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The trouble with SPF

Most consumers choose a sunscreen product based on its sun protection factor, or SPF, often reaching for those with a high SPF value, assuming they offer the best protection from the sun’s harmful ultraviolet, or UV, rays. But that is often far from the truth.

SPF values are an unreliable measure of a sunscreen’s effectiveness. A good sunscreen should provide equal broad-spectrum protection, protecting against both UVA and UVB rays. But the SPF value reflects only how well a product will protect from UVB rays, the main cause of sunburn and some skin cancers, such as squamous cell carcinoma.

Reducing sunburn was the original intent of sun protection products, but it is now known that some UV rays don’t cause sunburn and instead lead to other health harms. SPF values do not reflect a product’s ability to protect from UVA rays, which penetrate the skin more deeply than UVB rays, and are associated with skin aging and cancer, such as melanoma.

SPF values are also unreliable because the test method that companies must use to determine a product’s value is imprecise. It requires someone to determine a change in the skin redness of a small handful of human participants exposed to UV light in a lab. These results may differ based on the evaluator, testing instrumentation or participant skin type. And SPF test conditions used for labeling significantly overestimate the protection a sunscreen may provide when it is used outdoors.

During the last two decades, EWG has tested products and reviewed the results of various other studies to verify the sun protection performance of U.S. sunscreen products. But the available data don’t instill confidence in SPF values alone as an accurate measure of protection.

Independent tests have also revealed shortcomings with the Food and Drug Administration’s current requirements for UVA protection from sunscreens.

An EWG peer-reviewed study published in Photodermatology, Photoimmunology and Photomedicine found a number of sunscreens sold in the U.S. provide inadequate UVA protection, compared to the listed SPF’s claim. This gives sunscreen users a false sense of protection, which can lead them to use less sunscreen than they need and risk overexposure.

A total of 51 sunscreen products were tested for UV absorption in a laboratory using in vitro methodologies, and results showed that, on average, products reduced the UVA exposure by only half of what would be expected based on the labeled SPF. Just 18 of 51 products passed the UVA protection test required of products sold in Europe. 

Unreliable protection

Given EWG’s findings, consumers should assume many sunscreen products on the market offer significantly reduced UVA protection compared to UVB protection. We found the UVA protection factor achieved was, on average, only a quarter of products’ labeled SPF.

Most sunscreens tested by EWG also failed to show reliable UVB protection. Our research found that most sunscreens provided just 42 to 59 percent of the UVB protection that might reasonably be expected from what’s stated on the SPF label.

U.S. sunscreens had higher labeled SPF values than tests would suggest they achieve, in addition to inadequate UVA protection, leaving consumers at potential risk for long-term harm from UV exposure.

Many products tested would not meet the UVA standards set by the European Commission for products sold within European Union countries. The European Commission recommends sunscreen products’ ratio of UVA protection to SPF be at least one-third. But only about a third of the products tested passed the EU standard, whereas more than nine out of 10 – 94 percent – would get the FDA’s green light.

Test results by the FDA published in 2019 also found significant differences in UVA protection among products with the same SPF. Despite the FDA’s awareness of large differences in UVA protection and the connection between UVA exposure and skin cancer, the agency has yet to strengthen the required UVA protection of SPF products. 

The FDA proposed new rules in 2021 that would require a slightly increased minimum level of UVA protection. But the proposed rules haven’t taken effect nor are they strong enough to ensure adequate UVA protection.

Problems with high SPF

People place too much trust in high SPF products. There are at least four flaws with a sunscreen that boasts an SPF value above 50+:

1. Poor UV balance

A sunscreen’s SPF rating has little to do with its capacity to shield skin from UVA rays. As SPF increases, the ratio of UVA protection decreases in U.S. sunscreens.

High SPF products suppress sunburn much more effectively than protect from UVA-induced damage, such as suppression of the immune system, formation of harmful free radicals in skin, and development of melanoma.

Compared to products sold in other countries, U.S. sunscreens offer far less protection against UVA than UVB rays because of inadequate UVA standards and limited options for providing UVA protection. This problem is even worse with products that have the highest SPF values.

2. Consumers misuse high SPF products

High SPF products tend to lull users into a false sense of security, so they stay in the sun longer and overexpose themselves to both UVA and UVB rays well past the point when users of low SPF products would likely head indoors. So they get as many UVB-inflicted sunburns as unprotected sunbathers and likely absorb more damaging UVA radiation.

Philippe Autier, a scientist formerly at the World Health Organization’s International Agency for Research on Cancer, was one of the first to conduct studies of sunbathers. Autier believes that high SPF products spur “profound changes in sun behavior” that may account for the increased melanoma risk found in some studies.

In two studies, one in 1999 and another in 2000, Autier first confirmed that European vacationers spent more total time in the sun if they were given a sunscreen with SPF 30 instead of SPF 10. A 2001 randomized control trial in France found similar results when comparing the behavior of participants using sunscreens with SPF 40 and sunscreens with SPF 12. EWG  assumes the difference would also apply to products with SPF values greater than 50.

Autier’s studies have been extensively cited in analyses of sun protection behavior, including in a 2014 literature review that summarized the associations between sunscreen application behaviors and sun protection.

Misinterpretations of the meaning of SPF have also been reported more recently, including in a 2018 study that reported dermatology patients answered questions about SPF and water-resistance of sunscreens correctly only about 30 percent of the time.

The FDA cited Autier’s 2007 review paper on the associations between SPF and sunscreen use behavior in the agency’s 2021 proposed new regulations for sunscreen.

3. Sunburn protection is only marginally better with high SPF

Sunbathers often assume they get twice as much protection from SPF 100 sunscreen as from SPF 50. But the extra protection is negligible.

Properly applied SPF 50 sunscreen blocks 98 percent of UVB rays; SPF 100 blocks 99 percent. When used correctly, sunscreen with SPF values between 30 and 50 offers adequate sunburn protection, even for people most sensitive to sunburn.

4. High SPF products may pose greater health risks

High SPF products require higher concentrations of sun-filtering chemicals than low SPF sunscreens do. Some of these ingredients may pose health risks when they penetrate the skin and have been linked to tissue damage and potential hormone disruption. Some may trigger allergic skin reactions.

If studies showed that high SPF products were better at reducing skin damage and skin cancer risk, the extra chemical exposure might be justified. But they don’t. So it’s prudent to choose sunscreens with lower concentrations of active ingredients, for example SPF 30 instead of SPF 70.

The FDA has long contended that SPF higher than 50 is “inherently misleading.” SPF values are limited to 50+ in most countries. In 2011, the FDA proposed prohibiting labels higher than SPF 50+.

But in its 2021 final draft sunscreen order, the agency proposed raising the cap to 60+. EWG believes the FDA should reconsider this change and instead cap values at 50+.