Sunscreen Safety and Oxybenzone

Is oxybenzone in sunscreen safe? From Squintmom/Beautiful EntropyI love getting questions about science-related issues from readers. I particularly love it when a question intersects with an issue I myself am curious about, as happened when a reader got in touch with me last week:

I need some advice about sunscreen. I just read some articles on CNN about new FDA guidelines and the Environmental Working Group’s 2012 sunscreen review. Of particular concern is oxybenzone. The FDA claims it’s safe and very effective at protecting against UVA and UVB rays. However, the EWG says that oxybenzone is carcinogenic. Hmm… use sunscreen to prevent skin cancer, but sunscreen causes… skin cancer? That seems like a big time conundrum to me. The other thing I wonder about is who is the EWG? All I really know is they came up with the “Dirty Dozen” foods you should always buy organic. So what’s the deal? Should I toss all of last year’s sunscreen with oxybenzone and buy new? Is the EWG generally a trustworthy, “non-woo” authority?

The oxybenzone molecule

Let’s start with my professional opinions of the Food and Drug Administration (FDA) and of the Environmental Working Group (EWG). The FDA is routinely accused by consumer groups and conspiracy theorists of being “in bed with Big Pharma,” engaging in cover-up operations, putting profit ahead of consumer health, and so forth. I really don’t agree with this take on the organization, as I discuss in this post. The FDA’s history in the US is one of a largely appropriate trajectory. They’re a behemoth organization, and as such, they move slowly. They’re slow to approve new drugs because they insist on rigorous testing; this is one of the things that pisses off consumers who want to see new drugs come to market quickly. They’re relatively quick to warn consumers if there’s evidence that a pharmaceutical or substance is harmful, though they’re not alarmist and rarely respond to the results of an isolated study. The FDA is, to put it simply, stuck performing an impossible balancing act: they’re under public pressure to approve substances quickly, while they’re simultaneously under public pressure to keep anything that could potentially be harmful off the market. These missions are mutually exclusive, and I have to say that for the most part, the FDA handles their task as elegantly as a behemoth government organization can do. Have they made mistakes? Absolutely. But what I appreciate about the FDA is that they correct over time, such that their trajectory is generally appropriate and stable.

The EWG, on the other hand, is far more alarmist than the FDA. They’re not a government organization, but are rather a research and lobbying group made up of citizens and scientists. A survey of toxicologists (unaffiliated with the organizations about which they were questioned) revealed that most felt the EWG overstates risks associated with products. Specifically, toxicologists gave the EWG an accuracy score of 4.2 (1 = significantly understates risks, 3 = accurately states risks, 5 = significantly overstates risks). By comparison, the FDA got a 3 from the toxicologists, indicating that they felt the organization was accurate in assessing and reporting risks. For those who are curious, the U.S. Centers for Disease Control and Prevention (CDC) and the American Medical Association (AMA) also scored near 3, reflecting accurate portrayal of risks, while Greenpeace got a 4.5 — the highest score given — for significant overstating of risks. The Pharmaceutical Research and Manufacturers of America (PhRMA), on the other hand, scored a 2.3 for being the most significant understater of risks. Note that PhRMA is not a government organization, and is not tied to the FDA, the CDC, or other government health regulators.

As far as the EWG goes, I think they have their place. They report on research, but often issue warnings on the basis of single studies or studies with limited applicability. Case in point, they warn consumers against sunscreen containing retinyl palmitate (vitamin A) on the basis of a 2009 study that looked at mice rubbed with the chemical and exposed to light. The vitamin A mice developed more tumors, leading the EWG to report a link between retinyl palmitate in sunscreen and cancer. However, there are significant issues that limit the study’s applicability. Most notably, sunscreen only ever contains a small amount of retinyl palmitate. Dose is very important in toxicology; any substance — even water — is toxic in sufficient quantity. As such, a pure retinyl palmitate rub applied to mice doesn’t provide information about the toxicity of small amounts of the compound in sunscreen. In the end, groups like the EWG help to promote research on issues pertaining to toxicology and public safety, but speaking for myself, I look for corroborating research or concern from more moderate institutions before acting on an EWG warning. In response to the question from the start of this post, I think we can safely say that the EWG is “non-woo,” but they are a little jumpy.

