Ask SciMoms: Is sunscreen necessary? Is sunscreen safe?

Sun protection, which includes sunscreen, is very important for adults and kids! Yet many parents have questions about sunscreen and proper sun protection including whether sunscreen is necessary, whether it is safe for our health and the environment, and what additional measures are needed for sun protection.

Exposure to UV light (from the sun or indoor tanning) is a major risk factor for melanoma and other types of skin cancer.  These statistics from the Skin Cancer Foundation highlight the risks associated with sun exposure:

  • About 90% of nonmelanoma skin cancers are associated with exposure to ultraviolet (UV) radiation from the sun.
  • The vast majority of melanomas are caused by the sun. In fact, one UK study found that about 86 percent of melanomas can be attributed to exposure to ultraviolet (UV) radiation from the sun.
  • An estimated 90 percent of skin aging is caused by the sun.
  • More people develop skin cancer because of indoor tanning than develop lung cancer because of smoking.

Sun exposure is especially concerning for kids and teenagers. Sunburns early in life increase the risk for all types of skin cancer, especially for melanoma (the deadliest type of skin cancer). Having five sunburns that blister between the ages of 15 and 20 increases the risk of melanoma by 80 and the risk for other types of skin cancer (basal cell carcinoma and squamous cell carcinoma) by 68%. Later in life, sun exposure mostly increases the risk of basal cell carcinoma and squamous cell carcinoma but not melanoma.

Fortunately, sun exposure is a “modifiable” risk factor and we can easily mitigate or reduce the risk of skin cancer by using sun protection. A risk factor is something that changes the chance of getting a disease in a population. Risk factors can be modifiable or non-modifiable. Modifiable risk factors (like exposures and lifestyle) can be changed. Non-modifiable risk factors (like genetics) cannot be changed. Risk factors can also be protective (decrease risk, usually called protective factors) or harmful (increase risk).

What can I do for sun protection?

Sunscreen is just one part of protecting our skin from UV rays. The Skin Cancer Foundation and the Cancer Council in Australia provide information on the many ways we can protect our skin. The Cancer Council calls this: slip, slop, slap, seek, slide.

  • Slip on sun-protective clothing that covers as much skin as possible. Not all fabrics provide sun protection, so it’s important to learn about which fabrics do. Garments with UPF labels can help guide your choice, but some fabrics are inherently sun protective. The Skin Cancer Foundation provides details here. The McGill Office for Science and Society recently published a guide to sun protective clothing that provides more details about what kind of clothing is sun protective.
  • Slop on broad-protection, water-resistant sunscreen. Apply according to the directions on the package. Some sunscreens take time to go into effect. The Skin Cancer Foundation recommends SPF15 or higher; Cancer Council recommends SPF30 or higher.
  • Slap on a hat with a broad brim.
  • Seek shade.
  • Slide on sunglasses with UV protection.

Babies, especially those younger than 6 months, should be protected from the sun by shade, clothing and hats. Sunscreen is not recommended for kids under 6 months old. At 6 months,  you can introduce sunscreen. As with all new skin care products, it is important to patch test to ensure your child (or you) don’t have a skin reaction to ingredients in a new product.

Broad spectrum” is defined by the FDA and indicates that the active sunscreen ingredients in a product protect against both UVA and UVB rays.

  • UVA is the most common because it is not absorbed by the ozone layer. It is also capable of penetrating past the top layer of our skin.
  • UVB is mostly absorbed by the ozone layer, but some still reaches us here on the surface of the earth. UVB rays don’t penetrate the skin as far as UVA rays. UVB rays are the rays that are critical for the production of vitamin D in the skin.
  • UVC rays are very dangerous, but you don’t need to worry about them because they are absorbed by the ozone layer. (This is why ozone depletion – the “ozone hole” – is such a big deal for human health. Without the ozone layer, more dangerous UV rays reach the surface of the earth and us.)

You can also check the UV Index, a measure developed by the EPA and the National Weather Service as a measure of the risk of overexposure to UV rays. The UV Index is measured on a scale of 1-15, with higher numbers representing a greater risk and a greater need for sun protection. You can use this information to help you decide how long to spend outside and what sun protection to wear to keep your sun exposure low. It’s also important to think about the time of day – your sun exposure will be greater at midday when the sun is directly overhead.

