Study supports the use of Zinc Oxide nanoparticle in sunscreens
Zinc oxide (ZnO) for long been known as an effective sunscreen agent. But lately, there have been demands for ban of sunscreens containing ZnO nanoparticles because of potential side effects in humans.
A new study states that intact ZnO nanoparticles neither penetrate the human skin nor cause cellular toxicity after repeated application to human volunteers under in-use conditions. This confirms that the known benefits of using ZnO nanoparticles in sunscreens clearly outweigh the perceived risks, reports the Journal of Investigative Dermatology.
UQ and UniSA lead investigator, Professor Michael Roberts, says the myth about sunscreen toxicity took hold after previous animal studies found much higher skin absorption of zinc-containing sunscreens than in human studies.
This study has shown that sunscreens containing nano ZnO can be repeatedly applied to the skin with minimal risk of any toxicity.
“There were concerns that these zinc oxide nanoparticles could be absorbed into the epidermis, with toxic consequences, including DNA damage,” Professor Roberts says.
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.
Researchers applied ZnO nanoparticles suspended in a commercial sunscreen base to the skin of volunteers hourly for six hours 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 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.” – Said 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.