Sunscreens, SPF and the Effect of Sun on Skin

Sunscreens, SPF and the Effects of Sun Exposure on Skin

Summer is upon us, and that means vacations, outdoor activities and longer hours in the sun. With that in mind, we thought it would be useful to review some information about the sun’s UV rays and how to protect your skin with the use of sunscreens. 

UV Radiation From The Sun

The sun emits three types of UV radiation, UVC, UVB, and UVA, which differ in their wavelengths and energy.  UVC radiation has the shortest wavelength and is the most energetic form of UV radiation. Exposure of skin to this form of radiation for even a few minutes would cause severe burning and long-lasting damage. Fortunately, none of the UVC radiation from the sun ever gets to the earth’s surface. The next most energetic form of UV radiation is UVB, and this is the type of radiation that causes sun burning (remember UV”B” for “burning”) and damage to DNA, and is most closely linked to the onset of basal and squamous cell cancers. Fortunately, only 5% of the UV radiation that reaches the earth’s surface is UVB. The form of UV radiation that accounts for 95% of the radiation we’re exposed to is UVA radiation. UVA radiation has a longer wavelength than UVB and is, therefore, less energetic. It is responsible for both the “immediate tanning” reaction (where you’re skin looks “tanned” after just a few hours in the sun) and (along with UVB), “delayed tanning” response (long lasting tan). Although UVA is not as energetic as UVB radiation, because it has a longer wavelength, UVA radiation is able to penetrate much deeper into the skin than UVB rays, and it reaches the dermis. In contrast, UVB rays can only penetrate into the epidermis. As you know, the fibroblasts in the dermis are the skin cells responsible for collagen and elastin synthesis, and these cells are very sensitive to UVA radiation and to free radicals (aka Reactive Oxygen Species; ROS). The result of skin exposure to UVA rays is damage to the dermal matrix, which includes a loss of collagen, an abnormally elevated production of abnormal clumps of elastin (elastosis), and a dramatic breakdown of the structural integrity, resiliency and elasticity of the skin.

This results in what we see as pre-mature aging. Because of this, UVA radiation is referred to as the “Aging” UV radiation (remember UV”A”- for aging). In addition, exposure of skin to both UVA and UVB radiation greatly increases the risk of skin cancer and melanoma.

NOTE: Suntan beds emit primarily UVA rays with a small amount of UVB. Since the UVA radiation tanning beds emit is about 3 times more intense than the sun, the effect of tanning beds on skin photoaging is pronounced. NO TYPE OF UV RADIATION IS GOOD FOR THE SKIN!

Sunscreens and SPF: What Does the Number Mean and Which Sunscreens are the Best?

 We all know how important it is to apply sunscreens when outdoors, but since there are so many sunscreen products available, how does one know which sunscreen is the best one to use?  Is it better to buy a lotion with an SPF of 70 versus one with an SPF of 30? While one would assume that the higher the number, the better the protection, this is not necessarily the case. The SPF number does not refer to the AMOUNT of protection from the sun. The SPF scale (Sun Protection Factor) was introduced over 50 years ago to measure HOW LONG a sunscreen can protect the skin from getting a sunburn from UVB rays (NOT UVA rays).  This time will vary depending on your skin type. For example, if you can be out in the sun for 20 minutes before developing any erythema (sunburn/redness), if you apply a sunscreen with an SPF of 30, in theory, you can now stay out in the sun for 30 x 20 minutes = 600 minutes, or 10 hours. Of course, in reality, if you’re out in the sun, the sweat from your skin will wash off sunscreens as will jumping into the swimming pool or ocean. Even “water resistant” sunscreens wash off. The recommendation from the AAD (American Academy of Dermatology) is that sunscreens should be re-applied every 2 hours, regardless of the SPF number. Although we know that SPF numbers refer only to HOW LONG a sunscreen will protect the skin from getting burned, never-the-less, it seems logical to assume that a sunscreen with a high number, like 70, should block about 4 times more UVB rays than would a sunscreen with an SPF of 15.  Interestingly, this is not the case.  A sunscreen with an SPF rating of 15 will block 94% of UVB rays while a sunscreen of 30 blocks 97%, which is only 3% more. A sunscreen of 70 blocks 98% of the UVB rays, or to put another way, only 1% more than an SPF of 30! Given this data, is there really any reason to use anything higher than a 30? The answer is; NOT REALLY. It is also worth keeping in mind that chemical sunscreens can cause skin irritation and skin sensitization in some users. Obviously, a product with an SPF of 70 will contain a much higher concentration of potentially irritating chemical sunscreen than a product with an SPF of 15. It is worth noting, however, that skin irritation and sensitization is not an issue if a physical sunscreen, such as zinc oxide, is used. Unfortunately, physical sunscreens can turn white on the skin, which consumers find undesirable.

