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.

Cosmetics, Nanoparticles and FOE-AUS

 Friends of the Earth - Australia (FOE-Aus) recently released a new report examining the presence of nanoparticles in cosmetics produced by such well known companies as Revlon, Max Factor, and The Body Shop.

In the press release accompanying the report, FOE-Aus noted that the labeling on cosmetics containers didn't reflect the presence of nanoparticles in the product:

“Of the ten products we surveyed, only one listed the use of nano-ingredients on the label. The government’s failure to require mandatory labeling of nano-ingredients denies women the capacity to make an informed choice about what they put on their skin.”

While this may be a legitimate complaint for the Australian regulatory agencies to consider, FOE-Aus loses much of its credibility by suggesting that the "big cosmetics companies" and nanotechnologies companies view Australian women as "guinea pigs" and by calling for

 a stop to sales of cosmetics that contain nano-ingredients, until the safety science catches up, and new laws are introduced to make companies test the safety of their products and to label all nano-ingredients,” said Ms Miller. “We are also calling for public participation in decision making about nanotechnology management”.

Considering the pace of legislation through any parliamentary body tends to be a slow process and that the issuance of regulations affecting labeling of products by the appropriate agencies would also be a long process, FOE-Aus is effectively calling for a moritorium on nano-based cosmetics for an unknown period of time.

It would be one thing if the report released by FOE-Aus supported these claims and demands. However, the report supports nothing at all.

As the report notes under the heading, "A General Note on the Study's Limitations":

This study was conducted with a limited budget and should be considered to be preliminary rather than comprehensive. Only a small number of observations of each sample were made. . . . While observations in this study of certain particle sizes does indicate that they were present in the cosmetics sampled, observations may not be statistically representative of the full sample. (Emphasis added.)

In another section of the report, we find this statement:

. . .  the particulates shown are those observed via SEM [ Scanning Electron Microscopy] and may not be representative of the average particle in the analysis. Such statistical analyses are time consuming to perform . . . and furthermore require human assisted particle identification to insure correct results. (Emphasis added)

According to anarticle in the Sydney Morning Herald, the Australian Cosmetic Trade Association has dismissed the report. Considering the limited number of products that were tested - just walk into the "Beauty Aids" section of any CVS and there will be more cosmetics than anyone can count -  and the limitations of the testing procedures that were done on them, the report that FOE-Aus presents is a weak base on which to make broad assertions about the safety of those products or to demand the shut down of an industry.