Research finds that sunscreen users receive less than half the sun protection they think

July 24, 2018

Researchers from King's College London have assessed just how much sun protection people actually receive, based on typical use. It is well known that people don't receive the full ultraviolet radiation blocking benefit of sunscreen, because they are applying it more thinly than manufacturers recommend. The findings are published in journal Acta Dermato-Venereology.

In the first experiment of its kind, the King's team assessed the DNA damage in the skin after lowering sunscreen application thickness below 2mg/cm2 - the amount manufacturers use to achieve their SPF rating.

Results showed that sunscreen with a sun protection factor (SPF) of 50, applied in a typical way, would at best provide 40% of the expected protection. The findings have prompted the King's team to suggest that consumers use a much higher SPF sunscreen than they think necessary, to ensure they're protected from sun damage.

As part of the research scientists divided a cohort of 16 fair-skinned volunteers into two groups of eight - (three women and five men in each). One group received a single UVR exposure, to simulate sunlight, to areas treated with high SPF sunscreen of varying thickness, ranging from 0.75mg, through 1.3mg up to 2mg/cm2.

The other group received exposures on five consecutive days - to mimic continuous holiday exposure. The amount of UVR exposure was varied during the course of the experiment, in order to replicate the conditions in holiday destinations, such as Tenerife, Florida and Brazil.

Biopsies of the UVR exposed areas of skin showed that, for the group that were repeatedly exposed to UVR, considerable DNA damage was found on the areas that received no sun protection, even though the UVR dose was very low.

Damage was reduced when sunscreen was applied at a thickness of 0.75mg/cm2 and considerably reduced when 2mg/cm2 of sunscreen was applied, even with much higher UVR doses.

Five days of exposure to high dose UVR with the sunscreen at 2mg/cm2 showed significantly less damage than just one day's low UVR dose exposure without sunscreen across all samples.

Report author, Professor Antony Young from King's College London said: 'There is no dispute that sunscreen provides important protection against the cancer causing impact of the sun's ultra violet rays. However, what this research shows is that the way sunscreen is applied plays an important role in determining how effective it is.

'Given that most people don't use sunscreens as tested as tested by manufacturers, it's better for people to use a much higher SPF than they think is necessary.

Nina Goad of the British Association of Dermatologists said: 'This research demonstrates why it's so important to choose an SPF of 30 or more. In theory, an SPF of 15 should be sufficient, but we know that in real-world situations, we need the additional protection offered by a higher SPF.

'It also shows why we shouldn't rely on sunscreen alone for sun protection, but we should also use clothing and shade. An extra consideration is that when we apply sunscreen, we are prone to missing patches of skin, as well as applying it too thinly.'
-end-
Notes to editors:

For further information please contact Garfield Myrie in the King's College London press office at: garfield.myrie@kcl.ac.uk / 0207 848 4334

King's College London

King's College London is one of the top 10 UK universities in the world (QS World University Rankings, 2018/19) and among the oldest in England. King's has more than 29,600 students (of whom nearly 11,700 are graduate students) from some 150 countries worldwide, and some 8,000 staff.

King's has an outstanding reputation for world-class teaching and cutting-edge research. In the 2014 Research Excellence Framework (REF), eighty-four per cent of research at King's was deemed 'world-leading' or 'internationally excellent' (3* and 4*).

Since our foundation, King's students and staff have dedicated themselves in the service of society. King's will continue to focus on world-leading education, research and service, and will have an increasingly proactive role to play in a more interconnected, complex world. Visit our website to find out more about Vision 2029, King's strategic vision for the next 12 years to 2029, which will be the 200th anniversary of the founding of the university.

World-changing ideas. Life-changing impact: https://www.kcl.ac.uk/news/headlines.aspx

King's College London

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