But despite those long-awaited changes, many sunscreens continue to carry SPF ratings that some experts consider misleading and potentially dangerous, according to a consumer watchdog group.
A survey of 1,400 sunscreen products by the Environmental Working Group finds that most products meet new federal requirements put in place last December. The rules from the Food and Drug Administration ban terms like "waterproof," which regulators consider misleading, and require that sunscreens filter out both ultraviolet A and B rays. Previously some products only blocked UVB rays, which cause most sunburn, while providing little protection against UVA rays that pose the greatest risk of skin cancer and wrinkles.
Despite that broader protection, one in seven products reviewed by the watchdog group boasted sun protection factor, or SPF, ratings above 50, which have long been viewed with skepticism by experts. In part, that's because SPF numbers like 100 or 150 can give users a false sense of security, leading them to stay in the sun long after the lotion has stopped protecting their skin.
Many consumers assume that SPF 100 is twice as effective as SPF 50, but dermatologists say the difference between the two is actually negligible. Where an SPF 50 product might protect against 97 percent of sunburn-causing rays, an SPF 100 product might block 98.5 percent of those rays."The high SPF numbers are just a gimmick," says Marianne Berwick, professor of epidemiology at the University of New Mexico. "Most people really don't need more than an SPF 30 and they should reapply it every couple of hours." Berwick says sunscreen should be used in combination with hats, clothing and shade, which provide better protection against ultraviolet radiation.
Some dermatologists say there may be some rationale for using higher SPF sunscreens, since users often don't apply enough of the lotion to get its full effect.
"The challenge is that beyond 50 the increase in UV protection is relatively small," says Dr. Henry Lim, chair of dermatology at the Henry Ford Hospital in Detroit.
The SPF number indicates the amount of sun exposure needed to cause sunburn on sunscreen-protected skin compared with unprotected skin. For example, a SPF rating of 30 means it would take the person 30 times longer to burn wearing sunscreen than with exposed skin.
There is a popular misconception that the SPF figure relates to a certain number of hours spent in the sun. However this is incorrect, since the level of exposure varies by geography, time of day and skin complexion.
The FDA itself said in 2011 that "labeling a product with a specific SPF value higher than 50 would be misleading to the consumer." At the time the agency proposed capping all SPF values at 50 because "there is not sufficient data to show that products with SPF values higher than 50 provide greater protection for users." But regulators have faced pushback from companies, including Johnson & Johnson, which argue that higher SPF products provide measurable benefits.
As a result, the FDA says it is still reviewing studies and comments submitted by outside parties, and there is no deadline for the agency to finalize an SPF cap.
It took the agency decades to put in place last year's sunscreen changes. FDA first announced its intent to draft sunscreen rules in 1978 and published them in 1999. The agency then delayed finalizing the regulations for years until it could address concerns from both industry and consumers.
The FDA is also reviewing the safety of effectiveness of spray-on products, which use different formulations from other sun-protection solutions. Among other concerns, the agency is looking at whether the sprays can be harmful when inhaled.
The survey by the Environmental Working Group found that one in four sunscreens sold in the U.S. is a spray product.
"People like the sprays because they are quick to put on and cover a lot of area," said Dr. Darrell Rigel, a dermatologist in New York. "The downside is that you usually have to apply two coats."
More than 76,000 men and women in the U.S. will be diagnosed with melanoma this year and 9,480 are expected to die from the aggressive form of skin cancer, according to the National Cancer Institute. The disease, which is often linked to ultraviolet exposure, is usually curable when detected early.