Setting The Sunscreen Story Straight

Main Category: Dermatology
Also Included In: Public Health
Article Date: 11 Aug 2007 - 0:00 PDT

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With the arrival of August, back-to-school shopping is replacing trips to the park or pool. But it's still important to replace those almost-empty sunscreen bottles, according to a University of Iowa dermatologist.

"While harmful ultraviolet rays are especially a concern during the summer months, their harmful effects are present throughout the year," said Marta VanBeek, M.D., assistant professor of dermatology in the UI Roy J. and Lucille A. Carver College of Medicine and a dermatologist at UI Hospitals and Clinics.

More than 1.5 million people are diagnosed with skin cancer every year in the United States, and many cases are due to exposure to the sun's harmful rays. Wearing sunscreen helps, but many people still neglect to use it or use it incorrectly.

VanBeek cleared up some misunderstandings about sunscreens, including the belief that a sun protection factor (SPF) level of 15 is the highest effective level and that sunscreen alone can always provide enough protection.

"The problem with sunscreen is that most people don't use enough to fully protect themselves," VanBeek said. "If used all over the body, an eight-ounce bottle should really only last a few applications. I usually tell people to use SPF-30 and figure they're getting the protection of SPF-15."

It is also important to use a sunscreen that protects against all of the sun's harmful rays. Most sunscreens guard against UVB rays, the shorter rays that cause sunburn. Some sunscreens now also guard against the longer, cancer-causing UVA rays. VanBeek said that in order to be protected from both types of rays, you should look for a sunscreen with a high SPF level plus UVA protection, and be sure to reapply it every one to two hours.

"A lot of people believe sunscreen doesn't work when they get burned after a full day of sun with a one-time application of sunscreen," she said. "But the real reason they're getting burned is because they don't put enough on and they don't reapply it."

Sunscreens are considered "waterproof" when they can withstand 80 minutes in the water. "Water-resistant" sunscreens withstand 40 minutes, so both types should be reapplied regularly. For exercising and other activities that cause perspiration, VanBeek recommends gel sunscreens because they tend to feel less greasy on the skin.

"The brand name doesn't matter," VanBeek said. "More expensive does not mean better as long as the sunscreen protects against both UVA and UVB rays."

A sunscreen's ability to protect skin comes from certain active ingredients such as zinc oxide, titanium dioxide, octyl methoxycinnamate, octyl salicylate and avobenzone (sometimes called parsol 1789).

Recent concerns about the potential of these active ingredients to cause cancer and other health problems has made some people shy away from using sunscreen at all. VanBeek, however, said there is currently no available evidence suggesting that the level of UV-protectant chemicals in sunscreen causes harm.

"There are groups of people with inherited disorders like lupus or xeroderma pigmentosa who have to use large amounts of sunscreen all the time," she said. "If there was a risk of harm from using these levels of sunscreen, we'd expect to see patterns of health problems in these groups of people. Thus far, we haven't seen any evidence of this."

Another reason people cite for avoiding sunscreen is concern about lack of vitamin D, which is formed in the body after sun exposure and helps maintain normal blood levels of calcium and phosphorus.

"If you put sunscreen on, you can still get some vitamin D," VanBeek said. "I also recommend drinking vitamin-D-fortified milk."

Ultimately, the only way to truly protect against the sun is to get into the habit of practicing various self-protective behaviors, VanBeek said.

"I always tell people that one self-protective habit isn't enough. You should combine several different habits, including wearing sun-protective clothing and a broad-rimmed hat, wearing sunscreen, and avoiding the sun between 10 a.m. and 4 p.m. when its rays are the most powerful," VanBeek said. "And never enter a tanning booth. They are not safer than the sun. In fact, they are probably worse."

People with risk factors for skin cancer such as blond or red hair, blue or green eyes, freckles, or a family history of skin cancer should see a dermatologist about once a year to be examined for possible signs of skin cancer.

"Screening for skin cancer used to be recommended at about age 50 or 60, but now we're seeing a lot more young people develop skin cancer, so it is a good idea to start earlier, especially if you have a positive family history," VanBeek said.

Health professionals also used to believe that most sun damage occurred prior to age 18, and that self-protective habits after age 18 would not reduce a person's risk of skin cancer. Now, VanBeek said, this isn't the case.

"That may have been true when the average life expectancy was 60," she said. "Now, if you want to live until you're 80 and you don't want the last 20 years of your life to be riddled with skin cancer surgeries, it's important to take the steps to protect yourself as a child and as an adult."

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