Earlier this year, the JAMA Network conducted a study that took a deeper look at the levels of several chemical UV filters present in the bloodstream. When the results were published, it raised quite a bit of attention in the media and some misleading headlines were written suggesting that sunscreen causes cancer and is unsafe.
This begs the question: are they right? According to this study, we can’t say for sure. The word “chemical” has a really bad rap nowadays with those praising all things green, clean, gluten-free, organic, and all-natural. But the word “chemical” isn’t equivalent to “bad.” So when some people hear “chemical sunscreens,” they think that it’s harmful when it’s really just saying the UV filters in chemical sunscreens are synthetic.
So what are the types of sunscreens?
There are two types of sunscreens: “Chemical” and “Mineral” sunscreens. The JAMA study focuses on chemical sunscreens so this is what we’ll be discussing. Chemical sunscreens typically use and contain UV filters like avobenzone, oxybenzone, octocrylene, ecamsule, etc. These UV filters work by absorbing UV rays and turning them into heat.
Mineral, or physical in some circles, sunscreens, on the other hand, use natural mineral compounds such as zinc oxide and titanium dioxide to block out UV rays. Fun fact: Zinc oxide and titanium dioxide are both naturally broad-spectrum, meaning they block UVA and UVB rays. This is what people used to call “sunblock” because it literally blocks UV rays and acts as a physical barrier on top of the skin. This type of sunscreen has tended to be less popular since it usually has a significant white cast on the skin (Anyone else remember not being able to rub the purple sunscreen in when we were kids?)
So what did the study consist of?
The study was very small (24 participants) and was focused on measuring the levels of the four chemical filters I listed above: avobenzone, oxybenzone, octocrylene, and ecamsule. Avobenzone and oxybenzone are incredibly popular in sunscreens in the US, mainly because they’re incredibly cheap to make. Participants in the study applied the recommended amount of sunscreen (2mg/cm²) to 75% of their body four times a day for four consecutive days and measured the absorption of the UV filters in the bloodstream for seven days.
If you want more detail, here is the study, and my dermatologist (who is also the editor and chief of the JAMA Network) speaking more about it on Wired. Dermatology Weekly also has a great podcast explaining the results in more depth.
The FDA recommends that sunscreen active ingredient absorption should not be above 0.5 nanograms. This study did show that all four UV filters were found at levels much greater than 0.5 nanograms. However, based on that fact alone, we cannot conclude that those levels are unsafe or indicate what absorption levels that high may cause, if anything.
Why should we take the results of this study with a grain of salt?
This study was not performed under realistic conditions.
First, most people don’t apply the recommended amount of sunscreen which is about a shot glass worth for the entire body. Second, most people don’t reapply sunscreen. More and more people are starting to apply sunscreen more frequently and in greater amounts which is why the sunscreen companies need to perform these toxicology studies but most people are not like the participants in this study. Third, the participants were not exposed to sunlight, water, or sweat which are normal conditions when we apply sunscreen in the real world.
It was a small pilot study and more research needs to be done to imply causation. We’ve known that these ingredients get absorbed in small quantities into the bloodstream for years because most things we put on our skin do get absorbed.
The Takeaway
We don’t know if chemical sunscreens are unsafe yet but if you’re concerned about those UV filters, the answer isn’t to skip sunscreen altogether. Opt for mineral sunscreens, hats, and shade. Here are a few of my favorites: La Roche Posay Tinted Mineral Sunscreen, Australia Gold Tinted Mineral Sunscreen, and Skinceuticals UV Defense Sunscreen.
Chemical sunscreens may be in question here but the sun isn’t. The sun’s UV rays are proven to cause cancer and, “more people are diagnosed with skin cancer each year in the U.S. than all other cancers combined.”¹ So wear your sunscreen and be on the look soon for posts going more into depth about how we’re using sunscreens all wrong.
¹Cancer Facts and Figures 2019. American Cancer Society. https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/cancer-facts-figures-2019.html. Accessed January 14, 2019.
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