Some sunscreens may be harmful or offer limited protection from dangerous sunrays. According to a collaboration study by the University of Leeds, Oregon State University, and the University of Oregon, sunscreens that contain zinc oxide can become ineffective within two hours of exposure to the sun.
Researchers are calling for new ingredients that can be used as UV (UV) filters in order to provide effective protection.
Richard Blackburn, Professor of Sustainable Materials, Leeds’ School of Design, was the leader of the Leeds portion of the study and collaborated with two US-based academic teams based in Oregon.
He stated that current testing methods, which involve examining individual ingredients rather than as a part of a formulation exposed directly to sunlight, need to be changed.
Professor Blackburn stated that zinc oxide alone is an effective and safe UV blocker. “Our research raised concerns about the interaction of individual ingredients in formulations during use, and this isn’t being tested currently by the industry.
Zinc oxide is able to destroy the UVA protection of other ingredients if it is exposed for at least two hours. Sunscreen could make matters worse. People may believe that they are protected from UV rays, and therefore put on sunscreen.
There are two types of UV light that can cause skin cancer: UVA and UVB.
UVB is more commonly associated with short-term, direct effects like sunburn. UVA, however, can cause longer-term DNA damage such as wrinkles and skin aging.
Sunscreens have a 5-star UVA rating. This indicates how well the lotion protects against harmful UV rays.
Zinc oxide is a component of many sunscreens that blocks UV rays. The researchers also examined the reaction of the mineral to other ingredients in sunlight exposure. They also calculated the UVA protection factor.
The study was co-led by Professor James Hutchison, and Dr Aurora Ginzburg (University of Oregon)
“During tests we found that zinc dioxide causes degradation of UV absorbers and that the protection provided by sunscreens was significantly reduced over a relatively short period of time,” stated Professor Hutchison. He is the Lokey-Harrington Chair of Chemistry and senior vice president at Penny Knight University for Accelerating Scientific Influence.
After two hours of UV exposure, the Oregon and Leeds teams found that the UVA protection factor had been reduced by between 84.3% to 91.8% in sunscreens mixed with zinc oxide particles. The original sunscreen without zinc oxide showed only a 15.8% decrease in UVA protection factor.
Professor Hutchison stated that “the degradation of UV filters not only reduced the effectiveness of sunscreen but also increased formula toxicity.”
“So, not only is it a problem that the product does not provide effective UV protection, but the product may also be causing damage when used in the sun.”
Zinc oxide is classified a mineral. It is used in cosmetic products as a “chemical free” ingredient.
However, Dr Ginzburg stated that this study challenges these assertions and demands that alternative options be considered.
She explained that zinc oxide particles are often combined with UV filters in hybrid sunblocks or by layering multiple cosmetics.
“It is therefore important that when designing future cosmetic formulations, the possibility of zinc oxide induced photodegradation or the combination of products on the skin be considered.
“Lossing UVA protection can be especially problematic for US sunscreens, where there is such a small list of approved filters.”
Professor Blackburn said that the study is a call for action to develop new sunscreen ingredients.
“An alternative is to use natural UV filters that work well, but it’s very expensive and time-consuming under current legislation.
“This is proving to have been a barrier for innovation, which could offer more effective, safer, and sustainable alternatives to existing ingredients.”