How much sunscreen do we need?
New discovery by Beiersdorf’s research and development department: IR imaging spectrometer visualises the optimal amount of sunscreen to apply
New feasibility study on how to apply sunscreen to provide effective protection to be presented at the EADV congress 2010 in Göteborg
(Hamburg, 13 Jule 2010) UV radiation causes various types of skin damage and promotes the development of dermatosis, photoallergic reactions and/or skin tumours. Comprehensive sun protection is therefore necessary, yet very few people apply sufficient sunscreen. Using an infrared imaging spectrometer, Beiersdorf’s research and development department has now succeeded in visualising the amount of sunscreen applied and thus the level of UV protection as well . “This technique now makes it possible to convince consumers using visual evidence that they need to apply greater amounts of sunscreen with a higher skin protection factor in future in order to provide optimal protection for their skin from the harmful effects of excessively high levels of UV radiation,” explains Dr. Elke Grotheer from the research and development department of Beiersdorf AG.
Fourier Transform Infrared Imaging Spectroscopy (FT-IR imaging spectroscopy) has proved to be an effective means of quickly visualising a very wide range of samples. The physical analytical technique, which operates using infrared light, enables spectral (chemical) and spatial information to be combined and visualised. A new and important use of FT-IR imaging spectroscopy lies in the field of in-vivo applications. “The feasibility study we are to present in Göteborg demonstrates for the first time using very graphic images the correct amounts of sunscreen to apply in order to guarantee optimal protection for the skin, as well as those amounts which do not suffice,” explains Dr. Grotheer. The colour scale of the IR images ranging from green through yellow up to red clearly shows that consumers use only between a quarter to a third of the required amount of sunscreen and that 2 mg of sunscreen per square centimetre should be applied to ensure the optimal effect on the skin.
Correlation between the amount of sunscreen applied and the level of UV protection
Various studies have established a linear correlation between the amount of sunscreen applied and the level of UV protection provided . International standards stipulate that UV protection be measured after applying 2 mg of the product per square centimetre. Optimal UV protection is therefore guaranteed only when this amount is applied [3, 4]. For use on the face, this amount equates to about half to one teaspoon of sunscreen. Studies have however confirmed that only few people apply this amount [3, 5, 6, 7]. Using the new technique, the dermatology researchers at Beiersdorf have now examined this matter in great detail.
In the course of the Beiersdorf feasibility study various in-vivo measurements were carried out on the forearms of four subjects. Three sunscreen products manufactured by Eucerin®* were tested, with each product being tested on different days. 12.5, 25 and 50 mg of sunscreen – corresponding to a dosage of 0.5, 1 and 2 mg per square centimetre of skin surface – were each applied on the right and left forearm, both areas measuring 25 square centimetres. In an additional test the subjects applied the amount of sunscreen they would usually apply.
Two measurements each shortly after application
In each case, two imaging measurements of the areas treated were made ten minutes after applying the product. The skin depth of the infrared measurements was approximately two micrometres. The IR images were produced by analysing specific IR bands of the UV filters and converting the so-called integral absorbances of these bands into a colour code, with green representing an adequate and red a small amount of UVA and UVB filters applied.
“The infrared images clearly show the differences between the varying amounts of sunscreens applied,” emphasises Dr. Simone Presto from the Department of Medical Affairs of Beiersdorf AG. “In all three products tested the best and safest sun protection was provided in all cases when the subjects applied 2 mg of sunscreen per square centimetre of skin.” In these cases the scale was nearly always green. By way of comparison, the UV filter was less clearly pronounced at 1 mg per square centimetre; apart from green areas there were also yellow and red areas.
An application of 0.5 mg of sunscreen per square centimetre showed the lowest number of UV filters and thus the least protection from harmful radiation. Each of the subjects carried out a test with all three products using the amount of sunscreen they would usually choose to apply before sunbathing. There was one result that gave rise to great concern: “The average amount of suncream applied here varied between 0.5 and 1 mg per square centimetre and is thus clearly below the amount that is recommended for optimal skin protection,” says Dr. Presto.
Sun protection is important: IR images for use in awareness campaigns
UVA and UVB rays trigger the development of skin damage such as sunburn, photodermatosis and skin ageing in different ways. “We need graphic and persuasive information material to convince consumers that they should in future use more sunscreen than they usually use,” is how Dr. Grothee assesses the situation. The FT-IR imaging spectrometer now provides an excellent way of meeting this need. With the help of these tests, visual proof can be provided that consumers use only between roughly a third and a quarter of the amount of sunscreen required. The IR images can be used for consumer guidance and education, according to Dr. Grotheer.
Eucerin has already provided additional practical help regarding the correct use of the product in the form of tips they issued last year on how to apply the sunscreen. Instead of using a teaspoon, which may of course not always be to hand, one can use the length of one’s hand as a measure of the correct amount of sunscreen .
Further chapter in the success story of dermatological research carried out at Beiersdorf AG
FT-IR imaging spectroscopy represents a further chapter in the success story of skin research carried out at Beiersdorf AG. The international Centre for Research and Development in Hamburg, which was extended in 2004, is regarded as one of the largest and most modern of its kind in Europe. Only recently, researchers from Beiersdorf caused a sensation in professional circles when, in collaboration with the renowned German Cancer Research Centre at Heidelberg (DKFZ), they were able to analyse in the genotype of skin cells chemical changes which are typical of cancer and which increase with age. These findings can greatly improve our understanding of the way in which environmental factors affect skin ageing and the development of cancer.
* Eucerin® Sun Fluid SPF 30, Eucerin® Sun Fluid SPF 50+, Eucerin® Sun Lotion for Dry Skin SPF 50+
 Grotheer E, Heinsohn G, Rapp C, Presto S, Rippke F, Conzelmann S, Uhlmann B: A Novel Method for the Visualisation of the Amount of Sunscreen Products Applied to Skin by In Vivo Attenuated Total Reflection FT-IR Spectroscopic Imaging. Poster EADV Congress Gothenburg, 2010 Oct.
 Bimczok R, Gers-Barlag H, Mundt C, Klette E, Bielfeldt S, Rudolph T, Pflucker F, Heinrich U, Tronnier H, Johncock W, Klebon B, Westenfelder H, Flosser-Muller H, Jenni K, Kockott D, Lademann J, Herzog B, Rohr M: Influence of applied quantity of sunscreen products on the sun protection factor - a multicenter study organized by the DGK Task Force Sun Protection. Skin Pharmacol Physiol 2007, 20(1): 57-64
 Schalka S, dos Reis VM, Cucé LC: The influence of the amount of sunscreen applied and its sun protection factor (SPF): evaluation of two sunscreens including the same ingredients at different concentrations. Photodermatol Photoimmunol Photomed 2009, 25(4): 175-180
 Osterwalder U, Herzog B: Sun protection factors: world wide confusion. Br J Dermatol 2009, 161 Suppl 3: 13-24
 Kim SM, Oh BH, Lee YW, Choe YB, Ahn KJ: The relation between the amount of sunscreen applied and the sun protection factor in Asian skin. J Am Acad Dermatol 2009 Dec 3 [Epub ahead of print]
 Neale R, Williams G, Green A: Application patterns among participants randomized to daily sunscreen use in a skin cancer prevention trial. Arch Dermatol 2002, 138(10): 1319-1325
 Jungman E, Maibach HI: Enhancing sunscreen efficacy in the 'real' world? J Dermatolog Treat, 2009 Oct.
 http://www2.eucerin.de/sun-special/bin/index.html -> Sonnenschutztipps -> Anwendungshinweise
Translation of the June Press Release
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