Nanotech trade body criticises study on sunscreen skin penetration

By Guy Montague-Jones

- Last updated on GMT

Related tags: Ultraviolet, Sunscreen

The Nanotechnology Industries Association (NIA) has hit back against a recent study which suggested sunburn may exacerbate skin penetration from nano-sunscreens.

The Brussels-based trade association defended the use of nanotechnology in sunscreens and questioned the relevance of the research, published last month in Nano Letters by scientists at the University of Rochester.

The paper had concluded that quantum dot nanoparticles penetrated UV damaged skin more than non-compromised skin, raising concern about the use of nanoparticles in sunscreens.

Conclusions of limited relevance

However, the NIA said the results can not be interpreted as applying to sunscreens that use Titanium Dioxide (TiO2) and Zinc Oxide (ZnO).

The scientists had used an in-vivo​ skin model that the NIA criticized for not being representative normal sunscreen use.

Mice were used to test the penetrability of nanoparticles even though the stratum corneum of their skin is much thinner than in humans and therefore more easily disrupted.

The study also uses quantum dots rather than the mineral UV-filters found in sunscreens to assess the extent of skin penetration.

The NIA claims this makes it unrepresentative because quantum dots are far smaller than mineral UV-filters.

Here the trade body conflicts directly with the authors of the study who had said “consumers often apply sunscreens containing metal oxide nanoparticles of similar size and raw material properties to UV-exposed skin.”

Even when these criticisms are not taken into account, the NIA said the paper clarifies that even after UV-irradiation, skin penetration was minute, with most of the quantum dots being found in hair follicles and skin folds.

The benefits of nanotechnology

The NIA also pointed out that numerous studies have demonstrated the ability of mineral UV-filters to significantly enhance the SPF-properties of sunscreens.

Most recently, scientists at L’Oreal in collaboration with researchers at the University of Queensland, Australia, reviewed the toxicity data on nanoparticles in cosmetics and concluded that they posed no risk to human health.

In a study published in Skin Pharmacology and Physiology the scientists concluded that “The current weight of evidence suggests that nanomaterials currently used in cosmetics preparations or sunscreens pose no risk to human skin or human health.

“On the contrary they provide a large benefit to human health by protecting human skin against the adverse effects of UV radiation.”

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