What sunscreen should I use?

You should use whichever of the FDA approved sunscreens that you will use with appropriate coverage and frequency to provide sun protection!

In the US, active ingredients typically found in sunscreen include: oxybenzone, avobenzone, octinoxate, octisalate, homosalate, octocrylene, titanium dioxide, and zinc oxide. There are 16 ingredients that are FDA approved, but these are the ingredients you will commonly find in the store. This piece is focused on ingredients available in the US.

In Europe and Australia, there are additional ingredients that are approved for use. However, they are not approved here for a variety of reasons including the fact that Europe regulates sunscreens as cosmetics and the US applies regulates them as over-the-counter drugs, which have a higher bar for approval. There is a backlog of sunscreen active approvals in the US and the complicated issues related to these delays are discussed in this article.

One caveat here relates to spray sunscreens. The FDA is currently exploring whether spray sunscreens provide effective sun protection in real life use. There is concern that people don’t spray enough sunscreen to get the full protection. Inhalation of spray sunscreen is also a potential but not well-understood concern. I will admit that we do use them for reapplying quickly when we are wet or sweaty, but we only use them outside and never spray our faces. If we need to use a spray on our faces, we spray into our hands and rub it on our faces. It is really important to never use sunscreen sprays near a flame; they often contain flammable ingredients and this can be very dangerous.

How do sunscreens work?

All sunscreens use chemicals to provide sun protection. There are two categories of types of chemicals.

Barrier sunscreens literally form a physical barrier that does not allow UV light through to your skin. These are sunscreens made from zinc oxide or titanium dioxide.

Chemical interactive sunscreens use chemicals that interact with the UV light, reducing its penetration and effects on the skin. These are all the other sunscreens on the market.

You will often see barrier sunscreens advertised as “natural”, “mineral” or “chemical-free” and as inherently safer. However, these are also chemicals with the potential to do harm in the wrong context or doses. The active ingredients in barrier sunscreens are subject to the same level of scrutiny for safety and effectiveness as chemical interactive sunscreens.

Different active ingredients protect again different wavelengths of UV light.

Ingredients can be used individually or in combination to provide broad-spectrum coverage, meaning they protect against UVA and UVB rays. Zinc oxide is the only currently FDA approved active that provides broad-spectrum coverage on its own. Unfortunately, many zinc oxide formulations are thick, difficult to apply and leave a white residue on the skin. This means that people don’t apply it well or often enough so real-world effectiveness is reduced. Fortunately, in the past couple of years, some brands have put out formulations that are easier to apply and I hope that these continue to improve.

Are these ingredients safe?

All the ingredients discussed above have been approved by the FDA for both safety and efficacy. This means that they have to work (protect your skin from UV rays) and be safe when used as instructed. It is important to remember that nothing is every 100% safe and “safe” really means minimally risky, not that there is no risk at all. What we do know is that risks of UV exposure and not using sunscreen are far higher than the risks of using sunscreen. No exposure occurs in isolation and must be considered within the landscape of all of our exposures.

Some of the chemical interactive sunscreens are part of a class of chemicals called salicylates. In some people, these ingredients (as well as a variety of medications) can cause photosensitivity. This report from the Skin Cancer foundation describes many types of medications and sunscreen ingredients that may cause photosensitivity in some people. To put this in perspective, some common classes of drugs that also can cause photosensitivity include oral contraceptives, anti-histamines, statins, and NSAIDs (like Advil).

As with all skincare ingredients, it is important to patch test any new product before use. This is especially true if you or your children have allergies or sensitive skin. Remember that most reactions to sunscreen are not due to the active ingredient, but to fragrances and other ingredients.

Should I worry about absorption of sunscreen ingredients through skin?

One week after the initial publication of this post, a new study was published in the Journal of the American Medical Association (JAMA) that has people worried about the risk of absorbing sunscreen into your bloodstream, but nothing about this study changes the recommendation to use sunscreen as part of your sun protection routine.

