Many people are questioning dermatologists' advice to wear sunscreen, after an environmental group challenged the safety of many popular brands.
“Patients are confused,” said Dr. 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?'”
The latest report comes from the Environmental Working Group, which claims that an investigation of nearly 1,000 sunscreen products showed four out of five offer inadequate protection or have ingredients that may pose a health risk.
But dermatologists who reviewed the research say it lacks scientific rigor. In particular, they criticize a sunscreen rating system that they say is without basis in any accepted scientific standard.
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“What they are doing is developing their own system for evaluating things,” said Dr. 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.
Sonya Lunder, a senior analyst with the Environmental Working Group, said the database and rating system were based on an extensive review of medical literature on sunscreens. Of nearly 1,000 sunscreens reviewed, the group recommends 143 brands. Most are lesser-known brands with titanium and zinc, which are effective blockers of ultraviolet radiation. But they are less popular because they can leave a white residue.
The group is especially concerned about oxybenzone, a compound in most popular sunscreens. But research on oxybenzone is limited.
Most recently, the U.S. Centers for Disease Control and Prevention analyzed 2,517 urine samples collected in 2003-04 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 prevent sunburn and skin cancer.
But a few animal studies have raised concerns that oxybenzone could disrupt endocrine functions. Several researchers say no such effect has been shown in humans.
Another study, published two years ago in Free Radical Biology and Medicine, raised 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.