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Wed May 09, 2012 2:50 am |
That micronized and nano zinc isn't actually stable has been known for ages. It breaks down in sunlight, just like any other filter does. Of course, people with $$$ interest in the whole thing and some mad "scientists" would have us believe otherwise, and we (meaning consumers) are shown data relating to classic bulk zinc oxide which has this incredible photo stability and amazing UV absorbtion range from UVC and even some of the visible light spectrum, but that has very little to do with the Finex, Z-Cote, Nanox and other zinc oxide forms used in sunscreens.
Whether that all applies to zinc that's on skin is same question as with titanium dioxide. That one also produces ROS, but whether they damage skin is not said. AFAIK.
Would I stress over it? No. What I personally do is I pick a sunscreen that has coated zinc oxide in it. Coatings of all kinds have always been shown to prolong the life of any sunscreen filter and help reduce ROS and other ugly things produced by sunscreen breakdown. |
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Wed May 16, 2012 8:57 am |
DarkMoon wrote: |
I know and EWG tends to be on the tough side of warnings!
My two Burnout SS are rated 1 for kids and 2 for the clean and clear. I just refuse to go crazy over this I am in South Florida and can't tolerate chemical SS on my face!  |
It makes no sense to fuss over every scientific finding they come up with IMO. It's good to be informed, but not too flustered. When it comes to cancer, I'm personally more concerned with what kind of food I buy in a supermarket, daily level of stress at work, do I live near the cell tower etc., rather than a small amount of SS I apply to my face. |
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Wed May 16, 2012 10:54 am |
From my (very limited) understanding the coating/carrier makes a difference in how stable the zinc particles are? For ex Blue Lizard sunscreen (which is either nano or microfine zinc based) has a silicone carrier. Remember this was an in vitro study of lung cells + nano zinc w/no carrier.
Anyway I'm not going to stress about it either, just keep my eye out for further studies. I use euro sunscreens most of the time but I hate having to order them online + they get expensive because I go through tons.
I sometimes wear a chemical zinc sunscreen around my eyes if I'm going to be outside exercising in the heat. I find US chemical sunscreens are much worse in terms of eye sting/sensitivity than euro chemicals sunscreens. On of the best things for the eye area is just a huge pair of sunglasses. I'm like a mole and practically blind in sunlight because I never go out w/out them. |
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Wed May 16, 2012 11:09 am |
fitgineer wrote: |
lagomorph wrote: |
From my (very limited) understanding the coating/carrier makes a difference in how stable the zinc particles are? For ex Blue Lizard sunscreen (which is either nano or microfine zinc based) has a silicone carrier. Remember this was an in vitro study of lung cells + nano zinc w/no carrier.
Anyway I'm not going to stress about it either, just keep my eye out for further studies. I use euro sunscreens most of the time but I hate having to order them online + they get expensive because I go through tons.
I sometimes wear a chemical zinc sunscreen around my eyes if I'm going to be outside exercising in the heat. I find US chemical sunscreens are much worse in terms of eye sting/sensitivity than euro chemicals sunscreens. On of the best things for the eye area is just a huge pair of sunglasses. I'm like a mole and practically blind in sunlight because I never go out w/out them. |
How can you tell that Blue Lizard has a silicone carrier? The sensitive version was recommended to me, so I've been considering it:
http://www.dermstore.com/product_Blue+Lizard+Sensitive+Sunscreen+SPF+30+Plus_27178.htm
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Ingredients: 10% Micronized Zinc Oxide, 5% Micronized Titanium Dioxide. Purified Water, C12-15 Alkyl Benzoate, Ethylhexyl Palmitate, Ethylhexyl Stearate, Polyglyceryl-4 Isostearate, Cetyl Dimethicone, Copolyol, Hexyl Laurate, Cetyl Dimethicone, Propylene Glycol, Trimethylated Silica/dimethicone, Methyl Glcose Dioleate, Octododecyl Neopentanoate, VP Hexadecene Copolymer, Tocopheryl Acetate (vitamin E), PEG-7 Hydrogenated Castor Oil, Beeswax, Hydrogentated Castor Oil, Sorbitol Oleate, Stearic Acid, Diazolidinyl Urea, Disodium EDTA, Methylparaben, Propylparaben And Ethylparaben.
Shake well prior to use. Apply liberally to dry skin before sun exposure. Children under 6 months of age: ask a doctor. Reapply to dry skin as needed or after towel drying, swimming or sweating. |
What European brands have you tried and liked?
TIA |
Yes on silicones...always look for the ingredients that end in cone eg:
Cetyl Dimethicone listed 2X
Trimethylated Silica/dimethicone |
_________________ I'LL SEE YOU ON THE DARKSIDE OF THE MOON.... |
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Wed May 16, 2012 11:13 am |
Always helpful, DM. Thank you!
DarkMoon wrote: |
fitgineer wrote: |
lagomorph wrote: |
From my (very limited) understanding the coating/carrier makes a difference in how stable the zinc particles are? For ex Blue Lizard sunscreen (which is either nano or microfine zinc based) has a silicone carrier. Remember this was an in vitro study of lung cells + nano zinc w/no carrier.
Anyway I'm not going to stress about it either, just keep my eye out for further studies. I use euro sunscreens most of the time but I hate having to order them online + they get expensive because I go through tons.
