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Wed Mar 21, 2007 3:44 pm  |
Piggybacking on helenzwl's prior post, I'd love to know about the best physical sunscreens people have used. These are s/s products in which titanium dioxide and zinc oxide are the active ingredients, with no chemical filters.
I am currently using Solaris SPF30 or Devita SPF30 moisturizer. I have others on my list to buy, but I haven't used them yet. |
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Wed Mar 21, 2007 6:30 pm |
| wow, I didn't even know there are 2 types - Physical versus chemical sunscreens. So what are chemical filters? Which one works better then? |
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Wed Mar 21, 2007 6:56 pm |
I have sensitive skin. The physical filters work much better for me -- no redness, stinging or other irritation. Sorry that I can't be more helpful on the chemical filters; the only attention I pay to them is in avoiding them. That's why I was hoping to get a thread and/or list started of good physical sunscreens.  |
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Wed Mar 21, 2007 6:57 pm |
| Anything that is not titanium dioxide or zinc dioxide is chemical I think. |
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Wed Mar 21, 2007 7:49 pm |
Cool thread
Physical sunscreens reflect the UVA away from the skin whereas chemical sunscreens absorb the UVA and convert it to a stable form that won't damage skin. That's about all I know
I do have some really good info that was kindly put together by Chillipadi on the Handbag forums. I'll copy it here. It is long though but really useful stuff to know.
SUNSCREENS and UV DAMAGE
UV RADIATION - WHAT IS IT?
A bit of science first. Ultraviolet radiation, or UV radiation, is radiation from the sun, some of which penetrates the earth's atmosphere, hitting the earth's surface and our skin. It is generally divided into three different sorts of rays: ultraviolet light A (UVA), UVB and UVC radiation. UVC has the shortest wavelength and has the most potential to cause relatively rapid and severe skin damage, but fortunately for us is almost completely absorbed by the ozone layer - however, in areas where the ozone layer has become depleted UVC rays may begin to become more of a concern. UVB rays are partially absorbed by the ozone layer and have a longer wavelength than UVC, but shorter than UVA - UVB encompasses the solar spectrum from 290 to 320 nanometers (nm), while UVA encompasses the spectrum from 320 to 400 nm. The different wavelengths have implications for our skin - the longer wavelength of UVA radiation allows deeper penetration into the skin.
UVA vs UVB
An understanding of both UVA and UVB rays is vital. Historically, it has been thought that UVB rays were the most important contibutors to skin cancer and other skin diseases, wrinkling etc., but more recently, information that UVA radiation is equally or even more important in the development of UV damage, and in fact is present in far higher amounts than UVB (UVA rays constitute 90-95% of the UV light reaching the earth) has filtered into the mainstream.
A simple and practical way to distinguish the two rays is that while UVB rays are the primary cause of sunburn (UVBurn), UVA rays (involved in the initial stages of tanning) have more potential to cause premature skin ageing (UVAgeing). This is not to say that UVB rays are not responsible for tissue damage resulting in wrinkles and premature ageing - they are - but the degree to which UVA radiation is present in the atmosphere makes it the primary suspect. Both UVA and UVB radiation (as well as UVC) are factors in the development of skin diseases, including skin cancer, however - so even if you couldn't care less about looking like an old leather handbag by the tender age of 35, regular sunbaking could still come back to haunt you in the form of something much more serious than crows' feet.
You also need to be aware that while you won't burn while sheltered indoors (as UVB rays are blocked by glass), UVA rays can penetrate (untreated) glass. That's why driving long distances even with your windows up can leave you with mismatched arms, and why it's of value to wear a light broad-spectrum sunscreen (more on this later) while indoors. Electrical and electronic appliances, like CRT computer screens (i.e. not LCDs like those on completely flat monitors and laptops), fluorescent and halogen lights, can also give off UVA rays, and while you shouldn't become paranoid about exposure, be aware that you may benefit from using a sunscreen when, for e.g., working all day in front of a CRT monitor under artificial lighting.
WHAT DOES UV DAMAGE LOOK LIKE?
As we've seen above, this doesn't just include serious skin diseases like skin cancers. Immediate effects of sun damage are usually seen in the form of sunburn - reddened, sore and peeling skin. This in itself is of concern as your potential for developing skin cancer is considerably heightened for every occurrence of serious sunburn.
