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What Is It: Titanium Dioxide

May 23, 2009 Reviewed by Marta 8 Comments

Soleo Organics is a new sunscreen that, amongst other things, proclaims that it is titanium dioxide free. Now why, thought I, should it do that? Is titanium dioxide, a physical sunscreen, something to be avoided? Having only recently put myself off most chemical sunscreens beginning with the letter O, was I now going to have to reconsider titanium dioxide as well? Many hours on Google later......

The basic distinction that is made between chemical and physical sunscreens is that chemicals absorb the UV rays and radiation, while physical sunscreens reflect and/or scatter UV rays and radiation. Actually, it turns out that this isn't entirely true, but I'll come back to that. In the meantime, you'll probably have noticed that titanium dioxide turns up almost every sunscreen with a physical blocker, because it reflects UVA and UVB rays and it doesn't discolor under ultraviolet light.  As a not entirely pointless aside, it is worth noting that titanium dioxide is a pigment and is sometimes used in toothpaste and to make skimmed milk look less like dishwater.

Controversy erupted when the International Agency for Research on Cancer (IARC) pronounced titanium dioxide to be a group 2B carcinogen, eg ''possibly carcinogenic to humans''. Now, any manufacturer that uses TD will be quick to point out the IARC conclusions were based on very specific evidence of high concentrations titanium dioxide dust in the respiratory tracts of rats. So not being a dust-inhaling rat why worry, just slather on the sun cream.

Well, it turns out that there might be one or two causes for concern.

For a start, TD doesn't just reflect rays, it also absorbs them. And this means that, like chemical sunscreens, TD is a photosensitizer, absorbed by the skin and resulting in an increased production of free radicals. In a book called Sunscreen Photobiology—Molecular, Cellular and Physiological Aspects, the author Francis Gasparro says TD illuminated by short wave UV kills human cells. "The distinction between 'chemical' sunscreens and 'physical' sunscreens, attractive though it may be to those who market them, is not based on any significant difference. Both varieties have the potential to produce reactive species that can attack biological materials (human skin cells) when they are exposed to normal sunlight... What is established is that particles of titanium dioxide as large as 220 nm can enter human cells in culture."

A study in 2001 concluded that sunlight-illuminated sunscreen TiO2 (titanium dioxide) particles catalyze DNA damage both in vitro and in human cells. The researchers said that the "results raise concerns on the overall effects of sunscreens and raise the question on the suitability of photoactive TiO2 as a sunscreen component without further studies. The photocatalytically active nature of these metal oxides necessitates some changes since even the TiO2 specimens currently used in suncreams cause significant DNA strand breaks."

The Australian government, which has a particular interest in sun protection since its country is under a big hole in the ozone, was (in 2006) more sanguine: "There is evidence from isolated cell experiments that zinc oxide and titanium dioxide can induce free radical formation in the presence of light and that this may damage these cells (photo-mutagenicity with zinc oxide). 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 (stratum corneum) of the skin."

UPDATE: In July 2016, the EU confirmed that accepted UV filters includes nano titanium dioxide with caveats that concentrations should not exceed 25% and be in products that could cause exposure to lungs.

From what I have read, there seems to be little doubt that TD induces free radicals in the presence of light - in fact some industries make use of this to, for example, eradicate bacteria. What is less clear, is whether the skin readily absorbs TD and the radicals with it. But in the meantime, I am relieved that my Abella sunscreen is zinc oxide only.

  • August 24, 2009

    by Alex

    apparently companies pay some people to promote some products and criticize others. in my opinion of course.

  • July 8, 2009

    by Jimmy

    I actually did some research, and found that sunscreens being commented on are not bad, but there are better ones for less money. Nano particles are a great concern, because they promote free radicals ( destroys DNA and damages skin ). Use the website below... It basically tested 485 sunscreens/sunblocks, ingredients, UVA/UVB, nano/non-nano, and a slew of other things. Soleo, and Badger concur with my research to be very good. ;)

  • May 25, 2009

    by marta

    Thank you Arandjel. On the nano question I decided to go with Environmental Working Group (if anything, this organization could be accused of scaremongering so if they think something is safe then it is worth taking notice). The EWG looked at 15 peer-reviewed studies before pronouncing nano-zinc safe:, and my post on Keys Solar:

    But as far as we are damned if we do and damned if we don't, I couldn't agree more. Sunscreen solutions are far from ideal.

  • May 25, 2009

    by Arandjel


    Thank you for an interesting post. However, you favoring the Abella sunscreen as some sort of a safe product surprises me, especially since so you appear to have done quite some research for the text above.

    I had a look at the ingredients for it, and the active agent present in Abella's line is Z-Cote, that is microfine zinc oxide. Being Brittish, I assume you to be at least slightly familiar with the European Union's stance on microfine zinc oxide. Qouting one of their reports: "Microfine ZnO has been demonstrated to be photoclastogenic, possibly photo-aneugenic, and a photo-DNA damaging agent in mammalian cells cultured in vitro. Clarification of the relevance of these findings is required by appropriate investigations in vivo."

    And in Sweden, where I'm currently situated, it is impossible to buy any sunscreeen/block with zinc oxide. Please visit the following site for an interesting article on the subject matter:

    As I see it, when it comes to sun protection, we are damned if we do and damned if we don't. But in the long run, I still think we - our skin - benefit from it, regardless the active ingredients.

    Best regards,


  • May 24, 2009

    by marta

    That's a great question and reminded me of ferulic acid, an antioxidant that research has shown works even better in sunlight and it prevents damage. So adding this to your sunscreen or favorite serum would probably be useful. Read more here:

    In the meantime, you could try Devita's sunblock with zinc oxide and antioxidants such as green tea:

  • May 24, 2009

    by marta

    Stephanie, you are right. Let's hope there isn't much of it.

  • May 23, 2009

    by Stephanie

    The Abella site says Colorshade:

    May contain iron oxides & Titanium Dioxide

    It's listed as the last thing in the ingredients list though.

  • May 23, 2009

    by mma

    With the evolving research on sunscreens and free radicals and chemical vs physical, can you recommend a non tinted sunscreen that has all the stuff you want and none of what you don't want? I am prone to melasma but do not have particularly sensitive skin. Here's a 2nd part to the question: does it make sense to put perhaps a copper peptide or some kind of anti oxident serum under your sunscreen to combat the free radicals that it seems like sunscreens might promote? thanks

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