Courtesy: Becky Woodruff
It’s no secret that swimmers log many hours in the sun, especially now that long course season is in full swing. All that time outdoors can take its toll, as skin cancer is the most commonly diagnosed cancer in the US. To prevent skin cancer and protect the skin from sunburn and other damage, the Food and Drug Administration (FDA) currently recommends wearing a broad spectrum sunscreen with an SPF of at least 15 upon any sun exposure. With daily use of sunscreen, we, as consumers, assume that what we buy in the stores and use on our bodies is safe. You might be shocked to know that this might not be the case, as many of the ingredients in sunscreen have never been tested for safety.
In a ruling issued in February 2019, the FDA marked only 2 of 16 active ingredients used in all sunscreens sold in the USA as “generally recognized as safe and effective”. Those two ingredients are zinc oxide and titanium dioxide, which are mineral or “physical” sunscreens that sit on top of your skin and reflect the sun’s rays. The FDA ruled that chemical sunscreens, which include the commonly used ingredients like avobenzone, oxybenzone, homosalate, octinoxate, and octisalate, do not have enough health data available to determine if they are safe and effective. Chemical sunscreens soak into the skin and work by absorbing UV rays and releasing them as heat. Chemical sunscreens are widely used by swimmers, as they tend to be easier to apply and more water-resistant than the physical sunscreens.
Although chemical sunscreens absorb into the skin, no one knew if these ingredients were then getting into our bodies. In a recently published clinical trial, scientists at the FDA studied the absorption rates of four commonly used chemical filter sunscreen ingredients during conditions that mimics daily use during outdoor activities. Even a small percentage of absorption when a product is used daily could be significant, as a drug can accumulate in the body overtime. This study found that all four of the active ingredients tested, including avobenzone, oxybenzone, octocrylene, and ecampsule, were absorbed between 2-6 hours after the first application, and continued to accumulate every day that the product was used.
The FDA has set a limit for absorption called the “Threshold for Toxicological Concern” where, if a chemical is absorbed over a certain concentration, further testing is warranted to determine if the chemical is carcinogenic or toxic. All of the ingredients tested met this limit on day 1 of use, and remained above the threshold level for 3 days after the last application.
The results of this study are a cause for concern for individuals using sunscreen on a regular basis, such as swimmers. Because these ingredients are absorbed and accumulate over time, swimmers could end up with high levels of these chemicals in their bodies. What we don’t know yet is if these chemical filters are harmful. Under the Sunscreen Innovation Act, these ingredients will now undergo extensive testing to determine if they can cause “cancer, reproductive harm, or endocrine effects” once in the body. For comparison, if an ingredient is absorbed below the threshold level, the FDA requires minimal safety data and mainly focuses on its effect on the skin (such as rashes or irritation). Currently, the FDA relies on the manufacturers themselves to conduct the studies to address the safety data gaps for the individual sunscreen ingredients.
Several of the chemical filters have preliminary safety studies that are alarming and indicate links to skin allergies or hormone disrupting properties, the latter of which can cause cancer, birth defects, or other developmental issues. Oxybenzone, a commonly used active ingredient in sunscreen, has been detected in more than 96% of Americans, and some studies have shown it to have hormone disrupting properties. Along with octinoxate, it has been banned by Hawaii and Key West because of its damaging effects on coral reefs. Avobenzone, on the other hand, provides the best UVA protection out of the chemical filters and currently has no studies linking it to hormone disruption.
The FDA is expected to update their current recommendations in the wake of the published study. Until then, the FDA is still recommending consumers to wear either physical or chemical sunscreens and take other sun-protective measures while outdoors. Those include limiting time in the sun while the sun’s rays are most intense, typically between 10AM and 2PM, and wearing clothing and hats to cover skin exposed to the sun.
For swimmers, it might not always be possible to avoid sunscreen exposure, so wearing sunscreen is key. Because getting in and out of the water is par for the course during meets in practice, swimmers should be careful to reapply sunscreen often, at least every two hours. No sunscreens are “waterproof” as they all wash off eventually, but look for those that are “water resistant”, as those are required to be tested and remain effective for 40 or 80 minutes, depending on the directions on the label. If choosing physical sunscreens with zinc oxide or titanium dioxide, be sure to apply more often, as these wash off easier.
Choose broad-spectrum sunscreens that protect from both UVA and UVB rays, with an SPF of 15 or higher, and apply around one ounce of sunscreen (about two tablespoons) to cover the body from head to toe. Spray sunscreens are hard to apply evenly or sufficiently to provide sun protection, and can pose an inhalation risk. Additionally, keep in mind that sunscreens with a higher SPF often have several different active ingredients and/or at higher concentrations, so get in the habit of reading your labels.
The Environmental Working Group (EWG) publishes a guide to safe sunscreens that has a searchable database where you can check your favorite products for a safety rating from 1 (safest) to 10 (most harmful). Aside from the active ingredients in sunscreen, other ingredients can be harmful or toxic. Personal care products are some of the least-regulated consumer products on the market. The FDA does not require that cosmetic ingredients be assessed for safety before they go on to the market, and they cannot issue a product recall. The EWG database takes other ingredients into account to publish its safety rating, and is a great guide when looking at the safety of your products.
The take home? Chemical sunscreen ingredients, such as oxybenzone, do get into your body at a level that has a potential for doing harm. More studies are needed to determine if any of these ingredients have any toxic effects. In the meantime, the most important thing to do is to continue wearing sunscreen, but choose physical sunscreens with zinc oxide or titanium dioxide, or choose chemical sunscreens with avobenzone as the active ingredient, if possible.
About Becky Woodruff
Becky Woodruff obtained her Ph.D. from Duke University in cell and molecular biology, with a research focus on developing new blood therapeutics. She is currently a health advocate/educator with Beautycounter. She swam at the University of North Carolina-Chapel Hill and is a coach at Cascade Swim Club in Seattle, WA.