I've read in many articles that nano titanium dioxide and zinc oxide are photocatalysts, meaning they can form free radicals under influence of UV light. The definition of what would be considered nano varies between countries, we look at the coated clumped together particles, but in Europe they look at the particles seperately. I've seen many "non-nano" sunscreens labeled as "nano" in Europe. So I would rather choose a sunscreen with coated particles, than a "non-nano" sunscreen that isn't coated, not knowing if it would be considered nano under stricter regulations.
I was wondering, coating the particles reduces the photocatalytic capacity, but to what extend? Is it for example 90% or less? How stable are these coatings? Are the particles photostable during a whole day? And are there possible other negative side effects from these sunscreen ingredients?
Comments
A sunscreen may be considered non-nano if more than 50% of the particles are larger than 100nm. So theoretically still 49% could be in the nano-range.
Size of Physical Blockers (as an example)
Zinc oxide size: 200-1000 nm
Zinc Oxide, Micronized: 30-55nm
Zinc Oxide, Micronized & Coated: 86nm
Titanium oxide: 200-250 nm
Titanium Dioxide, Micronized: 15 nm
Australia's Therapeutic Goods Administration (TGA) website (the TGA is the Australian equivalent of US's FDA) has rigorously studied nano particles in sunscreen. They conducted an updated review of the scientific literature in relation to the use of nanoparticulate zinc oxide and titanium dioxide in sunscreens and concluded that:
@preciousia
The articles do say that nano titanium dioxide in both rutile and anatase form are photocatalysts, however because they concluded the penetration is limited to the stratum corneum, they say it doesn't do any harm. That's why inhaling the particles is cytotoxic and genotoxic. Titanium dioxide has more photocatalytic activity and zinc oxide has a higher penetration risk, so for both of them a stable coating would be beneficial. UV-radiation will cause free radicals deep in your skin, but free radical formation with particles that might end up deeper in skin after very long daily usage doesn't sound very good to me either. You have to realise there are almost no studies which have investigated the effect of using sunscreen on human skin every day for several years. Especially the long term studies on impaired skin are scarce. So it can be concluded that physical filters are safe and okay to use in cream form, but I do think there still is some uncertainty and we might find better alternatives in the future with the first 8 sunscreens I mentioned in my post being good options.
Agree that when applied, there is no risk. Inhaled is another matter! Due to titanium dioxide smaller size perhaps, I do notice it is present in many makeup powders eg Bare Minerals foundation ... If inhaled accidentally it is not good. I dare dare bare minerals titanium is proper uncoated too? Need to double check.
I am positive my sunscreen spray contains zinc oxide (unclear if coated). Can't read Japanese. At least THA concluded that the body is able to break down Zinc Oxide if it is absorbed.
I believe many people here in Australua are living examples of using the mineral sunscreens everday for many years. I myself have been using mineral sunscreens (doctor's private label) for over 10 years.
Those who yacht /boating for a hobby/livelihood use invisible Zinc or even Zincstic. I'll find out what works from those in the Australian sun more than me.
The TGA have been studying this issue of nano particles for over 10 years as well since 2006. Will check to see if all 8 chemicals from your list are approved here in Australia, eg Tinosorb is not approved in USA but approved in Australia. Tinosorb absorbs heat which is a concern for my pigmentation.
Here again
https://www.tga.gov.au/literature-review-safety-titanium-dioxide-and-zinc-oxide-nanoparticles-sunscreens
@preciousia
As far as I know most make up powders use pigment grade titanium dioxide, meaning non nano. But there are also powders where they list titanium dioxide [nano]. I haven't seen many studies where they follow a large group of persons for several years, most studies only last for 2 weeks to 6 months.
