Is Sunscreen Toxic and What it Really Contains? | Chris Kresser
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Are Your Skincare Products Toxic? Sunscreen.

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People are told to slather on the sunscreen to protect themselves from the sun, but could we be doing more harm than good?

is sunscreen toxic
Sunscreen protects us from excessive sun exposure. But it the sunscreen itself toxic? iStock.com/shalamov

So far in this series, I’ve discussed why you might want to be wary of conventional skincare products like soap, shampoo, lotion, makeup, and deodorant. In this fourth and final article of the series, I want to focus on sunscreen. “Natural” sunscreens can be a hassle, but there are some very real health concerns associated with the ingredients in conventional sunscreens that might encourage you to seek out nontoxic alternatives.

Aluminum in Sunscreen

We left off last time talking about aluminum in deodorant, and why it might be prudent to avoid. Incidentally, many sunscreens also contain aluminum, so for that reason alone you should use an alternative to conventional sunscreen. For one sunscreen that was analyzed for aluminum concentration, a single application would provide 200mg of aluminum. (1) Another concern is that, as an oxidant, the aluminum in sunscreen might contribute to oxidative damage in the skin, increasing the risk of cancer.

However, of larger concern are the ingredients that actually block UV rays. Sunscreens can block sunlight in two ways: with organic (meaning carbon-based) filters, or with inorganic filters that act as a physical barrier. Let’s start with organic UV filters.

Organic UV Filters: Easily Absorbed, and Potentially Harmful

Evidence indicates that organic UV filters are readily absorbed into the skin. One commonly used UV filter, oxybenzone, was detected in the urine, plasma, and breast milk of human volunteers after full-body sunscreen application, and was found in 96% of urine samples collected in the US during 2003 and 2004. (2, 3, 4) Other UV filters have been detected in 85% of breast milk samples in Switzerland. (5)

Many of these chemicals aren’t very stable when exposed to UV radiation, and they can form reactive oxygen species (including the oft-maligned “free radicals”) and cause oxidative damage. (6, 7, 8) One UV filter, PBSA, has been shown to induce DNA damage in human skin cells after exposure to UV rays. (9) This means that the use of chemical sunscreens could increase the risk of cancer. Some filters even lose their ability to block UV rays once they penetrate the top few layers of skin, rendering them useless. (10) To top it off, these compounds are also a common cause of photoallergic contact dermatitis. (11)

Find out why your sunscreen may be doing more harm than good.

Beyond the local effects from formation of reactive oxygen species (ROS), systemic toxicity becomes a concern, since these UV filters are absorbed into the bloodstream. One of the primary concerns is their potential for endocrine disruption. Several animal and in vitro studies have found adverse developmental and reproductive effects of UV filters. (12)

For example, administration of oxybenzone (the same chemical found in 96% of urine samples in the US) to mice resulted in decreased sperm density and increased numbers of abnormal sperm. (13) And although many animal studies measured toxicity through oral administration, the authors of one review point out that exposure through dermal absorption may pose an even greater toxicity risk because the compounds aren’t digested and metabolized by the liver before entering systemic circulation. (14)

Inorganic UV Filters: Zinc Oxide and Titanium Dioxide Nanoparticles

Inorganic filters are usually nanoparticles of either zinc oxide or titanium dioxide. Like organic filters, both types of nanoparticles can form ROS, particularly when exposed to UV light, and in vitro studies show that they can damage human cells. (15) That said, one study using human immune cells found that levels of ROS generated by nanoparticles in combination with UVA light was not greater than the level of ROS generated by UVA light alone, so nanoparticles might not contribute significantly to oxidative damage caused by sun exposure. (16)

Either way, these effects are only relevant if nanoparticles can actually penetrate the top layer of skin and reach living cells. Their ability to do so is controversial, but most evidence indicates that they can’t. Even in skin that is sunburnt or affected by psoriasis, zinc and titanium nanoparticles only penetrate the top layer of skin (the stratum corneum), which is made up of dead cells, and don’t reach living cells. (17, 18)

That said, sunburn did result in deeper penetration into the stratum corneum, and I certainly wouldn’t dismiss the possibility that repeated application of sunscreen to freshly shaven skin that is then exposed to sunlight for long periods of time (in other words, normal summertime behavior) could cause nanoparticles to make their way into living tissue. And remember those PEG compounds that can enhance the absorption of other chemicals in personal care products? They’re found in sunscreens, too.

Based on the evidence, I would avoid sunscreens using either nanoparticles or organic UV filters. Nanoparticles definitely appear to be the less harmful of the two options, and nano zinc oxide seems to be both slightly less toxic and slightly less apt to penetrate the skin compared with nano titanium dioxide.

But keep in mind that commercial sunscreens also contain many other questionable ingredients, some of which we’ve discussed in previous articles in this series. You’re better off finding a natural alternative, some of which I’ll discuss below.

