Number 13, March 2007, PB Surf Club CURRENTS

SKIN CANCER AND THE SURFER

By Dr. Derek Lodico

Skin cancer is the most prevalent cancer in our society with over 1 million new cases annually. Skin cancer is becoming more common in children and accounts for approximately 4% of pediatric malignancies (cancers). It is estimated that 90% of all skin cancers are preventable. This is a staggering statistic when you consider that one American dies every hour from skin cancer. There are three major types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. Anyone can get skin cancer but inherent risk factors are very important. Skin color, eye color, freckling tendency, nevi count (moles flat, or raised, number of moles), and family history increase one's risk of developing skin cancer. However, the individual's childhood sun-exposure history appears to significantly influence the risk of skin cancer. Skin cancers are associated with both intense, sporadic sun exposure (sunburn) and with chronic sun exposure (tanning). One sunburn may double a child's risk for developing melanoma. Parental attitudes that a child looks "healthier with a tan" may be a contributing factor influencing sun damage and skin cancer risk.

Studies indicate that sun-protection measures are infrequently utilized to prevent sun damage. Sunscreens, hats, sunglasses and avoiding midday sun are routinely used by less than one-third of children. California has led the way in this effort to encourage the use of sunprotective items with the ratification of the Billy Bill (CA-SB 310). This bill prevents schools from prohibiting children from wearing sunglasses or hats on campus.

Ok, so I know I need to use sun protection, but I surf and my options are more limited. What if I wear a tshirt while I am surfing during the summer? Clothing will protect me, right?

Summer clothing usually provides limited protection because of the looseness of weave, ranging from 2 to 6.5 SPF (sun-protection factor). Remember it is the UVA/UVB (ultra violet light A and B) that cause damage to the genetic machinery in our skin cells that cause them to not behave as they should and grow out of control (cancer).

Sun-protective clothing is now widely available and can be found at local stores or via the Internet. Coolibar, Sun Precautions, Nozone, and Solartex are some of the retailers that offer these garments for children and adults. The styles are practical and stylish and have become popular with children and adults worldwide. Laundry additives can enhance the sun protection afforded by garments by boosting the SPF in garments. Rit® Sun Guard™ is one commercially available additive available at local drugstore retailers or via the Internet.

Now the big question: does sunscreen and sun block prevent me from getting skin cancer?

The SPF, spectrum of protection, vehicle (what it is delivered in cream, liquid, spray), and substantivity (water resistance) should be considered when recommending a sunblock. Sun-protection factor is a concept that surfers must understand, because it is a measure of protection afforded by sunblocks against ultraviolet B (burning rays) only. The SPF rating is calculated based on the time it takes for the skin to develop minimal erythema (sunburn) with the application of 2 cc/cm2 of sunscreen. Minimal erythema or sunburn is the result of overexposure to UVB rays. SPF is not a measure of the potential damage from UVA rays and does not denote protection from the tanning rays. There is no official rating system for UVA protection at this time. A label that specifies broad-spectrum protection is the best indication of UVA protection.

Proper sunscreen application is the only way to achieve the SPF rating indicated by the manufacturer. A consumer must apply one ounce of sunblock per total body application (a handful) for an adult and half ounce for the average child. A SPF 15 sunscreen rating indicates that the protected skin is shielded from UVB radiation for 15 times longer than unprotected skin. On a day with high UV intensity (>6) a person with pale skin would burn in an average of 10 minutes. Therefore, a SPF 15 sunscreen applied in the appropriate dose would protect the individual for approximately 150 minutes, provided there isn't any heavy perspiration or prolonged water submersion. However, because most consumers apply a sub-therapeutic dose of sunblock (too little) there is a resulting relative lowering of the sun-protection factor. For example, when a surfer applies 25% of the recommended dose of a SPF 15 sunblock instead of the correct dose, the sunblock protection approximates a SPF 4.

So what is all this water-proof labeling about?

Water resistant denotes a longer period of protection than water-proof. Waterproof claims indicate that a sunscreen maintains its SPF after two 20-minute water immersions or moderate physical activity. Water resistant claims indicate that a sunscreen maintains its SPF after 80 minutes of water immersion or extreme physical activity. I don't know about you, but I spend more that 20 minutes in the water when I surf.

Titanium dioxide, zinc oxide, or Avobenzone, a PABA derivative, provide excellent broad-spectrum protection. Sunblocks should be applied 30 minutes before sun exposure and reapplied every two hours or after swimming or heavy perspiration. Although spray sunblocks are appealing due to the ease of application, their coverage is often inadequate due to difficultly of judging dosing and thickness of application and are not recommended. Because sunblocks/sunscreens work by reflecting or absorbing ultraviolet radiation, they are broken down or depleted more quickly on a high UV intensity day.

Sunscreens alter the wavelenght of UV radiation by chemically absorbing it and transforming it to a less harmful form. Sunblock does not alter the UV wavelength of light but blocks its absorption. Many sun products were inapproprrately using the term sunblock on their packages when indeed they were actually sunscreens. Research has been mixed in the past regarding the effectiveness of sunscreen and its prevention of skin cancer. UVB caused our skin to burn, UVA does not cause redness or burn of the skin. It was initially thought that UVB was the sole cancer-causing wavelength of light. Studies since then have shown that not only is UVA radiation composed of greater than 90% of the UV rays that we are exposed to, but that it also causes skin cancer. Some studies have shown that the use of sunscreen puts people at risk for skin cancer. People who use sunscreen stay out in the sun longer because they are not burning, but still absorbing harmful UVA radiation. SPF rates the effectiveness of UVB radiation. So be cautious about feeling comfort with a high SPF number. The more appropriate shopping questions for a surfer should be, "does it cover UVA and UVB" and "is it water-proof or water-resistent."

The only sun product ingredient that has shown a decreased risk of developing skin cancer, more specifically the big melanoma, is zinc oxide and titanium dioxide. It is less cosmetically pleasing due to the hue left after applied and that it does not "rub in." New products out have micronized zinc in them and will have a more cosmetic effect for you gals and metro's out there.

So to wrap it up, I wanted to get the following points across:

1. Sunscreen use has not been proven to reduced the incidence of skin cancer, just burns.

2. Not all sunscreens contain protection from UVA and B.

3. If you are going to use sunscreen, use it properly. Apply it 30 minutes to dry skin before entering the water and reapply it ever 30 minutes. For sunblock (Zinka, Headhunter), apply it 30 miutes before, and then every two hours after.

4. Use a product that has ZINC or TITANIUM DIOXIDE in it as it has been shown to reduce your risk of skin cancer.

5. Use water-resistent, not water-proof.

6. Use common sense by wearing sunglasses and protective clothing (hats, long sleeve shirts, etc.) when you are out of the water.

Next issue I will go over what a surfer needs to look for on their skin as a warning sign of cancer and when you need to go see the doctor and get checked out, stay tuned.