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0701ctt sunscreen sign lo res

Published on July 1st, 2015 | By: April Gocha, PhD


Sunscreen science: Protect your fun in the sun with advanced materials

Published on July 1st, 2015 | By: April Gocha, PhD

[Image above] Good advice. Credit: Alex Liivet; Flickr CC BY 2.0



As a redhead with fair skin, I am all too familiar with the danger of the sun. I’m not one of the lucky people who develop a nice golden sun-kissed hue every summer.


Nope—I sear. I sizzle. I burn. I blister.


That’s because I am a mutant. 


Many redheads (and also some blonds) carry a mutation in a membrane protein of their skin cells called the MC1R receptor. That mutation is responsible for the fair skin, propensity to sunburns, and increased skin cancer risk—all related phenomena.


The MC1R receptor affects how skin cells respond to sunlight by governing what type of pigment, called melanin, the cells produce.


When skin cells are exposed to UV irradiation, they ideally initiate a signaling and reorganizational cascade designed to protect the cell’s most important resource—the DNA in its nucleus.


To protect DNA, the cells put up a sort of umbrella, made of pigment molecules, to shield the nucleus from damaging UV rays. The MC1R receptor directs the signal for melanin to relocate to the surface of the cell, where the pigment strategically positions itself in between the sun and the cell’s nucleus.

0701ctt sun lo res

Credit: lee; Flickr CC BY-NC-ND 2.0

There, the melanin absorbs UV energy really well, preventing damaging energy from reaching the cell’s DNA. The melanin reorganization also changes the skin’s color—it creates a tan.


Melanin itself comes in a few varieties. Eumelanin is the tanning pigment that protects cell nuclei, because the compound is a naturally existing nanocomposite. But there’s another type of melanin—pheomelanin—that doesn’t make a very good umbrella.


Fair-skinned people with the mutated MC1R variant disproportionately produce more pheomelanin and less eumelanin, and hence the difficulty tanning. So fair skin cells allow more UV irradiation to reach the nuclei, catalyzing potentially cancer-causing mutations in their DNA.


Which is why good advice will tell you to wear sunscreen. It’s crucially important for fair skin, but also important for darker skin, too, because even eumelanin can’t protect against all of the sun’s energy.


Sunscreens protect skin with a mix of organic and inorganic chemicals, with some familiar metal oxides in the inorganic list—zinc oxide and titanium dioxide. Inorganic nanoparticles deflect UV rays and absorb their energy, preventing it from reaching deeper into cells and deep down into tissues.


Today’s sunscreens contain organic compounds, too, which primarily absorb the sun’s energy. Absorbing that energy makes some of the organic compounds break down—which is a large part of why sunscreen requires reapplication every few hours.


Sunscreen protection itself can be a confusing topic. This infographic from Compound Interest, an infographic-laden blog that explores everyday chemistry, might help.



0701ctt Sunscreen infographic lo res


There have been many concerns about the safety of sunscreen’s metal oxide nanoparticles being absorbed into skin. Research has shown, however, that the particles don’t penetrate down into deeper layers of the dermis, making them safe to use.


Even the Environmental Working Group, which takes a pretty conservative stance on the use of chemicals in consumer products, has concluded that nanoparticles in sunscreen are safe and effective.


And yet Americans still may not be getting the best sun protection available, thanks to complicated and lengthy approval processes by the FDA.


Eight additional advanced sunscreen molecules are available in Europe that aren’t currently available in the United States. Europe has a total of 27 approved sunscreen molecules, while the U.S. has just 16—and only half of those are regularly used in consumer sunscreen products.


All eight of the advanced Europe-only molecules have been submitted to the FDA for approval. But the agency still maintains that not enough is known about the compounds to give them a pass into the American market.


According to a Chemical & Engineering News article, that’s partly because sunscreens are considered cosmetics in Europe and over-the-counter drugs in America.


But, regardless of the classification, some of those compounds have been pending approval since 2002, meaning that there are several years of exposure and use in Europe that should be able to help guide decisions about safety and efficacy.


And, advocates argue, constantly increasing skin cancer rates mean that more effective ways to protect skin in the sun are desperately needed.


Despite legislative action late last year (the Sunscreen Innovation Act) to try to get the new compounds pushed through the approval process, the FDA is not budging on these advanced sunscreens.


For more about the back-and-forth, see the comprehensive Chemical & Engineering News article.


But even if those of us in the U.S. can’t yet get the most comprehensive sunscreen options, there are other strategies to protect yourself from the sun’s scorch. One of the most high-tech is a flurry of new wearable devices to track, monitor, and advise on sun exposure.


One such UV sensor-equipped device is JUNE, a wearable that provides expected risk based on daily forecasts and gives recommendations on how to best protect yourself from being scorched by the sun.


So, as you hopefully enjoy some summer sun this holiday weekend, just remember to protect your skin from those damaging UV rays. After all, the sun is a mass of incandescent gas—a gigantic nuclear furnace.





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