More long-term effects are of significance as well. Premature wrinkling, hyperpigmentation (e.g. brown spots on the skin, including freckles), loss of skin elasticity, coarsening of skin texture, and the presence of a tan are also due to UV damage - in fact, dermatologists today say that up to 90% of premature skin ageing is caused by sun exposure. The issue of whether a tan protects the skin from UV radiation isn't a clear-cut one - although it may do so marginally, in the sense that the skin's protective response to UV assault is to produce melanin (the pigment that tans our skin), practically speaking, that protection is an exercise in damage limitation. Once a tan has occurred, damage has already been done. Naturally darker skins aren't exempt from UV damage either, and those with such skintones should realise the importance of wearing a broad-spectrum sunscreen daily as well, as they are also at risk for the whole range of UV damage listed above.
Perhaps more importantly, though, you need to know that you don't need to be a sunbather to get UV damage. Day-to-day casual exposure damages your skin over time as well. And UVA rays in particular penetrate gloomy skies, so even in blighty Britain, you need to be wearing a broad-spectrum sunscreen (more about this later) every day, 365 days a year.
And don't forget your eyes. Unprotected sun exposure can lead to cataract formation. Wear sunglasses or treated spectacles that filter out 100% of UV light.
SUNBEDS - YES OR NO?
In a word - no. There are many misconceptions about sunbeds, including the belief that it can help 'prepare' your skin for a tan, and that it is not damaging to the skin as modern sunbeds 'only utilise UVA rays, not the burning UVB rays'. Whether you tan using a sunbed or outdoors with 'real' sun, you are damaging your skin. Consumers need to be aware that sunbeds provide no safety net whatsoever - conversely, by tanning using sunbeds, they are actually exposing themselves to much higher levels of UVA radiation than they would probably be exposed to through sunbathing outdoors. Avoid.
HOW CAN I PROTECT MY SKIN?
First, we need to establish one thing - sunscreens are not a miracle product. They cannot block out 100% of UV rays, and need to be used in conjunction with sensible behaviour. The use of sunscreens should never be relied upon to prevent skin cancer. The Australian mantra "Slip, Slop, Slap" is of use here - slip on a long-sleeved shirt, slop on the sunscreen, slap on a hat. No, it doesn't sound like much fun. But you need to know about it anyway, and practise it in moderation. Aussie awareness about the importance of sun protection is widespread because of the high risk of skin cancer in Oz, but skin cancer is on the rise in Britain (not least due to the British propensity to remove all clothing and lie on the grass the minute the sun breaks through the clouds), and knowledge which you can then adapt to feasible and practical extents is an invaluable tool.
Just as important as using sunscreen and covering up is sensible sun exposure - cover up and stay out of the sun during the hottest part of the day (typically 10am to 2pm). In addition to that, use sunscreen, and reapply at regular, frequent intervals when outdoors for prolonged periods, whether you're sunbathing, doing sport, gardening or even just walking miles shopping on the high street! Remember too that sunlight is strongly reflected from sand, snow, ice and concrete and can significantly increase your direct sunlight exposure.
Now, covering up is obviously not an option when sunbathing. I should stress that frankly I don't advise sunbathing at all, because as already mentioned, there is no way of completely preventing sun damage, and further, given that the purpose of sunbathing is presumably to get a tan, that tan is skin damage you can do without (fake tan is an option, but that is an entirely different ballgame!). But that lifestyle change is not something everyone is prepared to do. So if you want to enjoy the sun and get a suntan, and don't wish to fake it, it would be in your best interests to stay out of the sun between 10am and 2pm (granted, not always possible in Britain where if you don't catch some rays between 10am and 2pm you may not see them again for the next 4 weeks, so possibly more easily applied in sunnier climes), wear sufficient amounts of a decent broad-spectrum sunscreen, and reapply generously at regular, frequent intervals (at least every two hours, as a general rule of thumb).
