Micronized titanium/zinc safe?

mattc · Joined: 10 Mar 2006 Posts: 3

Hello

I've heard that there may be safety concerns with micronized titanium dioxide and zinc oxide, because the "nanoparticles" can penetrate the skin and cause damage....Is there any validity to this?

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

Micronized Zinc has particles in the range 100-200 nm. This is the size of some viruses. As far as I understand viruses don't penetrate skin physically, they need 'receptors' to pull themselves inside the cells.

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

That's right. Even individual proteins, which are smaller than that, generally do not penetrate skin significantly. Besides, zinc in microgram amount is relatively non toxic. (Although titanium might be if absorbed)

mattc · Joined: 10 Mar 2006 Posts: 3

Thanks for the responses! I found a site that has micronized titanium dioxide that is supposedly in the 10 to 20 nm range....But it sounds like this isn't anything to worry about.

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

At least in theory, titanium has more potential for toxicity than zinc and 10 nm size might be small enough to penetrate under certain circumstances. Whether this represents any cinically significant danger is hard to say without running a study.

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

Mattc, could you give the link of the site? 10nm size of Titanium dioxide is kind of hard to achieve with the current technology so I wanna check that out.

mattc · Joined: 10 Mar 2006 Posts: 3

I found it on one of those ingredient supply sites:

www.makingcosmetics.com

Click Ingredients > Sunscreens. Scroll down to their Titanium Dioxide (micronized). The description states that the primary particle size is 10-20 nm. Could this be a typo...or false advertising?

MC82 · Joined: 14 Mar 2006 Posts: 3

Can anyone point me in the right direction in finding out more about the benefits of zinc? Im about to try a new product and would love to learn more since I have never tried a zinc based serum before.

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

I searched the internet and it turned out that indeed there is Titanim Dioxide with particles about 10nm. We can't say if the one sold by the site has such particle size really. I would refrain from using TiO2 with such small particles till the controversy about it toxicity clears up.

I noticed also that the site sells micronized ZnO2, particle size < 200 nm at very acceptable price.

I bumped on the following article about the safety issues with the nanoparticles:
http://www.etcgroup.org/article.asp?newsid=392

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

Thanks for finding such a study. This is in line with concerns expressed above. At this point, it wouild be wise to refrain from using TiO2 sunscreens with such nanoparticles.

joey · Joined: 19 Dec 2005 Posts: 27

Orangehrzn,

Thanks for this great info .
I am using Neutrogena sunblock SPF 30 it has titanium dioxide.... it is white when applied on my skin before outdoor exercise . Is this one ok ?
any suggestion for a good zinc sunscreen ?

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

The study whose pdf file I linked does NOT prove that nanoparticles penetrate stratum corneum under normal conditions. First, the skin in that study was bent at 45 degress 20 times per minute (it is not clear what exactly was meant by that), which may create microcrevices. Second if they observe penetration of even one particle in a given skin sample they count that sample as 'penetrated'. If you look at their pics the number of particles that penetrated is a few per sample versus god knows how many particles deposited on stratum corneum.

The study shows that under certain extreme conditions stratum corneum can be penetrated by a few particles but that is all. Notice they say that skin that wasn't bent wasn't penetrated in any of the samples. On the other hand, the smalles particle they studied was 0.5 micrometers = 500 nm, it is not clear if a particle of 10 nm would penetrate more.

orangehrzn · Joined: 23 Feb 2005 Posts: 1005

MaryDarnell · Joined: 29 Mar 2006 Posts: 1 Location: Miami, FL

You have to keep in mind that the Z-Cote micronized zinc oxide comes in two forms. There is z-cote and z-cote hp1. Z-cote is just the zinc oxide micronized, but the Z-Cote HP1 is zinc oxide coated with Triethoxycaprylysilane. I recommend just using a product with the regular micronized zinc oxide, it creates the same protection but isn't pasty (the z-cote hp1 with that Triethoxycaprylysilane coating I have found to be a little pasty, plus I don't know what the health ramifications are of that substance are). As far as Titanium Dioxide, I'd recommend just using regular instead of the microfine, especially considering it has a higher sun protection factor than zinc so you can use it at lower levels and still get a higher SPF. I asked the manufacturer about the SPF of zinc and titanium and they said in both the regular and micronized forms zinc oxide has about an SPF of 1 per 1% used (so if it was at 5% in a formula it would have an SPF of 5) however they said the Titanium (whether micronized or regular) was about 3 SPF points per 1% used, so an SPF of 15 would require 5% Titanium Dioxide. I'd say use a sunscreen with micronized Zinc Oxide but regular Titanium, then just use less titanium to keep from getting a pasty looks (such as maybe 3% titanium dioxide and 6% micronized zinc oxide for an SPF of 15). As long as the titanium is at 5% or less and the micronized zinc is at 7.5% or less it shouldn't be too pasty, though you may have to expirement with different products to find the least pasty one. I've had good results with the Sunguard Moisturizing Complex at xeridianskincare.com that has an SPF of 20 (it's for the face) and they have a body product with an SPF 15. Both are still a white lotion texture (not a clear gel or anything) but they don't leave me pasty. Both goes on a little white but after you smooth it over your face and body it disappears.