Is more zinc oxide necessarily better?

skincarefreak · Joined: 05 Aug 2005 Posts: 67

Hi Dr. Todorov,

I did a search on this question but couldn't find an answer so I thought I'd ask it here. I've been using a rather pricey sunblock that leaves a white cast on my face. It has 13.9% zinc oxide in it and 7.5% octinoxate. I found another that has a tint to it and I can get more for the same amount of money, but it has more chemicals in it :( The percentages are: zinc oxide 8.8%, octinoxate 7.5%, titanium dioxide 6.6%, octisalate 2.0%. Would this be considered a good broad spectrum sunscreen? I'm medically photosensitive and thought the titanium can only help. Would the 2% octisalate really make a difference? I'm not a fan of chemical sunscreens.

drtodorov · Site Admin Joined: 10 Dec 2004 Posts: 3177

Zinc oxide is the broadest of that list. If you don't spend much time outside, just zinc oxide based block may suffice. If you are outside a lot or are photosensitive, look up Fallene Total Block.

skincarefreak · Joined: 05 Aug 2005 Posts: 67

Thank you!

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

I think there is still this controversy about uncoated Titanium Oxide creating free radicals so I prefer Zinc Oxide better. Micronized Titanium oxide blocks more than micronized Zinc Oxide at the same concentration but Zinc Oxide has broader spectrum of UV protection.

I would suggest Blue Lizard sunscreens. They have formulas with micronized physical blocks only (for babies and for sensitive skin) and are VERY cheap, about $2/oz.

Another possibility is Birch Trees SPF 15 which is only micronized ZnO2 and is very cheap also.

For more elaborate choice see this article:

makeupalley.com/user/notepad/sunscreens

Reading the article requires membership of makeupalley which is free. Alternatively, you can enter the link in google exactly the way you see it here and it will give you a link to the page. I can see the page that way without membership.

ynwen · Joined: 27 Jul 2005 Posts: 28 Location: singapore

Hi orangehrzn,

how can we know if a sunscreen contains uncoated or coated Titanium Oxide?

Can one mix pure zinc oxide with oil like emu/raspberry oil?

ynwen

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

ynwen · Joined: 27 Jul 2005 Posts: 28 Location: singapore

Thanks orangehrzn.

Have you come across or tried any zinc oxide based sunblock thats suitable for sensitive acne prone skin?

regards
ynwen

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

My skin doesn't get irritated from ZnO, TiO or Octinoxate (chemical sunscreen). Any composition of those is good for me. The most elegant combinations (most non greasy and non whitish) are usually combination of ZnO and Octinoxate. There are many sunscreens like that.

Take a look at 'Elta Gold UV Shield 45 Oil-Free' on dermstore.com or 'Ultimate UV Defense SPF 30 by SkinCeuticals' which is similar but most expensive. Both are reportedly 'less greasy'. Both won't be able to mattify if your skin produce oils but are good compromise.

There are matte ZnO sunscreens but exessively overpriced like Shiseido for example.

jessica9 · Joined: 16 Aug 2005 Posts: 137 Location: Washington DC

orangehrzn,
i used skinceuticals for a while. whatever their highest block was. i'm thinking of going back to a physical blocker again. from your experience, since you seem to have done a lot of research, which physical blocker is most effective at blocking uva rays? i am also looking for something that is sweatproof if possible. white cast is a deterence for me, but i am willing to experiment some. skinceuticals uses z-cote from what i remember.
i suppose more in a nutshell, what physical blocker on the market do you think is the most thorough uva blocker despite cosmetic elegance, which one is the most cosmetically elegant but perhaps not the best block, and have you found a compromise between the two that you think is effective and well-worth investing in? thanks.

jessica

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

The best combo of physical blocks would be ZnO and TiO. Only ZnO requires pretty high concentrations to achive moderate UVA protection.

Try Blue Lizard Sensitive Skin SPF 30 (ZnO 10%, TiO2 5%) which is quite cheap. I am not sure the level of greasiness but it is not oil slick for sure.

A more expensive but more matte version is DHC White SPF 25 (ZnO 10%, TiO2 5%). It is reported matte.

Both sunscreens have estimated PPD factor (UVA protection) of 10.

