Sun Protection and its Effects

Sun Protection and Its Effect

There are many pathogenic effects surrounding unprotected ultraviolet radiation (UV) exposure from the sun, which include damage to the skin barrier leading to sunburns, photoaged skin, and the development of skin cancer. In fact, UV exposure is associated with 80-90% of skin cancers, and accounts for 1 in 3 cancer cases worldwide. To prevent carcinogenic outcomes and premature aging, sunscreen is used as an FDA-approved topical product containing the active ingredients, zinc oxide, avobenzone, octinoxate, or oxybenzone, to block UV radiation. Likewise, sunscreen or sunblock use has been proven to reduce the incidence of both melanoma and nonmelanoma skin cancers. According to the Canadian Dermatology Association and the American Academy of Dermatology, it is highly recommended that all individuals use sun-protective products for the prevention of skin cancer. Those who live in hotter climates are more likely to be exposed to the sun’s harmful UV rays, and thus, its use is strongly encouraged.

UV radiation is the natural energy produced by the sun, and its rays are strongest generally in the late-morning to mid-afternoon (not taking into consideration season and climate). Its short wavelengths on the electromagnetic spectrum makes it not visible by the human eye and includes two types that contribute to skin cancer: ultraviolet A (UVA) and ultraviolet B (UVB). UVA has a longer wavelength than UVB and accounts for about 95% of the UV radiation reaching the earth. UVA rays maintain a constant intensity during daylight and are associated with photoging and carcinogenesis. It penetrates the skin more deeply and causes genetic cell damage on the innermost part of the top layer of the skin, an area common to skin cancers. To prevent further damage, the skin protects itself by darkening. Prolonged or constant exposure to UVA will eventually lead to premature aging and skin cancer. UVA is associated with the “broad-spectrum protection” written on the products’ labels, indicating protection against both UVA and UVB (in the past, sunscreen products only provided UVB protection; this is no longer the case). On the other hand, UVB has a shorter wavelength and is associated with skin burning. It has the ability to penetrate and damage the outermost layers of the skin, the epidermis. Hence, overexposure results in a suntan, sunburn, and blistering. UVB is associated with the Sun Protection Factor (SPF) visible on products’ labels. The number next to the SPF indicates the time it takes for the sun’s radiation (UVB and some of UVA) to cause skin reddening when using that product compared to the time without sunscreen. For example, if an individual’s skin starts to turn red and burns under 10 minutes of unprotected sun exposure, using a product with SPF 15 means that it will take 150 minutes of sun exposure to experience the same consequence (increased by a factor of 15).

Without the use of protected mechanisms, exposure to these UV rays damages the DNA present in skin cells and produce genetic defects or mutations that result in skin cancer, which include basal cell carcinoma, squamous cell carcinoma, and melanoma, and premature aging. Additionally, it has been shown that they can alter suppressing tumor genes, thereby increasing the risk of sun-damaged skin cells developing into skin cancer. Not only do UV rays damage the skin, these rays can damage the eyes, leading to cataracts and cancer of the eyelids. Despite the body’s ability to perform DNA repair, accumulation of unrepaired damage triggers mutations that cause malignant tumors due to the rapid multiplication of skin cells. The degree of damage is dependent on UV ray intensity (UV index), how long the unprotected skin has been exposed, and the skin’s location of exposure. Fortunately, skin cancer is curable through early detection and treatment.

There are two types of sun-protective products that currently exist on the market: sunblock and sunscreen. These terms are often misused interchangeably and have different mechanisms of action, depending if the active ingredient provides physical or chemical protection. Physical filters contain active ingredients titanium dioxide and zinc oxide, and are referred to as sunblock. They function by reflecting or refracting UV radiation away from the skin. In contrast, chemical active ingredients include oxybenzone, avobenzone, octocrylene, and ecamsule, and are referred to as sunscreen. These are aromatic compounds capable of absorbing high-intensity ultraviolet radiation, resulting in excitation to higher energy states. When the molecules return to their ground states, the absorbed energy converts into lower-energy wavelengths. In lay terms, chemical sunscreen absorbs UV rays, converts it in the form of heat, and releases them from the body. To prevent carcinogenic outcomes and ensure optimal skin health, it is imperative for healthcare professionals to raise awareness and provide patient education on unprotected sun exposure and skin cancer and promote the use of sun-protective agents and practices, such as wearing sunglasses and hats.

