Enveloping our body like a piece of clothing, our skin is a miraculous organ that both forms a barrier against potential invaders and plays a crucial role in the maintenance of vital functions. It is a mirror that reflects our experiences, memories, and fate with the lines and marks on it. With a surface area of 1.72 square meters and a weight of approximately 9.6 kg, including the fatty tissue under it, the skin is the largest organ in our body and life cannot possibly be maintained without it.[1] It is through the skin that we learn knives cut, fire burns, and our mother has very soft hands. We don’t even realize, but the skin quietly carries out other numerous functions such as sweating toxins out of the body, maintaining body temperature, and synthesizing vitamin D.[2] Some of these functions are related to the sun and the protection of our body from it.

The sun emits all kinds of rays across the electromagnetic spectrum. The lethal ones among these rays are filtered by the atmosphere that envelops the Earth, so very few of these dangerous rays reach the land.[3] The rays that reach Earth are visible (wavelengths of 400-700 nm) and ultraviolet (wavelengths of 100-400 nm) rays. Ultraviolet radiation comes in three types: UVA, UVB, and UVC.

Having wavelengths of 320-400 nm, UVA rays make up 90% of the UV that reaches Earth’s surface. Regardless of whether it is cloudy or sunny, the same amount of these rays reaches Earth and penetrates as far as the lower layers of the human skin. UVA rays damage the connective tissue under the skin, causing the skin to get old and the formation of free radicals, which indirectly cause DNA damage, hence terminal skin cancers or melanoma. Rays that come in these wavelengths are also largely responsible for allergic reactions on the skin.

With wavelengths of 280-320 nm, UVB rays make up 5-10% of the UV radiation reaching Earth. These rays help with the synthesis of vitamin D but also cause sunburns and the synthesis of melanin in the skin. UVB rays also have a role in mutating genes that prevent growth of tumors, thus leading to the development of skin cancers other than melanoma.

With wavelengths of 100-280 nm, UVC rays are harmful to living things. When they reach the Earth’s atmosphere, UVC rays interact with the oxygen atoms here. This interaction leads to the formation of the ozone layer, which prevents UVC rays from almost never reaching the ground. These dangerous waves have been put into humankind’s service by being employed in the creation of the protective ozone layer.

Ultraviolet rays and the harmful effects of visible light on the skin

There are short-term and long-term effects of UV rays on the skin.

The short-term effects are sunburn, heat stroke, allergic reactions, suntan, and viral diseases such as herpes, which are usually felt shortly after exposure to the sun and can be triggered by suppression of the immune system. The long-term, accumulative effects are photo-aging (the skin getting wrinkly due to solar rays), sunspots, cataracts, and the development of skin cancers.[4]

On the other hand, our skin is not entirely unprotected against the dangerous effects of the sun. The keratin layer in the epidermis, the uppermost layer of the skin, absorbs or disperses light, so the amount of light penetrating into the layers below is significantly lowered. Beta-carotene in the skin along with some enzyme systems reduce free oxygen radicals released after exposure to the sun and thus eliminate solar damage. Likewise, melanin, which gives our skin its color, lies above the nuclei in skin cells and acts as an umbrella that protects the cellular DNA from solar radiation.[5]

Six subgroups of skin types have been determined according to color of the hair, eyes, and skin, as well as the skin’s reaction to solar rays. This classification is widely accepted for identifying risk groups and determining specific protection measures.[6]

Although the number of melanosomes, or melanin-producing cells in the human skin, is the same in all humans, the color of the skin is determined by the genetic differences in the type, amount, and size of melanin pigments. Melonosomes in Europeans are small and light, while those of Africans are larger and darker.[7]

The importance of protection from the sun

The frequency of skin cancer has been increasing, which is precipitated by the fact that the ozone layer has gotten thinner and people are not well informed about UV protection. Many people take beach vacations and sunbathe, do mountain sports, have tanned skin, work in open air professions (such as construction workers, lifeguards, and tour guides), and they do so without much care.

For protection, we should first know that harmful effects of solar rays accumulate over time. The damage caused by the sun is stored in the body, just like change we save in a piggy bank. Unfortunately, we accumulate 40-50% of the total damage we are exposed to in a lifetime in the first quarter of life – that is, during childhood and our teenage years.[8] The skin’s natural protection mechanisms are not fully developed during these periods, nor is our understanding of protection. A research study carried out in Australia has shown that the rate of malign melanoma seen in young people can be reduced by 73% through effective solar protection methods.[9]

The major reason for wrinkles, the primary and fundamental indication of aging skin, is not in fact our age but the sun. UVA and UVB rays break down the connective tissue below the skin, disrupt the skin’s repair mechanisms, and cause skin aging (or photo-aging). Therefore, photo-aging takes place faster and earlier in people who work outside.[10]

{Picture: Photo-aging visible on one side of a truck driver’s face}[11] 

It’s imperative that we begin teaching children and adolescents about UV protection: having suffered five sunburns in childhood and early youth increases the risk of developing melanoma by 80%.[12] Children shouldn’t spend long hours in the midday, summer sun. 

