Facts about Sunscreen Safety
UVA versus UVB rays
Most sunscreens fare well when it comes to UVB protection–the most superficially penetrating rays, responsible for giving us a suntan (or burn). UVB rays also contribute to skin cancer and aging.
UVB protection is measured by Sun Protection Factor (SPF). "If you have a sunscreen with an SPF15, you can stay out in the sun for 15 times longer than you could without that sunscreen and not get a sun burn," says Dr. Paul Cohen, a Toronto-based dermatologist. But SPF doesn't protect us from UVA rays.
"UVA rays penetrate deeper than UVB," says Dr. Cohen. Although they do not physically tan or burn your skin, they are the primary rays responsible for premature aging and skin cancer.
"There are only four approved ingredients known to block UVA rays," says Sean Gray, a senior analyst with the EWG. These include: zinc oxide, titanium dioxide, avobenzone, and mexoryl. So a parent simply needs to look for one of these four ingredients on sunscreen labels, right?
It's not quite that simple. The later two ingredients are highly unstable and break down quickly in sunlight. "Many companies use avobenzone as a UVA blocker," says Gray. "And on it's own, it just doesn't cut it."
Companies such as Neutrogena, La Roche-Posay, Vichy and Ombrelle add ingredients to increase the photostability of avobenzone, so you can rest a bit easier. "At the time, however, there's no third-party verification," says Gray. "So if you're relying on avobenzone to block UVA, it's a trust issue."
To be safe, parents should look for a sunscreen with at least a seven percent concentration of zinc oxide or titanium dioxide. These are stable ingredients that will protect against UVA rays for at least two hours.
