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With summer rapidly approaching, I thought we’d spend a few
minutes and discuss one of my favorite topics, using sunscreens to
prevent skin cancers.
More than one million persons in the United States develop skin cancer
every year. In fact, skin cancer is so common, it is considered the most
prevalent type of cancer in the U.S., even though newspapers and
television media-articles would lead us to believe other cancers such as
lung cancer and breast cancer were seen more often.
Sunlight is composed of three different types of radiation or
ultraviolet rays, UVA, UVB, and UVC. We really don’t have to worry about
UVC radiation, as it is mostly absorbed in the ozone layer and rarely
makes it to the earth’s surface (See, the ozone layer is good for
something!). But, it’s those UVA and UVB rays that tend to cause all our
problems.
Being exposed to UVA and UVB rays over a long period (20 to 30 years) is
what causes skin cancers known as squamous cell cancer and basal cell
cancer. These are usually slow growing and therefore don’t cause us to
seek medical attention until they really look bad by changing colors,
ulcerating and bleeding, or growing lumpy. Both squamous cell and basal
cell cancers tend to grow just in the areas where located.
In contrast, the really bad skin cancer, malignant melanoma, seems to
occur in fair skinned persons who get maybe one or two really bad
blistering sunburns a year. Malignant melanomas are usually very dark,
irregular in shape and thickness and need immediate attention, as they
tend to spread rapidly to nearby skin and even distant areas
(metastasize).
Now that we’ve covered the basics, what’s the skinny on sunscreens?
Sunscreens are rated based on the SPF or sun protection factor rating
from zero to 100 or higher. SPF is calculated by comparing the amount of
light needed to cause a predetermined degree of redness in unprotected
skin to the same light exposure redness induced in sunscreen lotion
protected skin.
Key point: The amount of time it takes to cause the redness is
not considered in calculating the SPF. Everyone absorbs UVA and UVB rays
at different rates, so one person may absorb the same radiation in one
hour as another absorbs in two hours!
Here are a few tips on use of sunscreens:
-A minimum SPF of 15 is advised for all of us who plan to be in the sun
-In order to work effectively, sunscreen should be applied 30 minutes
before exposure
-You must be sure to apply the lotion thick enough to cover exposed
skin. Most of us tend to try to cover large areas, such as the chest and
back with as little as can possibly be rubbed in. This does not provide
adequate protection. You should read the product instructions about how
much to apply.
-An SPF lotion of 30 does not protect you from twice as much radiation,
nor does it allow you to stay out in the sun twice as long!
-Sunscreen should be reapplied every two hours while exposed and more
often if sweating excessively or swimming.
-An SPF 15 sunscreen blocks 92% of UVB rays and an SPF 30 blocks 97%.
So, very little additional radiation blocking occurs with SPF values
above 30 to 40.
-SPF values are more a measure of protection from UVB rays, not UVA
radiation. However, you should chose a sunscreen that specifically
blocks both UVA and UVB rays as the National Institutes of Health has
decided both can cause skin cancer.
In addition to these tips on using sunscreens, here are more tips on
avoiding sunburn and excessive exposure in addition to using SPF
lotions:
-Avoid being in direct sun between 11 am and 3 pm when radiation is at
it’s worst
-Wear a hat for scalp protection and clothing rated for an SPF of 15 or
greater (some manufacturers put these ratings on the labels)
-Avoid using sun lamps or tanning beds to get a start on the season.
(Doing so increases the amount of skin damage faster and can cause early
wrinkling)
-Check your skin weekly for signs of changes in moles or birthmarks. If
you find any, please see your doctor for evaluation.
Sunlight is important to all of us. Our bodies require sunlight in order
to convert vitamins to active forms and to regulate our metabolism. In
addition, our brains need sunlight to help prevent mood swings and
depression. Overall, as keepers of our body, we must as usual balance
what is good against what is bad and take care of ourselves so we can
live long and prosper.
Dr. Frank
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