Sunburn

A sunburn is a radiation burn to the skin produced by overexposure to ultraviolet (UV) light, commonly from the sun's rays. A similar burn can be produced by overexposure to other sources of UV, such as tanning lamps and welding arcs. Exposure of the skin to lesser amounts of UV will often produce a suntan.

Development and consequences

Sunburns usually develop as a result of over-exposure to sun or, less commonly, occupational exposure.

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Sunburn occurs when exposure to UV light exceeds the protective capacity of an individual's melanin. Melanin content varies greatly, but in general darker-skinned people have more melanin than lighter-skinned ones. This leads to a reduced incidence of sunburn amongst dark-skinned individuals.

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Ultraviolet radiation is divided into UVA, UVB and UVC subtypes. Ozone in the Earth's atmosphere filters out some UV radiation. UVC is almost entirely eliminated by the atmosphere, but enough UVA and UVB remain that sunburn can occur in less than 15 minutes. http://203.202.189.11/browse.asp?ContainerID=1560 UVB was thought to be the causative agent in skin cancer, but there is a growing body of evidence to support the theory that both UVA and UVB cause skin cancer.

Related Topics:
Ozone - Earth's atmosphere

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Sunburn is usually not immediately obvious. After being burnt, skin may turn red 2 to 6 hours later. Pain is worst 6 to 48 hours afterward. The burn continues to develop for 24 to 72 hours after the incident. Skin peeling begins 3 to 8 days after the burn occurs. Common outcomes include tenderness, pain, oedema, red and/or peeling skin, rash, nausea and fever. Sunburns may be first- or second-degree burns.

Related Topics:
Pain - Oedema - Fever - Burns

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Minor sunburns typically cause nothing more than slight redness and tenderness to the affected area. In more serious cases blistering can occur. Extreme sunburns can be painful to the point of debilitation and may require hospital admission.

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The major danger of sunburn is the increased risk of future skin cancer. At the cellular level, UV light causes DNA damage which may be passed onto subsequent generations of a cell's progeny, leading to increased risk of skin cancer. Damaged cells die and release toxins which are responsible for nausea and fever. If many die, peeling may result. All sunburns result in permanent and irreversible damage. One incident of blistering sunburn doubles the risk of malignant melanoma.

Related Topics:
Skin cancer - DNA - Malignant melanoma

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