Chasing the Sun


Everything you nee to know about SPF (Sun Protection Factor)

By Thaddeus C. Hinunangan, M.D.

It’s summer. Everybody is heading to the beach or even the mountains for outdoor activities, and this also puts everyone at risk for sun damage. Actinic keratosis, basal cell carcinoma, and melanoma- these definitely don’t sound like spa treatments. These are pre-malignant and malignant conditions which result from the sun’s damaging ultraviolet rays. Apart from smoking and poor nutrition, sun damage causes signs of premature aging like pigmentation, sun spots, and wrinkles. Furthermore, getting sunburned can bring excruciating pain. The signs of aging are definitely a high cost to pay for that tan.

How does the sun damage your skin? The two types of ultraviolet (UV) rays from the sun that are significant are UVA and UVB, since UVC is absorbed by the earth’s atmosphere. UVA is a long wave that is not absorbed by the atmosphere, and it damages the DNA of the cells of the skin. Wrinkles are caused by the destruction of collagen and elastin fibers of the skin by UV rays. UVB is medium wave and mostly absorbed by the atmosphere, but the rays that hit the skin causes sunburns and even skin cancers with chronic, prolonged exposure.

It is also important to note these factors which affect the amount of UV rays that affect the skin:

1. The sun’s rays are strongest at noon all the way to late afternoon, so it is still safer to avoid exposure at these hours.
2. Distance from the equator—so for tropical countries such as the Philippines, we definitely get among the strongest UV rays.
3. Cloud cover is not a guarantee of UV protection because UV rays can still permeate through the clouds and cause sunburns.
4. Reflection on surfaces like pavement, water in the beach can also intensify UV exposure.

The melanin pigment in our skin, produced by cells located in the basal layer of the epidermis called melanocytes, is a determinant of skin color and also have some protective functions. Melanocytes produce granules of melanin in vesicles called melanosomes which accumulate in the keratinocyte cells of the epidermis, protecting the DNA in the cell nucleus from solar damage.

Don’t just pack your bikini just yet and hide in the nearest cave. There is hope for sun worshippers in the form of sunscreens. Organizations such as the American Cancer Society recommend the use of sunscreen to prevent malignancies caused by solar radiation. Sunscreens that are broad spectrum which block both UVA and UVB rays are the ideal.

Sunscreens are rated with a Sun Protection Factor (SPF), which is a measure of the fraction of the UV rays that reach the skin. For example a sunscreen with an SPF of 50 means that 1/50 of the UV radiation reaches the skin through the sunscreen. As a caveat, swimming, toweling, sweating may cause the sunscreen to be wiped off, applied unevenly or too thinly. A single application may last for only an hour, or two hours the most. After which, reapplication is needed.

What are the active ingredients that you should look for when checking the label of your sunscreen? Oxybenzone, octylmethoxycinnamate, phenylbenzimidazole sulfonic acid, octocrylene are organic chemical compounds and particulates that absorb ultraviolet light. These molecules absorb high energy UV rays and release the energy as low-energy rays. A personal favorite which I use contain inorganic particulates such as titanium dioxide and zinc oxide which reflect, scatter, and absorb UV light. They are usually termed “sunblocks” which are the more opaque sunscreens which effectively block both UVA and UVB. These are also the active ingredients used for sunblocks intended for sensitive skin, as they cause less irritation than UV absorbing chemicals and more environment friendly than chemicals like oxybenzone.

Still, even with sunscreens, it is very prudent to still take precautions like wearing wide brimmed hats both to protect from the sun’s rays and avoid noontime sun. Have a fun and safe summer!

“There is hope for sun worshippers in the form of sunscreens”

June 2018 Health and Lifestyle

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