May 24, 2010 -- An environmental group is once again questioning the effectiveness and safety of top-selling sunscreens, claiming that many contain potentially hazardous ingredients and make exaggerated claims.

In its fourth annual Sunscreen Guide, the Environmental Working Group (EWG) evaluated 500 sunscreens and found only 8% to be acceptable.

EWG Senior Vice President for Research Jane Houlihan called most of the best-selling sunscreens in the U.S. “the equivalent of modern-day snake oil,” claiming they do not protect as well as they say they do and may be dangerous.

The group is specifically warning against high-SPF sunscreens, which Houlihan says promote a false sense of security for users. The EWG also warns against products that have little or no protection against ultraviolet A (UVA) rays and products that contain the vitamin A derivative retinyl palmitate, which has been linked to the accelerated growth of skin lesions in some lab animal studies.

Representatives for the sunscreen industry strongly disputed the group’s claims, and a dermatologist interviewed by WebMD called the claims unsubstantiated.

“EWG is kind of the Chicken Little of the sunscreen arena,” St. Petersburg, Fla., dermatologist James Spencer, MD, tells WebMD. “There is no evidence that the active ingredients in sunscreens are dangerous. These are products used by millions of people every day. There is real danger all around us, and one very real danger is skin cancer and skin aging from sun exposure.”