Chasing Life

Hey there, welcome to Paging Dr. Gupta. This is the show, of course, where I get to answer your health questions. You know, Memorial Day is now in the rearview mirror and the official start of summer is shimmering just ahead. So no doubt, plenty of us are gonna be spending more time in the sun. And that means it's a good time to turn our attention to summer health concerns. And you have a lot of questions about this. So Jennifer, what do we have first?

Alright Sanjay, up first we have a couple of questions about sunscreens, namely whether mineral sunscrees are better than chemical sunscrens and whether certain ingredients should be avoided. What do you think?

I have a lot of thoughts on this, Jennifer. People are going to be spending more time outdoors. Hikes, bike trips, festivals, backyard barbecues, pool parties, the beach. Preventing sunburn, taking care of your skin, obviously, a great idea. An important idea for now and for your future. So I'll tell you what you need to consider when buying sunscreen after this short break. Welcome back to Paging Dr. Gupta. To mark the unofficial start of summer, we went into our mailbag to tackle a sometimes slippery topic, sunscreens, and what you should really consider when choosing one. First of all, quick reminder of why I talk about this topic so much, why wearing sunscreen is so important. Number one, your skin is your largest organ in your body, and sunscreen can help prevent that organ, your skin, from developing cancer.

Skin cancer is caused by exposing the cells in the skin to UV radiation and particularly UVB radiation. So UV radiation comes in different flavors, so to speak. So those most harmful rays cause skin cancer by causing mutations in the DNA in our cells. So if you get one, it's generally not a big problem, but what happens if that mutation occurs in a gene that's really important for DNA repair for example, so our cells are not so good at DNA repair and then we get another mutation and then potentially get another mutation and eventually we tip our cells over into forming into a skin cancer.

That was Dr. Rachel Neale, a principal research fellow at the QIMR Berghofer Medical Research Institute in Brisbane, Australia. She has been studying skin cancer for about 30 years and spoke to my colleague Meg Tirrell on this show a couple summers ago. Dr. Neale's research in the 1990s and early 2000s really helped establish that sunscreen is effective at reducing skin cancer rates, including for the most deadly kind.

So there are three main types of skin cancer. The one that's most dangerous is melanoma and people do die from melanoma every year because it can spread beyond the skin. So if it's not picked up early enough, then by the time it's diagnosed. It can have spread to other organs in the body. And then we've got these other types of skin cancer. So these are squamous cell carcinoma and basal cell carcinoid and collectively, we call them keratinocyte cancers because they arise from a type of cell called a keratinocytes in the skin.

Now importantly, Dr. Neale said that sunscreen helps guard against some of the most deadly skin cancers by both preventing those blistering sunburns that can be common in childhood and also reducing lifetime exposure to UVB radiation. Now the second reason sunscreen is a good idea is that it protects you from premature signs of aging, such as wrinkles and brown spots. You see, the thing is UVA and UVB rays can both damage cells on the top layer of skin, and that can lead to red, rough, and scaly patches, which can get worse over time. UVA rays in particular can penetrate to the deeper layers of the skin, damaging the cells that are responsible for giving you a tan. They are called melanocytes. And what happens is you might get hyperpigmentation, brown spots, sometimes called age or liver spots. UVA, incidentally, also breaks down elastin and collagen. Those are proteins that live in the even deeper layers of the skin. And that's what causes the loss of elasticity, wrinkling, and thinning of the skin. Now, that takes us to sunscreens. Most, if not all, sunscreens have what is known as an SPF number on the label. This stands for Sun Protection Factor. The higher the number, the better the protection. But importantly, SPF only refers to protection against UVB rays. So it's important to look for broad spectrum sunscreens which protect against both UVA and UVB. Okay, you got that? So SPF only refers to protection against UVB rays so you need to find broad spectrum. Also choose a sunscreen with a high enough SPF for your skin coloring, for the time of year, for your planned activities. But generally speaking, experts say there are diminishing returns when going much higher than 50. Because when you get an SPF of 50, that essentially is blocking 98% of UVB rays. That's compared to a sunscreen with an SPF of 100, which blocks out about 99%, so just about a percent more. Now, I want to say a couple words about ingredients. There's been a lot of attention on this lately, and you may have heard that sunscreens come in two basic varieties, chemical sunscreens and mineral sunscreens. Now, mineral sunscreens are made with either zinc oxide or titanium dioxide, and they sit on top of the skin. So they're sort of physically blocking the UV rays by reflecting them away. They're usually opaque and can leave a white cast. They can be a bit sticky. Newer formulations may minimize those effects. Now these types of mineral sunscreens start working right away. Chemical sunscreens. They essentially absorb the UV rays, convert it into heat, and then dissipate it from the skin. They are usually transparent and easier to apply, but importantly, they need some time to be absorbed by the skin before doing their job. Since chemical sunscreens are absorbed into the skin, there is also some concern about certain ingredients getting into the bloodstream. So how concerned should you be about that? We'll tell you, right after the break. All right, I hear another question coming in. Jennifer is back. What do we have next?