References

Sander, Megan, et al. “The Efficacy and Safety of Sunscreen Use for the Prevention of Skin Cancer.” CMAJ : Canadian Medical Association Journal = Journal de l’Association Medicale Canadienne, 14 Dec. 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7759112/.

“The Difference between Physical and Chemical Sunscreen," www.piedmont.org/living-better/the-difference-between-physical-and-chemical-sunscreen#:~:text=The%20active%20ingredients%20in%20chemical,active%20ingredients%20in%20physical%20blocks. Accessed 25 May 2023.

“UV Radiation.” The Skin Cancer Foundation, 21 July 2022, www.skincancer.org/risk-factors/uv-radiation/.

Sunscreen and why you need it

Contrary to popular belief, sunscreen for your face should be incorporated into your skin regimen every day, not just in the summer or when you are going to the beach and pool. The sun gives off radiation which can be harmful to the skin and lead to sunburn and eventually skin cancer (melanoma, squamous cell carcinoma, etc). The sun gives off both UVA and UVB rays; proper sun protectant should block both. UVA consist of 95% of solar radiation and suppresses the immune system by affecting primary and memory t cell function. UVB is only 5 % of solar radiation, however it is responsible for most skin damage and is more intense during the summer and mid-day. Another misconception is that sunscreen and sunblock are the same products, and the word is often used interchangeably. However, sunscreen and sunblock are two different things. Sunscreen is a chemical defense which forms a film or coating on the surface of the stratum corneum which absorbs the UV rays before they reach and damage the dermal layers. Some sunscreens include avobenzone, oxybenzone, and Para-aminobenzoic acid (PABA). Sunblocks are agents which scatter radiation, these are opaque particles of inorganic materials. Typically, sunblock includes zinc oxide or titanium oxide. Sunblocks are often opaque and noticeable when applied to the skin.

According to the Skin cancer foundation, for those with sensitive skin, sunblocks are better tolerated and provide less irritants than sunscreen. Those who might have certain skin conditions such as rosacea or psoriasis should avoid sunscreen as the active ingredients, oxybenzone, and PABA, could cause a reaction. Also, these patients should only purchase fragrance free, and if possible preservative free sun protectants. Additionally, for infants (6 months and older) and small children sunblock is preferred over sunscreen. When searching for a sun protectant it should be at least an SPF of 30, but an SPF of more than 70 will not really provide additional benefit. Furthermore, it should be broad spectrum protection (protection against both UVA and UVB rays) and water resistant. SPF stands for Sun protection factor, which indicates how well a product will protect you from the suns UV rays. The SPF number tells you the amount of time it takes for the skin to burn upon exposure to the sun with protection as opposed to non-protection. For example, if a person normally burns in 10 minutes and applies SPF 30, now they can stay in the sun for 10 x 30 = 300minutes before burning. If used exactly as directed, a product with SPF 30 will take the sun 30 times longer to burn the skin than skin directly exposed without protection. A product with SPF 50 will take 50 times longer.

Finally, when using and applying sunscreen, proper application is more important than SPF number. Apply the product 15- 30 minutes prior to sun exposure to allow absorption through the skin. Reapply every 2 hours if tanning/ sunbathing, and every 40-80 minutes if swimming. Additionally, avoid the direct sun from 10:00 A.M. – 3:00 P.M; when the sun is the strongest, wear sunglasses that filter UV light, and wear protective clothing such as opaque long sleeve shirts, pants, and a hat.

References:

Elchaar, Gladys.Sunprotection: Clinical application.Lecture presented at St. John's University.September 2019.Queens, NY

Tamminga MA, Lipoff JB. Understanding sunscreen and photoprotection misinformation on parenting blogs: A mixed-method study. Pediatr Dermatol. 2021;38(1):88-91. doi:10.1111/pde.14411

Tanning pills are a non-prescription medication that usually contains canthaxanthin. Canthaxanthin is a naturally occurring carotenoid found throughout the environment in living organisms such as mushrooms, bacteria, crustaceans, sea trout, and algae. Canthaxanthin is FDA approved in minute quantities for use as a coloring agent for food. These pills are readily available to people to purchase on the Internet. The effect consuming canthaxanthin has on the epidermis and subcutaneous fat, is the formation of an orange-brown discoloration of the skin. The FDA has banned canthaxanthin-containing tanning pills due to their significant adverse effects. Some of the side effects of consuming large quantities of this drug include gastrointestinal problems, urticaria, hepatitis, retinopathy, and aplastic anemia. Beta-carotene is another common ingredient in tanning pills. Beta-carotene is in our daily consumption through fruits and vegetables and causes the yellow pigment of human skin. It is thought to contribute to photo-protection from the effects of both natural and artificial UV light exposure, and raising the minimum amount of UVR exposure needed to burn. Higher daily intakes of fruit, vegetables, and beta-carotene have been shown to increase the yellow appearance of skin.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4345932/