On to sunscreen safety. First and foremost, there’s a major risk-to-benefit analysis that one must conduct when determining whether to use sunscreen and what type to use. This is because the sun emits ultraviolet radiation (UV) that damages cells, leading to development of wrinkles, aging of tissues, and skin cancer. Sunburns are an indication of particularly severe cellular damage — just one or two sunburns before the age of 18 significantly increases risk of skin cancer later in life — but even a so-called “healthy” tan is a sign that damage has occurred. Sunscreen is a part of protecting the skin from sun damage, but it’s not the entire equation. In fact, staying out of the sun during intense radiation hours (midday) and using physical protection such as clothing, sunglasses, and hats provides the best protection from harmful UV radiation. No sunscreen provides complete protection. To this end, one of the new FDA regulations regarding sunscreen labeling is that sunscreens will no longer be allowed to refer to themselves as “sunblock,” on the grounds that this inappropriately overstates protection. While there’s been some muttering by the EWG and other groups about whether sunscreen truly helps to prevent skin cancer, these concerns are largely based upon use of sunscreens that protect from only one type of UV radiation (broad-spectrum sunscreens are best, but not all sunscreens are broad-spectrum) and inappropriate use of or reliance on sunscreen. The general consensus among medical and government organizations, including the CDC and the AMA, is that sunscreen is an important component of safe-sun behavior.

The active ingredients of a barrier sunscreen.

There are two major classes of sunscreens: barrier sunscreens containing minerals (like zinc oxide and titanium dioxide) that reflect light, and chemical sunscreens that absorb the light and prevent it from penetrating cells. There is essentially no risk of absorbing the barrier compounds through the skin, leading even the EWG to note that these sunscreens are likely the safest and most effective. In times past, barrier sunscreens were unpopular because they had a greasy white appearance on the skin (remember Zinka from the 80s?). Newer technology allows for smaller particles (nanoparticles) of barrier compounds, which are less visible on the skin, though some formulations may still be greasy. There’s also some question as to whether these nanoparticle formulations appropriately protect from UVA, one of the types of UV (UVB is the other type). Unfortunately, while the sunlight reaching Earth is made up of mostly UVA, the SPF rating on sunscreen applies to UVB protection only. The new FDA regulations propose a set of standards for reporting UVA protection, as UVA exposure also leads to skin cancer. With regard to barrier sunscreens, then, the most effective UV protection comes from the old-school stuff: greasy, white, and slathered on thick. The next most effective UV protection comes from a nanoparticle formulation combined with a chemical sunscreen containing oxybenzone or similar for enhanced UVA protection. Of course, protection from UV is only part of the equation when it comes to assessing sunscreen safety; the other part is the safety of the sunscreen ingredients themselves.

The active ingredients of a chemical sunscreen.

Oxybenzone is currently raising hackles at the EWG, and is one of the reasons that their Sunscreens 2012 report contains so few “approved” choices. The compound occurs in nature — it’s in flower pigments — and is incredibly common in personal care products. It’s not only a sunscreen, it’s also a fragrance enhancer, preservative, flavor enhancer, and so on. The CDC reports that a recent random sample of Americans revealed oxybenzone in 97% of urine samples (Calafat et al). However, the significance of this information has not yet been determined. The EWG calls oxybenzone a “potential hormone disruptor,” citing the European Commission on Endocrine Disruption (pdf) (ECED), which basically means that the EWG is saying they don’t like oxybenzone on the grounds that the ECED doesn’t like oxybenzone. As to why the ECED takes issue with it, they (like the EWG) are exceedingly cautious. The EWG cites two studies (Ma et al,* Ziolkowska et al) that show the potential for weak endocrine disruption. {Note that the Ma et al reference is incomplete on the EWG website, and I was able to find no evidence of it in the scientific literature}. The extent to which the results of these studies, conducted on cells with pure oxybenzone compound, are relevant to use of the compound in sunscreen are unknown. As the American Cancer Society points out:

Virtually all substances known to cause cancer in humans also cause cancer in lab animals. But the reverse is not always true – not every substance that causes cancer in lab animals causes cancer in people. There are different reasons for this.

First, most lab studies of potential carcinogens (cancer-causing substances) expose animals to doses that are much higher than common human exposures. This is so that cancer risk can be detected in relatively small groups of animals. But doses are very important when talking about toxicity. For example, taking a couple of aspirin may help with your headache, but taking a whole bottle could put you in serious trouble. It’s not always clear that the effects seen with very high doses of a substance would also be seen with much lower doses.

Second, there may be other differences between the way substances are tested in the lab and the way they would be used, such as the route of exposure. For example, applying a substance to the skin is likely to result in much less absorption of the substance into the body than would be seen if the same substance is swallowed, inhaled, or injected into the blood. The duration and dose of the exposure also help determine the degree of risk.

