Sun Radiation

Sun Radiation


What is UV radiation and why is it dangerous?

Ultraviolet radiation is a form of non-ionizing radiation, part of the electromagnetic spectrum with a wavelength of 100 to 400 nanometers (nm). It is classified into 3 subtypes: UVA, UVB, and UVC. Its main natural source is the sun. All UVC and most UVB are absorbed by the ozone layer. Thus almost all the ultraviolet radiation that reaches the earth consists of UVA rays, which penetrate deeper into the skin up to its basic layer, where the melanocytes are found.1
Artificial sources are the tanning beds (solarium), mercury lamps, mercury and mercury some laser devices. The degree of exposure to ultraviolet radiation varies depending on the day, the season, the latitude or the altitude, while it is related to the profession such as working in the countryside, and lifestyle such as sunbathing, water sports and artificial tanning. .2.3
Ultraviolet rays are reflected in sand, water, snow and ice and penetrate clouds or windows (UVA). Both UVA and UVB radiation affect health. Of course, its effect on the production of vitamin D is positive. Overexposure to ultraviolet radiation is potentially dangerous for the body, as it stimulates melanin-producing cells and the appearance of "tanning", a sign of skin and DNA damage, while more intense Exposure to UVB and UVA leads to burns, indication of more cell death.4
Long-term exposure to UVA leads to photoaging (wrinkles, pigmentation, thinning and atrophy), precancerous lesions (such as radial hyperkeratosis), noncancerous , squamous cell carcinoma) and melanoma.5,6 In addition, it is associated with an exacerbation of photosensitivity skin diseases such as lupus erythematosus and late skin porphyria and ocular lesions such as cataracts and tumors. Ways of protection from ultraviolet radiation Since in our country exposure to ultraviolet radiation is year-round, our protection from it must become a way of life. Protective measures should be taken daily, even on cloudy or rainy days.

The following are suggested:

  • ● Avoid or reduce to a minimum the direct exposure to the sun during the hours from 10:00 to 16:00, especially during the summer months.
  • ● Avoid sunbathing and seek shade. Let us not forget that we receive radiation even in the shade, such as under an umbrella, tent or tree, but to a lesser extent.
  • ● Use clothing that covers, if possible, the upper and lower extremities, a wide-brimmed hat to cover the head, ears and neck, and sunglasses with UVA and UVB filters. People who do water sports or work outdoors should wear special protective clothing.
  • ● Covering windows in buildings and cars with UV protection film.
  • ● Reduce or avoid artificial tanning with solarium devices.
  • ● Use sunscreen 365 days a year. According to the recently revised FDA guidelines and recommendations, 7 the sunscreen should have broad-spectrum UVA and UVB coverage, at least SPF30 protection index and be used in large amounts on the face and other areas half an hour before exposure in the sun, paying special attention to areas that we often neglect such as lips, eyelids, ears and extremities hands or feet.8,9 It is recommended to repeat it every 2 hours if the exposure continues, or after exercise, sweating, swimming or playing outdoors space. In this case, the use of SPF50 + DNA REPAIR formulation is recommended. Products containing Photolyase are considered more effective!!

