For years, dermatologists have told us sunscreen protects skin. Now, many people are questioning that advice after an environmental group challenged the safety of many popular brands.
"Patients are confused," said Darrell Rigel, a clinical professor of dermatology at New York University who is a skin cancer researcher. "I've had patients come in and ask, 'Am I harming myself by using it?' I've spent a lot of time talking to people about it."
The latest report comes from the Environmental Working Group, which claims that in an investigation of nearly 1,000 sunscreen products, four out of five offer inadequate protection from the sun or contain ingredients that may pose a health risk.
But dermatologists who reviewed the group's research say the biggest problem is that it lacks scientific rigor. In particular, they are critical of a sunscreen rating system that they say is arbitrary and without basis in any accepted scientific standard.
"What they are doing is developing their own system for evaluating things," said Warwick Morison, professor of dermatology at Johns Hopkins and chairman of the Skin Cancer Foundation's photobiology committee, which tests sunscreens for safety and effectiveness. "Using this scale to say a sunscreen offers good protection or bad protection is junk science."
Morison has no financial ties to sunscreen makers, and his work with the Skin Cancer Foundation is unpaid.
Sonya Lunder, a senior analyst with the Environmental Working Group, said the database and rating system were based on an extensive review of the medical literature on sunscreens. Of nearly 1,000 sunscreens reviewed, the group recommends only 143 brands. Most are lesser-known brands with titanium and zinc, which are effective blockers of ultraviolet radiation. But they are less popular with consumers because they can leave a white residue.
The group is especially concerned about the safety of a compound called oxybenzone, which is used in most popular sunscreens. But the research on oxybenzone is limited.
Most recently, the Centers for Disease Control and Prevention analyzed 2,517 urine samples collected in 2003-4 from a representative sample of the population over age 6 as part of a national health and nutrition survey. The analysis, published this month in the journal Environmental Health Perspectives, found oxybenzone in 97 percent of the samples.
The study goes on to note that human exposure to oxybenzone "has not been associated with adverse health effects" and that sunscreen is an important tool to protect against sunburn and skin cancer. But the researchers said further study was needed to determine whether the chemical had any meaningful effect on the body.
"What's the meaning of it?" said Rigel, who has consulted for sunscreen makers. "Nobody's seen any problems from years of these agents being used. To call it dangerous is misleading."
A few animal studies have raised concerns that oxybenzone could disrupt endocrine functions. Several researchers say that this is a theoretical concern and that no such effect has been shown in humans.
Another study, published two years ago in Free Radical Biology and Medicine, raised troubling concerns about what happens when sunscreen is absorbed into the skin and reacts with the sun. The report suggested that under certain conditions, sunscreens with oxybenzone and other ultraviolet filters could lead to free-radical damage to the skin, a process that in theory could lead to skin cancer. The study used laboratory models of skin, so some researchers say it is not a reliable indicator of what happens in people.
But the authors noted that the damage occurred only when ultraviolet light reached sunscreen that had penetrated the skin. The solution, they say, is to keep applying sunscreen to block out the UV rays.
"It may seem counterintuitive, but by reapplying sunscreen we protect ourselves from the UV light reaching any of the UV-filters that may have penetrated to the skin," said Kerry Hanson, the lead author of the report and a senior research scientist at the University of California, Riverside. "At this point, I don't think there's enough evidence to firmly claim that sunscreens containing oxybenzone are unsafe."
Still, Hanson added that the UV filters used in sunscreens needed testing "to give us a better understanding of how these molecules behave in the skin."
One solution, she said, may be to add antioxidants to sunscreen to counter the effect. She said she had consulted with sunscreen makers on the issue.
The Food and Drug Administration is preparing rules that will give consumers more information on the label about the sunscreens they buy. Most doctors still recommend sunscreens with a high SPF number and a combination of avobenzone and oxybenzone, ingredients that protect the skin from two types of ultraviolet rays, UVA and UVB.
Avobenzone, also called Parsol 1789, can degrade quickly in the sun. But many top brands, including Johnson & Johnson's Neutrogena with Helioplex, Aveeno with Active Photobarrier Complex and several Coppertone brands, are formulated to prevent that. L'Oréal products containing the new ingredient Mexoryl also offer broad-spectrum protection, doctors say.
It is important to keep in mind that sunscreen is only one way to protect the skin. Not only do people typically not use enough sunscreen, but they don't take other steps to protect themselves from the harmful effects of the sun."People focus so much on sunscreens," Morison said. "It should be a package of protection. A hat, staying out of the sun, avoiding the hottest part of the day and covering up are all part of the whole story. It's not just the sunscreen."