Are Inorganic Sunscreens Better Than Organic Ones? Part I: Irritation Potential and Aesthetics

I’m always getting asked whether I prefer inorganic mineral-based sunscreens like titanium dioxide and zinc oxide, or inorganic ones like avobenzone and octinoxate. In order to come up with a more holistic and unbiased conclusion, the following characteristics will be considered in a series of FIVE articles:

Part I: Irritation Potential and Aesthetics

Part II: Photostability, Permeability, and Photoreactivity

Part III: Toxicity

Part IV: Level of Protection, and Practicality

Part V: Conclusion and Product Recommendations

***In this series, I will refer to inorganic sunscreens as iOSs (not Apple, mind you) and organic sunscreens as OSs. While there are many individual compounds in each group—particularly OSs, for the purposes of this post, I will only refer to individual iOSs and OSs as parts of their respective groups. Complete and comparative ingredient profiles will not be seen in this series. Furthermore, I will attempt to discuss technologies that are more relevant and reflect the sunscreen technologies and tendencies of the current market. For example, while para-aminobenzoic acid (PABA) has many documented negativities, it will be ignored in our discussion, due to the fact that it is hardly used nowadays in sunscreen formulations.

Irritation Potential

An extreme case of hives. Ouch!

The irritation potential is how likely a compound will innately trigger a negative reaction, whether in the form of redness, stinging, and/or an allergic response. Keep in mind that this negative reaction occurs without UV radiation. Negative reactions upon UV exposure are not included in this section, and will be discussed in subsequent weeks.

Now, it is a well-known fact that IOSs are much less irritating and trigger significantly fewer occurrences of contact dermatitis and allergic responses than OSs. IOSs like micronized zinc oxide (ZnO) are inert chemicals that simply reflect and scatter light. In fact, ZnO has been used in a petrolatum base to alleviate diaper rashes in infants (1). While the inclusion of petrolatum certainly reduced skin barrier damage and erythema (the markers used in the study), it didn’t do it alone. If it did, why wouldn’t they just use petrolatum as a cure-all for dermatitis? I won’t deny that the study would have been more conclusive if it were vehicle-controlled. Despite that fallacy, the study still suggests that ZnO didn’t increase irritation.

On the other hand, several commonly-used OSs have triggered negative reactions, due in-part to OSs’ mechanism of action against UV light (they absorb UV light and transform it to some other energy form) and their similarities to other known irritants including fragrances such as those of the cinnamates family. Numerous cases of allergic reactions such as anaphylaxis have been documented for multiple types of OSs, including benzophenones like oxybenzone (2), and dibenzoylmethanes like avobenzone (3). While the total number of reported cases of irritation from OSs is small compared to the general population as a whole, as well as varying in intensity, why take that risk at all?

Based on the evidence and the historical tendencies of the general public, the win goes to iOSs.

iOSs = 1; OSs = 0

Aesthetics

While providing excellent UV protection via micronized ZnO and TiO2, the Blue Lizard Sensitive SPF 35+ sunscreen leaves a faint white cast, and is thick and unpleasant to apply.

This characteristic considers how easily a sunscreen can be applied, and how cosmetically pleasing it looks on the skin.

Until the advent of nanotechnology in recent years, iOSs have always been thick, greasy, and opaquely white. This was because both titanium dioxide (TiO2) and ZnO, are minerals that have high refractive (ability to reflect light) properties, with the former being more white (4). The greasiness comes from the emollient vehicles that had to be used to properly and evenly disperse the particles in solution. Even now, with micronized versions, this whiteness can still be seen as a faint white/gray cast. Furthermore, while the micronized versions have reduced the level of opacity, the fact that thicker and more emollient vehicles disperse particles better than more elegant solutions, still holds true. Therefore, many of the available micronized inorganic sunscreens are still a bit greasy. For example, while the Blue Lizard Sensitive Skin SPF 30+ sunscreen provides excellent protection, the texture is still a bit goopy and thick.

OSs on the other hand, while being intrinsically greasy (since they’re oil-soluble), can easily be implemented into cosmetically elegant water and oil emulsions such as gels, serums, and lotions. They are completely translucent, and with a little help from solvents like ethanol, can have textures as light as liquids.

