Via the Los Angeles Times:
“The agency has developed new protocols for testing the products’ effectiveness at blocking the sun’s damaging ultraviolet rays. Under the new guidelines, sunscreens may be labeled “broad spectrum” if they block UVB radiation and a percentage of UVA radiation. UVB is the major cause of sunburn, while both UVA and UVB cause early skin aging and skin cancer.
Products that are broad spectrum and have a sun protection factor of 15 or higher may be labeled to say that they reduce the risk of skin cancer and premature skin aging. Conversely, those that are not broad spectrum or that have an SPF lower than 15 will be required to carry a warning that they have not been shown to reduce such risks.
Sunscreens will no longer be able to claim to have a specific SPF above 50: The highest category now will be 50+. “We don’t have sufficient data to show that those with an SPF higher than 50 provide greater protection,” [said Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research].
Products will no longer be allowed to be labeled as sun blocks because there is no evidence that they block all the radiation in sunlight. Products also may no longer be labeled “waterproof” or “sweat proof.” Instead, they can only be called “water resistant,” and labels must state clearly how long such protection lasts — either 40 minutes or 80 minutes.
Labels with these new requirements must be in place by summer 2012, Woodcock said, but the agency hopes that companies will implement them sooner.
Woodcock also noted that there had been some concern about sunscreens containing nanoparticles of zinc oxide or titanium dioxide, which block sunlight. Some critics have suggested that the extremely small particles can penetrate the skin and cause health problems.
But Woodcock said the agency had recently performed animal testing and found that the nanoparticles do not penetrate the skin. The findings are in agreement with studies that have been published in scientific journals, and there is currently no evidence to suggest that other chemicals commonly used in sunscreens are dangerous, she added.”