In response to the article "Time to Regulate Nanoparticle Safety?"[1] it occurred to me that there is a recognized disease that seems to parallel the fears of nanoparticle absorption through the skin. Podoconiosis, an endemic disease of agricultural workers in the tropics (commonly called "mossy foot" disease) is thought to be caused by absorption of ultrafine silica particles from volcanic soil through bare feet.[2] These ultrafine particles cause debilitating non-filarial elephantiasis and affects possibly 10% of the agricultural workers in the endemic areas. Perhaps studying the etiology of this disease would shed light on possible side effects of unintentional epidermal absorption of nanoparticles.