Overall, iOSs tend to be heavier and faintly white, while OSs are lighter and completely transparent.

iOSs = 1; OSs = 1

Conclusion

Right now the score is tied at 1-1. Stay tuned for next week’s continuation of this series. The discussion of the three P’s: photostability, permeability, and photoreactivity (which rhyme by the way), is sure to include some seriously heavy reading. Speaking of heavy reading, check out the 3,000+ post I did on Retinol FAQs HERE!

Links/References:

  1. http://www.ncbi.nlm.nih.gov/pubmed/11720074
  2. http://www.docstoc.com/docs/73348448/Anaphylaxis-caused-by-topical-application-of-sunscreen
  3. http://www.ncbi.nlm.nih.gov/pubmed/19856938
  4. http://www.ncbi.nlm.nih.gov/pubmed/10759815

About the author: John Su is an established skin care expert and aspiring dermatologist. He also runs a blog, The Triple Helix Liaison, dedicated to providing unbiased, meaningful, and insightful information about skin care. For his full bio, please visit our About Page.

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by Nicki Zevola

23 thoughts on “Are Inorganic Sunscreens Better Than Organic Ones? Part I: Irritation Potential and Aesthetics

  1. May says:

    Hi John, do you know why so many mineral-based sunscreens typically have higher percentages of titanium dioxide than of zinc oxide, even though zinc oxide deflects more of the UV spectrum and titanium dioxide actually has a whiter cast to it? The only possible explanation I can come up with is that zinc oxide might be rarer than titanium dioxide?

    As for myself, I only use physical sunscreens due to the fact that every single chemical sunscreen I have ever tried has irritated my skin. I agree that as far as aesthetics and application go, physical sunscreens could stand to be improved as a whole. In terms of application, the best physical sunscreen I have found is Clarins’ UV Plus HP SPF 40, but it only uses titanium dioxide. How I wish they would make a zinc oxide formulation of it instead! So I’m still on the hunt for my “holy grail” of physical sunscreens.

    For me, physical/inorganic/mineral sunscreens win hands-down. :)

  2. Pedro says:

    In fact, the inorganic sunscreens I use are extremely matte and can dry out my skin due the fact ZnO and TiO2 are very absorbent and they are dispersed in very thin – almost like water – silicones-based emulsions. The white cast is minimal and disappears quickly. On the other hand, organic sunscreens with a high % of octocrylene give me a very evident white cast.

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  4. John says:

    @Mary

    TiO2 is usually higher because it is much better at reflecting UVB rays than ZnO. Therefore, if formulators don’t want to include organic sunscreens to boost UVB protection, they just use more TiO2. :) But you’re right, ZnO has a wider protection spectrum, and is less white.

    We’d love to hear what sunscreens you’ve tried and what ones you’re looking at as potential HGers!

  5. John says:

    @Pedro

    Well, just because the ones that you use are matte (which I’m curious to know which ones specifically), doesn’t mean that they accurately represent iOSs in general. I know there are iOSs that don’t leave white casts, but in the article, I said that overall, iOSs leave more apparent white casts and are thicker than OSs. The ones you use probably utilize ethanol to thin the solution out, which is fine. But the ethanol will dry the skin out comparatively more than the TiO2 and/or ZnO. As for no apparent white cast, it could be that perhaps you’re not using enough of your iOS for it to actually leave a (faint) white cast. Also try going out into directly sunlight and holding a mirror up to your face. Just some food for thought.

    As for having high concentrations of octocrylene leave a white cast, that’s pretty much impossible since octocrylene is a translucent clear to yellow fluid that’s also quite viscous. Most likely, the OSs you’re referring to contain some TiO2 or ZnO, or even some other mineral. Several metal and metalloid oxides that are frequently used as pigments and absorbents (not sunscreen), are included in OSs to increase opacity and texture. They can definitely leave a white cast. Or perhaps there’s some kind of interaction that’s creating a precipitate. Who knows? But the white cast is independent from the OS ingredient; meaning that the OS itself (in this case octocrylene), cannot leave a white cast.

  6. May says:

    Hi John, I did not know that titanium dioxide is better at reflecting UVB rays than zinc oxide. All I’ve ever read is that titanium dioxide doesn’t reflect long UVA rays, which zinc oxide does, and that both reflect UVB and short UVA rays. Could you please explain what makes titanium dioxide a better blocker of UVB rays? Thanks!

    So in your opinion, should the ideal physical sunscreen contain both zinc oxide AND titanium dioxide?

