After noting last week that one of the experts at the nanotechnology hearing held by Canada’s House of Commons Standing Committee on Health seemed unfamiliar with nanosunscreens and skin (he claimed they can’t penetrate the skin and I stated incorrectly that they can), this June 24, 2010 item by Laura Walter for EHS Today caught my eye,

Two experts from Wake Forest University School of Medicine discussed the good, the bad and the ugly aspects of nanomaterials at the American Society of Safety Engineers (ASSE) Safety 2010 conference in Baltimore.

…

[Christopher] Kolbash pointed out that nanomaterials may be able to penetrate cellular membranes. They are respirable, so they can be inhaled deep into the lungs and then possibly pass into the bloodstream. Some researchers also are concerned that nanomaterials could migrate through the skin.

In other words, there is no equivocal proof for either position regarding nanoparticles as penetrating or not penetrating the skin. [I have updated my June 23, 2010 posting with a correction.]