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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 and are associated with skin aging and cancer.

SPF values are also unreliable because the test method companies must use to determine a product’s SPF 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 overestimate significantly the protection the sunscreen may provide when it is used outdoors.

In the past decade, EWG has tested products and reviewed the results of various studies to verify the sun protection performance of U.S. sunscreen products. But the available data doesn’t instill confidence in SPF values alone as an accurate measure of protection. Independent tests have revealed a lot about the shortcomings of the FDA’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 what the listed SPF would indicate, which gives sunscreen users a false sense of protection. 

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. Just 18 of 51 products passed the UVA protection test required of products sold in Europe. 

Given EWG’s findings, consumers should assume many sunscreen products on the market offer lower balanced UVA and UVB protection. We found the UVA protection factor was only a quarter of the labeled SPF, on average.

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 the SPF label. U.S. sunscreens had higher labeled SPF values than tests would suggest, 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 in Europe. 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 green light from the Food and Drug Administration.

Test results by the FDA published in 2019 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 rules are not yet in place nor are they strong enough to ensure adequate UVA protection.

What’s wrong with high SPF

Sunscreen products with SPF values above 50+ tend to give users a false sense of security. They not only overpromise protection but may also overexpose consumers to UVA rays and raise their risk of cancer, according to the FDA. Many studies have found that people are more likely to use high SPF products improperly and, as a result, may expose themselves to more harmful ultraviolet radiation than do people who rely on products with lower SPF values.

People trust these high SPF products too much. There are four strikes against SPF values greater than 50+. They include:

Poor balance 

A sunscreen’s SPF rating has little to do with its capacity to shield the skin from UVA rays. As SPF increases, the ratio of UVA protection decreases. 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. As a result of inadequate UVA standards and limited options for providing UVA protection, U.S. sunscreens offer far less protection against UVA than UVB rays, and this is worse for products with the highest SPF values.

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, has conducted many studies of sunbathers and 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. We assume 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.

Sunburn protection is only marginally better 

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.

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 choosing sunscreens with lower concentrations of active ingredients – SPF 30 instead of SPF 70, for example – is prudent.

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+.