This Twitter thread by Dr. Ade Adamson, a dermatologist and Assistant Professor in the Department of Internal Medicine at Dell Medical School at the University of Texas at Austin, captures the take home messages from this new study, but I’ll also summarize them here:

  1. This study does not show that sunscreens are unsafe, nor does it change the recommendation to wear sunscreen. Because this study looked at absorption after “maximal use,” it’s important to keep in mind that actual absorption levels in people applying sunscreen in real life will likely be much lower. This also isn’t new information as we have known since at least 1997 that sunscreen ingredients can be absorbed through the skin and excreted in urine. Even so, this doesn’t change the big picture that any potential risk of harm from using sunscreen is far lower than the known risk of too much sun exposure. There remains little evidence of harm from the use of sunscreen.
  2. The FDA conducted this study because companies that make chemical sunscreens delayed in responding to FDA requests for additional safety data on these ingredients (see “What sunscreen should I use?” section above). Specifically, there is a new proposed FDA rule that requires companies to conduct additional toxicology testing for any sunscreen active ingredient absorbed into the blood at a concentration greater than 0.5 ng/ml. On the other hand, ingredients below this threshold can potentially be declared GRAS (generally recognized as safe, which we have previously explained in this post) and exempted from further testing. This does not mean that these levels are harmful, only that the FDA will not grant GRAS status and will not approve without further studies. The FDA requested this information, but since the companies failed to run the requested studies, the FDA stepped in and conducted the study themselves.
  3. Levels that exceed this threshold do not necessarily pose a health risk. After all, we have been using these ingredients for years, and there is little evidence of harm from the use of sunscreens. This threshold is only about whether an ingredient is eligible for GRAS status, not whether it poses an actual risk to human health. The risks of not using sunscreen still outweigh the potential risks of using a sunscreen with these ingredients.
  4. This commentary in the same issue of JAMA helps to put the study’s results in context:

“The findings of the study by Matta et al will likely raise concerns in the medical community, as well as among sunscreen users. Until more information is available, it will be important to continue to reinforce clinical recommendations regarding the beneficial effects of photoprotection for skin cancer prevention that are rooted in strong biological rationale and modest clinical evidence. Avoidance of the sunscreen ingredients highlighted in this study, or of sunscreen altogether, could have significant negative health implications. At a minimum, physicians should recommend use of sunscreen formulations containing GRASE ingredients such as titanium dioxide and zinc oxide as part of a larger program of photoprotection that includes seeking shade, and wearing protective clothing, hats, and sunglasses, until meaningful answers to these questions are available.”

So, barrier methods are the first choice but, again, if you’re unlikely to apply the barrier formulation properly, you should instead choose the sunscreen that you will actually use with appropriate coverage and with appropriate frequency. Cost may also be an issue. Generic brand sunscreens with these ingredients are still few and far between and not everyone can afford premium prices for a “fancy” name brand.

Is sunscreen bad for coral reefs?

Coral reefs are dying and certain sunscreen ingredients may be contributing to their death. While the FDA approved ingredients have met standards for human safety, there is research indicating that they are not good for coral reefs. After all, humans are not coral and coral is not human – chemicals affect us differently.

In particular, oxybenzone and octinoxate have been the subject of most of the research into the effects of sunscreen active ingredients and coral reef health, leading some places to ban these ingredients. This has led to yet another new, unregulated label: “Reef Safe”. While this might make consumers feel better, because this label is not regulated, any manufacturer can make a claim of “reef safe” even if it contains oxybenzone or octinoxate. In addition, some scientists are concerned about the effect other sunscreen actives may have on coral reefs. These include certain formulations of zinc oxide and titanium dioxide, octocrylene, and anything with microspheres or microbeads.

This research has caused a debate within the scientific and regulatory communities about how can we both protect human health and the environment. Some argue that we should wait for stronger scientific evidence, but others feel that, if we are wrong, we could lose coral reefs forever. If we ban sunscreen actives to avoid doing more damage to coral reefs, how do we prevent a major increase in skin cancer?

Part of the solution is to encourage all the other good sun protection practices mentioned above that do not involve sunscreen. We also need research that aims to develop sunscreens that are safe for both humans and the environment and research that explores ways to remove sunscreen ingredients from the water. Most of all, we need new sunscreen active ingredients and product development, and the FDA to process applications for approval in a timely manner (see the section above about the backlog of sunscreen approvals).