    Finally, can you please explain what the percentages of active sunblock ingredients really mean? I used to assume that higher percentages means more protection, and I believe that this is generally true, but I know for sure that I have seen sunblocks with higher percentages of active sunblock ingredients yet they actually had lower SPFs than sunblocks with lower percentages of the exact same active sunblock ingredients!

  7. Pedro says:

    @John

    “Well, just because the ones that you use are matte (which I’m curious to know which ones specifically), doesn’t mean that they accurately represent iOSs in general. (…)”.

    I agree with you. I was only giving my personal experience. :)

    “(…) The ones you use probably utilize ethanol to thin the solution out, which is fine. But the ethanol will dry the skin out comparatively more than the TiO2 and/or ZnO. (…)”.

    Some contain alcohol (ethanol), some don’t. Shiseido Anessa Mild Face Sunscreen SPF 46 PA+++ is an example of alcohol-free sunscreen which is extremely matte for my skin – it’s so matte I have to put a lot of moisturisers before applying it LOL. The article is in Portuguese, but I translated the ingredients to INCI and you will find them (in fact, this sunscreen contain a bit of an organic filter, but it’s mostly Ti02/ZnO based):

    easttowestskincare.com/2012/08/09/shiseido-anessa-mild-face-sunscreen-spf-46-pa/

    In this case, this sunscreen doesn’t leave white cast because they contain a bit of iron oxides (so, yes, you’re right, I’m not disagreeing with you, just commenting…).

    “(…) As for having high concentrations of octocrylene leave a white cast, that’s pretty much impossible since octocrylene is a translucent clear to yellow fluid that’s also quite viscous. (…)”

    According to some formulators OCT isn’t always clear and can leave white streaks: personalcaretruth. com/2011/05/is-octocrylene-safe/

    But again: I’m not saying you’re wrong. You’re giving an overall view while I’m comment about some exceptions. Anyway, according to my experience, just in the US 100% physical sunscreens usually are very thick. In Japan 100% physical sunscreens usually are very thin (even the alcohol-free ones). I’ve seen in Japan even a sunscreen with a lot of ZnO (again: without alcohol) in a aerosol!

  8. Trae says:

    Sunscreens are one of my favorite topics — I’m really looking forward to all of the parts of this series of articles ^^,

    My Baumann skintype is DSNW (my ‘S’ score is close to borderline, though, so my skin’s only minorly sensitive) and seems to do best with inorganic filters. Personally, for regular daily use, I like products that are based on both ZnO and TiO2 with ZnO present at at least 5 %, but that are also tinted. Two of my staples in this regard are Elta MD UV Physical and Skinceuticals Physical Fusion. Both were able to earn ‘Broad Spectrum’ designations when they underwent relabeling to conform to the updated FDA standards, and thus should exhibit critical wavelengths >= 370 nm (and supposedly Physical Fusion UVA-PF tested at PPD 21, though that’s per Skinceutical’s internal testing, as far as I’m aware) which makes me feel comfortable about using them to reduce photoaging from incidental, daily sun exposure. For some reason UV Physical feels more inert, albeit more matte, on my skin than Physical Fusion does: if my skin is sensitized for whatever reason, Physical Fusion can sometimes feel irritating upon application, whereas UV Physical never does. I suspect that this may be due to some of the ingredients Physical Fusion incorporates in its base to allow it to be in a liquid form (UV Physical, by contrast, is a thicker cream) though I’m not 100 % certain as to why one’s more irritating than the other.

    Around my eyes, I like to use untinted inorganic sunscreens specifically for the brightening effect, and my favorites for that purpose are Skinceuticals Sheer Physical and MD Solar Sciences Ultra Mineral Gel (the former of which is essentially the untinted version of Physical Fusion and thus similarly poses the problem of irritation when my skin is sensitized, and the latter of which has a base heavily composed of silicones, making it feel a lot like a cometic primer).

    For my hands, I keep a tube of Vanicream SPF 60 in both my car and messenger bag: it’s an *extremely* emollient product, but that makes it great for my hands ’cause it also prevents them from overdrying during the winter and from frequent handwashing. For whatever reason, Vanicream’s sunscreen is completely transparent (at least to my eyes) once rubbed in — moreso than any other physical/inorganic sunscreen I’ve tried (I suppose they *could* be using unusually small particle sizes of ZnO and TiO2).

