A new study conducted by two Australian universities – the University of Queensland and the University of South Australia, showed that nanoparticles of zinc oxide used in sunscreens do not cause cell toxicity, even after repeated use.
The main achievement of this research is that it proved that nanoparticles of zinc oxide (ZnO) does not penetrate the skin, refuting the beliefs of insecurity sunscreens based on nanoparticles.
“There were concerns that nanoparticles of zinc oxide can be absorbed in the skin with toxic effects, including DNA damage,” said lead researcher Professor Michael Roberts. According to Roberts, this myth originated after previous animal studies have shown a high level of m & a zinc skin.
However, the results of this study demonstrate that ZnO nanoparticles can be repeatedly applied to the skin with minimal risk of toxicity, and even in this case, it is much safer than no sunscreen at all. “The terrible consequences of skin cancer and photoaging is much higher than any risk of toxicity associated with approved sunscreen,” commented Roberts.
The team investigated the safety of repeated use of nanoparticles of zinc oxide with the help of five volunteers aged 20 to 30 years. Participants in the experiment was applied to the ZnO nanoparticles, in the quantities in which they are contained in sunscreen every hour for six hours for five consecutive days to simulate regular use of sunscreen. Using multiphoton tomography with fluorescence imaging microscopy, the scientists found that the nanoparticles remain on the surface of the stratum corneum and in the furrows of the skin.
Influence of ZnO nanoparticles on human skin has also been studied in a clinical setting. The results shows that these substances do not penetrate into viable epidermis, and the cellular toxicity was not observed even after repeated hourly or daily applications, typically found in sunscreens.
“With the excellent imaging techniques, we found that nanoparticles remain in the surface layers of the skin and do not cause cellular damage,” said Roberts. The researcher hopes that positive results will have an impact on consumers: “We hope that these results will help to increase consumer confidence in these products and, in turn, will lead to better protection from the sun and to reduce the incidence of skin aging and cancer caused by ultraviolet radiation”.