SO WHAT'S A 'DECENT BROAD-SPECTRUM' SUNSCREEN THEN? (THE LONG SECTION)
And so we come to sunscreens. This is a huge topic, but we'll keep it as straightforward as possible. What you need to get will depend on what sort of exposure the sunscreen is meant for, but whatever the case, you should look out for several things:
(a) The SPF rating (this relates to protection against UVB rays); AND
(b) The UVA rating (UK star rating, Asian PA rating) or the presence of dependable UVA filters as active ingredients in the ingredient list; AND
(c) What the actual UV-blocking or UV-filtering ingredients are.
'Broad-spectrum' refers to the fact that a sun protection product should protect you through the whole UVA and UVB spectrum. We'll reach a verdict on what a 'decent' product constitutes within this section!
(a) There are a huge range of sun protection products on the market now, and the thing they all have in common is the presence of an SPF (sun protection factor) rating, which relates to UVB protection only. It gives you absolutely no information on UVA protection, and if a product doesn't state that it provides UVA protection it probably doesn't (this is frequently the case with makeup and many sunscreen-containing moisturisers - check the ingredients (as we'll see in (c)).
The SPF rating indicates the length of time you can spend in the sun without burning as opposed to how long it would take had you not used the product - for e.g. if you would normally burn within half an hour, an SPF 15 would turn that into seven and a half hours. In practice this is often much less, however - to achieve the stated level of protection you need to apply the right amount (we'll come to this in the next section).
The amount of UVB rays that are filtered goes up as the SPF rating rises, but as you reach higher SPFs the difference becomes smaller and smaller. For example, while an SPF2 blocks about 50% of UVB rays and SPF15 blocks approximately 95% of UVB rays, SPF30 blocks approximately 97%.
How high an SPF you need depends on what you're using the sunscreen for. For daily use, most health professionals agree that an SPF15 is sufficient. Any greater exposure to the sun and an SPF30 (and higher) is ideal. This needs to be adapted to your skin and personal preference, though - my daily sunscreen is an SPF50, but then again I'm more paranoid than most about sun damage, and I would probably advise people with high-risk skintypes (e.g. those with Celtic skins) to get a minimum of SPF30 for daily use. If you are spending extended periods in the sun under very hot conditions or going skiing, you may want to consider getting an SPF60 and above.
A good product needs good UVA protection as well, which brings us to (b).
(b) UK products use a UVA star rating in sun products that is meant to serve as an indicator of the level of UVA protection provided by the product, and I would advise you not to get anything below a 4-star rating. A similar rating system (I have seen this on Helena Rubinstein products in the UK, but am not sure if any others have this as well) can be found on products for the East and Southeast Asian market (again, I'm not sure if this is to be found elsewhere), where ratings from PA+ to PA+++ are used, and in this case I prefer to get only those products with a PA+++ rating. There is a European UVA rating similar to the UVB rating (for e.g. on Avene products) that I know little about - if anyone knows how this works exactly I would be grateful for any information.
However, while the ratings are a good guide, there's nothing like knowing what ingredients to look out for, which brings us to (c). Always read the ingredient lists, and don't assume that all sun products made by a company will contain the same UV protection ingredients.
(c) UV blocks and UV filters are not quite the same thing, and this distinction can also be expressed in terms of physical and chemical UV blockers/filters. Physical UV blocks work by forming a layer over the skin that physically scatters and reflects UV rays, while chemical filters act by absorbing UV rays.
Whether physical or chemical or a combination of the two is best is really a personal choice that comes down to skintype, lifestyle and attitude towards sun exposure. Physical blocks tend to be heavier and more occlusive (although you can get 'micronised' forms, it's not been established whether these actually provide inferior protection to non-micronised forms) and can be a bit too much for oilier and acne-prone skins, but they are photostable (i.e. they don't degrade in sunlight, unlike a lot of chemical sunscreens) - another advantage is the fact that you don't really need to reapply them unless perspiring a lot or swimming. Products containing purely chemical sunfilters are typically much lighter (and therefore those used most commonly in makeup products (e.g. foundations with SPF)) and feel better on the skin, but some people are sensitive to chemical sunscreens, and because they have a limited capacity as to the amount of radiation they can absorb, you need to reapply them if you're getting any more than incidental exposure to the sun. Nowadays I personally opt for a combination of the two in a product that you unfortunately can't get in this country, which contains Mexoryl SX and Mexoryl XL as well as titanium dioxide (read on for more info about these sunscreens).