    My new HG for lips is definitely LipCotz (thanks to Dr Cynthia Bailey’s recommendation of the product on her site): it contains decent concentrations of ZnO and TiO2, is invisible on the lips once applied…and hey, the flavor’s pretty good, too LOL !

    I have also recently been trying out ZnO / EHMC combo sunscreens, since they can appear almost transparent on the skin (compared to the ZnO / TiO2 combos I usually like) if properly formulated, which may be better for the occasional situation where esthetics of the product are of utmost importance (e g, giving presentations or being at an event where pictures may be taken). So far, EltaMD UV Daily has been my favorite of all that I’ve tried of this type, given it’s more-moisturizing product base. I also have on hand Obagi Sun Shield and DCL Super Sheer, both of which contain a bit more ZnO than UV Daily does, but I want to try them a few more times before coming to a final conclusion about them — so far, though, they seem relatively translucent and non-whitening, but perhaps a bit more matte and drying, at least on my skin.

    But yeah, I definitely have a growing inorganic sunscreen ‘collection’. Thought I’d share my current favorites of the bunch with everyone, though, and I have a feeling that this is going to be a great series of articles ! ^_^

  9. Lisa says:

    I agree with Pedro, TiZo2 is by far the best facial sunscreen I have ever used. The slight tint makes it disappear on my skin. Even after hours at the beach I don’t get burned or even much tan.

    Similar product available at Ulta is CoTZ Face. Definitely worth a try. Silicone base in both make it feel and act like a facial primer, dry not wet. I can’t stand the wetness left by organic sunscreens, making you wait before putting makeup on.

  10. John says:

    @May

    I actually planned to address these issues you brought up in Part IV when I made product recommendations, and explained why I made those recommendations. But I’ll give you a short preview. :)

    In a same way that ZnO is better at reflecting UVA1 rays, TiO2 is better at reflecting UVB rays. Part of the reason includes the latter’s higher refractive index, and the way it interacts with other ingredients and coating materials, that allows it to be more easily built up to a higher SPF value.

    Yes, in my opinion, both ZnO and TiO2 are necessary in the ideal product. Or the ZnO needs to be combined with an organic sunscreen, just to boost the UVB protection. It’s quite baffling when I see SPF 50+ on a product that contains only ZnO. However, that’s a whole other debate.

    Now, the percentage only tells how much of an ingredient is present in comparison to the product as a whole. Generally, higher percentages do mean more protection. However, keep in mind that the vehicle, how the sunscreen actives are coated, interaction between sunscreen actives, particle size, can all affect the SPF value. However, with that in mind, since the packaging doesn’t infer the level of UVA protection, I always want a higher percentage just to be safe. I too have seen inorganic sunscreens with like SPF 50+ that only contain like 5% of TiO2 and ZnO. I won’t use it, just because even if the SPF rating is true (which I kind of doubt; though apparently that rating is regulated by the FDA), how do we know how much UVA protection is given? I’d rather go with something with a higher percentage. .

    I hope that made sense and stay tuned for later parts!

  11. John says:

    @Pedro

    I apologize if I came off a little crazy. I did know that you were just giving your personal experience, I just wanted to make sure the other readers knew that as well.

    Also, just to note, the octocrylene post you linked from personalcaretruth, a blog I also read!, didn’t actually say that OCT will leave white streaks. It says why a cosmetic chemist would want to REPLACE TiO2 with something like octocrylene! One of the reason why because the TiO2 could leave white streaks, not the OCT.

    But you are right that Asian inorganic sunscreens tend to be more elegant overall than Western ones. But even then, Asian organic ones are too. So overall, the rule of thumb still applies. And aerosol sunscreens are not recommended! But that’s a whole other discussion.

    Teehee, thanks again for commenting! The more perspective, the better.

  12. John says:

    @Trae

    Holy @#%. That is a long reply! Thank you for taking the time to share your ideas with us! I’ll be sure to consider the products you mentioned when I write Part IV of this series.

    The Vanicream doesn’t have a white cast because it has such an emollient base, which disperses the sunscreen particles really well! But personally for me, I can’t use an emollient hand cream since I’ll leave behind sunscreen fingerprints everywhere. No thanks! xD

    Again, thanks for sharing and commenting. I hope you find your true HG product soon!

  13. John says:

    @Lisa

    I’m not really sure what you’re referring to by “TiZo2,” but that’s still great! Lol!