Unfortunately we don't have that many options of fragrance free physical sunscreens in Europe. Maybe Tinosorb M is the best hybrid, it absorbs some radiation and scatters/reflects some.
ingredients:
Gluten-free: Yes
Paraben-free: Yes
Unscented: Yes
Shade: Fair
Active Ingredients: Titanium Dioxide 23.9%; Zinc Oxide 24.1%
Inactive Ingredients:
Fair: Mica, Dimethicone/Vinyl Dimethicone Crosspolymer, Corallina Officinalis Extract, Methicone, Dimethicone, Calcium Silicate, Triethoxycaprylylsilane, Sodium Sulfate, Laureth-4, Iron Oxides (CI77491, CI 77492, CI 77499)
Shade: Medium
Active Ingredients: Titanium Dioxide 23.9%; Zinc Oxide 24.1%
Inactive Ingredients:
Mica, Dimethicone/Vinyl Dimethicone Crosspolymer, Algae Extract, Mannitol, Methicone, Dimethicone, Calcium Silicate, Triethoxycaprylylsilane, Sodium Sulfate, Laureth-4, Diatomeaceous Earth, Zinc Sulfate, Iron Oxides (CI 77491, CI 77492, CI 77499)
Shade: Tan
Active Ingredients: Titanium Dioxide 23.9%; Zinc Oxide 24.1%
Inactive Ingredients:
Mica, Dimethicone/Vinyl Dimethicone Crosspolymer, Algae Extract, Mannitol, Methicone, Dimethicone, Calcium Silicate, Triethoxycaprylylsilane, Sodium Sulfate, Laureth-4, Diatomeaceous Earth, Zinc Sulfate, Iron Oxides (CI 77491, CI 77492, CI 77499)
Shade: Deep
Active Ingredients: Titanium Dioxide 23.9%; Zinc Oxide 24.1%
Inactive Ingredients:
Mica, Dimethicone/Vinyl Dimethicone Crosspolymer, Algae Extract, Mannitol, Methicone, Dimethicone, Calcium Silicate, Triethoxycaprylylsilane, Sodium Sulfate, Laureth-4, Diatomaceous Earth, Zinc Sulfate, Chromium Oxide Greens (CI 77288), Iron Oxides (CI 77491, CI 77492, CI 77499)
I must have been a sucker. i bought this Zinc oxide powder from Japan
I'll be happy to guinea pig and do swatch test and feedback on the texture / if sticky / white cast etc of all the sunscreens i will be trying.
I have been using my dermatologist's sunscreen for over 10 years. One brand. So there's a lot of sunscreen to try but only one face. If you really want to try something. i will be happy to mail you a sachet in the post, a sample of the sunscreen sealed it in a mylar bag
With compliments. If you like it, you can get it from anywhere, if not. no worries. i understand what it's like to buy a whole bottle and not like the product (kind of what i am doing with my Moogoo... dreading)
TBH most mineral sunscreens are awful in texture, white cast! Nothing. not even the "invisible" ones are really invisible. They "reflect". Some girls who are really fussy have special "day foundation" and "night foundation"... erm the diff is no flashbacks when camwhoring.
Coola is a very good brand. (i never tried) It really depends on what you define as white cast. If you see the Babo Botanicals swatch i did, is that acceptable? I am pretty fair. MAC NC15. So it's easy when buying makeup, i'm usually the lightest shade, and sometimes the lightest shade is too dark for me
I found moisturisers with sunscreen good for layering but NOT good as the main source of sunscreen.
My dermatologist always say.. get the sunscreen. not the multi-purpose product.
i refer to Almay new marketing campaign, digging at the Korean 10 step routine.
no way i am using their product for all my needs. Jack of all trades...
is Peter is right about The chemical filters, this is the one i really want to try
Kanebo ALLIE Extra UV Gel SPF50+ PA++++
Active Ingredients: Zinc Oxide, Octinoxate, Uvinul A Plus & Tinosorb S
Skinfit technology making it more resistant to water, sweat and sebum therefore last longer
Includes blend of skin beautifying treatment
Full ingredients here: http://www.ratzillacosme.com/sun/kanebo-allie-extra-uv-gel-mineral-moist-neo/