I have been using Elta MD UV shield SPF 45 (ZnO 9.0%, Octinoxate 7.5%) but realized it has too low UVA protection.

drtodorov · Site Admin Joined: 10 Dec 2004 Posts: 3177

Here's an interesting bit on TiO2 I came across. Unfortunately, I haven't seen any corroborating data from other sources.
----------------------------------------------------------------------------

TiO2:Mn nanoparticles as enhanced UVA absorption, photostable sunscreen components

A. Duggan and G. Wakefield
Oxonica Materials Ltd, UK

Keywords:
sunscreen, photostability, titanium oxide, manganese, UVA

Abstract:
Conventional sunscreen formulations typically contain, in addition to organic UV absorbers, inorganic nanoparticles such as titanium oxide or zinc oxide. Titanium oxide nanoparticles have significant drawbacks due to a high photoactivity which results in degradation of other organic formulation components and loss of efficacy during topical use. This effect is particularly evident in loss of UVA protection. Doping a low level of manganese ions into the titanium oxide nanoparticle lattice results in an almost total quenching of photoactivity, an increase in intrinsic UVA absorption, and significant free radical scavenging activity. As a result of this, sunscreen formulations containing TiO2:Mn nanoparticle based formulations significantly outperform commercially available sunscreens over extended exposure to simulated solar radiation, resulting in high protection, UVA stable performance for all day UV protection.

jessica9 · Joined: 16 Aug 2005 Posts: 137 Location: Washington DC

thanks for the reply orangehrzn....

thing is...my chemical sunscreen has a ppd of 31! i mean...that is a huge difference in uva protection! and i think most suncare obsessed persons are mostly concerned with uva damage. i thought physical blockers blocked a higher percentage of uva rays than that. i don't know if i want to switch to a physical blocker now. i don't mean this rudely (i just want to make sure since things can be interpretted incorrectly online), but why are you opposed to sunscreens? it seems like the evidence of sunscreens causing free radical damage is not conclusive, though it does worry me myself.

dr. todorov....i am not good at this chemistry stuff. could you answer some basic questions in regard to your post? first off - how does one know if their sunscreen has TiO2 nanoparticles. That may sound like a stupid question. But if my sunscreen lists Ti2O, should I assume it has Ti2O nanoparticles? How does one know? I know my Ti02 is coated because there is avobenzone in my formula. What difference does that make? Does it make any? How does one know if a formula contains TiO2:Mn? And if it does degrade UVA protection, does anyone know how significant the degradation is? And does it just degrade the protection of the TiO2? Sorry for so many questions, but if you could answer them, I would really appreciate it. Thank you!

drtodorov · Site Admin Joined: 10 Dec 2004 Posts: 3177

Nanoparticles are ultrafine particles. Only some suscreens use those, so you can't assume that an arbitrary sunscreen with TiO2 has nanoparticles. Furthermore, if this effect of nanoparticles is real, it is unclear to what degree larger TiO2 particles suffer from the same problem. This data is just a food for thought at this point. There's not enough research to reach firm conclusions.

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

Chemical sunscreens are irritable to me, havent tried tinosorb and mexoryl but avobenzone is for sure. Looking at the reviews chemical sunscreens are irritable to many people not only me.

You can't achieve PPD higher than 10-15 with physical only sunscreens. On the other hand PPD of 10 blocks 1-1/10= 90% of UVA, PPD of 30 blocks 1-1/30 = 97%. To me that difference is not THAT significant to justify higher price and possible irritability of chemical sunscreen. It may be justified with someone with melasma.

If the ageing due to UVA is proportional to the energy of UVA exposure, then PPD of 10 allows only 10% of the UVA to pass which means you are going to age 10 times slower. So in the following 50 years your skin is going to age only 5 years, of course if we could turn off the genetical ageing. That is perfectly acceptable for me.

jessica9 · Joined: 16 Aug 2005 Posts: 137 Location: Washington DC

hmmm....orangehrzn....thanks for sharing. yeah...a seven percent difference is not all that significant. i totally understand the whole thing with irritation of chemical sunscreens. i know a lot of people with that problem - i think most people have some reaction. i guess i'm lucky my skin doesn't react badly to them, but now that you described the ppd to me, i totally see why physical blockers are also a great and reliable option. i'm looking into them still. i'm looking at the blue lizard and total block. it just makes more sense to use a physical blocker on the beach than reapplying like mad every two hours!

haha...love the way you phrase the aging process and sunscreen. eating five donuts yesterday like i did and being inactive certainly aren't going to help me age. i am naturally thin and have no incentive to exercise or eat the right foods. though skin integrity is a incentive - i definately notice a difference in my skin when i eat poorly! thanks for sharing your knowledge with us again. you have a lot of good suggestions and i've learned a lot from your posts.