Screening the sun
20 November 2012
Covering up and staying out of the sun for prolonged periods of time, especially in the middle of the day, is still the best way to protect ourselves from damaging ultraviolet (UV) radiation, claims a University of Sydney researcher.
According to Jane Hanrahan, Associate Professor in the Faculty of Pharmacy, sunscreens should only form one part of our sun protection strategy. If sun exposure cannot be avoided, then the use of a broad spectrum high SPF sunscreen, applied according to directions to protect against sunburn, photoageing and photocarcinogenesis, is essential.
However, Professor Hanrahan says there is very little to be gained by using 50+ sunscreen if it is not re-applied regularly, as people are less cautious after using it and they can still find themselves sunburnt at the end of the day.
When applied correctly, an SPF 30+ guards against 96.7 percent of UVB rays, while an SPF 50+ only takes protection to 98 percent. If it takes your skin 10 minutes to burn without sunscreen, it would take you 300 minutes with an SPF30+ and 500 minutes with an SPF 50+. However, the recent changes have seen improvements made to the standards and technique for measuring ultraviolet A protection.
"Sunburn is caused by ultraviolet B (UVB) radiation, but ultraviolet A (UVA) may be more damaging to the skin. Sunscreens should ideally block both wavebands," warns Professor Hanrahan.
Sunscreens may be organic or inorganic chemicals and many sunscreens contain a mixture of both to provide protection against both UVA and UVB radiation, says Professor Hanrahan. Regular use of a broad spectrum sunscreen has been shown to reduce the development of actinic keratosis, squamous cell carcinoma and melanoma.
Recent studies have indicated the incidence of skin cancers (particularly melanomas) has continued to increase in Australia despite 30 years of 'slip, slop, slap'.
"We have only been using broad spectrum sunscreens since the mid-1990s. The long latency between sun exposure and the appearance of skin cancers means that the efficacy of broad spectrum sunscreens in preventing skin cancer may not become apparent for another 25 years or more when the population born in the 1990s reach the age when most skin cancers begin to appear."
"Sunscreens have been found to be a safe and effective way of protecting the skin from UV radiation, if excessive sun exposure cannot be avoided, then the use of a broad spectrum high SPF sunscreen, applied according to directions will protect against sun damage."
Anyone who would like more information about the correct use of sunscreens should consult their pharmacist, says Professor Hanrahan.
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