Zinc Oxide Nanoparticles in Sunscreens Are Safe, Say Researchers

Researchers have found that zinc oxide nanoparticles found in sunscreens are safe for application.

The sun emits two kinds of UV rays, UVA (those that cause long term damage like ageing) and UVB (those that cause short term damage in the form of burning). A sunscreen, thus, is a very important way of protecting your skin against the damage that the sun’s ultraviolet rays can inflict on you.

One of the most widely used components in sunscreens are zinc oxide nanoparticles. However, some public advocacy groups have questioned the safety of these nanoparticulate-based sunscreens.

A potential danger, therefore, is that this concern may also result in an undesirable downturn in sunscreen use, possibly increasing the incidence of skin cancer.

A new study, published in the Journal of Investigative Dermatology, has provided the first direct evidence that zinc oxide nanoparticles neither penetrate the human skin barrier nor cause cellular toxicity after repeated application to human volunteers over five days.

As reported in Science Daily, investigators studied the safety of repeated application of agglomerated ZnO nanoparticles applied to five human volunteers (aged 20 to 30 years) over five days.

They applied ZnO nanoparticles suspended in a commercial sunscreen base to the skin of volunteers hourly for six hours and daily for five days. Using multiphoton tomography with fluorescence lifetime imaging microscopy, they showed that the nanoparticles remained within the superficial layers of the stratum corneum and in the skin furrows.

The fate of ZnO nanoparticles was also characterized in excised human skin in vitro.

The terrible consequences of skin cancer and photoaging are much greater than any toxicity risk posed by approved sunscreens. This study has shown that sunscreens containing nano ZnO can be repeatedly applied to the skin with minimal risk of any toxicity.

Lead investigator Michael S. Roberts, PhD, Therapeutics Research Centre

These findings are hopeful in restoring consumer confidence in these products, and in turn lead to better sun protection and reduction in ultraviolet-induced skin aging and cancer cases.