Sunscreen Users More Likely to Burn?
More Sunscreen, More Sunburns
“I was quite surprised to find the associations that we’ve found with the different types of sun protection,” says study researcher Eleni Linos, MD, DrPH, MPH, a dermatologist at Stanford University.
“What we saw was that wearing long-sleeved clothing, wearing a hat, and staying in the shade were associated with fewer sunburns,” she says. “However, wearing sunscreen was actually associated with more sunburns.”
Linos is quick to point out that her results don’t mean that sunscreen doesn’t work or shouldn’t be used.
The study was designed to look at patterns, not to prove cause and effect.
It’s possible that people with the fairest, most easily burned skin are also simply the group most likely to use sunscreen.
But if that were the case, Linos says, she would have expected to see the same phenomenon across all the different groups. That is, frequent shade seekers and long-sleeve wearers would also report having more burns compared to those who rarely reported those tactics.
The more likely explanation, she thinks, is user error -- people simply aren’t applying as much sunscreen as often as they should.
Numerous studies have shown that most people, even after they’re carefully schooled in proper sunscreen application, still don’t get enough on.
One of the latest, from researchers in Brazil, asked study participants to cover both forearms with sunscreen, and 30 minutes later, to reapply the sunscreen to just one arm.
Researchers used tape strips to measure how thickly the lotion went on.
Sunscreen is tested to work at its SPF when it’s applied to a depth of at least 2 milligrams per square centimeter on the skin.
After the first application, study participants got only a quarter of that amount on. For the arm that got the second application, the depth of the sunscreen eventually reached half of what it should have been, suggesting that even people who remember to reapply aren’t being fully protected.
Shade, Hat, Sleeves
Another problem is that many people rely on sunscreen as their sole form of protection, when really, shade and protective clothing need to be part of a multi-pronged approach to avoiding sunburns, which increase the risk of skin cancer.