Sunburn Facts
How We Tan
Skin colour is dependent on a pigment called melanin. This is produced by specialized cells called melanocytes. Melanocytes produce packets of melanin called melanosomes and transfers them to the skin cells of the epidermis. Melanocytes are found throughout the skin. All races have the same number of melanoctyes. Black skin, however, has more melanosomes, giving better sun protection and more pigmentation.
There are two types of melanin pigmentation:
- Genetically inherited skin tone
- The other caused by sun exposure
Melanin protects your skin by absorbing harmful UV radiation and it darkens when doing so, producing pigmentation and leaving you with a sun tan.
Sunburn Facts
Sunburn is a reaction to exposure of UV radiation. The superficial layers of the skin release chemicals that cause your blood vessels to expand and leak fluid causing swelling, pain and redness. Without sun protection, UV radiation start to penetrate deep into the layers of the skin causing damage to the skin cells. Skin turns red within 2-6 hours of being burnt. This process continues on for the next 24 to 72 hours
UVA radiation
If the barrier function of skin is compromised it can have serious consequences eg. severe burns can cause fluid loss and dehydration and increase the risk of severe infection.
UVB radiation
This penetrates the superficial layer of skin and is the main cause of skin tanning and sunburn
Danger times for sunburn
UV radiation is most intense between 10am to 2pm (or 11 am to 3pm during daylight savings). In Australia, sunburn can occur in less than 15 minutes on a fine January day. As UV radiation is not related to temperature, many people get sunburnt when the temperature is between 18-27oC. People are most likely to get burnt when participating in activities such as gardening or golf.
Peeling
Damaged skin cells self-destruct and peel off in sheets. It is the body’s way of ridding itself of damaged skin cells that might develop into cancers
Sunburn and skin cancer risk
Studies show that sunburn during childhood can double a person’s risk of skin cancer (1,2). Further studies looking at migration have found that individuals moving to areas with higher UV exposures eg. Australia have higher melanoma risks if they arrive as children than as adults (3,4.) Interestingly, protective attitudes to sun exposure during childhood can lead to fewer moles, a known risk factor for melanoma. Hence it is imperative that children are educated about sun protection and sensible precautions. Further work has shown that some people have a higher risk of melanoma if they have fair skin, blue, green or hazel eyes, freckles (5), and tan poorly or burn easily (6).
Awareness of these facts and protecting your skin when UV radiation levels are dangerous can avoid sunburn and lower your risk of developing skin cancer.
For information on how to adequately protect yourself go to PROTECTION
References 1.Elwood, J. and J. Jopson, Melanoma and sun exposure: an overview of published studies. Int J Cancer, 1997. 73: p. 198-203.
2.Gandini, S., et al., Meta-analysis of risk factors for cutaneous melanoma: II. Sun exposure. Eur J Cancer, 2005. 41(1): p. 45-60.
3.Khlat, M., et al., Mortality from melanoma in migrants to Australia: variation by age at arrival and duration of stay. Am J Epidemiol, 1992. 135(10): p. 1103-13.
4.Mack, T. and B. Floderus, Malignant melanoma risk by nativity, place of residence at diagnosis, and age at migration. Cancer Causes Control, 1991. 2: p. 401-11.
5.Gandini, S., et al., Meta-analysis of risk factors for cutaneous melanoma: III. Family history, actinic damage and phenotypic factors. Eur J Cancer, 2005. 41(14): p. 2040-59.
6. Gallagher, R., et al., Sunlight exposure, pigmentation factors, and risk of nonmelanocytic skin cancer. II. Squamous cell carcinoma. Arch Dermatol, 1995. 131: p. 164-9