While the above refers to cancer risk, the same is true of other toxic effects of compounds that are revealed through laboratory and animal studies. With specific regard to cancer and oxybenzone, even the cautious EWG notes that there’s no evidence that oxybenzone is carcinogenic — or, more accurately, THERE IS evidence that oxybenzone IS NOT carcinogenic (non-mutagenic in 4 of 4 studies: CTFA, 1980; DHEW, 1978; Hill Top Research Labs, 1979; Litton Bioneics, 1979).

Taking all the information together and conducting a risk-to-benefit analysis, I think it’s fair to say that because of the limited data available and the availability of alternatives to oxybenzone, it may be worth avoiding it in sunscreen, but there’s no reason to get particularly excited about previous use or occasional future use. Given that it’s present in almost all chemical (non-barrier) sunscreens, this essentially leaves the barrier sunscreens containing zinc oxide and titanium dioxide. If one chooses to use the nanoparticle formulations with somewhat reduced UVA protection, one must then decide whether to use a chemical sunscreen for additional protection — but this once again leads to oxybenzone exposure.

One last thing: with regard to old sunscreen, if in doubt, throw it out. The CDC recommends that sunscreen be no more than three years old if there’s no expiration date on the bottle. If the bottle has an expiration date, abide by it. The protective chemicals in sunscreen break down over time, meaning that protection wanes.

Science Bottom Line:* Given that there is no sunscreen that provides complete protection, the evidence suggests that the safest choice (particularly for children) is the use of zinc oxide or titanium dioxide sunscreen (I prefer nanoparticle formulations for convenience and aesthetics), without a chemical sunscreen backup. This should be augmented through the judicious use of shade, clothing, sunglasses, and hats, particularly during the most intense periods of sunlight.

 

How do you protect your family’s skin outdoors?

 

References:

Calafat et al. Concentrations of the sunscreen agent benzophenone-3 in residents of the United States: National Health and Nutrition Examination Survey 2003–2004. Environ Health Perspect. 2008 Jul;116(7):893-7.

Ziolkowska et al. Endocrine disruptors and rat adrenocortical function: studies on freshly dispersed and cultured cells. Int J Mol Med. 2006 Dec;18(6):1165-8.

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15 Comments (+add yours?)

  1. Ashley @ C is for Cockerham
    May 31, 2012 @ 09:41:39

    We love white sun hats. Here is Tully in the 0-6 month one. I recently bought the same hat in 2T, and it fits him nicely at 14 months. I think it will fit for a while. He keeps it on for the most part too, and I like that the flaps cover his ears and neck. We also put sunscreen on him daily when he plays outside. I use a physical block for my face, but I just checked his “baby” sunscreen, and it’s only chemical. Ugh. I know better. I’ll have to get one with the “ides” in it next time I’m at the store.

    Reply

    • SquintMom
      May 31, 2012 @ 11:18:19

      What a cutie! W isn’t generally great about wearing hats, which is a shame, because she’s very fair. Sigh.

      Reply

  2. Rachael French
    May 31, 2012 @ 21:00:39

    Our issue with the chemical sunscreens isn’t that the chemicals are necessarily endocrine disruptors or carcinogens, but the fact that every sunscreen containing oxybenzone (et al., since multiple chemicals come in a group in most of these) aggravates my kids’ eczema – even the ones that say “gentle” or that are specifically labeled for use on babies.

    The zinc oxide and titanium dioxide sunscreens don’t seem to cause outbreaks, for us.

    Reply

    • SquintMom
      May 31, 2012 @ 21:38:13

      Hmmm. That could be due to other ingredients present to stabilize the oxybenzone. Hard to say. Oxybenzone itself isn’t too likely to cause breakouts. Regardless, if the stuff irritates your kids’ skin, the definitely go with mineral!!

      Reply

      • Rachael French
        Jun 01, 2012 @ 21:01:00

        Yeah, I have no idea what’s causing it, but we did the experiment (gosh, I love experimenting on my own F1s), and sure enough, it’s coming from the oxybenzone-containing sunscreens.

        My kids got the short end of the genetic stick when it comes to skin, though. My husband has eczema that’s triggered by using the wrong soaps/shampoos, and I have…well, every fragrance used in laundry detergent (including lavender oil), and almost every metal that contacts my skin gives me hives. So it could be anything – not really blaming the chemicals themselves. 😉

        Hell, I can’t even put gold in my ears anymore. GOLD. One of the more nonreactive metals….

      • SquintMom
        Jun 01, 2012 @ 21:30:51

        Yeah. I’m not surprised the chemical sunscreens cause reactions on sensitive skin. Oxybenzone and the like are reactive (hence their ability to absorb UV light and function as sunscreens), so they have to be stabilized in solution. You can sometimes (not always, but sometimes) find gentler inactive ingredients in the mineral sunscreens, as you’ve found.

