Sunscreens protect skin from ultraviolet radiation with one of two kinds of filters: mineral or chemical. Mineral filters use zinc oxide or titanium dioxide to reflect UV rays. (They tend to leave a white sheen on the skin.) Chemical filters absorb the UV radiation and release it as heat.
Cosmetic-safety advocates often recommend avoiding chemical sunscreens because they typically contain two hazardous ingredients: oxybenzone and retinyl palmitate, a form of vitamin A. Studies have linked oxybenzone to hormone disruption and connected retinyl palmitate to increased skin lesions in mice, notes Sonya Lunder, MPH, a senior analyst at the Environmental Working Group who specializes in toxic chemicals.
But even mineral sunscreens don’t keep you protected unless you reapply them often.
“Thanks to overblown marketing claims, people overestimate the amount of protection they get,” Lunder explains. Anything that claims to have an SPF rating higher than 30 offers only marginally more protection and can produce a false sense of security. An SPF 100 sunscreen can easily lull you into using too little and staying out in the sun too long.
The key to protection is applying enough. She recommends “a shot-glass-full for your whole body,” and reapplying every two hours when you’re outdoors.
Lunder acknowledges that it’s far better to use sunscreen than to be unprotected, but she underlines its limitations. “Sunscreen is losing its protective power as soon as it’s applied — it’s rubbing off,” she says. “A light layer of clothing is your best protection.”
This originally appeared “I’ve heard certain sunscreens can be toxic. Are there types I should avoid? What else can I do to protect my skin from overexposure?” in the July/August 2018 print issue of Experience Life.