Science of Skin

Skin Cancer Prevention

Certain skin cancers can be directly attributed to chronic skin damage from ultraviolet (UV) radiation, while other skin cancers (such as melanoma) are also believed to be the contributed to by this damage. The best way to reduce your risk of skin cancer is to adhere to a regular regime of skin photoprotection (protection from UV and light) before skin is exposed to UV light.

Sunburn is only one indicator of skin damage from ultraviolet light, caused by UVB light (in the range of 310-280 nm). More recently we have begun to understand that UVA light (in the range of 310-400 nm) can also cause damage to skin, leading to skin cancer. Therefore, protection from UVA and UVB is vital to reduce the risk of skin cancer.

For most fair skinned individuals, precaution should be taken whenever the UV index is 3 or above, but for certain people (such as those with suppressed immune systems or conditions such as albinism), a daily photoprotective routine is vital.

Photoprotection

Protecting skin from UV light is vital to reducing the risk of skin cancer. This involves both avoiding the sun at times of higher risk, and using physical barriers, such as clothing and sunscreens to protect skin from UV.

Sun avoidance

During the middle of the day, the sun is at its peak and the intensity of UV radiation reaching the earth is much greater than during the early morning or late evening. The World Health Organisation (WHO) recommends limiting exposure to sunlight during the hours of 10am-4pm; advice backed by most national sun safety programs.

UV radiation peaks during the middle of the day.
To see today’s UV index forecast for Melbourne, showing a typical UV index peak: click here

Sunscreens

When sun exposure is unavoidable, sunscreens and clothing can provide adequate protection from UV damage if used correctly. Sunscreen should be at least SPF 15+ and be broad spectrum: providing protection from both UVA and UVB, the wavelengths of light known to cause sun damage (photoaging, sunburn) and skin cancer.

Correct sunscreen use is vital to be truly effective in preventing sun damage. Research has suggested that most people only use 25-50 percent of the recommended amount of sunscreen (approximately one teaspoon per extremity; arms, legs, face). Sunscreen should be applied at least 20 minutes prior to sun exposure and reapplied at least every two hours; more frequently if swimming or sweating.

Clothing

Tight weave clothing covering the arms and legs and broad brimmed hats provide an important physical barrier between the skin and sunlight. Specific clothing with ultraviolet protection factor (UPF) ratings can be bought. UPF measures clothing’s ability to reflect, refract or absorb both UVA and UVB as a standardized, numerical rating. A UPF rating of 50 means that only 1/50th (or 2%) of the UV light can penetrate the fabric. Like sunscreen SPF, UPF ratings have been shown to be affected by water, so clothing should only form part of a photoprotective regime, particularly when swimming.

Clothing colour has also been shown in research to affect the UPF of fabric with darker colours, particularly dark blue, providing greater protection to skin than lighter colours, such as yellows and whites.

Most government health agencies also recommend the use of wrap around, polarized sunglasses to protect eyes from sun damage.

Medical check ups

Regular skin checks from a physician or dermatologist, particularly for older individuals or those who have had large amounts of sun exposure, are vital to identify and remove precancerous lesions (such as actinic keratoses) and moles which may metastasize into skin cancers. The American Academy of Dermatology’s website provides basic information on how to perform a self examination for skin cancer and the key signs of suspect lesions. For more, see the AAD’s mole map.

References

  • American Academy of Dermatology, Melanoma Monday. [Online]. Available online. [Accessed 19/3/2010].
  • American Chemical Society (2009), Some color shades offer better protection against sun’s ultraviolet rays. [Online]. Available online. [Accessed 19/3/2010].
  • Gambichler, T et al (2008). “Influence of wetness on the ultraviolet protection factor (UPF) of textiles: in vitro and in vivo measurements.” Photodermatology, Photoimmunology & Photomedicine. 18 (1): 29-35.
  • Hong Kong Observatory, Health effect and protective measures against UV radiation. [Online]. Available online. [Accessed 19/3/2010].
  • Riva, A et al (2009). “Modeling the Effects of Color on the UV Protection Provided by Cotton Woven Fabrics Dyed with Azo Dyestuffs.” Ind. Eng. Chem. Res. 48 (22): 9817-9822.
  • Sunsmart, When is it safe to be outside without sun protection? [Online]. [Accessed 19/3/2010, no longer online].
  • World Health Organisation, Sun protection in schools. [Online]. Available online. [Accessed 19/3/2010].
  • World Health Organisation, Sun protection. [Online] Available online. [Accessed 19/3/2010].
  • World Health Organisation, Is it true that clothing always provides good UV protection? [Online] Available online. [Accessed 19/3/2010].

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