Nontoxic Alternatives to Sunscreen

One problem with sunscreens in general is that often, they allow us to stay in the sun for much longer than would typically be considered healthy for our skin. We get sunburnt for a reason – it’s our bodies telling us to get out of the sun – and since some sunscreens block the rays that burn us without completely blocking the rays that can cause skin damage, we might be harming our skin without realizing it.

For this reason, the best approach to sun exposure is to build up sun tolerance gradually, and get in the shade or cover up with a hat and shirt once you’ve had enough sun. Tanning is fine – just try to avoid getting burned!

Mark Sisson also reviews some simple dietary changes you can make to prevent sunburn, including eating more antioxidants to protect against sun damage.

That said, I know there are times when you have to (or want to) be in the sun all day, and might not be able to cover up or seek shade. In those cases, I recommend using non-nano zinc oxide sunscreens, which have particles large enough that they aren’t absorbed into the skin. These posts from Wellness Mama and Mommypotamus have recipes for homemade zinc sunscreens, as well as links to good commercially available products.

Environmental Working Group has an online Guide to Sunscreens with tips to keep in mind before you go outside and their latest sunscreen research. They also put together an annual wallet card, Guide to Safer Sunscreens, with tips on how to read sunscreen labels, how to make smart and healthy choices when shopping for sunscreen, and other valuable information.

I hope you’ve enjoyed this series on nontoxic alternatives to conventional skincare products. My intention was not to freak out my readers about the personal care products they use, or to perpetuate the fear-mongering that often accompanies discussions about chemicals we’re exposed to in our daily lives. But while there isn’t (and probably never will be) conclusive evidence that some of these chemicals can cause harm or contribute to toxin build-up in the body, there’s also not conclusive evidence that they don’t.

Given how much our bodies already have to handle thanks to modern life, I don’t see any reason to risk increasing that burden. We can’t really do much about our exposure to pollution or off-gassing building materials or a slew of other toxic things, but it’s so easy to shift to natural, non-toxic personal care products that to me, any evidence of possible toxicity from chemicals in conventional products is enough to sway me to avoid them.

Thanks for reading, everyone. As always, share your thoughts (and your favorite non-toxic sunscreen recommendations) in the comments below!

  1. So… I guess that could explain why I did not have a menstrual cycle for three or four months after I went to Costa Rica fishing? Despite using sun shirts and hats I slathered on sunscreen every day

  2. All is helpful except the idea that tanning is good…tanning it not good for your skin! Any change to your natural skin color, over time, changes your DNA and, ultimately increases your risk of developing skin cancers. So, stay out of the sun, use zinc based products that do not easily rub into your skin, and find shade…..Jami- 17.5 year skin-cancer survivor

  3. One recommended application of petrochemical sunscreens on a whole body is equal to daily hormonal therapy for menopause whether you’re a man, woman or child. Scary. And It may increase asthma and allergies.

  4. Tomorrow I have an appointment with a liver specialist. I had been using chemical sunscreen daily for about 4 months while I was allergic to it. I was an extremely healthy person and now I have high liver enzymes for no apparent reason. The only lifestyle change that I had made was using Chemical sunscreen on a daily basis all over. I stopped using the sunscreen and my rash went away almost over night and I began to feel better. I wonder if the sunscreen caused these reactions in my body.

  5. I have yet to find a solution for my pale skin living in a tropical country. I don’t have a car and so get plenty of exposure to the very strong sun here walking around every day. The non-nano particle zinc oxide makes me look like a ghost–okay for the beach but not a look I’m going for at work or school. I always wear a hat but still am perpetually sunburned. I started wearing a regular commercial sunscreen–I worry about the toxicity but I don’t think it’s healthy to be sunburned constantly either.

    • Check out beautycounter sunscreen! Tararandall.beautycounter.com
      safe non toxic, easily absorbed non greasy.
      Worth every penny I won’t use anything else

    • This company is extremely strict with their screening process. They have banned over 1500 chemicals from use in their products. As a country, we have only banned 11. I discovered them when searching for products due to our autoimmune issues. There is a section on my website explaining the screening process. If I can help let me know.

  6. I would have to agree with the earlier commenter. I am not sure what makes Chris an authority on so any topics? An acupuncturist?

  7. I’ve always just eaten more blueberries to protect my skin. Podcast guest Dr. Peter Osborne was the guy who brought me onto the idea of not using sunscreen… and I’m Irish!

  8. Thanks for addressing the topic of sunscreen and skincare as I have yet to find a sunscreen that isn’t annoying to put on (because it’s so thick with zinc oxide {I believe}) and feels like its irritating my eyes when I sweat. I am on the hunt for the perfect holistic solution.

    Thanks for your expertise!

  9. Somehow whenever I read Chris’ articles there is a calming affect. I can get so overwhelmed with all that is out if my control, unfair about that, and not my choice. I live in the desert and with fair skin I take this topic seriously. Thank you.

  10. As a kid and young adult, I burned so easily… I also ate a ton of dairy products and not many fruits and veg. When my diet changed to a whole foods one filled with produce, specifically berries, I noticed I was less sensitive to the sun.