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Answers to burning questions about sunscreen

As the weather warms, the shelves of department, pharmacy and grocery stores are lined with bottles of sunscreen, one claiming to provide more protection than the next. How do you choose which level of protection is right for you?

Sunscreen protects the skin by absorbing and reflecting the sun’s UVA and UVB rays. The FDA requires all sunscreens to be labeled with a “Sun Protection Factor” (SPF). The SPF is relative to the amount of sunburn protection the sunscreen can provide when properly used.

How much SPF do you need? 
According to the American Melanoma Foundation, dermatologists strongly recommend that sunscreens with an SPF of at least 15 be used year round. SPFs can range anywhere between 10 and 100, so does the higher number really offer that much more protection?

SPF protection does not increase proportionally with an increased SPF number. For example, SPF 15 protects the skin from 93 percent of UVB radiation, and SPF 30 provides 97 percent protection. The chart below shows the level of SPF protection.

Sunscreen SPF coverage graph [View Image]One way to determine what SPF is best for you is by using the following equation:

Minutes to burn without sunscreen x SPF number = maximum sun exposure time

For example, if you burn after 10 minutes of sun exposure, an SPF of 15 will allow you to be in the sun for up to 150 minutes without burning. Note that this equation should be used as a general rule because it is not 100 percent accurate and can vary depending on skin type.

What does “broad spectrum” mean?
Most sunscreens only protect from UVB rays, but “broad spectrum” sunscreens protect from both UVB and UVA rays. Since UVA rays penetrate deeper into the skin, broad spectrum sunscreens are highly recommended.

How do you properly apply sunscreen?
Sunscreen should be applied at least 30 minutes before going out into the sun in order to allow it time to absorb into your skin. It should also be applied generously and regularly, at least every two hours, or more often if you are swimming or perspiring. Do not forget to apply sunscreen to your lips, ears, feet, hands, scalp and back of the neck. Also remember to check your sunscreen’s expiration date as they become less effective over time.

According to the Skin Cancer Foundation, you should use approximately 1 oz of sunscreen, or the equivalent of two tablespoons, to the exposed areas of the face and body and a nickel-sized dollop for the face. If you’re using a spray, apply until an even sheen appears on the skin.

Sunscreen vs. sunblock
Sunscreens are classified as chemical or physical. Chemical sunscreens contain ingredients that act as a screen to reduce ultraviolet radiation (UVR) penetration to the skin. Chemical sunscreens are often colorless and give the skin a light sheen.

Physical sunscreen, also known as sunblock, contains ingredients such as titanium dioxide and zinc oxide that physically block UVR. Sunblocks have a visible coloring (most often white, but now come in bright colors). The amount of sun protection that sunblock provides cannot be quantified in the same manner as sunscreen SPFs, and they do not protect against UVA rays.

Natural sunscreen/sunblock alternatives
There are natural alternatives to sunscreen and sunblock, and many companies are now offering natural sunscreens that are made with organic and mineral ingredients. But there is no scientific evidence to support that natural alternatives are safer or more effective than regular sunscreens.

New FDA requirements for sunscreen 
In June 2011, the FDA announced new requirements for sunscreens currently sold over-the-counter (i.e., non-prescription.) The requirements are outlined below and can be found on the FDA Web site:

  • Broad spectrum designation. Sunscreens that pass FDA’s broad spectrum test procedure, which measures a product’s ultraviolet A (UVA) protection relative to its ultraviolet B (UVB) protection, may be labeled as “broad spectrum SPF [value]” on the front label. For broad spectrum sunscreens, SPF values also indicate the amount or magnitude of overall protection. Broad spectrum SPF products with SPF values higher than 15 provide greater protection and may claim additional uses, as described in the next bullet.
  • Use claims. Only broad spectrum sunscreens with an SPF value of 15 or higher can claim to reduce the risk of skin cancer and early skin aging if used as directed with other sun protection measures. Non-broad spectrum sunscreens and broad spectrum sunscreens with an SPF value between 2 and 14 can only claim to help prevent sunburn.
  • “Waterproof,” “sweatproof” or “sunblock” claims. Manufacturers cannot label sunscreens as “waterproof” or “sweatproof,” or identify their products as “sunblocks,” because these claims overstate their effectiveness. Sunscreens also cannot claim to provide sun protection for more than 2 hours without reapplication or to provide protection immediately after application (for example, “instant protection”) without submitting data to support these claims and obtaining FDA approval.
  • Water resistance claims. Water resistance claims on the front label must indicate whether the sunscreen remains effective for 40 minutes or 80 minutes while swimming or sweating, based on standard testing. Sunscreens that are not water resistant must include a direction instructing consumers to use a water resistant sunscreen if swimming or sweating.
  • Drug facts. All sunscreens must include standard “drug facts” information on the back and/or side of the container.

Written by: Alaina Schneider

Posted on: April 29, 2013

Category: Prevention & control

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