This website http://www.dermatology.org/skintherapy/stl0205.html includes a table of sunscreens which shows you various chemical and physical sunscreens and the ranges they absorb through (btw above 400 nm is visible light and infrared radiation). From the list it should be clear why I personally favour titanium dioxide, zinc oxide and Mexoryl SX (listed as 'terephthalylidene dicamphor sulfonic acid' on ingredient listings) in my sun protection products. I would also look out for:
- Mexoryl XL (drometrizole trisiloxane)
- Tinosorb S (bis-ethylhexyloxyphenol methoxyphenyl triazine)
- Tinosorb M (methylene bis-benzotriazolyl tetramethylbutylphenol)
Mexoryl is a L'Oreal patent, and as such can be found in a wide range of products from groups under the L'Oreal umbrella - L'Oreal, Lancome, Helena Rubinstein, Vichy, Ambre Solaire, La Roche-Posay etc. Tinosorb is RoC's equivalent of Mexoryl and can be found in Avene products as well. Both are excellent UVA absorbers and are photostable, unlike older UVA blocks like avobenzone which is highly volatile in sunlight and is not something I recommend (it can be stabilised with various chemicals, but the findings on this are not conclusive and I wouldn't risk it personally, not when better UVA sunscreens are easily available.
Of the physical sunscreens, zinc oxide is a better block than titanium dioxide, but also more occlusive and opaque. Both titanium dioxide and zinc oxide can give a white cast to the face and for that reason can be unappealing cosmetic options unless you're extremely pale-skinned, but the protection these physical blocks provide should absolutely not be rejected when there are so many good products available and technology is improving all the time.
HOW MUCH SUNSCREEN DO I NEED TO USE?
A great deal of us use much less sunscreen than required - you could be getting less than half the stated amount of protection, so you really need to make sure you're applying enough. As a guide, you need to use about half a teaspoon EACH for the face, each arm and the neck, and slightly more than one teaspoon EACH to each leg, the chest and the back. The bigger you are, the more you need, obviously. And it always helps to err on the side of caution if you're spending extended periods in the sun. For daily use and when most of you is covered up in adequate clothing, application to the face, neck and hands is frequently sufficient.
CAN YOU RECOMMEND SOME SUNSCREENS TO ME?
There are so many on the market that it would be difficult to narrow down the field, but as mentioned above, the L'Oreal group of companies is a good place to start for excellent UVA protection. I realise that a lot of you boycott L'Oreal because of its animal testing policies, and in this case the other information provided above should be useful - e.g. Avene and RoC (unless someone knows otherwise?) for brands and titanium dioxide and zinc oxide for ingredients (you could consider brands like Peter Thomas Roth, DDF, Dermalogica and MD Formulations). |
_________________
"When you arise in the morning, think of what a precious privilege it is to be alive - to breathe, to think, to enjoy, to love." |
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Wed Mar 21, 2007 8:11 pm |
I have ultra sensitive skin and so far, my fave has been DDF Organic Sun Protection SPF 30 - no oils, preservatives, and it doesn't turn my face white like a lot of other physical sunscreens I've tried.
Main ingredients are:
Micronized Titanium Dioxide
Micronized Zinc Oxide
VItamins A,C and E
Alpha Lipoic Acid
Co-Q10
Genistein
Glutathione
Grape Seed Extract
N-Acetyl-Cysteine
Pyconol
Zinc |
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Wed Mar 21, 2007 8:15 pm |
Hi rebelgirl,
You are certainly an expert in this topic. Thank you so much for the detailed and valuable information.
I have a dumb question to ask: do you think the LED light from those home use hand held devices would have any adverse impact on your skin much like the tanning bed? |
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Wed Mar 21, 2007 8:26 pm |
I'm also searching for a non-chemical sunscreen with moisturizer.
I think skinsceuticals has a non-chemical sunscreen but I find it way too heavy for my face. |
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Wed Mar 21, 2007 8:29 pm |
| jjb wrote: |
I have ultra sensitive skin and so far, my fave has been DDF Organic Sun Protection SPF 30 - no oils, preservatives, and it doesn't turn my face white like a lot of other physical sunscreens I've tried.
