Sunscreens for Swimming

July 15, 2019

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THE BEST protection against the sun’s harmful UV rays would require staying indoors or in the shade during the brightest midday hours. But on occasions when that’s impossible, such as wishing to swim when the weather app says 40% chance of thunderstorms all day, any break in the clouds means you’ve got to go.

Water magnifies the burning effects of the sun and can disable some of the best sun-protection formulations.  While all sunscreens should be reapplied every two hours, the SPF can drop by as much as 50% after just 40 minutes in water and possibly faster in salt water.

Sunscreens labeled waterproof (technically “water-resistant”) should offer at least 80 minutes of protection. For non-swimmers, water-resistant sunscreens last longer in sweaty weather.

Choosing the best sunscreen for any occasion is always a trade-off between two kinds of barriers—with two categories of ingredients: the physical, or mineral, uses zinc oxide and titanium dioxide; the chemical includes avobenzone, oxybenzone, octinoxate and octisalate.

Sunscreens that create physical barriers on the skin’s surface begin to work immediately but also wash off more quickly, with most products listing endurance at 40 minutes. Zinc oxide may offer better protection than titanium dioxide, but for those who recall the white noses of tennis players and skiers in the old days, high zinc concentrations at the “paste” level these days are sold only for use on horses’ heels.

“None of the mineral sunscreens in our tests this year did well enough to make our list of recommendations” is the latest conclusion from Consumer Reports.

Chemical sunscreens, because they must be absorbed by the skin to work, require application 15-30 minutes before needed but can last up to 80 minutes in water.  Based on the math, they offer longer protection but only with advance planning.

On the other hand, many of these chemicals harm the environment, notably coral reefs, and possibly their users as well. Based on recent human health-related findings, the FDA is expected to propose “big changes to sunscreen regulations” in late 2019, which might obviate the selection process entirely.

While using both physical and chemical sunscreen at the same time might seem like a good way to get the benefits of each, such a combination risks diluting or even canceling out the protection offered by either one.

As for SPF, experts disagree: Some assert little benefit in any SPF over 30, while others recommend the highest number possible (100+) for longest-lasting as well as highest-level protection.

According to Consumer Reports, “no sunscreen blocks 100 percent of UVA or UVB rays. The breakdown: SPF 30 blocks 97 percent of UVB rays, SPF 50 blocks 98 percent, and SPF 100 blocks 99 percent.”

Also from Consumer Reports: “The SPF number gives you no information on how well a sunscreen protects against UVA rays. That’s why you need to look for a broad-spectrum sunscreen, which protect against both UVA and UVB.”

Based on the discovery that the true SPF of many products is lower than listed, Consumer Reports notes that choosing “a sunscreen with chemical active ingredients and an SPF of 40 or higher will give you a better chance of getting at least an SPF 30.” Dermatologists surveyed by Prevention Magazine suggest SPF 50 and higher.

Achieving the posted SPF requires heavy application—some say a shot-glass worth over the whole body.  Lotions can be applied more evenly and generously, while sprays make it harder to reach sufficient SPF.  And sunscreen included in moisturizers is too diluted to offer much protection.

An additional concern is the pore-blocking or comedogenic properties of different sunscreens.  Maryland editor C.M. and her daughters —a self-described acne-prone family—have sampled many options only to agree: “there is no such thing as non-comedogenic.”  They also deem avobenzone “the worst offender” among sunscreen ingredients for leaving yellow stains on white clothes.

In the end, though, dermatologists and others observe that everybody’s skin is different, and some do better with unlikely formulations—which refers the testing and selecting back to the individual.

Once the choice has been made, expiration dates are important.  Products not stored in a cool, dry place can become less effective before the printed end-date. Also, shake before using to make sure the sun-protecting ingredients are spread throughout.

Only Lifejacketadvisor gives recommendations for the best water-resistant sunscreens (all for 80 minutes): for physical barriers, Blue Lizard Australian SPF 30 as “simply the best water-resistant,” and EltaMD UV Sport SPF 50; and for chemical formulations, Neutrogena Beach Defense SPF 70.

The only general sunscreen review to include “best water-resistant” (also 80 minutes) named Sunology Mineral Sunscreen SPF 50.

While sunscreen reviews differ almost entirely on their top pick, the one overlap goes to EltaMD UV Broad-Spectrum SPF 46 (physical), winning “best overall sunscreen” on New York Magazines’s Strategist as well as from dermatologists polled by Prevention Magazine.

Number one from Consumer Reports – also mentioned on Forbes—is La Roche-Posay Anthelios SPF 60 (chemical).

When choosing sunscreens, don’t forget the lips. To be avoided: lip gloss, which can attract UV rays; ingredients like menthol and camphor, which can be drying and irritating; and beeswax, which can cause an allergic reaction. Winners from reviewers: EltaMD SPF 31 and Vanicream Lip Protectant SPF 30—both physical; and for chemical, Banana Boat Sport Performance Lip Balm SPF 50.

Best known for protection against jellyfish, the whole-body suit is a completely different kind of physical barrier, made of synthetic materials, including nylon, and effective against sunburn as well.

For the face alone, some prefer wearing a swim mask with snorkel.  Or a balaclava — made of synthetic material like the jellyfish suit with a mask-sized opening—protects the entire head and neck as well.

A similar, newer option with tiny separate slits for the eyes, nose and mouth—although some complain about trouble breathing—is the “facekini.” In the end, though, there’s the Consumer Reports conclusion: “Research shows that people who rely on sunscreens alone tend to burn more than those who stay in the shade and wear long sleeves.”

—Mary Carpenter

Well-Being Editor Mary Carpenter reports on news you can use right here every Tuesday. 


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