Solar damage isn’t just more likely in children and teenagers, but also in people with skin type 1 or 2 (light skin), red hair, and/or colored eyes (blue); people, especially light-skinned people, with many skin moles; people whose family members have or had skin cancer; those who have a skin disorder triggered by the sun (lupus, dermatomyositis, rosacea); and people who have innate light sensitivity (albino, xeroderma pigmentosum, etc.). All these groups must be particularly careful about protecting themselves from the sun.

What are some ways to protect ourselves from UV Rays? Well, because UV radiation bombards the Earth most intensely at noon during the summer, staying indoors is greatly recommended between the hours of 10:00 am and 4:00 pm.  Additionally, the reflection rate of solar rays is higher by the seaside and in snowy environments.[13]

Wearing appropriate clothes is still the most effective and the least expensive method of sun protection. Clothing can have a solar protection factor (SPF) of 15-30. The level of protection is determined by the type of fabric, number of pores, and type, color, and thickness of weaving. The best clothes are made from cotton, silk, and denim and are unbleached and woven tightly. Wet clothes are more permeable. The use of wide hats, sunglasses, and umbrellas are also important for protection.

In addition to these measures, sun protection creams should also be used. The idea that protection creams will prevent the synthesis of vitamin D, voiced frequently lately, should not prevent the use of sun protection because the solar rays we receive during the day from the face and hands are sufficient for the synthesis of vitamin D. A person should pick a sun cream appropriate for their skin and apply it in sufficient amounts 20 minutes before going out. Babies should be protected through natural means, and physical sun protection should be used for children and pregnant women. A person should reapply sun protection products every two or three hours while outside, and, if planning to swim, they should choose water resistant products.

Besides physical protection that blocks, scatters, or reflects solar rays, there are also skin-absorbable chemical protections with cosmetically accepted formulations that eliminate light by absorbing it.

Generally speaking, a good sun protection should protect against both UVA and UVB rays. It should be cosmetically acceptable, non-toxic, water and perspiration resistant, and at the appropriate SPF (sun protection factor) level. However, because reapplication is required every two to three hours, protection above SPF 50 is the same. Therefore, it is no use buying a more expensive, higher protection product.[14] For people with type 3 skin (darker white skin with gold tone), SPF 30 is sufficient. For light skinned people, children, and pregnant women, however, SPF 50 is recommended.

SPF is the number indicating by how many more times a sunscreen protects the skin against UVB than the skin itself. Skin type is very important in sunscreen choice. The natural protection period of a person with type 1 skin is 5-10 minutes, while it may go up to 90 minutes for a person with type 6 skin. In other words, a light-skinned person gets a sunburn in 5-10 minutes of exposure, while a dark-skinned person may not get one at all. Therefore, these people should not choose products at the same SPF level. For example, if the skin’s self-protection duration is five minutes, a sunscreen with a SPF of 30 provides the same protection for 150 minutes.

Apart from sun protection creams, oral products can also help with sun protection. For example, oral zinc intake is proven to prevent cellular and DNA damage caused by UV radiation. Vitamin C is effective at preventing UVA rays due to its antioxidant properties and vitamin E at preventing UVB rays. In addition, the intake of beta carotene (a precursor of vitamin A) and bioflavonoids (also called vitamin P which generally has effects similar to vitamin C), found in orange and red fruit, protects against UV damage. Polyphenolic compounds in green tea also display protective properties against UV radiation.[15]

Finally, we should remember that using a sun protection product is a small part of our attitude toward your overall protection from the sun. Considering the role of the ozone layer in filtering the sun’s harmful rays, we should protect the perfect balance in the universe and re-evaluate our responsibilities and future actions for the maintenance of this balance.

Notes

[1] livescience.com.

[2] Gilchrest BA. “Sun exposure and vitamin D sufficiency,” Am. J Clin Nutr. August 2008, Vol. 88 # 2 570S-577S.

[3] Understanding UVA and UVB. skincancer.org.

[4] sciencelearn.org.nz.

[5] “The Protective Role of Melanin against UV Damage in Human Skin.” Photochem Photobiol. 2008; 84(3):539-549.

[6] laserdocs.co.uk/easy-way-to-find-out-your-fitzpatrick-skin-type/

[7] Ibid.

[8] Adele CG, Sarah C Wallingford and Penelope M. “Childhood exposure to UV radiation and harmful skin effects: Epidemiological evidence.” Prog Biophys Mol Biol. December 2011, 107(3): 349-355.

[9] Green AC, Williams GC, Logan V, Srutton GM. “Reduced Melanoma after Regular Sunscreen Use: Randomized Trial Follow-Up,” Journal of Clinically Oncology. 20 January 2011, Vol. 29 # 3:257-263.

[10] Fitzpatrick’s Dermatology in General Medicine.

[11] www.nejm.org/doi/full/10.1056/NEJMicm1104059.

[12] Markovic SN, Erickson LA, Rao RD, et al. “Malignant Melanoma in the 21^st Century, part 1: Epidemiology, risk factors screening, prevention and diagnosis.” Mayo Clin Proc, 2007; 82: 364-380.

[13] Skin cancer prevention and early detection. www.skincancer.org.

[14] www.dermnetz.org.

[15] Halliwell B. “Free radicals, antioxidants and human disease.” Lancet 1994; 344-:721-724.