Nano Sunscreen Particles
Not Too Small for Your Own Good

Recently there has been an increased concern expressed about the absorption into the skin and ultimately into the blood stream of nanoparticles of zinc (also ZnO) and titanium (Ti02) when used in sunscreens. The question of nanoparticle absorption has been asked of Elta MD, so we researched the collective clinical data on this issue. This is an aggregation of the clinical analysis and scientific conclusions on this topic.

The Basics:

First, defining a set of basic standards and terms is helpful in understanding this topic:

Sunscreen Nanoparticles

·         Nanoparticles are generally described as particles ≤ 100 nanometers (nm)

• Particles being used by EltaMD for sunscreens exist in our products in the following ranges:
• Zinc – 40 nm to 140 nm
• Titanium – 50 nm to 150nm

  Skin

  • Any particles that have a molecular weight greater than 500 g/mole have negligible penetration of intact skin. 500 g/mole equates to a size of approximately 1 nm.
  • Hair follicles can provide for a depression where particles can accumulate, but offer no larger opening than intact skin. Hair follicles make up approximately 0.1% of skin surface.

    The Conclusions:

    The data suggests that nano zinc and titanium do not penetrate the skin. Numerous peer-reviewed studies have validated this information. Only if the integrity of skin has been compromised, can any of the particles or chemicals contained in sun screens enter the body. 

    EltaMD products have been designed to provide the highest possible UV protection using the safest natural materials while avoiding the use of harmful chemicals that can irritate, damage skin or penetrate the skin.

    References:

    Below is a list of clinical evaluations that were conducted to address skin penetration of nano particles. Many tests conducted in several countries have confirmed the conclusion stated above.

    Baroli B, Ennas MG, Loffredo F, Isola M, Pinna R, Lopez-Quintela MA. 2007.

    Penetration of Metallic Nanoparticles in Human Full-Thickness Skin. J Invest Dermatol.

    BASF, i.A. Schulte, BASF Aktiengesellschaft, Regulatory Affairs Cosmetic Solutions, Z-COTEâ Grades – Statement on Particle Size Distribution and Safety.

    Borm PJ, Robbins D, Haubold S, Kuhlbusch T, Fissan H, Donaldson K, et al. 2006. The potential risks of nanomaterials: a review carried out for ECETOC. Part Fibre Toxicol 3: 11.

     Cross SE, Inness B, Roberts MS, Tsuzuki T, Robertson TA, McCormick P. 2007. Human Skin Penetration of Sunscreen Nanoparticles: In-vitro Assessment of a Novel Micronized Zinc Oxide Formulation. Skin Pharmacol Physiol 20(3): 148-154.

    Gamer AO, Leibold E, van Ravenzwaay B. 2006. The in vitro absorption of microfine zinc oxide and titanium dioxide through porcine skin. Toxicol In Vitro 20(3): 3001-7.

    Lademann J, Weigmann H, Rickmeyer C, Barthelmes H, Schaefer H, Mueller G, et al. 1999. Penetration of titanium dioxide microparticles in a sunscreen formulation into the horny layer and the follicular orifice. Skin Pharmacology and Applied Skin Physiology 12: 247-56.

    Nohynek GJ, Lademann J, Ribaud C, Roberts MS. 2007. Grey goo on the skin? Nanotechnology, cosmetic and sunscreen safety. Crit Rev Toxicol 37(3): 251-77.

     

    SCCNFP. 2000. Opinion concerning Titanium Dioxide. Opinion: European Commission – The Silent Committee on Cosmetic Products and Non-Food Products Intended for Consumers.

     

    TGA. 2006. Safety of sunscreens containing nanoparticles of zinc oxide or titanium dioxide. Australian Therapeutic Goods Administration.

     

    © 2009 Swiss-American Products

    LMP   Issued 10/09