  3. Becky
    Jun 02, 2012 @ 05:19:11

    I am a bit confused by your conclusion. It seems like there is VERY limited evidence that oxybenzene may be a “weak” endocrine disruptor, while the other reputable agencies say it is safe. Considering the LACK of data on its harm, and since it provides broader spectrum protection, I don’t understand why you then concluded to avoid chemical sunscreens. It just doesn’t seem to fit your review of the reliability of the health organizations, and your review of the data.

    Reply

    • SquintMom
      Jun 02, 2012 @ 09:37:50

      Well, it’s a risk-benefit, right? When we have unknown risks (as we do with oxybenzone), we can’t make an informed decision. Remember, limited evidence doesn’t mean that a chemical is safe, or said another way, “absence of proof is not proof of absence.” If there were no alternatives to oxybenzone, we’d have to weigh the risks (unknown) against the benefits (protection from UV). We’d have to make a very difficult decision. Since there ARE alternatives, however, and they have known risks, the most reasonable scientific decision is to go with the alternatives for which we CAN do an informed risk-to-benefit analysis. For mineral (barrier) sunscreens, the risks are known and minimal, while the benefits are known and great. Make sense?

      Of course, decision making is a partly objective and partly subjective process. Your decision might be different than mine. For instance, perhaps your kids react strongly to inactive ingredients present in mineral sunscreens, and break out in rashes. With those unavailable as options, then, you might decide that an oxybenzone sunscreen is preferable to no sunscreen at all. Alternately, you might decide to use a non-oxybenzone chemical sunscreen (there are a few, though none have absolutely complete safety data available). Stated simply,the decision-making process in real life generally has two components: scientific analysis (risk/benefit) and non-scientific issues (values, extenuating circumstances, etc).

      Reply

      • Becky
        Jun 14, 2012 @ 05:39:13

        Ah, I see. I had thought that oxybenzene containing sunscreens tend to have broader spectrum, more complete protection. Am I wrong on that? In any case, I’d be most likely to accept the rankings of sunscreens by the Skin Cancer Foundation than to worry about unproven possible side effects.

        You also aren’t taking into account two of my primary concerns — affordability and accessibility. I can easily find effective, affordable sunscreens, if I’m not worried about what the EWG has to say about them.

      • SquintMom
        Jun 14, 2012 @ 08:37:03

        Oxybenzone-containing sunscreens are definitely good protection. However, so are mineral sunscreens, as long as they’re not nano-formulations.

        Mineral sunscreens are also affordable and accessible; they’re typically available at stores like Target. I think the most important thing to keep in mind is that no matter what sunscreen you use, a sunscreen is not carte blanche to spend all day in the summer sun; no sunscreen provides complete protection.

        I appreciate your comment about the EWG; I don’t necessarily take them at face value either, which is why I look into and analyze the statements they make (as I did here).

  4. theadequatemother
    Jun 04, 2012 @ 06:35:03

    I use chemical sunscreen on myself and my baby and I don’t worry about it at all. We live in Canada so we really only have to rely on sunscreen for about 1/3 of the year. I might feel differently if we lived further south, in a sunnier climate or at altitude.

    I am of northern european in ancestry so I tend to burn while watching a weather report on the TV. My lifetime risk for skin cancer I would rate as “probable” while my lifetime risk of hormonal disruption from oxybenzone or cancer attributable to it I would rate as “unlikely.” I suspect my baby will take after me. One of the most common places to get melanoma btw, is on your feet and legs…we tend to focus on our faces, shoulders and neck when slathering sunscreen on..ldon’t forget the tops of your feet if you are wearing sandals!

    Interestingly, we have family members that own a small sunscreen company and they tell us there is no difference in the formulations of sunscreen marketed as “baby” vs sunscreen marketed to adults…generally just a different bottle so buy whatever is cheaper per ounce.

    Reply

    • SquintMom
      Jun 04, 2012 @ 07:49:50

      I think you make some great points. I really like the way your comment demonstrates that different people in different circumstances, armed with the exact same information, can come to different conclusions.

      One of the most important things is that whether someone chooses to use or not to use oxybenzone, the fact is that there isn’t any real evidence to show that it’s a problem (it’s an unknown), meaning that this isn’t an issue worth stressing about.

      Reply

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  7. Kaitlyn
    Dec 16, 2012 @ 15:45:18

    I’m doing a research project on Oxybenzone and i need to know who, or what company, created oxybenzone. i need the history behind this compound.

    Reply

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