https://www.ncbi.nlm.nih.gov/pubmed/23053552

The presence of atypical nevi or numerous common nevi has been associated with an increased risk for melanoma. The idea is that sun-protective measures in children may prevent nevi formation. It has been linked with the development of fewer nevi in studies. One randomized controlled intervention trial looked at the prevention of nevi or moles by reducing sun exposure through the use of sun-protective clothing. The study involved 652 Caucasian children aged 0-35 months f living in the high-solar-irradiance environment of Townsville, Queensland, Australia. At baseline, the two groups were similar with respect to nevi, phenotype, age, demographic characteristics, sun-protection habits, and history of sun exposure. The higher melanocytic nevus counts were associated with children who spent more time outdoors and with a history of sunburn. The patients with sunscreen use, particularly during the mild winter months, appeared to have a protective effect. These findings strengthened the hypothesis that nevus development in young children is related to sun exposure.

https://www-ncbi-nlm-nih-gov.jerome.stjohns.edu/pubmed?term=22994908

https://www-ncbi-nlm-nih-gov.jerome.stjohns.edu/pubmed?term=15746470

As warmer weather approaches the bugs begin to come out. Two of the most common repellents used to prevent insect bites are DEET (N,N-diethyl-3-methylbenzamide) and picaridin (KBR 3023). DEET is said to be active against a number of insects including mosquitoes, biting flies, and ticks. It has been used for more than 70 years and is favored over other repellents because of its coverage and duration of action. There are many formulations of DEET differing in concentrations. In a study conducted on different repellents, a DEET formulation with a concentration of 23.8% had an average protection time of about 5 hours. The higher the concentration the longer the duration however, effectiveness plateaus at approximately 30%. DEET is said to be safe for children older than 2 months and pregnant women. Picaridin is another repellent with activity against mosquitoes, sand fly, and ticks. It is available in the US as 7, 15, and 20 percent formulations and has been used for many years in Europe, Australia and the US. In a number of studies conducted, picaridin has shown to be as effective as DEET however the potency of the picaridin fades after an hour and DEET proves to be superior. With all repellents, events such as swimming, washing, sweating and raining can negatively affect the ability for repellents to keep insects away. In this case, they should be reapplied to ensure proper protection.

https://www.ncbi.nlm.nih.gov/pubmed?term=12097535

https://www.ncbi.nlm.nih.gov/pubmed?term=12900480

https://www.uptodate.com/contents/prevention-of-arthropod-and-insect-bites-repellents-and-other-measures?search=mosquito%20spray&source=search_result&selectedTitle=3~150&usage_type=default&display_rank=3

With the upcoming summer season along the way, it is important to acknowledge the importance of skin protection from the sun. The sun gives off 2 types of ultraviolet (UV) radiation, which can be harmful to skin. UVA and UVB should be screened while enjoying the sun, and knowing which protective measures to take is valuable. Inorganic sun blocks, known as titanium dioxide and zinc oxide, reflect both UVA and UVB rays from the skin. This type of sun protection has minimal adverse reaction, and is generally safe to use. Although, the use of this type of sun protection could be seen as controversial, because it is important to maintain a certain amount of vitamin D for immune health. Alternatively, there are sunscreens that are made of organic chemicals that absorb different wavelengths of UV radiation. Sunscreens should be applied 15 minutes before sun exposure to ensure benefit. Likewise, an SPF from 15-30 is recommended for maximal benefit and minimal adverse drug reactions. ADE occur due to the organic chemicals present in sunscreens such as avobenzone, benzophenone, dioxybenzone, oxybenzone, and sulisobenzone. The adverse effects seen with sunscreens are typically redness, itchiness, dryness, blisters, stinging, and swelling. For sun protection in children, using sunscreens is not recommended due to the organic chemicals present. They are more than likely to cause atopic dermatitis. Subsequently, it is recommended to use inorganic sunblock as mentioned above.

https://link.springer.com/article/10.2165/00128071-200203030-00005

https://www.ncbi.nlm.nih.gov/pubmed/25207381