BEND, Ore. (KTVZ) --Sunscreen that includes zinc oxide, a common ingredient, has been found to lose much of its effectiveness and becomes toxic after two hours of exposure to ultraviolet radiation, according to a study that included Oregon State University scientists.
The OSU study was meant to question how stable, safe, and effective are sunscreen ingredients in combination rather than as individual compounds.
It also looked into the safety of any chemical products that result from reactions caused by exposure to sunlight.
Diana Stevens, a Bend resident, said Thursday she has never liked applying sunscreen on herself or her children. She’s always questioned its ingredients and how safe it is to wear.
“I’ve tried really hard to find sunscreen that is not toxic, mainly for the health of my children and myself, and it’s hard to find one,” Stevens said.
Instead, she chooses to find shady areas and wear protective clothing when going outdoors.
“It actually feels safer not to have the chemicals around my face and mouth,” Stevens said.
What the public thinks about sunscreen safety has caused manufacturers who often have on limited data to use lots of some ingredients while limiting others. For example, oxybenzone has effectively been discontinued because of concerns that it harms coral reefs.
The study of measuring toxicity in sunscreen involved using zebrafish, which share a similarity to humans at the molecular genetics and cellular levels, meaning many zebrafish studies are relevant to people.
Chris Martindale, who was out enjoying the Bend Whitewater Park Thursday afternoon, has become conscious of the sunscreen products, and suggests others do the same.
“When it comes to the sunscreen products that we use, I would probably just take a second look at what you’re putting on your body -- how it affects you, how it affects the environment around you," Martindale said. "If it's worth paying the extra $3 or $4 for a sunscreen that is going to do good in the long term, that’s probably the best route to take.”
The researchers exposed a number of sunscreen mixtures to ultraviolet radiation for two hours to look into what sunlight did to the compounds in the mixtures and their UV-protective capabilities.
The zinc-oxide-induced mixtures caused significant increases in defects to the zebrafish used to test toxicity. OSU faculty suggest zinc oxide particles are leading to degradants whose introduction to aquatic ecosystems is environmentally hazardous.