Nanoparticles Penetrate the Intact Skin, Greater Penetration of Damaged Skin

BrooklynDodger(s) comment: Currently a prominent use of nanoparticles is nano sized titanium dioxide (an IARC 2B carcinogen) in skin treatments. Another post noted that these titanium dioxide particles could penetrate the olfactory epithelium and find there way the brain. Here's a study of silver nanoparticles (does anyone know what they might be used for?) penetrating the regular skin in a laboratory study.

This study should be considered hazard identification - at least as far as exposure goes. The next step in the NAS paradigm is dose-response assessment. We need more than two points - intact and damaged - and more than a single application in a laboratory system.

ToxicologyVolume 255, Issues 1-2, 8 January 2009, Pages 33-37

Human skin penetration of silver nanoparticles through intact and damaged skin

Francesca Filon Laresea, , , Flavia D’Agostina, Matteo Croserab, Gianpiero Adamib, Nadia Renzic, Massimo Bovenzia and Giovanni Mainad
"There is a growing interest on nanoparticle safety for topical use. The benefits of nanoparticles have been shown in several scientific fields, but little is known about their potential to penetrate the skin. This study aims at evaluating in vitro skin penetration of silver nanoparticles. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. Physiological solution was used as receiving phase and 70 μg/cm2 of silver nanoparticles coated with polyvinylpirrolidone dispersed in synthetic sweat were applied as donor phase to the outer surface of the skin for 24 h. The receptor fluid measurements were performed by electro thermal atomic absorption spectroscopy (ETAAS). Human skin penetration was also determined by using transmission electron microscope (TEM) to verify the location of silver nanoparticles in exposed membranes.
Median silver concentrations of 0.46 ng cm−2 (range Our experimental data showed that silver nanoparticles absorption through intact and damaged skin was very low but detectable, and that in case of damaged skin it was possible an increasing permeation of silver applied as nanoparticles. Moreover, silver nanoparticles could be detected in the stratum corneum and the outermost surface of the epidermis by electron microscopy.
We demonstrated for the first time that silver applied as nanoparticles coated with polyvinylpirrolidone is able to permeate the damaged skin in an in vitro diffusion cell system