By Alan S. Peterson, MD
Sun is the biggest culprit in the formation of skin cancer. Sunlight – both the UVB and UVA part of the spectrum – is the cause of at least 90% of the three primary skin cancers. These include melanoma, basal cell carcinoma, and squamous cell carcinoma. Excessive sun exposure is the most common preventable cause of these skin cancers.
A catch phrase being used to trigger the attention of both children and adults is “Slip, Slap and Slop”. Slip on a shirt, slap on a hat and slop on some sunscreen. The cornerstone of sun protection continues to be the liberal use of full or broad spectrum sun screen that blocks both UVB and UVA rays and has an SPF of at least 15.
SPF applies solely to the UVB rays which are short wave-length burning rays from the sun. A SPF of 15 means that a person can stay out in the sun 15 times longer before he or she experiences a burn. If a person normally burns in 15-20 minutes, then he or she can stay in the sun theoretically for 4-6 hours before burning. That assumes many things of course, including the fact they have not been in a swimming pool or had the lotion wash off at the beach. It also assumes that they’ve used enough lotion to begin with and that they haven’t sweated any off. Don’t forget to use the lotion around the eyes and on all of the feet (top and bottom).
SPF does not apply to the UVA part of the spectrum. These longer wave-length rays do not cause sunburn, but also can add to sun damage, photoaging, adverse affect of our immune system, and can lead to skin cancers. So it is true that you can get skin cancer without having been sunburned. This is why it is important to have a full spectrum sunscreen, one that blocks both UVB and UVA.
To be sure, read the label when buying sunscreen to review the ingredients. Physical blockers that provide broad spectrum protection, specifically in the UVA range, are zinc oxide or titanium dioxide in micronized form. A good chemical blocker for UVA is avobenzone or parsal 1789. Ecamsule, also called Mexoryl SX is new to the United States and was recently approved for use by the FDA, and it appears to be more photo stable than parsal 1789.
It can’t be underscored enough that one must insure adequate protection with sunscreens. This means reapplying them frequently and thickly. One ounce is the recommended amount to cover the average body.
Obviously one should seek shade whenever possible. Plan outdoor activities early or late in the day to avoid peak sunlight hours which are between 10:00 am and 3:00 pm. Wide brimmed hats and long sleeve shirts can also be helpful. A baseball cap is not enough.
A word of warning concerning artificial tanning with the use of tanning beds! This is not a safe alternative to outside sun exposure. Ultraviolet light from any origin has been officially identified as a cancer causing carcinogen. There is a proven causal relationship between melanoma and exposure to sun beds and sunlamps. We are seeing more people with melanomas and this includes children and generally a younger age group of patients.
The World Health Organization has issued an official statement calling for nations everywhere to ban sun bed use for individuals in the younger age groups and to restrict tanning machine use for people of all ages. Unfortunately Pennsylvania does not have tanning bed regulations or restrictions. Self-tanner lotions are a safe alternative to the sun. These contain dihydroxyacetone which interacts with proteins in the skin to produce an orange/tan that doesn’t wash off. These tanning options do not prevent skin cancer or burning when the skin is exposed to the sun.
Dr. Peterson is a doctor of Family and Community Medicine at the Walter L. Aument Family Health Center, 317 S. Chestnut St., Quarryville.