Main ingredients are:
Micronized Titanium Dioxide
Micronized Zinc Oxide
VItamins A,C and E
Alpha Lipoic Acid
Co-Q10
Genistein
Glutathione
Grape Seed Extract
N-Acetyl-Cysteine
Pyconol
Zinc |
According to the ingredients listed on EDS the DDF Organic sunscreen does have preservatives (parabens).
Ingredients:
Active Ingredients: Zinc Oxide 6%, Titanium Dioxide 3.2%
Other Ingredients: Water, Ethylhexyl Palmitate, Glyceryl Stearate, Dimethicone, Cyclomethicone, Propylene Glycol, PEG-100 Stearate, Cetearyl Alcohol, Polyglycerol-6 Isostearate, Polysorbate 80, C10-15 Alkyl Benzoate, Aloe Barbadensis, Allantoin, Panthenol, Disodium EDTA, Redox I [Retinyl Palmitate (Vitamin A), Magnesium Ascorbyl Phosphate (Vitamin C), Tocopherol (Vitamin E), Zinc Gluconate, Thioctic Acid (Alpha Lipoic Acid), Pyconol, Acetyl Cysteine, Glycine Soja (Soybean) Sterols, Ubiquinone (CoQ-10), Lutein, Anthocyanins], Camellia Sinensis (Green Tea) Leaf Extract, Centella Asiatica (Gotu Kola) Extract, Laminaria Digitata Extract, Methylparaben, DMDM Hydantoin, Phenoxyethanol, Propylparaben.
Now I'm no expert on ingredients but a lot of those in the list certainly don't sound too "organic"  |
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Wed Mar 21, 2007 8:39 pm |
That's really weird - the site I bought it from specifically directed me to it because they said it doesn't contain parabens! I already threw out the box, so I can't confirm, but the ingredients on their site are as follows (true they are hardly all "organic", but then again, a lot of organic stuff breaks me out... ):
Active Ingredients:
Zinc Oxide 6%, Titanium Dioxide 3.2%
Inactive Ingredients:
Water, Ethylhexyl Palmitate, Sodium Acrylate/sodium Acryloyldimethyl Taurate Copolymer And Polyisobutane And Caprylyl/capryl Glucoside, Glyceryl Stearate And PEG-100 Stearate, Cyclomethicone, Dimethicone, Polysorbate 80, C12-15 Alkyl Benzoate, Cetyl Alcohol, Polyglyceryl-6 Isostearate, Propylene Glycol, Sodium Levulinate, Allantoin, Disodium EDTA, Panthenol, Fragrance, Aloe Barbadensis Leaf Juice, Anthemis Nobilis Flower Extract, Camellia Japonica Leaf Extract, Magnesium Ascorbyl Phosphate, Tocopherol, Acetyl Cysteine, Genistein, Pinus Pinaster Bark Extrac,t Retinyl Palmitate, Thioctic Acid, Zinc Gluconate, Anthocyanins, Tagetes Erecta Flower Extract, Ubiquinone.
Looking around, I'm starting to wonder if they changed formulations or something - I bought mine about a year ago... |
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Wed Mar 21, 2007 8:53 pm |
That's so bizarre, perhaps they have changed their formulation.
Either way there's a few ingredients in there I'd rather avoid. I didn't think it would be so hard to find a decent sunscreen  |
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Wed Mar 21, 2007 9:09 pm |
| lorisu wrote: |
That's so bizarre, perhaps they have changed their formulation.
Either way there's a few ingredients in there I'd rather avoid. I didn't think it would be so hard to find a decent sunscreen |
Tell me about it - I hate spending so much on something just to find out it irritates my skin or breaks me out! So far, the DDF one that I have has been working out, but I wouldn't be surprized if it's been changed. I emailed them tonight to ask.
I've also been eyeing the Rosacea Care Sunscreen "30", but I just can't bring myself to try again ... |
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Wed Mar 21, 2007 10:06 pm |
wow...that's a very informative guide on sunscreen. thank you! 
as of now, i am using juice organics spf 30 for my face and california baby spf 30 no fragrance for body.
i like that because i'm trying to avoid chemicals and the juice organics doesn't leave my face pasty white.
the california baby takes a while to soak in but also fades without leaving a white residue. |
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Thu Mar 22, 2007 5:20 am |
just want to throw this out there...
