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The ingredients of sunscreens have some people concerned about whether they're being absorbed by the body, and what the effects of that might be. While this study doesn't provide evidence that sunscreen is harmful, closer examination is needed.


Related HCT episodes:
1. We're getting closer to summer! If you haven't seen our episode on some summer-related myths, check it out here: https://www.youtube.com/watch?v=DA536xRzlYw

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#healthcare #sunscreen #skincancer
You know those chain emails and social media posts warning about the dangers of sunscreen? I've been rolling my eyes, but my eye roll is a little less sure than it use to be. This is Healthcare Triage News.

[Intro]

Skin cancer is terrible. It's the most common malignancy in the United States, hitting more than 3 million people per year. Reducing sun exposure and using sunscreen are the mainstays of prevention. 

Sunscreens were originally approved as over-the-counter meds before current guidelines for the evaluation of drugs were put in place by the FDA, and there are a lot of people concerned about their safety. Some have been concerned about the ingredients of sunscreens being absorbed by the body and what the effects of that might be.

Recently, in JAMA, a study was published that will likely get a lot of play in the media. Last summer, researchers got 24 healthy people together and randomized them to one of four sunscreens. Two of them were sprays, the third was a lotion, and the fourth was a cream. They applied the sunscreens to 75% of their bodies four time a day for four days, and 30 blood samples were drawn over a week.

For avobenzone, the mean maximum plasma concentrations were 4 nanograms per milliliter for spray 1, 3.4 nanograms per milliliter, 4.3 nanograms per milliliter for lotion, and 1.8 nanograms per milliliter for the cream. The FDA's guidance says that any active ingredient that achieves systemic absorption greater than 0.5 nanograms per milliliter should undergo non-clinical toxicology assessments, and we don't have those.

For oxybenzone, all four forms of sunscreen blew past the 0.5 nanograms per milliliter level the FDA has set. Same for octocrylene. Only cream has ecamsule, but it also blew past the limit at 1.5 nanograms per milliliter.

For all four products, systemic concentrations pass the 0.5 nanograms per milliliter after the four applications on the first day. The levels were higher than the limit for the entire week for all the products, except the cream. They also went up from day 1 to 4, meaning that there was accumulation of the drug in the body systemically with continued use.

Let me say this as clearly as possible: This is not evidence that sunscreens are harmful. We don't know that the amounts being absorbed are harmful. But, that's the point, we don't know. We should be checking that out. We often just assume that if stuff is being sold that the companies have done basic studies on safety. We assume the professionals like me have demanded the evidence to weigh benefits and harms.

Later this year, we're expected to see some official guidance from the FDA on the safety of ingredients as known. The rule proposes that both zinc oxide and titanium dioxide be designated "generally regarded as safe and effective." Para-aminobenzoic acid (or PABA) and trolamine salicylate will be not generally regarded as safe and effective. 12 more, including those discussed in this episode, will be... there's insufficient evidence.

If companies don't do studies of safety, those products might get pulled by November. If they commit to those studies, the deadlines can be extended. 

I'm going to quote the paper here: "These results do not indicate that individuals should refrain from the use of sunscreen." We do need more research. You could always do what I do, and always, always wear a hat and a UV-protective swim shirt in the sun. I get made fun of by my family for that, but I'm right. I keep as little skin exposed as possible, which means I need less sunscreen than many others do. You can also favor products recognized as generally regarded as safe and effective. No matter what, remember that skin cancer is terrible.

[Outro]

If you liked this episode, you might also like another video on summertime myths like poison potato salad and citronella. 

We'd like to thank all out patrons at Patreon, especially our research associate, Joe Sevits, and our surgeon admiral, Sam. Go to Patreon.com/HealthcareTriage for more information.

Also, my book, The Bad Food Bible, is now available in paperback. Please go get it!