    Even when using inorganic sunscreens, I still wait a good 15 minutes before setting it with (powder) makeup. I mix in some liquid foundation with SPF into my regular sunscreen to offset the white cast. I find that it’s important to allow the sunscreen to set, before applying any makeup, because application of the makeup (with brush, fingers, sponge) can move or even remove the parts of sunscreen. And since inorganic sunscreens function by reflecting UV light, if you move/remove some, those areas won’t get any protection. :(

  14. Trae says:

    @John That’s interesting to know that it’s the emollient base itself that causes Vanicream to be transparent — I hadn’t thought of that, but it makes sense. As you mentioned, it will leave fingerprints upon contact with dark surfaces, like most other emollient products applied to the hands, but with Vanicream’s sunscreen they’ll mostly just appear to be ‘grease fingerprints’ — as if I had been eating fast food and had forgotten to use a napkin LOL — but not the whitish fingerprints I’d experience with other physical sunscreen products applied to the hands that might make it look as if crime scene fingerprinting had been performed ._. I do know some individuals who only apply their sunscreen product to the tops of their hands to prevent product transfer and the resultant fingerprinting effect, and that seems like it could also be a good option, as most of the photoaging concern I’ve seen expressed is with regards to the tops, and not so much the palms, of the hands.

  15. John says:

    @Trae

    It’s not always the cause, but an emollient base is usually the reason why an iOS doesn’t have a white cast. And I get that you only apply to the top of your hands. But for me, someone who wears a lot of long sleeves, something that doesn’t soak in and doesn’t set, will stain my sleeves. :( It’s something I think no one wants!

    And lol @ “greasy” fingerprints! Haha!!

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  17. Amy says:

    Hi John,

    I am trying out new sunscreens around the market and am trying to find a good one. I came across this article and found it very interesting.

    First, I want to say that you are a very good writer. You write very succinctly yet make sure readers get the info they need. Awesome job!

    I have a few questions I was hoping you could help me out with:
    A) What would be some sunscreens that you would recommend to try? Can you give me two suggestions, (1) drugstore, affordable and the second a high-end splurge?

    B) Would you recommend for or against using eye creams with SPF, or just replacing them with regular sunscreen instead?

    C) Why would you not recommend aerosol sunscreen?

    P.S. (I have combination, acne-prone skin, early 20s, East Asian descent)

    Thank you very much!!!

    Best,
    Amy

  18. John says:

    @Amy

    I’m sure you noticed that this is going to be a four part series,. So, I really want to get through all the aspects that need to be considered when looking for a sunscreen, before giving out product recommendations. If you see above, that will be done inpart four! But I can tell you now, that most of the sunscreens that I plan to recommend are quite affordable! Nothing is really “high-end.” Sunscreen should usually not be a splurge, because the amount you have to apply to achieve the labeled SPF rating is very high! For example, while the Diorsnow SPF 50 sunscreen contains like 19% ZnO, and 7.5% octinoxate in a silky light silicone and water base (which are all excellent characteristics), it’s $50 for 1.3 oz… You’ll be going through a bottle like once every two weeks. Ridiculous!! But if you’re willing or have the means to spend oh… (50 x 52 x 2) like $13,000 on sunscreen PER YEAR, then be my guest. Lol!

    But yeah, if it’s possible and I hope I’m not asking too much, can you please wait 2 more weeks until part 4 is released? :)

    But I can answer your two other questions! No I don’t think eye creams with SPF are necessary. Your facial SPF is just fine. I addressed this issue in my eye cream post. I’ll simply link it for you!

    http://www.futurederm.com/2012/07/27/are-eye-creams-necessary/

    Okay, I just checked, and the answer is actually in my response to Alice in the comments section of that post. Haha! Check there.

    Finally, I don’t recommend aerosal sunscreens because there’s no “rule-of-thumb” or way to tell if you’ve applied enough to obtain an even, thick coat of protection. Furthermore, inorganic and organic sunscreens have negative effects when ingested and inhaled. And when things are aerosolized, the risk of inhalation is significantly higher when they’re not. But that should be obvious! Anyways, this issue will be further addressed in Part 3. But yeah, those are the two main reasons why aersol sunscreens aren’t dependable or good in my opinion.

    Thanks for commenting!

  19. Amy says:

    Hi John,

    Thanks for the reply! No worries, I’ll wait until part four. I’m glad the sunscreens you’ll recommend are affordable =D

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