  • What is Actinic hyperkeratosis?
    Chronic and cumulative exposure to ultraviolet radiation leads to the formation of actinic hyperkeratosis, which is a common skin lesion in people over the age of 50 and is located on the exposed parts of the body, mainly on the face, scalp, neck, chest, back, arms and tibias.10
    Although they come in many forms, they are usually presented as variously sized palpable hard patches on the surface of the skin with scales, sometimes accompanied by pain, burning or itching. In other cases they manifest as hypertrophy or skin atrophy, hyperpigmentation, cheilitis or look like a small animal horn, while sometimes the lesions are not visible to the naked eye.11
    They occur more often in middle-aged and immunosuppressed men, with light skin color and eyes, with red or blond hair (Phototypes I and II according to Fitzpatrick), in geographical areas with high sun exposure.12 Genetic disorders, a history of sunburn in childhood, and a high-fat diet are also risk factors. Natural factors such as ozone depletion, and increased activities such as sunbathing, tanning, and outdoor work have greatly increased the global incidence of the disease in recent years. They are considered precancerous lesions, since in a percentage from 0.1% to 20% they develop into squamous cell carcinoma.13
    Although early diagnosis and treatment of the disease is of great importance for public health, it often does not receive the necessary attention from patients due to lack of information, as well as from doctors of other specialties due to lack of information and untimely referral to a dermatologist.
    How to prevent actinic hyperkeratosis
    Prevention of actinic hyperkeratosis can be achieved to a significant degree by properly informing the public about the nature of the disease and the negative effects of chronic exposure to ultraviolet radiation, but also self-examination for any changes in the skin with timely referral for medical examination. Regular dermatological examination and absolute consistency in sun protection measures is recommended. New medical devices that combine a high photoprotection index (SPF 50 +) with DNA repair enzymes are proposed instead of the standard sunscreen, for daily use by people with extensive sun damage at high risk of developing precancerous lesions and skin cancer.14
    Treatment of actinic hyperkeratosis
    Actinic hyperkeratosis must be treated, as clinically we can not determine which lesion will develop into squamous cell carcinoma, with possible metastasis and death.15
    The approaches available today are divided into 2 categories. The first includes treatments that individually target each lesion, such as liquid nitrogen cryotherapy, scraping or surgical removal, diathermy and sublimation with laser carbon dioxide or Erbium YAG.
    The second concerns field treatments, targeting multiple lesions per area at the same time, such as the use of chemicals (fluorouracil, imicimod, diclofenac with hyaluronic acid, retinoids, ingenol mebutate), chemical exfoliation with trichloroacetic acid. use of newer therapeutic agents, such as resiquimod, betulinic acid, piroxicam, and dobesilate.18
    As they all have advantages and disadvantages, the choice of the appropriate treatment is made by the treating physician based on the nature, location and number of lesions, as well as the general condition of the patient. The above options can be combined with the best clinical outcome, with a reduction in the duration and side effects of treatment. In any case, due to the chronicity of the disease and the continuous appearance of new lesions, it is necessary for the patient to comply with the treatment and medical instructions for sun protection, and long-term follow-up by a dermatologist.
    1. Watson M, Holman DM, Maguire-Eisen M. Ultraviolet radiation exposure and its impact on skin cancer risk. Semin Oncol Nurs. 2016; 32(3):241-254.
    2. Richards TB, Johnson CJ, Tatalovich Z, et al. Association between cutaneous melanoma incidence rates among white U.S. residents and county-level estimates of solar ultraviolet exposure. J Am Acad Dermatol. 2011; 65(Suppl 1):S50.e1-S50.e9.
    3. Milon A, Bulliard JL, Vuilleumier L, et al. Estimating the contribution of occupational solar ultraviolet exposure to skin cancer. Br J Dermatol. 2014; 170:157-164.
    4. Gilchrest B, Eller M, Geller AC, et al. The pathogenesis of melanoma induced by ultraviolet radiation. N Engl J Med. 1999; 340:1341-1348.
    5. Karagas MR, Weinstock MA, Nelson HH. Keratinocyte carcinomas (basal and squamous cell carcinomas of the skin). In: Schottenfeld D, Fraumen JF, editors. Cancer epidemiology and prevention 3. New York, NY: Oxford University Press. 2006; 1230-1250.
    6. Amaro-Ortiz Α, Yan Β, D’Orazio JA. Ultraviolet radiation, ging and the skin: Prevention of damage by topical cAMP manipulation. Molecules. 2014; 19:6202-6219.
    7. Food and Drug Administration. Sunscreen drug products for over-the-counter human use. 2019.
    8. Holman DM, Berkowitz Z, Guy GP Jr, et al. Patterns of sunscreen use on the face and other exposed skin among US adults. J Am Acad Dermatol. 2015; 73:83-92.<
    9. Kann L, Kinchen S, Shanklin SL, et al. and the Centers for Disease Control and Prevention. Youth risk behavior surveillance-United States, 2013. MMWR Suppl. 2014; 63:1-168.
    10. Schmitt JV, Miot HA. Actinic keratosis: a clinical and epidemiological revision. An Bras Dermatol. 2012; 87:425-434.
    11. Moy RL. Clinical presentation of actinic keratoses and squamous cell carcinoma. J Am Acad Dermatol. 2000; 42:S8-10.
    12. Salasche SJ. Epidemiology of actinic keratoses and squamous cell carcinoma. J Am Acad Dermatol. 2000; 42:4-7.
    13. Casari A, Chester J, Pellacani G. Actinic keratosis and non-Invasive diagnostic techniques: An update. Biomedicines. 2018; 6(1):8.
    14. Krutmann J, Berking C, Berneburg M, et al. New strategies in the prevention of actinic keratosis: A critical review. Skin Pharmacol Physiol. 2015; 28(6):281‐289.
    15. Ceilley RI, Jorizzo JL. Current issues in the management of actinic keratosis. J Am Acad Dermatol. 2013; 68(Suppl 1):S28-38.
    16. Chetty P, Choi F, Mitchell T. Primary care review of actinic keratosis and its therapeutic options: a global perspective. Dermatol Ther (Heidelb). 2015; 5(1):19‐35.
    17. Del Rosso JQ, Kircik L, Goldenberg G, et al. Comprehensive management of actinic keratoses: practical integration of available therapies with a review of a newer treatment approach. J Clin Aesthet Dermatol. 2014; 7(9 Suppl S2-S12):S2‐S12.
    18. de Oliveira ECV, da Motta VRV, Pantoja PC, et al. Actinic keratosis-review for clinical practice. Int J Dermatol. 2019; 58:400-407.

    Email to
    Phone to
    Back to top