New study of nanoparticle skin penetration

As engineered nanoparticles (ENPs) become increasingly common in consumer products and the environment, concern over their possible effects on human health also rises. There is concern over the possible penetration of human skin by ENPs. "However, the evidence whether nanoparticles can infiltrate into underlying tissues is conflicting . . .  clarification of the issue is essential. . .."

With this in mind, Christopher. S.J. Campbell of Mango Business Solutions, L. Roderigo Contreras-Rojas, M. Begona Delgado-Charro, and Richard H. Guy, of the University of Bath Department of Pharmacy & Pharmacology have recently published a study "Objective assessment of nanoparticle disposition in mammalian skin after topical exposure" in the Journal of Controlled Release discussin the results of their attempts to measure the extent and depth that ENPs are able to penetrate the skin, in the case of this study the specially cleaned and prepared skin of a pig.

Following exposure to ENPs, the skin samples were examined using a laser scanning  confocal microscope. The reported results indicate that ENPs did not fully penetrate the skin, but only penetrated where a crease or a crack in the skin was present.

The authors note and warn about the limited nature of their research:

It should be emphasised that this research has clearly not been able to make a systematic evaluation of nanoparticle disposition on the skin for the entire spectrum of particle properties, including shape and charge. . . .the observations and their analysis cannot explain, with any degree of certainty, why others have reported nanoparticle uptake into living skin layers following their topical application . . . . While speculative alternatives might be proposed, such as accidental contamination on sectioning, or invisible flaws in skin integrity (across which, for example, a very small quantum dot of a few nanometres diameter might be able to travel), complete understanding will only be possible with further, scrupulously controlled experiments coupled with objective data analysis and interpretation.

According to  a recent article in the Sydney Morning Herald, the study has been criticized by Dr. Gregory Crocetti of Friends of the Earth Australia and Professor Brian Gulson of the Department of Environment and Geography at Macquarie University.

The study is not the definative work in this area and the authors have noted its limitations; it is one more contribution to a growing body of scientific literature on the subject of nanoparticles and human health.