We have a few callers here who are worried about the ingredients in chemical sunscreens. They're wondering about how much of that gets into our bodies and what it might be doing.

'The U.S. Food and Drug Administration is looking at the amount and the safety of the ingredients being absorbed into our bodies through some of these sunscreens. But that's going to take a while to get some answers. Over the last several years, the agency has made a few changes to which active ingredients are generally regarded as safe and effective, something known as GRASE. So 16 ingredients used to be on this list, two were pulled off due to safety concerns. Something known as FABA, F-A-B-A and trolamine salicylate. Two are still on the list, meaning they are generally recognized as safe and effective, and those are zinc oxide and titanium dioxide. Those are the ones in mineral sunscreens. 12 others still need more data to be considered safe and effective. And you may be wondering, why am I just hearing about this? Why has the FDA begun the process of re-evaluating ingredients in sunscreen that for a long time had been thought to be safe and effective. Well, two big shifts happened since sunscreens were first evaluated in the 1970s. First of all, scientists didn't know that chemicals in these sunscreens were actually getting absorbed in any significant amount. That they were getting absorbed through our skin and then circulating in our body, sometimes even staying in the bloodstream for a couple of weeks. We know that now. Also, the way we use sunscreens has changed. We no longer just dab a little bit on our noses at the height of summer. For many of us, it's become a daily part and an important part of our skincare routine. As a result, many of us are using much more of it, we're reapplying it much more frequently, and that's something that makes dermatologists happy, but at the same time may worry some endocrinologists, doctors who study hormones.

If you use it as intended, which is what would make it effective, there's a lot more of it that's ending up in our bloodstream than we realized. And the concern is that we don't know enough about its safety. So what the FDA has asked the manufacturers of these chemicals and really these products to do is to do studies where the sunscreen would be used as intended and then see how much of these chemicals end up in the bloodstream. Because the FDA has standards for how much of these chemicals should be in our blood and currently they can't meet that standard of both safe and effective.

That was Dr. Laura Vandenberg, a professor of environmental health sciences at the University of Massachusetts Amherst, talking on the podcast a couple of years ago. She studies how hormones impact the body, and she became interested in how some sunscreen ingredients can affect that process. In other words, could some of these ingredients be what are known as endocrine disruptors? And you might be surprised to know that those 12 chemicals that we just talked about, the ones that are not generally recognized as safe and effective, many of them are still in use today.

You know, I spent a lot of my career criticizing the way that regulatory agencies make decisions. I think we should actually give them credit when they can acknowledge that what they thought before, there isn't enough evidence to support it. In this case, I think that really what they're doing is signaling that there isn't enough evidence to say that they're dangerous, but that's not the standard that we should have for products that we're putting all over our body, for products we're put on the bodies of children. We want to know that they are safe. But we also wanna know that they're doing the job because the job of sunscreens is really critical.

'So what does that mean for you? Well the experts say no matter which type of sunscreen you choose, chemical or mineral, it's important to just make sure to actually use it, make it a part of your daily routine. Also remember to get the full benefit, you have to put on enough sunscreen, which is probably more than you think, about a shot glass full for your body, and more even for your face, and you have reapply it as directed which could be as frequently as every 90 minutes. Make sure it's not expired. Don't store it in a very hot place, like the glove box of your car. Also keep in mind, there should be other things you're doing to protect your skin. Avoid direct sun exposure during peak times, 10 a.m. to 4 p.m. Seek out shade under a tree or a beach umbrella. Wear clothing with ultraviolet protection factor. Wear a hat, and don't forget about protecting your eyes with UV blocking sunglasses and your lips with an SPF containing lip balm. Now if you're interested in those ingredients that we were just talking about, you can see which sunscreens are recommended in the annual report of the Environmental Working Group, or EWG. That's a non-profit health and environmental advocacy organization, and we put a link to their latest report in our show notes. You'll also find a link to that earlier podcast I mentioned as well. And that's our show for today. Keep the questions coming. If there's something health-related you've been wondering about, send it to us and we might answer it next week. Record a voice memo, email it to pagingdrgupta at cnn.com, that's paging dr gupta at cnn.com or give us a call 470-396-0832 and leave a message. Thanks for listening and join us on Friday!