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Skin cancer is a big problem. Sunscreen can help protect your skin. All this is very well known. It turns out, though, that the active ingredients in sunscreen can get into peoples' bloodstreams in pretty high concentrations. And the effects of sunscreen on the environment isn't well studied. While sunscreen probably is safe for human use, and might be bad for the environment, we should still look closely at the products we're using to protect ourselves.

Related HCT episodes:
1. Sunscreen Works, if You Use it Right: https://youtu.be/bvG4sy_YfXM


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Credits:
John Green -- Executive Producer
Stan Muller -- Director, Producer
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Skin cancer is the most common malignancy in the United States affecting more than 3 million people each year. Using sunscreen is one mainstay of prevention, but the recent news that sunscreen ingredients can soak into your bloodstream has caused concern.

Later this year, the Food and Drug Administration will offer some official guidance on the safety of such ingredients. We touched on this a few weeks ago on Healthcare Triage News, but let's delve in. What should people do this summer? That's the topic of this weeks Healthcare Triage.

[Intro]

The only proven health risks so far is too much sun exposure. Some may think covering up and limiting time in the Sun is important only for those with lighter skin, but the recommendations against UV exposure apply to everyone. Yes, you should probably keep using sunscreen. Although, some who may want to play it safe could switch to sunscreens that contain zinc oxide or titanium dioxide. 

Sunscreens were first regulated by the FDA in the 1970s, and they were considered over-the-counter medications before current American guidelines for the evaluation of drugs were put in place. Because of this, sunscreens didn't undergo testing the way modern pharmaceuticals would.

In Europe, things are even more lax. Sunscreens are regulated as cosmetics, and because of this, many more sunscreens are approved there than here in the United States.

The FDA, however, has wanted to know: to what degree are chemicals applied to the skin absorbed into the body and what are the possible effects of those chemicals?

We know have information about the first question. A few weeks ago, as we covered before, a study was published in JAMA that randomly assigned 24 healthy people to one of four sunscreens. Two of them were sprays, third was a lotion, fourth was a cream.  Participants were instructed to apply the sunscreens to 75% of their bodies 4 times a day for 4 days, and 30 blood samples were drawn over a week.

The FDA's guidance says that any active ingredient that achieves systemic absorptions greater than .5 nanograms per milliliter of blood should undergo a toxicology assessment to see if it causes "cancer, birth defects, or other adverse effects."

The study examined four common sunscreen components: avobenzone, oxybenzone, octocrylene, and ecamsule. For all four, systemic concentrations passes the nanogram threshold after the applications on the first day of the study. The levels were higher than the limit for the entire week for all the products except the cream. They also increased for Day 1 to Day 4, meaning that there was accumulation of the chemical in the body with continued use.

This is not evidence that sunscreens are harmful! It's entirely possible that the amounts absorbed are completely safe. In fact, given the widespread use of sunscreen and the lack of any data showing increases in problems related to them, it probably is safe. Sunscreens are a key component of preventing skin damage that can lead to skin cancer. But, this doesn't mean the effects of absorption shouldn't be checked. The FDA is preparing a final recommendation.

For now, the proposed rule, which is still open for public comment, suggests that sunscreens with para-aminobenzoic acid (which is associated with allergies) and trolamine salicylate (which is associated with bleeding) should not be given the designation "generally regarded as safe and effective."

The rule also proposes that sunscreens that rely on zinc oxide and or titanium dioxide should be generally regarded as safe and effective. These inorganic compounds are not absorbed into the body and sit on the skin reflecting or absorbing the Sun's harmful rays.

Because they aren't absorbed, they're also noticeable. Most people prefer sunscreens that are not noticeable and are absorbed. Lots of parents, in particular, prefer sprays, because they're easier and faster to apply to children, who weren't even part of this study.

In recent years, vacation destinations, like Hawaii, Palau, and Key West have started to ban sunscreen with organic ingredients, because they may be damaging coral reefs. Those ingredients include oxybenzone, octinoxate, and parabens. These products can accumulate in living organisms over time in both vacationing humans and sea creatures. Significant doses collect when tens of thousands of people wear sunscreen while swimming in the ocean. These quantities only increase when we wash them off in showers and baths into the water that eventually find its way into the ocean.

The International Coral Reef Initiative says that more research is necessary, but that while we wait for such work to happen, we should be careful. A review in the Journal of the American Academy of Dermatology agrees, but points out that most studies have been limited to the lab. Many have argued that we should shift to safer "reef-friendly" products.

It's not clear, though, that sunscreens containing inorganic ingredients are good for the environment, either. A study last year pointed to the fact that zinc oxide and titanium dioxide could also have bleaching effects on coral.

When it comes to personal health, a basic plan to cover up seems sensible. I wear a UV protective swim shirt and hat in the Sun. My kids tell me I don't look as cool as the other dads, but I need to use a lot less sunscreen than they do. That not only makes my life easier, it might help the environment, too.

[Outro]

Hey did you enjoy this episode? You might might enjoy this vintage episode of Healthcare Triage that talks about the proper way to apply sunscreen, and why it's still a good idea.

We'd especially like to thank our research associate, Joe Sevits, and, of course, our surgeon admiral, Sam, for their support of the show. And you all can support the show at Patreon.com/HealthcareTriage.

Also, my book, The Bad Food Bible, is out in paperback. Go buy a copy.