Those looking to stay safe from the sun should steer far clear of do-it-yourself sunscreens, a new study out Monday suggests. The study looked at recipes of homemade sunscreens shared on the popular website Pinterest and found these concoctions were woefully worse at actually protecting our skin from UV radiation than commercial sunscreens.
Pinterest, like other social media sites, has quickly become a haven for users to upload and share information (in this case, images) on so-called natural and alternative treatments made at home. It’s a trend that hadn’t gone unnoticed by the study authors.
“It made us want to look at what people are making themselves that could be potentially harmful for them or their children. And coconut oil was having a moment—everything seemed to have coconut oil in it. So that made us want to look at homemade sunscreens, because it’s very common there,” senior study author Lara McKenzie, a principal investigator in the Centre for Injury Research and Policy at Nationwide Children’s Hospital in Ohio, told Gizmodo via phone.
So McKenzie and her team, whose study was published in Health Communication, conducted two searches on the site, using the terms “homemade sunscreen” and “natural sunscreen.” Then they took a sample of the searches—every fifth image—and studied their contents more closely using whatever information was available.
Nearly all of the 189 images they studied contained glowing praise for homemade sunscreens, with around two-thirds offering recipes for how to make your own. A third also claimed the sunscreen would provide a specific amount of SPF protection against UVB rays, up to as high as 50 SPF. But across the board, the researchers found, many if not all these sunscreens simply didn’t pass muster.
Coconut oil, which did turn out to be the most commonly featured ingredient in these recipes, has only been shown to provide up to seven SPF worth of UVB protection in lab tests, for instance (30 SPF is the minimum recommended level of protection in typical sunscreens, a level which can block 97 per cent of UVB rays). Equally concerning is that these homemade sunscreens almost certainly can’t provide broad-spectrum protection, meaning they can’t protect against both UVA and UVB rays. And the false sense of security they provide could actually cause its users some harm.
“Some of those ingredients naturally offer some protection against the sun, but not to the degree that these pins were claiming. That combination of recipe ingredients is not going to give you an SPF of 50,” McKenzie said. “So what’s really at risk here, at best, is a really bad sunburn. And at worst, potentially skin cancer down the road.”
In some cases, the failure comes more from how these homemade products are made. Zinc oxide and titanium oxide, for instance, were listed in many recipes. But though these are some of the best ingredients available for sun protection, they likely won’t work as well as they would in commercial sunscreens.
These homemade sunscreens may not contain enough zinc, or the zinc could be unevenly distributed across the mixture, either of which can result in inconsistent protection. And unlike commercial sunscreens, homemade sunscreens might not be water-resistant or stable when exposed to sunlight.
Of course, there’s long been a scepticism of mainstream consumer and medical products like sunscreen. More recently, some fuel has been added to the fire, after a study earlier this May led by the Food and Drug Administration found that some sunscreen ingredients can be absorbed into the blood at noticeable levels.
But though there should be further research into whether this absorption could be linked to any health effects, there’s no evidence of commercial sunscreens hurting people, and public health experts — including at the FDA — have continued to recommend that people use sunscreen whenever it needed.
The last thing anyone should do, McKenzie noted, is turn to Pinterest for alternatives.
“I think it’s great to try a dinner recipe you find on there, because the risk is very low. People might like it or they might not like it. But when it comes to something like sunscreen, that is not something you want to make yourself—that is not the time to DIY a solution,” she said.