I think it's best to use NON micronized titanium and zinc so they are not absorbed into the bloodstream.
VERY difficult to find, but it looks like ddf's product is not micronized.
haven't tried this, but got good review at the skin bio forum:
http://store.annabellina.com/spfsu8oz.html
also...
there may be some issues with using the zinc at the same time as using copper peptides???
i plan on getting some of skin bio's suntanning lotion - but i'm more in the moderation camp when it comes to sun exposure.
thanks for starting this thread |
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Thu Mar 22, 2007 5:46 am |
Aww thanks Iaimei but I feel I'm more the messenger as all the info was Chilli's hard work.
Paula Begouin is another good source of info
Cosmetics Cop
| iaimei wrote: |
Hi rebelgirl,
You are certainly an expert in this topic. Thank you so much for the detailed and valuable information. |
I can understand your worry as there's so many things we use and so many scare stories out there. I used to be worried about the computer screen cos I'm always on it  but Paula Begouin cleared that up for me. I can't find her article but here's another good one. How much radiation is your pc screen emitting?
| iaimei wrote: |
| "I have a dumb question to ask: do you think the LED light from those home use hand held devices would have any adverse impact on your skin much like the tanning bed? |
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_________________
"When you arise in the morning, think of what a precious privilege it is to be alive - to breathe, to think, to enjoy, to love." |
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Thu Mar 22, 2007 11:03 am |
| bubbleoffplumb wrote: |
just want to throw this out there...
I think it's best to use NON micronized titanium and zinc so they are not absorbed into the bloodstream.
VERY difficult to find, but it looks like ddf's product is not micronized. |
Could you elaborate on this? What particle size are you referring to when you say micronized? Also, what evidence do you use to draw the conclusion that these micronized particles are absorbed into the bloodstream? I do think that the non-micronized zinc oxide and titanium dioxide offer better UVA protection than the micronized stuff so if that is a concern then this would be one reason to chose the non-micronized versions but I haven't seen anything that would indicate that the micronized versions are unsafe becasue they can be absorbed into the skin. I suppose too that it depends on how you define micronized! Yet I am starting to see that the bulk of the evidence seems to indicate that even the very small particles (20-30nm) do not penetrate the skin.
| Quote: |
also...
there may be some issues with using the zinc at the same time as using copper peptides??? |
Carol Demas said in her book "Make your own effective cosmetics treatments" that CPs should not be used with zinc oxide because the free ions compete for the same receptor sites. I am not sure what that means exactly but it would support what you said about not using zinc oxide and CPs at the same time. |
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Thu Mar 22, 2007 11:08 am |
| iaimei wrote: |
I have a dumb question to ask: do you think the LED light from those home use hand held devices would have any adverse impact on your skin much like the tanning bed? |
Of the LED light devices that I am aware of I know this-they do not emit UV radiation. They emit wavelengths that fall under the visible light part of the spectrum and alot of them also emit infrared light so it is not like a tanning bed at all which emits UVA radiation. I do have vague concerns about the infrared radiation emitted by some of these LED devices but this has nothing to do with UV radiation. |
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Thu Mar 22, 2007 11:17 am |
I also want to know the result! |
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Fri Mar 23, 2007 7:20 am |
| TheresaL wrote: |
| bubbleoffplumb wrote: |
just want to throw this out there...
I think it's best to use NON micronized titanium and zinc so they are not absorbed into the bloodstream.
