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Lack Of Evidence Shows Sunscreens Are Safe For Humans With Normal Use

SCOTT SIMON, HOST:

This Memorial Day weekend, parents will begin the summer sunscreen slog, trying to put sunscreen on squirming toddlers. But what kind of sunscreen is safest? We're joined now by Tara Haelle. She's a regular contributor to NPR's health blog, SHOTS. And she joins us from Peoria, Illinois. Sun's always shining in Peoria, isn't it?

TARA HAELLE, BYLINE: For the most part, it actually is quite a bit.

SIMON: First, let's get this established. You really should put sunscreen on your children, right?

HAELLE: Absolutely. One thing that gets tricky with discussing safety of sunscreen, especially when there's different places telling you that this one's better or safer, is that sunscreen is all about benefit and risk. And the risk that you're trying to avoid is a risk of cancer.

SIMON: Now, there are two kinds of sunscreen, I learned a few minutes ago when I picked up this sheet of paper - physical and chemical. And there have been a lot of criticisms about the chemical kind in the past few years, hasn't there?

HAELLE: There has been. A lot of it is based on preliminary animal studies that hasn't really shown harm in humans, even though they have done a lot of long-term epidemiological studies, which basically means it's impossible to test it by putting people - you know, give this group a whole bunch of sunscreen and this group not and put them in the sun for 10 hours because that would be unethical. You're referring - you know, you're putting one group at risk of cancer.

But what we can do is, you know, find out what people have been using over a period of time or follow them forward and then see if one group has a greater risk of some kind of, you know, health or medical concern in their body. And we haven't actually seen that. So it's always important to realize that what happens to a mouse or a rat doesn't always translate to humans.

SIMON: Let me ask you about one particular chemical, oxybenzone.

HAELLE: The oxybenzone is often the one that you hear about as the bogeyman. Part of it is because some studies have found what's called estrogenic activity. Basically it means there's a concern that it messes with your hormones. It's the same concerns that people have about certain plastics like BPA.

SIMON: Yeah.

HAELLE: And we do have experimental evidence that it does that. What we don't have is any proof that the amount that humans absorb into their skin has any impact. And in fact, one of the studies that looked at a whole bunch of sunscreens found that any kind of sunscreen product that has, you know, just 1 to 6 percent of oxybenzone, which is fairly standard, doesn't possess any kind of significant sensitization or irritation potential for the public. That refers mainly to allergies. But we don't have any evidence that at those small doses it's affecting major hormone or endocrine systems either.

SIMON: What about another ingredient, retinyl palmitate?

HAELLE: That one, there is a little bit more concern in terms of the impact it had on hairless mice. They found that when they applied this - you know, a cream with retinyl palmitate on the skins of hairless mice, it sped up the rate at which those mice developed tumors and lesions on their hairless skin. We don't know if that would translate to humans. But we do know that it appears to further sensitize you to the sun.

SIMON: So, I mean, so what do you do short of just staying out of the sun?

HAELLE: Well, one thing you can do is you choose a sunscreen that has an SPF up to 50. It's not the kind of thing where you need to stand in Walgreens and inspect the labels of every single one of them.

I think if you're picking it up and looking at it, you do a quick look and say, oh, hey, doesn't have retinyl palmitate and it has either zinc or avobenzone or titanium dioxide to prevent you from the UVA rays, you're going to be OK. We don't have a lot of evidence to say that these things are as dangerous or risky as some publications will sensationally suggest.

SIMON: Tara Haelle is a regular contributor to NPR's health blog, SHOTS, and co-author of the book "The Informed Parent: A Science-Based Resource For Your Child's First Four Years." Thanks for being with us.

HAELLE: Thank you very much. Transcript provided by NPR, Copyright NPR.