Sunscreens
Daily application of a broad spectrum SPF 30+ sunscreen is the most important part of your skincare regime for the prevention of premature ageing and skin cancer.
As Australia has the highest incidence of skin cancer in the world we hope this information will increase your knowledge about ultraviolet radiation (UVR) and sunscreens and encourage you to protect yourself effectively.
Visit our skin concerns page on sun-damage to find out the effects UVR has on the skin.
Types of sunscreens:
- Chemical
- Prevent sunburn by absorbing UVR and re-emitting it as heat
- Often combined with ‘physical’ sunscreens to create high SPF products
- Often cause allergic reactions
- Some chemicals are absorbed systemically so should not be used in children under 2 years old
Physical
- Reflect and scatter UVR
- Block the widest range of light – UV, visible and infrared
- Recommended for intense sun exposure
- Rarely cause allergic reactions
- Recent preparations are more cosmetically acceptable (micronised titanium/zinc oxide)
Your sunscreen needs to be a broad spectrum in order to protect you against UVA and UVB rays. The SPF or sun protection factor rating is only a measure of protection against UVB rays or the time it take you to go red from sun exposure.
Ultraviolet radiation:
- UVA I – 340 - 400nm
- UVA II – 320 – 340nm
- Not filtered by ozone layer – 20 x higher amounts than UVB
- Very few sunscreens protect against UVA I
- Longer wavelengths penetrate into the deep dermis
- Can penetrate glass
- Produces pigmentary changes without preceding erythema (redness)
- May play a significant role in the development of malignant melanoma
- UVB - 280 – 320nm
- Large proportion filtered by ozone layer
- Responsible for sunburn and immediate tanning
- Increases production of MMPs (protein degrading enzymes)
- Multiple assaults of sunburn in early life have been linked to Basal Cell Carcinoma and melanoma
- Long term exposure is linked to Actinic keratoses and Squamous Cell Carcinoma
- Absorption of UVB by DNA mutates the p53 tumour suppressor gene, thus increasing risks of skin cancer
Sun protection measures:
- No sunscreen can effectively block all parts of the UV spectrum therefore a variety of measures are essential for effective sun protection
- Avoid direct sun exposure between 10am to 3pm
- Wear hats and protective clothing
- Window shields
- Correct application of sunscreen
Correct Application:
Sunscreens must be applied properly, regularly and in recommended amounts to all sun- exposed areas for optimum protection against UVR.
How much should I apply?
2mgs of sunscreen needs to be applied per square centimeter of exposed skin, in order to achieve the indicated SPF rating. This equates to approximately 1 teaspoon per limb. Inadequate application may result in a 50-80% reduction of the SPF rating.
How often should I apply it?
It is recommended that sunscreen is applied 20-30 minutes prior to sun exposure and re- applied approximately every 2 hours and after swimming, perspiring or mechanically wiping off the sunscreen.
Common Misconceptions about sunscreen use:
- I don’t go out in the sun
It is thought that the average person receives approximately 18 hours of incidental sun exposure per week, performing everyday things such as; driving your car, hanging out the washing and checking the letterbox. It is these small regular doses of UVR that result in chronic sun damage.
- Sunscreens feel greasy, and cause my skin to breakout
There are many sunscreen formulations these days with several being oil free or gel based so it’s just a matter of finding one that you like.
- Sunscreens irritate my skin
Physical sunscreens or blockers, are often recommended due to the calming and soothing properties of ingredients such as zinc dioxide. Specific formulations for sensitive skin types will also have removed known irritants such as PABA, synthetic chemical sunscreens, fragrances and preservatives.
- I only need to wear sunscreen in summer
Summer sun is certainly the most aggressive but the rest of the year UV rays are still damaging. According to The Cancer Council 80% of UV radiation is able to penetrate light cloud cover and haze can actually increase UV levels. Snow reflection will double your exposure to UV radiation and sunburn occurs most often when the temperature is between 18-27C.
For more information on skin cancer and sunscreens etc, visit the following links:
http://www.skincancer.gov.au/internet/skincancer/publishing.nsf/Content/home
http://www.sunsmart.com.au/browse.asp?ContainerID=1539