VERY difficult to find, but it looks like ddf's product is not micronized. |
Could you elaborate on this? What particle size are you referring to when you say micronized? Also, what evidence do you use to draw the conclusion that these micronized particles are absorbed into the bloodstream? I do think that the non-micronized zinc oxide and titanium dioxide offer better UVA protection than the micronized stuff so if that is a concern then this would be one reason to chose the non-micronized versions but I haven't seen anything that would indicate that the micronized versions are unsafe becasue they can be absorbed into the skin. I suppose too that it depends on how you define micronized! Yet I am starting to see that the bulk of the evidence seems to indicate that even the very small particles (20-30nm) do not penetrate the skin.
| Quote: |
also...
there may be some issues with using the zinc at the same time as using copper peptides??? |
Carol Demas said in her book "Make your own effective cosmetics treatments" that CPs should not be used with zinc oxide because the free ions compete for the same receptor sites. I am not sure what that means exactly but it would support what you said about not using zinc oxide and CPs at the same time. |
I have been searching the web - looking for verification of my (dramatic  ) statement above. seems the jury is still out on whether these smaller particles are considered dangerous.
there's extensive chit/chat on the skn biology forum about finding a sunscreen - and I seem to remember reading a response from Pickart concerning this - darned if I could find it now. the only thing that's clear is that he does not like the micronized particles on the skin. in (what's left of) my mind - I guess i assumed it had to do with absorbtion ) these statements clarify my concerns -
PLEASE NOTE: these are NOT published/medical findings - they came from various (questionable?) web sources - I added the "BOLD":
"Titanium dioxide and zinc oxide are typically used in sunscreen products and cosmetics and have been generally considered safe.
However, studies show that cellular damage from titanium dioxide, occurs with exposure to sunlight, and depends upon the type of titanium dioxide and the size of the particles. Cellular damage has been shown to occur when the particle size is smaller than the size of the cell. The smallest particles, the micronized or nanoparticles, are the most injurious. Some say that the large particles are less harmful, yet others say they’re safe.
According to Lori Stryker of the Organic Makeup Company, who has done considerable research into the safety of titanium dioxide in its various forms, “if the particle size is too large for the cell membrane to allow it passage internally, then the danger of intracellular mutation is not there.” Still, there are those who say that even the larger particles can pass through the skin to some degree, and are just less absorbable than the small particles. They suggest that even the larger particles may contribute some harm.
Obviously, the safety of the larger particles of titanium dioxide and zinc oxide is not well established and agreed upon within the scientific community. There is clearly a need for more research into the mechanism of how the larger sized particles of titanium dioxide and zinc oxide affect the skin and the cells beneath the skin when exposed to the sun."
and
"Studies have shown that ultrafine particles can penetrate the skin, enter the cell and cause DNA damage. There is concern that this could possibly result in skin cancer. These studies have been done on titanium dioxide.
As of 2005, "The National Toxicology Program is developing a broad-based research program to address potential human health hazards associated with the manufacture and use of nanoscale materials," using existing testing methods and developing new methods to "adequately assess potential adverse human health effects."
Currently, the FDA’s National Center for Toxicological Research and the National Toxicology Program’s Center for Phototoxicology are conducting research "to examine the potential dermal toxicity of nanoscale materials." In this study they are investigating titanium dioxide and zinc oxide.
Based upon the studies being done and in development, it appears that not only are micronized minerals not well defined and not adequately tested, but also, the technology necessary to adequately test them for safety has not yet been completely developed."
"According to the FDA, there is no official definition of "micronized," but they refer to these particles being less than 250 nanometers, and they also regard nanoscale titanium dioxide as "micronized titanium dioxide."
the above is from:
http://feeds.feedburner.com/DyingToLookGood
and this from:
http://www.thegreenguide.com/blog/worrywart
"And, according to Dr. Kazutaka Hirakawa of Shizuoka University in Japan, TiO2 under normal conditions does not pose a toxic threat as a sunscreen. But because the jury's still out on the possible health impacts of nano micro-particles, sometimes used to make zinc or TiO2-based sunscreens transparent, we've selected products that are either non-micronized or use micro-particles in the bigger range. The sunscreen smart shopper's card specifies whether micronized formulations are used. For now, it's good to know that the Australian government's January, 2006 survey of studies to date on micronized sunscreens concludes that "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."
