreen - the need for regulation.

    The US-based Environmental Working Group has extensively researched chemicals and minerals used in sunscreens, and come up with its 2012 Sunscreen Guide. It favours zinc and titanium products over chemical products and considers the potential risks of nanomaterials are lesser than the known risks of chemical sunscreens.

    See the TGA review of the safety of zinc oxide and titanium dioxide in nanoparticulate form.

    Hamilton Laboratories has released a position paper on Hamilton sunscreens and nanoparticles.

    See our article on mineral foundations and nanotechnology and food for more research information.

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