Scientists Develop Clear Alternative to Opaque Mineral Sunscreen
Researchers at Yale have developed a non-mineral sunscreen that doesn’t penetrate the skin. (Photo: Getty)
Dermatologists, beauty editors, and mothers around the world all recommend wearing sunscreen as their number one beauty tip, but recently, we’ve discovered that not all sunscreens are created equal: In our pursuit to avoid damage, some studies claim that ingredients in chemical sunscreens can seep into our skin and possibly enter our bloodstream. Consequently, frequent and consistent applications of these everyday sunscreens have been linked with hormonal side effects and possibly certain kinds of skin cancer.
As a result, there has been a rise in mineral sunscreen usage. The big drawbacks? Physical sunscreens tend to rub off easily (especially when wet) and often leave behind a white residue. But on September 28, a team of researchers at Yale University published a study in Nature Materials journal, claiming that they have developed a new sunblock made of bioadhesive nanoparticles (very small particles) that stay on the surface of the skin, and doesn’t give you a milky residue. According to the study, tests also showed that the sunblock stayed on the skin days after initial application, though it can be removed entirely with vigorous rubbing. “Nanoparticles are large enough to keep from going through the skin’s surface, and our nanoparticles are so adhesive that they don’t even go into hair follicles, which are relatively open,” Mark Saltzman, the Goizueta Foundation Professor of Biomedical Engineering and the paper’s senior author, explained in a press release.
Sejal Shah, MD, a Manhattan-based dermatologist tells Yahoo Beauty that sunscreens, mineral and non-mineral, are heavily regulated by the FDA, which means that they’re very safe. But according to the Environmental Working Group, common sunscreen ingredient oxybenzone can cause reproductive toxicity, endocrine disruption, allergies, and organ system failure. Shah says the 2011 study which linked oxybenzone to harmful effects was performed on immature female rats that ingested the organic compound. “A follow up study showed that it would take 200 years of daily application to get the exposure that the rats got,” Shah clarified. “There have been lab and animal studies conducted, but there’s nothing on humans.” Saltzman tells Yahoo Beauty that before the Yale team’s sunblock formulation hits the market, it’ll be tested on humans.
For those who prefer these supposedly healthier mineral sunscreens, you’ll have to deal with the active ingredients like titanium dioxide or zinc oxide in their formulations remaining opaque on the skin, and potentially clumping up or rubbing off when you break a sweat. “The opaqueness is necessary to block out visible light,” Saltzman explains. “The physical mineral, or oxide, scatters and defects light.”
The Yale team’s sunblock avoided this issue by using nanoparticles to encase an active ingredient and hydrophobic chemical called padimate O, which is used in many commercial sunscreens. They tested their studies by placing strips of adhesive tape to mice skin that had been prior treated with one of two types of sunscreen: The Yale team’s and a commercial brand. Upon ripping off the tape, the sunscreen and a thin layer of skin were removed. The researchers kept repeating this procedure in order to penetrate the outer layers of skin, measuring how deep into skin the chemicals had seeped. Turns out, there were traces of the chemicals from the commercial sunscreen soaked deep within the skin. The Yale team’s sunscreen came off completely with the adhesive tape.
“Commercial chemical sunblock is protective against the direct hazards of ultraviolet damage of DNA, but might not be against the indirect ones,” Michael Girardi, MD, a professor of dermatology at Yale Medical School and a co-author of the paper explains in a press statement. “In fact, the indirect damage was worse when we used the commercial sunblock.” Shah disputes the claims of damage done: “There was a study where humans applied three times as much sunscreen daily for a week, and the active ingredient was found in the urine, but that means it was never absorbed into the body and there wasn’t any hormonal disruption,” she explains. “Current sunscreens on the market already work very well and safely.”
“The benefits of using sunblock in today’s available formulations far outweigh the potential issues,” Girardi tells Yahoo Beauty. “That said, there’s clearly room for improvement.” For example. Girardi notes that the FDA regulated that oxybezone should not be used on infants because that’s a chemical known to have binding properties to estrogen receptors. Girardi also notes that mineral sunblocks can only get SPF levels up to about 30, while the Yale team has taken an organic sunblock agent, with the potential for higher SPF levels, and made it into a non-reactive, hence functionally non-chemical, sunblock. The team’s sunblock formulation, however, has yet to be tested against mineral sunblocks that are currently on the market.
“What is clear is that the molecules in the formulations do penetrate your skin,” Saltzman explains. “Maybe they’re not harmful. But if you had the choice of having the molecules in your body or not in your body, we’ve developed the technology to let you make the choice.”
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