JUST TO REITERATE:
the above are NOT from verified medical/scientific sources - reader beware
that said -
i've also read (from various internet sources) that the larger particles do provide better protection.
because they stay on the surface of the skin,
but they are not as "cosmetically elegant" as the smaller particles.
a few other things worth noting....
it is my understanding that titanium dioxide primarily provides protection against UVB and short-wave UVA, but not long-wave UVA.
zinc oxide--provides protection against UVB and both short and long UVA radiation.
at the skin bio forum, Dr. Pickart has mentioned on more than one occasion (tho, I've never read a post from anyone who experienced this) that people's pores have appeared larger after using zinc oxide  
for me personally, until I learn more,
I'm gonna stick with the larger non-micronized particles.
if nothing else, it'll narrow down the selection . |
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Fri Mar 23, 2007 8:24 am |
bubbleoffplumb-thanks for your reply and an extra thanks for the disclaimer! I will do some research on the information that you provided links to when I have the time but offhand the sources seem IMO to be a little alarmist and like you said do not offer evidence to back up their claims or views.
Now a few comments..........
As to the size effecting how well these sunscreen ingredients work, here is what I have read on this. As the particle size decreases UVB protection increases but UVA protection decreases. So the microfine and nano particle mineral sunscreens will offer better UVB protection but not be as effective as the non-microfine ones at UVA protection. Although I do think that the microfine zinc oxide does still offer good UVA protection. These size dependant variances in UV protection are due to factors other than whether it is absorbed by the skin or not so I would say that it is not quite correct to say that the larger particles provide better protection becasue they stay on the surface of the skin while the smaller ones don't. Of course you are absolutly right that the smaller particles are alot more cosmetically elegant, this has to do with the fact that they let alot more visible light through while the larger particles reflect this light. If you think of visible light as 400nm and up and think how the microfine particles let more of this through then if you go down a few nanometers into the UVA range you can only guess that the microfine ones will let more of that through too. So that is how it offers less UVA protection. I hope this makes sense!!
Your understanding on titanium dioxide mostly protecting against UVB and UVAII (short wave UVA) agrees with what I have read on this too. It does provide protection against UVAI (long wave) but that protection IMO is not adequate and is why I personally chose to not use titanium dioxide only sunscreens or sunscreens that are mostly titanium dioxide with only a little zinc oxide.
One concern that I do have is that uncoated titanium dixoide and zinc oxide have been shown to generate free radicals when exposed to UV radiation. I am almost certain that this happens regardless of particle size but particle size may be an issue here if the particles do penetrate the skin. I am still researching this to see if it really matters that they generate free radicals especially if they just sit on the skin instead of penetrating. I get the impression that it is only a concern if the particles penetrate the skin but I am not certain on that. If this is a big concern then you would of course want to go with the coated versions and not the uncoated ones!
Here is a link if you are interested. It is to a summary of evidence for the saftey of nanoparticle zinc oxide and titanium dioxide sunscreens. I beleive it is the research that the Austrailian government used to determine that these were safe. I am actually still making my way through all the studies but it is IMO a very good, non-alarmist resource.
http://www.tga.gov.au/npmeds/sunscreen-zotd.pdf |
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Fri Mar 23, 2007 8:43 am |
| On top of my alpha hydrox spf15 sunscreen, I just apply mmu (contains lots of titanium dioxide and zinc oxide) to provide more sun protection. I guess mmu could be considered as some sort of physical sun screen? |
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Fri Mar 23, 2007 9:46 am |
TheresaL
thank you for the link!
just the sort of information i'm looking for.
all I need now is a cuppa coffee and a dictionary - it'll keep me entertained for hours.
please do add any other info you come across
I'm an info-maniac at heart. |
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Fri Mar 23, 2007 6:30 pm |
Wow so much information for me to digest. I am really learning a lot here  |
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Fri Mar 23, 2007 6:34 pm |
| sunscreen again, good lecture. |
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Fri Mar 23, 2007 11:17 pm |
Wow, lots of good info here.
I really like Juice Beauty SPF 30, a physical block.
Not sure how big the "particles" are, but I'm happy with this one! So i'm sticking to it.
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SKIN: 33,fair.My work env't is skin hell! (flight attend. = dryness&eye circles!) AM: Lavantine Cleansing Oil, squalane, ISOMERS carnosine complex (250x more pow'ful than Idebenone), eye cream varies, JuiceBeauty Antiox Serum, Anthelios SS. PM: Lavantine, squalane, Remergent DNA Repair. Want: Silk Dust |
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