Mothers & Children

Sun damage and sunburn

Kids on beach. Image: Marcin Chady on FlickrExposing a child’s skin to the sun can pose a serious risk to their health, both short and long term. Ultraviolet radiation (UVR), part of the invisible light emitted by the sun, can cause sunburn, scarring, eye damage, premature skin aging and can also damage skin cells leading to a long term risk of skin cancer. The best way to avoid such damage is to prevent excessive exposure by following a sensible sun safety regime.

Sunburn

Sunburn is the result of overexposure of skin to ultraviolet radiation (particularly UVB wavelengths 280-320nm), which penetrates the skin and causes it to burn. The severity of sunburn will depend on the amount of time spent in the sun, the intensity of the sunlight and a child’s skin type. The skin reddens 2-6 hours after UV exposure and the burn further develops for the following 1-3 days. When a child is sunburnt, the top layer of their skin (called the epidermis) becomes red, hard and, in severe cases, forms blisters. They may also feel lethargic or fatigued, due to dehydration.

The skin cells damaged by sunburn often undergo a process called ‘apoptosis’ where they are programmed to die. It is generally thought that the body does this when the cells are damaged beyond repair, to stop them from becoming malignant (cancerous). If the sunburn is extensive, these dead cells can be shed in vast numbers, this is the peeling skin seen on severely sunburnt skin.

Symptoms of sunburn may include: redness and inflammation (erythema); swelling; pain or stinging; a hot or burning sensation; tingling; blistering; headache; tender, aching or throbbing skin; fever; chills; nausea and vomiting; faintness or weakness. Dryness, itchiness and peeling may occur in the following days.

For first aid and at-home care advice on sunburns, see the article Relieving sunburn.

Sunburn can range in severity from mildly red, inflamed skin to deep reddening with extensive blistering and strong pain. In the case of severe sunburn - particularly if a child is suffering from fever, chills, nausea, vomiting, faintness or weakness - seek medical treatment.

Occasionally, heat stroke (sunstroke) can accompany acute sunburn; the child’s internal temperature rises dangerously high and can cause death if not treated quickly. Heat stroke is more common in young children as they have a larger surface area to body weight ratio, and hence, poorer temperature regulation. If your child has a very high body temperature, a dry swollen tongue, rapid pulse, shallow breathing, faintness, headache, fever, chills, confusion, nausea or loss of consciousness, seek emergency medical assistance.

The Science of skin website has more information and references on sunburn.

Skin aging

Chronic exposure to UV radiation also promotes photoaging - premature aging of the skin. Photoaging presents as wrinkles, age/liver spots, broken blood vessels and skin which is dry, leathery, sagging, discoloured or fragile; such damage is cumulative and irreversible. Photoaging is often visible on areas where the skin has been exposed long-term to UV light, such as the face, hands, arms and legs.

While human skin will naturally age, UV accelerates this process by damaging the collagen fibres in the skin. Found in the dermis (middle layer of skin), collagen is responsible for the strength of skin, providing firmness and flexibility. When UV radiation penetrates skin, it acts by two mechanisms to reduce the amount of collagen present, resulting in visible damage. UVA (radiation between 320-400nm in wavelength) has been identified as the primary cause of photoaging, as the longer wavelengths are able to penetrate deeper into the skin to cause damage.

For more details, refer to the photoaging article.

Skin cancer

Skin cancers are malignant growths, or tumours, which usually appear on the epidermis (the outer layer of skin), though can occur in other areas of the body such as inside the mouth, nose and on the nail beds. The three most common forms of skin cancer are basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma. Melanoma is the least common of the three (approx. 5% of cases), but also the most lethal. It is fast growing and once metastasised is frequently fatal.

Chronic exposure to ultraviolet radiation, in combination with genetic predisposition, is the single most important factor contributing to skin cancer. UV radiation is believed to cause skin cancer by damaging the genetic information (DNA) within skin cells and by inducing oxidative damage.

The cumulative amount of lifetime sunlight exposure is the most important contributing factor to the development of SCC. While this is also a factor in melanoma incidence, more significant is the number and extremity of sunburn episodes. Periods of high UV exposure and severe sunburn incidents - those which result in blistering or peeling of the skin, particularly in childhood - have being strongly associated with the development of melanoma later in life.

References

Boukamp, P 2005, ‘UV-induced Skin Cancer: Similarities - Variations’, Journal der Deutschen Dermatologischen Gesellschaft, 3(7):93-503.

Helfrich, YR, Sachs, DL & Voorhees, JJ 2008, ‘Overview of skin aging and photoaging’, Dermatology Nursing, 20(3):177-83.

Kang, S, Fisher, GJ & Voorhees, JJ 2001, ‘Photoaging: pathogenesis, prevention, and treatment’, Clinics in Geriatric Medicine, 17(4):643-59, v-vi.

Lucile Packard Children’s Hospital 2010, ‘Facts About Sunburn’, retrieved 28 June 2010, <http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/burns/sunburn.html>.

NSW Government, 2008, ‘NSW Health Factsheet: Heat Stroke’, retrieved 28 June 2010, <http://www.health.nsw.gov.au/factsheets/environmental/heat_stroke.html>.

SunSmart Victoria, 2009, ‘Sunburn’, retrieved 28 June 2010, <http://www.sunsmart.com.au/browse.asp?ContainerID=1561>.

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