WASHINGTON (AP) -- Federal regulators will require sunscreen manufacturers to test their products' effectiveness against sun rays that pose the greatest risk of skin cancer. Under new rules published Tuesday, they also will have to follow stricter guidelines when describing how well their products block ultraviolet B rays.
The Food and Drug Administration announced new regulations Tuesday designed to enhance effectiveness of sunscreens and make them easier to use.
Sunscreens that don't protect against both ultraviolet A and B rays and have a sun protection factor, or SPF, below 15 will have to carry warning label: "This product has been shown only to help prevent sunburn, not skin cancer or early skin aging."
Currently, the FDA only requires testing for ultraviolet B rays that cause sunburn. That's what the familiar SPF measure is based on.
But the new regulations require testing for the more dangerous ultraviolet A rays, which can penetrate glass and are most commonly linked to wrinkles and skin cancer.
FDA will also prohibit sunscreen marketing claims like "waterproof" and "sweatproof," which the agency said "are exaggerations of performance."
Products that protect against UVA and UVB will be labeled "broad spectrum." In an effort to clear up the confusing mix of numbers, acronyms and symbols on sunscreen labels, the FDA says manufacturers must phase out a four-star system currently used by some companies to rate UVA protection.
The FDA rules will also standardize the older SPF protection rankings for UVB rays. Only sunscreens with an SPF of 15 or higher can claim to lower the risk of cancer. The FDA also proposed capping the highest SPF value at 50, unless companies can provide results of further testing that support a higher number. Some products on the market claim to offer SPF protection of a 100 or higher.
The SPF figure indicates the amount of sun exposure needed to cause sunburn on sunscreen-protected skin compared with unprotected skin. For example, an SPF rating of 30 means it would take the person 30 times longer to burn wearing sunscreen than with exposed skin.
FDA announced its intent to draft sunscreen rules in 1978 and published them in 1999. The agency then put the plan on indefinite hold until it could address issues concerning both UVA and UVB protection.
The delay in FDA regulations means many companies have already adopted the some of the language. For example, all Coppertone products from Merck & Co.'s Schering-Plough unit and Neutrogena Sunblock from Johnson & Johnson already boast "broad spectrum UVA and UVB protection."
Most dermatologists recommend a broad spectrum, water-resistant sunscreen of SPF 30 or higher every two hours while outside.
Last year an estimated 68,130 people in the U.S. were diagnosed with melanoma - the most dangerous form of skin cancer - and an estimated 8,700 died, according to the National Cancer Institute. Nearly $2 billion is spent treating the disease each year.