- This topic is empty.
-
Posts
-
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?Honestly, I don’t know Peter. I haven’t seen any research that would specifically answer your questions about sunscreen particle coating.
I’ve found an article from Europe: Collipa Opinion on Titanium Dioxide, which is the organisation which approves sunscreens in Europe.
“The photocatalytic activity can be greatly reduced by coating the surface with various compounds. For example, the photo-catalytic
activity of titanium dioxide when coated with silicon dioxide and alumina to the extent of 3.5%
of the weight of titanium dioxide will reduce photo-catalysis to 1% of that found in the uncoated
titanium dioxide. Although a few studies showing coating stability have been provided, it is important to know whether this, for example, could lead to the release of aluminium ions from alumina that may be present after the coating process and which may dissolve in the final formulation. It is less clear how stable the coatings are in final formulations. The photocatalytic activity data, measured in formulations, indicate that either some of the materials were not completely coated, or some of the coatings were not stable in the formulations. SCCS has considered acceptable an arbitrary level of up to 10% photocatalytic activity of a coated or doped nanomaterial, measured in terms of % to a reference standard”….”It is therefore possible that a trace amount of nanoparticles may remain embedded in stratum corneum, in hair follicles, and/or sweat glands, potentially over several days after skin application of a product and washing off”…”Three other rutile coated nanomaterials also have comparatively lower but still significant levels of photocatalytic activity (S75-C, S75-D,
4 S75-E)”…”further investigations over longer post-application periods taking into account the potential photocatalytic activity post-application, whilst allowing for appropriate lag-time and using realistic application scenarios may be necessary to ascertain that they do not pose a risk due to photocatalytic activity.”There’s also a table with the remaining photo-catalytic activity after coating, it varies from 0.3% to 11.8%. Trimethoxycaprylylsilane still has 10% activity, alumina/stearate around 7% and the lowest with alumina/silicones 0.3-0.7%Well there not that many real non nano sunscreens, and besides some companies are not completely honest about what they’re using. I would rather use a coated nano sunscreen that doesn’t leave a white cast, then a sunscreen with physical filters that are not coated without knowing for sure if there are nano particles present.
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.
@Peter Thanks for raising the awareness about coated ZnO & TiO2.
From my limited knowledge, coated zinc/titanium / micro sizing is proprietary currently… so not too much research out them for us lay people to peruse
The technology differs a lot from company to company. One of the companies that were successful with this technology, Invisible Zinc was a local Australian company but bought over by larger USA company now. IMHO, it’s the best Zinc sunscreen that i can buy here currently.
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
Noted that due to TiO2 smaller size, it has been used more frequently in makeup compatible primers / bb cream / moisturisers etc as opposed to ZnO. UVA protection by TiO2 isn’t as good as ZnO though. We have to be careful as consumers here in AU to lookout for “broad-spectrum” protection since PPD isn’t rated on our sunscreens.The other point is ZnO is toxic if “breathed”, Yet, i have a Japanese sunscreen spray that contains ZnO. peculiar indeed.@escherichia To answer your question plainly. Yes.
I overcome it with a layer of BB cream. No issue. I am Mac NC15, so very fair but i still find the sunscreen too white for my skin.
@escherichia to be fair. ALL the mineral sunscreens will give you a white cast.
You want to consider Babo Botanicals.The white cast is really minimal. I have worn it out (after 2pm) and it seem to have protected me well enough. http://loveneedwant.wixsite.com/blog/single-post/2016/09/24/Review-Babo-Botanicals-SPF40-Daily-Sheer-For-Face-SunscreenBefore
After 2 layers:
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:
- Several in vitro and in vivo studies using both animal and human skin have shown that these nanoparticles do not penetrate the underlying layers of skin, with penetration limited to the stratum corneum. This suggests that systemic absorption is unlikely.
- In conclusion, on current evidence, neither TiO2 nor ZnO nanoparticles are likely to cause harm when used as ingredients in sunscreens.
For the full TGA report on the safety of Titanium and Zinc, please use this link: https://www.tga.gov.au/literature-review-safety-titanium-dioxide-and-zinc-oxide-nanoparticles-sunscreens. The report confirms that all research thus far shows these ingredients to be safe and the best protection from the sun.I refer to the Cytotoxicity and genotoxicity section that even uncoated Nano-TiO2 is not cytotoxic or genotoxic.The TGA have paid such close attention to this topic because Australia is the perennial front runner in cases of skin cancer per capita. They want to know what works to help prevent skin cancer but are also concerned with safety.The Cancer Council Australia reported further in early 2014 that a recent Australian study found that human immune cells (macrophages) exposed to zinc oxide nanoparticles effectively absorbed the nanoparticles and broke them down.So, zinc oxide and titanium dioxide nanoparticles aren’t absorbed through the skin into the bloodstream and, in the event that they do get into the bloodstream (for zinc oxide at least), the body’s immune system can deal with them effectively.The overall conclusion is that there’s no known health risk from these nanoparticles and you can safely use sunscreens that contain them.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.
My dermatologist’s private label sunscreen is SPF50+, tinted (perfect Colour) and it is pure mineral. No white cast, it doubles as a light BB cream/ makeup primer/base. Have noted many dermatologist recommending pure mineral sunscreen.
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.
The previous link may be problematic,
Here again
https://www.tga.gov.au/literature-review-safety-titanium-dioxide-and-zinc-oxide-nanoparticles-sunscreens -
- The forum ‘Ask the Beauty Brains’ is closed to new topics and replies.