Broad spectrum sunscreens needed to block UVB and UVA

Writing in the latest edition of Australian Prescriber, Associate Professor Jane Hanrahan from the Faculty of Pharmacy, University of Sydney writes that UVB is the cause of sunburn, but UVA can be more damaging to the skin. It is therefore best to use broad spectrum sunscreens that block both wavebands.

Sunscreens were originally developed to prevent sunburn caused by ultraviolet B (UVB) radiation, but we now know that it is just as important for them to block ultraviolet A (UVA) radiation, which is responsible for some types of skin cancers as well as premature ageing of the skin.

“The incidence of skin cancers, particularly melanomas, has continued to increase in Australia despite 30 years of the 'Slip, Slop, Slap' sun protection campaign. This is partly due to the fact that the sun protection factor rating, or SPF, in sunscreens is biased towards protection from UVB rays and prevention of sunburn, but does not measure how effective a sunscreen is at blocking UVA,” Associate Professor Hanrahan writes.

“The newer broad spectrum sunscreens that have been available since the 1990s and protect against UVA and UVB wavebands, provide hope of a decrease in the incidence of some skin cancers in the future.”

New Australian and New Zealand standards now permit sunscreens to have an SPF rating of up to 50+. Previously, only SPF 30+ was available in Australia.

There have been concerns in the past that newer sunscreens, which offer cosmetic benefits in terms of looking more transparent when applied, may in fact be harmful because of the absorption of nanoparticles into the skin, which could have toxic effects on the body.

The Therapeutic Good Administration, however, found that nanoparticles in sunscreens do not penetrate deep enough into normal intact skin to be toxic.

“Despite possible concerns about the long-term safety of sunscreens, the benefits of using sunscreen outweigh the possible harms,” Associate Professor Hanrahan concludes. “However sunscreens should only be one part of a sun protection strategy. Staying out of the sun where possible and covering up exposed parts of the body are still a priority.”

Other articles in this issue look at the rise of herpes zoster and an update on antivenom.

To read the full article and others visit www.australianprescriber.com

Source:

NPS MedicineWise

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