A practical dermatologist’s advice on sunscreen safety and what you can do to protect yourself.
A recent, disturbing study just published in the Journal of the American Medical Association shows that sunscreen chemical filters are readily absorbed into the human bloodstream under normal use. This new information is important and relevant to your immediate sun protection choices.
What did the new scientific study on sunscreen absorption show about sunscreen risks?
In the study, 24 participants used commercial sunscreen on ¾ of their skin surface at the recommended dosage. An adult in a swimming suit exposes at least this much skin surface. To get the SPF needed to protect your skin from sun damage, you are supposed to use 1 ounce of sunscreen for this surface area and reapply every 2 hours, or earlier, after swimming, sweating or wiping off your sunscreen when you are in the sun. A day at the beach can use 4 ounces of sunscreen and sunscreen is often sold in a 4 oz tube. This is what it takes to keep harmful UV rays off your skin, and protect you from sun damage and a future of potential skin cancers.
The participants applied this much sunscreen 4 times a day for 4 days – a real life similarity to a 4-day beach vacation. Products included sprays, lotions and creams. Sounds like what I see when I travel to a tropical vacation. Researches took blood samples daily for a week testing for chemical sunscreen filters avobenzone, oxybenzone, octocrylene and ecamsule (Mexoryl, one of the European sunscreen filters that the US consumers have been wanting here). These are common, chemical-active sunscreen filters.
Results showed that every sunscreen chemical entered the bloodstream in excess of the level that the FDA considers safe (0.5ng/ml) within a day of use.
It did not matter if the sunscreen was a spray, lotion or cream. All chemicals except one maintained this excess blood level for the full 7 days of study. This is not good!
- Avobenzone (the main UVA-blocking chemical sunscreen filter used in non-mineral sunscreens) achieved excessive blood levels within 6 hours. Concentrations climbed over the days of exposure.
- Oxybenzone, a known hormone-disrupting chemical, reached disturbingly high levels quickly. Within 2 hours on day 1, blood level concentrations were as high as 209.6nb/ml! Blood levels continued to climb over the 4 days. Oxybenzone is a known, hormone-disrupting chemical and has been found in breast milk, amniotic fluid, urine and blood in prior studies. This is not good in my opinion!!
- Octocrylene also demonstrated blood levels in excess of FDA limits on day 1 and continued to rise over the 4 days.
- Ecamsule also demonstrated excess blood levels on day 1 of use.
All participants had healthy skin that did not suffer from skin problems that could increase the absorption of sunscreen ingredients. One would expect even more absorption when sunscreen was applied to injured or fragile skin such as that with a sunburn, eczema, abrasion etc.
What is my opinion about this sunscreen safety study and what do I recommend?
I am not surprised. I actually predicted this based on my common sense and natural skepticism of sunscreens that rely on the body absorbing ingredients to protect against harmful rays. Sunscreens are big business, and chemical sunscreens make me crazy as a dermatologist. I have not recommended chemical sunscreens for over 25 years for 2 key reasons:
- They are fragile, and I’ve watched my patients who use them sunburn when they thought they were protected. This makes me mad. These chemical filters lead to surprise sunburns because chemical sunscreens break down when they absorb UV rays, necessitating diligent every 2 hour reapplication.
- They also irritate sensitive skin and sting eyes.
In my opinion, you never could trust chemical sunscreen filters. The sunscreen market is flooded with them, and any of my friends or family who have watched me read sunscreen labels have watched me go crazy over the chemical UV filters, which we know know are also absorbed through the skin and into the body.
In contrast to sunscreens that rely on chemical UV filters that are absorbed into the skin, I have always I recommended (1) zinc oxide sunscreens, (2) sun protective clothing to minimize exposed skin surface area, (3) shading skin with hats and (4) protecting the eye area with UV blocking sunglasses.
The one caveat where I did acquiesce to the combination of chemical UV filters into mineral zinc oxide sunscreens is with the older technology mineral sunscreens. They were not transparent, and people were reticent to use them. A combination of zinc oxide with octinoxate provided a good and trustworthy protection and a good compromise. Now, even octinoxate has been found to damage ocean coral so I’m steering beach goers away from it. We will also see a blood level study from these same researchers soon. I predict bad news – and that’s good news, actually. Yes, I really said that.
