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Test Your Knowledge About Sunscreen

CancerWise - July 2007

Sunscreen helps reduce sun exposure, but people need to know when and how to use it.

“Proper application of sunscreen is necessary to lower the lifetime risk of developing skin cancer," says Carol Drucker, M.D., an associate professor in
M. D. Anderson’s Department of Dermatology. "Most people need to know more about sunscreen."

Take this true or false quiz to see what you know.

Sun protection factors do not vary greatly.

True. A sunscreen’s sun protection factor (SPF), a scale for rating the level of sunburn protection, does not increase proportionately with each SPF level.

“For example, SPF 15 absorbs 93% of the sun's burning rays, while SPF 30 absorbs 97%,” Drucker says.

Most dermatologists recommend an SPF of at least 15. Beyond that, there is little difference between 15 and 30, 45 or 60.

Sunscreens reduce exposure of all ultraviolet rays.

False. A sunscreen's SPF only reflects the product's screening ability for ultraviolet radiation B (UVB rays). UVB rays are more likely than ultraviolet radiation A (UVA rays) to cause sunburn, but UVA rays pass deeper into the skin, according to the NCI.

Currently, there is no U.S. Food and Drug Administration (FDA)-approved rating system that identifies and rates UVA protection.

Still, most sunscreens offer some UVA protection, so people should look for sunscreen that addresses UVA and UVB rays. Broad-spectrum sunscreens, which contain ingredients such as zinc oxide and titanium dioxide, offer the best UVA protection.

People also should remember that ultraviolet rays come from sun lamps and tanning beds, as well as the sun.

Children do not need special sunscreen.

True. “Children older than six months can use the same sunscreen as adults,” Drucker says. “For infants younger than six months, just cover them up.”

Sunscreen must be reapplied often.

True. Sunscreen should be applied to dry skin 15-30 minutes before going outdoors and reapplied every two hours. One ounce (enough to fill a shot glass) is considered the amount needed to properly cover any exposed areas of the body. Lips can get sunburned, too, so it is important to apply a lip balm that contains sunscreen with SPF 15 or higher.

Many factors reduce sunscreen effectiveness.

True. Sunscreen protection can be altered by wind, humidity, perspiration and facial movement, as well as uneven product application. Many people also wait too long to reapply.

Waterproof sunscreens protect completely.

False. The terms "waterproof" and "sweatproof" are no longer allowed by the FDA because no sunscreen is waterproof. "Water-resistant" is more accurate.

It is safe to use sunscreen on a daily basis.

True. All sunscreens are safe to use on a daily basis. No evidence exists that suggests daily use of sunscreen is unsafe.

Sunscreen blocks out the sun.

False. Properly applying sunscreen on a regular basis greatly reduces a person's exposure to the sun's harmful rays, but it does not eliminate sun exposure.

"Most people have the misconception that sunscreen use allows a person to spend unlimited time in the sun," Drucker says.

In addition to wearing sunscreen, people should also:

  • Avoid the sun between 10:00 a.m. and 4:00 p.m.
  • Seek shade whenever possible
  • Wear protective clothing, such as:
    • Wide-brimmed hats
    • Long-sleeved shirts
    • Pants
    • Sunglasses
  • Avoid tanning beds

Sunscreen can lead to vitamin D deficiency.

False. Just a small amount of sunlight – not a suntan – is needed to meet the body's daily recommended requirement for vitamin D. Sunscreens do not contribute to vitamin D deficiency because regular sunscreen use does not eliminate sun exposure. Taking a daily supplement of vitamin D can further alleviate concerns about this issue.

According to the American Cancer Society (ACS), more than one million cases of basal cell and squamous cell cancers, the most common types of skin cancer, occur annually. The most serious form of skin cancer is melanoma, which the ACS estimates will be diagnosed in 60,000 people in 2007.

– From staff reports

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© 2014 The University of Texas MD Anderson Cancer Center