Retinyl palmitate is added to products as a stabilizer. It's also an anti-aging ingredient that can make skin more sensitive to sun. The EWG says studies show retinyl palmitate, found in 1 of 4 products that were reviewed, may actually promote cancer when it's used on sun-exposed skin.
Oxybenzone is an active ingredient found in more than half of all beach and sport sunscreens. Some studies suggest the chemical may mimic the hormone estrogen in the body. The EWG suggests avoiding sunscreens formulated with oxybenzone.
In general, the EWG says mineral sun blockers like zinc and titanium make for safer sunscreens.
Doctors, Industry Respond
Darrell S. Rigel, MD, is a dermatologist at New York University's Langone Medical Center and a former president of the American Academy of Dermatology. He studies sunscreens and skin cancer. He has also consulted for sunscreen manufacturers.
"I sort of cringe a little bit when I see these recommendations," Rigel says.
His main objection is that he feels the report looks at studies out of context.
For example, for an article that raises concerns over the sunscreen ingredient oxybenzone, the EWG cites research including a 2001 study published in the journal Environmental Health Perspectives. In that study, Swiss researchers fed high doses of oxybenzone to rats. After four days, the rats' reproductive organs had grown by 23%, suggesting that the chemical was acting like the hormone estrogen.
Realizing that study was causing concerns over the safety of some sunscreens, Steven Q. Wang, MD, a dermatologist at Memorial Sloan-Kettering Cancer Center in New York, tried to find out how much sunscreen a person would need to apply to get the same dose of oxybenzone that was fed to the rats.
In a study published in July 2011 in the Archives of Dermatology, Wang calculated that a person would need to slather on sunscreen, at recommended amounts, head-to-toe, daily for 34 years to reach the same exposure.