• Jena Martin MD

Margarine and the sun.

2019 has been quite the bad year for sunscreen and it's not yet summer in my hemisphere.

Earlier this year I wrote a blog post about a then recent article from Rowan Jacobsen in Outside magazine. His piece was entitled, Is Sunscreen the New Margarine? It was meant to create a lot of outrage, and in certain circles it did. From the title to the tone, the author was outraged about a lot of medical advice.

In my commentary (linked here), I focused on how the author was arguing against sun protection - in any form. I did not focus on his problems with sunscreen in particular, as I thought from the pathology-biology perspective, I had more to say about cancer, Vitamin D and his disdain for general advice about UV exposure.

Now I’m back re-reading his article in light (no pun intended) of the recent recent article in JAMA (Effect of Sunscreen Application Under Maximal Use Conditions on Plasma Concentration of Sunscreen Active Ingredients https://jamanetwork.com/journals/jama/article-abstract/2733085 ). It adds more urgency to the question Mr. Jacobsen posed: Is sunscreen the new margarine?

The editorial accompanying this article is a great summary and I would recommend it to those who are interested. But if you’re not going to read that now, here is my 2 sentence summary: This is a small study that demonstrated substances in many readily available sunscreens, applied as indicated on the label (avobenzone, oxybenzone, octocrylene, and ecamsule) are absorbed into the bloodstream. The effects of these chemicals is not known; there are concerns for the environment, reproductive effects and cancers.

Is sunscreen effective?

We recommend sunscreen to prevent skin cancer yet there is surprisingly little data to support the clinical effectiveness of these products. For example, a public advisory panel convened by the FDA found evidence for protection against squamous cancers, but that evidence that sunscreen protects against melanoma is “not high quality”.

There are side effects:

As the editorial makes clear, this is not the first study to indicate that these chemicals are absorbed after application on the skin. In fact, there are a lot of holes in the science of sunscreens - there is a complicated history of sunscreen manufacturers refusing to conduct their own safety trials. The side effects of these substances in chemical sunscreens are not known and have the potential to cause harm.

Claims about both the effectiveness and the side effects of chemical sunscreens need further study.

Are you thinking that you’ve been given a green light to sunbathe with no concerns? Please think again. Some concerning facts about the cause behind skin cancers: having 5 or more blistering sunburns early in your lifetime increases your risk of melanoma by 80%; using a tanning bed before age 35 increases your risk for melanoma by 75%. Even if sunscreen is the new margarine, questions and concerns about chemical sunscreen safety and effectiveness do not alter the risks about sun exposure and the need for sun protection.

Sun exposure and subsequent skin cancers have real risks. Even the less deadly cancers, such as Basal cell carcinomas and Squamous cell carcinomas contribute to a substantial amount of morbidity amongst white people. These cancers may not kill you, but it's nice to avoid them - ears, eyelids and nose tips are all common excision sites. And how can you avoid them, if you are in the higher risk groups? Avoid sun exposure. I’ll add here, as I did in my previous post, that the main reason many people avoid the sun is not for cancer prevention but to prevent premature aging.

Modern medicine has made a lot of mistakes in the pursuit of preventing disease. Where we continue to make mistakes is in communicating about complicated risks. Reporting about sun protection becomes lopsided and without nuance, with medical professionals and skeptics squaring off against one another. No one is advocating for a general recommendation for complete sun avoidance, and no one should be advocating for no sun protection.

My nuanced interpretation? We need moderate natural sun exposure to reduce inflammation, reduce cancer risks and improve our circadian rhythms (via several possible mechanisms including vitamin D and nitric oxide). For some people, these needs should be balanced with sun protection appropriate for their skin type and risks; for other people, the benefits of these factors outweigh the risks of skin cancer.

Per the JAMA Editorial:

“At a minimum, physicians should recommend use of sunscreen formulations containing generally regarded as safe and effective ingredients such as titanium dioxide and zinc oxide as part of a larger program of photoprotection that includes seeking shade, and wearing protective clothing, hats, and sunglasses, until meaningful answers to these questions are available.”

Full disclosure: I am a dermatopathologist who has diagnosed thousands of skin cancers. I’m also a middle-aged white woman and I avoid the sun. I personally dislike sunscreen; it’s gloppy, gets on my clothes and I want to wash my hands after applying. I don’t sit on the beach in a suit and usually cover up (hats and clothing) for my sun avoidance.

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