Just because a sunscreen has an SPF rating of, say, SPF 30, doesn’t mean the sunscreen is one you should use. 50 years ago when the SPF scale was developed, scientists and physicians, alike, assumed that since science had shown that UVB rays caused skin burning and DNA mutations, this was the wavelength of UV light that sunscreen products should block. As a result, the SPF scale was set up for measuring a sunscreen’s ability to block  UVB rays. But, as discussed above, we now know that: 1) UVA rays penetrate into the skin much deeper than UVB rays, 2) 95% of the sun’s radiation that reaches the earth is UVA, while only 5% is UVB,  3) UVA rays CAN cause DNA damage, 4) UVA rays damage the skin’s dermal matrix and causes skin aging, and, most importantly, 5) UVA radiation increases the risk of melanoma.

So, given the need for a sunscreen that has both UVA (both UVA1 and UVA2 wavelengths) and UVB protection, what should you look for when shopping for a sunscreen? In the U.S., the approved UVA chemical sunscreens are Avobenzone, Dioxybenzone, Ecamsule, Meradimate, Oxybenzone, Sulisobenzone. The UVB sunscreens that are typically used include Aminobenzoic acid, Homosalate, Octocrylene,  Octyl methoxycinnamate, and Octisalate. Two sunscreens, Oxybenzone and Octinoxate, have now been banned in Hawaii because of limited scientific data that they may damage the coral reef. The sunscreen you pick should have both a UVB and UVA blocker, and this should be indicated on the front label (e.g. “broad spectrum”, “UVA/UVB protection”). For the safest, and least irritating broad spectrum sunscreen, ZINC OXIDE is always the best choice. It is a physical sunscreen that provides excellent protection against UVB,UVA1 and UVA2, and it’s non-irritating. The downside is that it turns white on the skin.

Recommendation: Zinc oxide provides an excellent physical barrier against UV rays, and is great for very sensitive skin. The only drawback is that most zinc oxide sunscreens turn white on the skin. If you’d rather use a sunscreen that is invisible on the skin, use a broad spectrum chemical sunscreen that states that it blocks BOTH UVA and UVB. There is no real need to ever use a sunscreen with an SPF greater than 30, since one should re-apply their sunscreen every 2-3 hours.    

Antioxidants Can Help Protect the Skin from Sun Damage by Inactivating UVR produced Free Radicals

 FREE RADICALS (aka Reactive Oxygen Species [ROS]) play a very important causative role in DNA mutation, skin damage and in skin aging. Free radicals produced in the skin by UV radiation, interact with proteins, cell membranes, and DNA and can not only cause gene changes that lead to skin cancer, but they can also cause the destruction of the skin’s normal structural matrix. They can suppress collagen synthesis and stimulate the production of inflammatory mediators that cause further damage to the skin. Given the significant role that ROS play in skin damage, any topical product used on skin that will be exposed to the sun’s UV rays, should contain powerful antioxidants that can trap and inactivate free radicals that are produced either by the sun, by other environmental “stressors” or by natural aging. By blocking the activity of free radicals, antioxidants preserve the structural integrity of the skin. While many skin care products contain common antioxidants like vitamin E, and vitamin C, these are somewhat unstable in skin care products, and are often used at concentrations too low to be very effective.

DermaMedics Products Contain the Patented Antioxidant, Therosol®

DermaMedics incorporates its patented, very potent and highly stable antioxidant, 4-propyl guaiacol (trademarked Therosol®) into all of its products and does so at the optimal concentration needed to provide long-lasting benefits against free radicals. Because DermaMedics owns worldwide patents for this antioxidant molecule as well as for other Small Molecule Actives (SMA), only DermaMedics products can incorporate this powerful technology into skin care formulations. So with summer coming, and with increased exposure of skin to the damaging free radicals produced by the sun, the use of DermaMedics’ antioxidant products Calm and Correct Serum and Intensive Relief, along with a sunscreen, should be part of everyone’s skin care regimen. Use these products before and after sun exposure to moisturize and calm the skin, and reduce visible skin redness.  And make sure you take these products along on vacations!


 Calm and Correct Serum (50ml)

               Calm and Serum is the “go to” product to use on skin that has had too much sun. When the day is done and you realize, when you look in the mirror, that you forgot to re-apply your sunscreen, and now are getting a sunburn, Calm and Correct Serum is the one product that glides on the skin with no pressure and no rubbing, and therefore no discomfort. And because this product is neither a lotion nor a cream, it contains NO soap-like emulsifiers that can sting when applied to burned or damaged skin. In addition, this Serum contains Therosol® , a patented unique antioxidant, which has been shown to improve skin texture and reduce the appearance of redness. Further, because Calm and Correct contains a high concentration of the moisturizing oils, jojoba, sunflower and squalane, this product will immediately arrest further dehydration of the skin. And with no water in the Serum, there is no need for any preservatives.  The result is a soothing, calming, non-irritating highly moisturizing product that is effortless to apply, and which will help your skin look much better the next day. It is the perfect “after-sun” product. Don’t go to the beach without it.

Shop now