I sometimes wear a chemical zinc sunscreen around my eyes if I'm going to be outside exercising in the heat. I find US chemical sunscreens are much worse in terms of eye sting/sensitivity than euro chemicals sunscreens. On of the best things for the eye area is just a huge pair of sunglasses. I'm like a mole and practically blind in sunlight because I never go out w/out them. |
How can you tell that Blue Lizard has a silicone carrier? The sensitive version was recommended to me, so I've been considering it:
http://www.dermstore.com/product_Blue+Lizard+Sensitive+Sunscreen+SPF+30+Plus_27178.htm
Quote: |
Ingredients: 10% Micronized Zinc Oxide, 5% Micronized Titanium Dioxide. Purified Water, C12-15 Alkyl Benzoate, Ethylhexyl Palmitate, Ethylhexyl Stearate, Polyglyceryl-4 Isostearate, Cetyl Dimethicone, Copolyol, Hexyl Laurate, Cetyl Dimethicone, Propylene Glycol, Trimethylated Silica/dimethicone, Methyl Glcose Dioleate, Octododecyl Neopentanoate, VP Hexadecene Copolymer, Tocopheryl Acetate (vitamin E), PEG-7 Hydrogenated Castor Oil, Beeswax, Hydrogentated Castor Oil, Sorbitol Oleate, Stearic Acid, Diazolidinyl Urea, Disodium EDTA, Methylparaben, Propylparaben And Ethylparaben.
Shake well prior to use. Apply liberally to dry skin before sun exposure. Children under 6 months of age: ask a doctor. Reapply to dry skin as needed or after towel drying, swimming or sweating. |
What European brands have you tried and liked?
TIA |
Yes on silicones...always look for the ingredients that end in cone eg:
Cetyl Dimethicone listed 2X
Trimethylated Silica/dimethicone |
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Wed May 16, 2012 11:53 am |
From what I'm told and have read on this subject, coating creates a sort of bubble around the filter substance, so it doesn't come in direct contact with skin. The filter itself might just as well degrade, but most of the mess created in the process is kept away from our skins. There might be other benefits as well, depending on the filter and the material used for the process.
I think it has to be imagined a bit like candied fruit, even if the apple within starts to rot, the sugar coat keeps the stench away.
That doesn't really apply to other substances in any given formula. Coatings vary greatly, in case of zinc oxide, from silicones to plain stearic acid. Coating has to be bonded with the zinc particle, simply adding some saturated fatty acids or silicones to the formula won't do the trick, even if the whole mix is stirred at high speeds for days like any proper sunscreen should be. If it would be that easy, which it obviously isn't, no one would pay the higher price for ready-made coated sunscreen filters, everyone would just throw some dimethicone in their formula. In other words, just because there is some ingredient that under other circumstances might double as coating doesn't yet mean that this particular sunscreen passes as coated-particle sunscreen. For some weird reason, coatings usually don't show up on ingredient lists, similarly as it is with preservatives and solvents used for extracts or actives. For example, Elta MD sunscreen filters are supposed to be coated, but even though lots of silicones and other polymers show up on their INCI lists, sunscreen coatings are not among them. It's infuriating.  |
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Fri May 25, 2012 10:27 am |
I found this article on the skin penetration of nano-sized TnO(2) particles (figured it might be of interest as well):
http://www.ncbi.nlm.nih.gov/pubmed/20118631
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Abstract
It is important for toxicological assessment of nanoparticles to determine the penetration of nanoparticle in skin qualitatively and quantitatively. Skin penetration of four different types of rutile titanium dioxide (TiO(2)) (T-35, 35 nm, non-coating; TC-35, 35 nm, with almina/silica/silicon coating; T-disp, 10 x 100 nm, mixture of almina coated and silicon coated particles, dispersed in cyclopentasiloxan; T-250, 250 nm, non-coating) was determined with in vitro intact, stripped, and hair-removed skin of Yucatan micropigs to study the effect of dispersion and skin conditions. The TiO(2) was suspended in a volatile silicone fluid used for cosmetics, cyclopentasiloxane, at a concentration of 10%. The suspension was applied at a dose 2 microl/cm(2) for 24 hr, followed by cyanoacrylate stripping. The Ti concentration in skin was determined by ICP-MS. T-35 and T-250 easily aggregated in suspension with a mean diameter greater than 1 microm. TC-35 and T-disp showed good dispersion properties with a mean diameter in suspension of approximately 100 nm. No penetration was observed regardless of TiO(2) type in intact and stripped skin. The concentration of Ti in skin was significantly higher when TC-35 was applied on hair-removed skin. SEM-EDS observation showed that Ti penetrated into vacant hair follicles (greater than 1 mm below the skin surface), however, it did not penetrate into dermis or viable epidermis. |
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_________________ Female, born 1985. HW Engineer, Fitness nut. Embarking on the war against the signs of aging... |
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Fri May 25, 2012 1:16 pm |
Coated zinc oxide (any size particle) is best. The problem with zinc is that it was shown to cause respiratory disease in rats when inhaled. Presumably they were subjected to a higher dose than humans would be if we applied it in lotion, cream or ointment form.
The problem with UNcoated titanium dioxide is that its photocatalytic, so its imperative to look for coated TiO2 if you want to use that ingredient in your sunscreen. When in doubt, ask the company that makes it if its coated. |
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Fri May 25, 2012 1:30 pm |
Of course, thanks for the reminder!  |
_________________ Female, born 1985. HW Engineer, Fitness nut. Embarking on the war against the signs of aging... |
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