The timing of this study is a wake up call when we need it. Yep, for all of us who love being outside during the summer and don’t want sun-damaged skin, we need to make compromises and be smart.
First, we know conclusively that UV rays harm skin, and we want to stop them from penetrating precious skin.
UV rays cause unwanted skin thinning, fragility, actinic purpura, wrinkles, hyperpigmentation such as Poikiloderma of Civatte, and sunspots. Over 90% of skin aging is due to sun exposure!
If you have doubts examine any sun damaged adult’s buttocks and compare it to their skin on the face and neck.. The buttocks skin looks so much younger. That baby smooth buttock skin is due to sun protection. If you don’t have this opportunity, compare the skin on the inner surface of your own arm to the skin on the outer surface. Look closely in good lighting. There is always more wrinkling, crinkling and freckling. It’s a living lab for sun damage changes. Eventually the skin on the outer surface will tear and bruise easily as the damage accumulates.
Importantly, sun exposure also increases the risk of skin cancer. I spent 30+ years, 5 days a week, diagnosing and treating skin cancer. Trust me, there are a lot more skin cancer on sun damaged skin.
A second conclusive fact: We know that the safety of sunscreens are not fully figured out for humans and the ecosystems that they wash into.
So, what can you do for yourself and your family for safe sun protection this year?
Remember seeing images or movies about Lawrence of Arabia? Remember the Bedouin attire that protected people from the unbelievably harsh sun of the desert? People in the Victorian era did the same. In fact, historically, most cultures use clothing to protect skin from the sun until the last century when a tan became a status symbol, and job security for dermatologists.
- I recommend you use clothing as your primary sun protection strategy. This will limit sunscreen exposure.
- For sunscreen, I recommend you use products made only or mostly from zinc oxide.
Dermatologists 4 recommendations for safe sun protection:
#1: Wear UPF 50 clothing. Not a wet tee shirt or loose-weave linen. You get more sun protection from fibers that are uniform in size and tightly woven. Natural fibers are uneven and leave spaces in a weave. Wet fibers will stretch and create space for UV rays to pass through fabric. I recommend using UPF 50 rated fabric garments for intense sun exposure situations such as sunny vacations. I personally wear Coolibar and Mott50.
Clothing is a brilliant and smart non-toxic sun protection strategy. Wearing sun protective clothing minimizes the surface area of non-covered skin, and this minimizes how much sunscreen you need. It’s math. Know that sunscreen SPF is dosed based on application of a 1 oz shot glass of product per bathing suit-wearing adult. Reapplication is needed every 2 hours. Because sunscreen is often sold in 4oz bottles, you should be using a bottle a day on a sunny vacation if you are wearing a bathing suit. If only your head and neck are exposed you need to apply ½ to 1/3 tsp for head and neck depending on your hairstyle and head size. The amount is the same for back of hands and tops of feet!
For all skin not covered by sun protective clothing, you need to ASK if your skin is protected:
#2: Apply zinc oxide sunscreen to all exposed skin. It’s no longer white and pasty. Technology has advanced to provide invisible zinc oxide sunscreen that does not need to be supplemented with chemical filters to reach high SPF in a transparent product. Use a water-resistant product if you will be swimming or sweating. Zinc oxide is considered reef-safe in the non-nano form. You will see people recommending titanium dioxide too, and I disagree. I prefer zinc over titanium due to free radical concerns and UV spectrum limitations with titanium dioxide. I’ve said this for years. Titanium dioxide technology is also not as transparent as zinc oxide.
#3: Shade your skin. Create shade with a hat, umbrella, or by seeking it out.
Sun protection is math. Every UV ray blocked is a win. You won’t be 100% perfect but try. Clothing, zinc oxide sunscreen, shade and knowledge set you up for a safe summer!
Murali K. Matta, PhD, Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients - A Randomized Clinical Trial, JAMA. Published online May 6, 2019. doi:10.1001/jama.2019.5586
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Janjua NR, et. al., Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methyl-benzylidene) camphor after whole-body topical application and reproductive hormone levels in humans., J Invest Dermatol. 2004 Jul;123(1):57-61.
Ghazipura Marya, et. al., Exposure to benzophenone-3 and reproductive toxicity: A systematic review of human and animal studies, Reproductive Toxicology, Volume 73, October 2017, Pages 175-183