Is using sun protection bad for Vitamin D levels?

UV light is required for your body to produce vitamin D and having sufficient vitamin D levels is really important for your health. So if you avoid the sun completely, you don’t have enough vitamin D. But you don’t need a lot of time in the sun to have adequate vitamin D levels. How much time you need depends on where you live, what season it is and the time of day. This Australian study suggests the following guidelines for people across Australia to ensure sufficient vitamin D levels.

  • In summer, 2-14 minutes at midday, 3-4 times a week
  • In spring or fall, 10-15 minutes mid-morning or 3 pm, 3-4 times a week

The way my family handles this in the summer is that if we apply sunscreen when we get to the pool, by the time we get everyone slathered up, we’ve all had enough sun exposure to take care of our vitamin D production.

What are the sunscreen recommendations for people of color?

As recently reported in a New York Times article, “Should Black People Wear Sunscreen?”, current sunscreen recommendations are based on a body of research that largely excludes people of color. While the NY Times article, in my opinion, overstates concerns about the safety of sunscreen ingredients based on the absorption study (as discussed earlier in this article) and miscategorizes barrier sunscreens as not “chemical”, it does provide insight into the issues surrounding recommendations for people of color. We summarize these points here but recommend reading the full article.

  • Dark-skinned individuals do not have the same relationship between UV light exposure and skin cancer as light-skinned individuals.
  • When dark-skinned people get skin cancer, it tends to be on areas of the body with the least exposure to the sun (like soles of the feet and palms of the hands).
  • Just like people with other skin types, black people can get sunburns and show signs of aging from sun exposure.
  • Different shades of skins have different sensitivity to the sun.
  • Dark-skinned individuals should pay attention to moles and get periodic skin checks because when dark-skinned people do get cancer, it tends to be more deadly (for reasons unrelated to UV exposure). This does NOT mean that people of color don’t get UV-related skin cancer – they do, but more cases are not UV-related. 

Dr. Ade Adamson, who we referenced above, has also written about this topic at The Conversation: “Sunscreen wouldn’t have saved Bob Marley from melanoma, and it won’t help other dark-skinned people.”

This Q&A from the Skin Cancer Foundation with Dr. Andrew Alexis, the chair of the Department of Dermatology at Mount Sinai St. Luke’s and Mount Sinai West and director of the Skin of Color Center also provides important information on skin cancer and sunscreen in people of color.

All of this means that the risk-benefit calculation for sunscreen use in people of color is unclear. As with any individual decision, the decision of whether to use sunscreen (the hazard) is somewhat dependent on how risk-tolerant risk-averse you are and which risks you are more or less tolerant of. For example, Kavin wrote: 

“I never wore sunscreen in childhood or even through my 20s because I didn’t think I needed to. But now I wish I had because of signs of aging. I wonder if maybe I’d have fewer wrinkles if I had started wearing it in my early 20s. Now, I apply it to my face and neck every day, and arms often. We don’t put it on our kids because the risk-benefit calculation is unclear and the effort-benefit calculation led us to conclude that it’s not really worth the effort.”

Given the lack of data on the benefits of sunscreen in people of color and the uncertainty about the potential harm, it is hard to know how much risk to tolerate. In general, the lower the benefit and the more severe the potential harm, the less risk we would tolerate. This issue also raises important points about the differences between population-based public health messaging and individual healthcare decisions; when risks and benefits are uncertain and/or small, these differences become harder to parse. Finally, like with many other health-related issues, the lack of sunscreen research on people of all skin colors reveals highlights how scientific institutions have failed people of color.

Other resources

Sunscreen causes cancer? What a dangerous lie: This 2015 article (also by Alison) delves into the science of UV rays and the research behind risks and benefits of sunscreen in more depth.

Skin Cancer Foundation

Cancer Council

Skin Cancer (CDC)

Sunscreen: How to Help Protect Your Skin from the Sun (FDA)

This post was updated on August 24, 2019 to add additional information about sun-protective clothing and sunscreen recommendations for people of color.