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A research study at the University of Oregon, USA, revealed that zinc oxide sunscreens lose much of their effectiveness and become toxic two hours after exposure to ultraviolet rays. The results were published in the journal Photochemical and Photobiological Sciences
According to the study, the toxicological analysis included zebrafish, which share remarkable similarities with humans at the molecular, genetic and cellular levels, which means that many zebrafish studies are directly relevant to humans. Important but largely neglected for the massive global sunscreen market, time now news reported.
Questions: How stable, safe, and effective are combined sunscreen ingredients rather than individual compounds which is how they are considered for FDA approval and what about the safety of any chemical reactions that result from exposure to sunlight?
“Sunscreens that contain inorganic compounds such as zinc oxide or titanium dioxide, which block UV rays, are increasingly being marketed as safe alternatives to organic small-molecule compounds that absorb radiation,” the researchers said.“.
The scientists made five mixtures containing UV filters the active ingredients in sunscreens from different products available in the US and Europe and also made additional mixtures of the same ingredients, plus zinc oxide at the lower end of the commercially recommended amount..
The researchers then exposed the mixtures to ultraviolet light for two hours and used spectroscopy to check their photostability. What did sunlight do for the compounds in the mixtures and their UV-protective abilities? The scientists also looked at whether UV rays caused any of the mixtures to become toxic to zebrafish, a widely used model organism, and found that the UV-exposed mixture without zinc oxide caused no significant changes in the fish..
But the scientists saw significant differences in photostability and phototoxicity when zinc oxide particles were added. The zinc oxide degraded the organic mixture and caused a loss of more than 80% in the organic filter’s protection from UV-A, which makes up 95% of UV rays. Violet that reaches the earth
The photolysis products caused by zinc oxide caused significant increases in the defects of zebrafish used in the experiments, and it was found that the addition of zinc oxide particles led to poisoning when exposed to ultraviolet rays..
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