Engineered metallic nanomaterial particles (MENAP) represent a significant break- through in developing new products for use by consumers and industry. Skin application (e.g., via creams and sprays containing nanoparticles) may provide a key route of potential intake of MENAP and can lead to retrograde transport from nerve endings in the skin to the somatosensory neurons in dorsal root ganglia (DRG). This paper uses a novel theoretical model (stochastic threshold microdose [STM] model) to characterize survival of DRG neurons exposed in cell culture replicates to copper nanoparticles, based on published data. Cell death via autophagy is assumed here to occur as a result of the uptake (called hits) of the nanoparticles by mitochondria. Theoretical results are presented for the existence of a hypersensitive fraction (about 20%) of neurons that are killed in significant numbers when on average > 1 hit to the at-risk mitochondria occurs. Further, most hypersensitive neurons appear to be killed by a cumulative exposure of about 2,000 micro- molar-hours and the remaining resistant cells may have dysfunctional mitochondria. Based on these theoretical findings, it is predicted that repeated exposure (e.g., over years) of the skin of humans to MENAP could lead to significant nervous system damage and related morbidity.
Scott, Bobby R
"ARE SOME NEURONS HYPERSENSITIVE TO METALLIC NANOPARTICLES?,"
Dose-Response: An International Journal: Vol. 10
, Article 5.
Available at: http://scholarworks.umass.edu/dose_response/vol10/iss1/5