High-SPF products tempt people to apply too little sunscreen and stay in the sun too long.
According to the EWG, there are five key strikes against SPF values greater than 50:
- Marginally better sunburn protection.Sunbathers often assume that they get 2x the protection from SPF 100 sunscreen as from SPF 50. In reality, the extra protection is negligible. Properly applied SPF 50 sunscreen blocks 98 percent of sunburn rays; SPF 100 blocks 99 percent. When used correctly, sunscreen with SPF values in the range of 30 to 50 will offer adequate sunburn protection, even for people most sensitive to sunburn.
- Poorer balance.The chemicals that form a product’s sun protection factor are aimed at blocking ultraviolet B rays, which are the primary cause of sunburn and non-melanoma skin cancers such as squamous cell carcinoma (von Thaler 2010). Ultraviolet A rays suppress the immune system, cause harmful free radicals to form in skin, and is associated with higher risk of developing melanoma. They also penetrate deeper into the skin and are harder to block with sunscreen ingredients approved by the FDA. A sunscreen lotion’s SPF rating has little to do with the product’s ability to shield the skin from UVA rays. Because UVA and UVB protection do not harmonize, high-SPF products suppress sunburn much more effectively than other types of sun damage.
- High-SPF products may not really be high-SPF.When Procter & Gamble tested a competitor’s SPF 100 product at five different labs the results varied between SPF 37 and SPF 75. The company determined that a very small difference in testing conditions can have a dramatic influence on the calculated SPF. In this case a 1.7 percent change in light transmission yields a SPF measurement of 37 instead of 100. Small difference in application thickness could have a similar effect. Because of the way SPF values are calculated these errors would be most dramatic for high SPF products. They concluded that SPF values should be capped at 50+ because the current system is “at best, misleading to consumers” and “may inappropriately influence their purchase decision” (P&G 2011).
- Consumers misuse high-SPF products.High-SPF products make people feel like it’s okay to stay in the sun longer, therefore overexposing themselves to both UVA and UVB rays.
- High-SPF products may have greater risks to health.High-SPF products require higher concentrations of sun-filtering chemicals than low SPF sunscreens. Some of these ingredients may pose health risks when they penetrate the skin, where they 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, that 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 wise.