New approaches in standardized sun protection factor determination of sunscreens: Project team in the 'Advanced UV for Life' consortium presents measurement system for non-invasive determination

12. July 2019

New approaches in standardized sun protection factor determination of sunscreens

Project team in the 'Advanced UV for Life' consortium presents measurement system for non-invasive determination

Messsystem zur LSF-Bestimmung © Charité

Measurement system for in vivo sun protection factor determination of sunscreens. Copyright: Charité

In June 2019, a meeting of ISO committee "Cosmetics" (ISO/TC 217) working group "Sun protection test methods" (WG 7) was held in Brussels. Prof. Dr. Jürgen Lademann, head of the “Center of Experimental and Applied Cutaneous Physiology” of the Charité and topic leader for medicine in the consortium 'Advanced UV for Life' was invited to present the latest research results on the non-invasive determination of the sun protection factor (SPF) of sunscreens.

To date, SPF values have been determined in special laboratories using a standardized measurement method on probands (in vivo). Skin treated with sunscreen is irradiated with a defined dose of ultraviolet (UV) radiation until sunburn occurs. The sun protection factor is determined from the irradiation dose and time. In other words, what is actually protected from by sunscreens is induced.

The Food and Drug Administration of the United States (FDA) and the European Union are urging the development of a method without skin damage. The ISO Committee 217 is therefore working on an international guideline for an in vitro method using artificial skin models instead of test persons. "Due to the specific texture of skin, such in vitro measurements have a significant disadvantage", Prof. Lademann knows. "The temperature and especially the biofilm of skin are very important for the application of sunscreens and their protective function. This cannot be achieved with plastic plates."

Together with the worldwide leader in skin testing equipment Courage + Khazaka electronic GmbH and the manufacturer of dermatological care products Hans Karrer GmbH, Charité develops a measuring system for non-invasive sun protection factor determination. Using light emitting diodes, UV radiation of a specific wavelength is applied via fibers to the sunscreen treated skin of test persons. Reflected and in the tissue scattered light is detected and the sun protection factor is determined directly – without time-consuming erythema assessment. "This measuring principle allows to consider the specific texture and reaction of skin without harming the probands", summarizes Prof. Lademann.

Thus, the project team convinced the ISO and was asked to advance the development and to characterize the measurement method as a possible standard process. The next step is a combination of the project team's non-invasive sun protection factor determination on test persons and a spectral analysis of the sunscreen product itself. "This hybrid method has a great advantage," comments Prof. Lademann. "Sun protection factors of 80 and 100 could be measurable in this way." According to the European Union, these high sun protection factors do not need to be listed - the upper limit here is 50+. However, such a measurement would be very important for cosmetics manufacturers. Sunscreens and their active ingredients can be characterized and their effects better understood. In order to exploit this potential, the project team also works on miniaturizing the measurement setups. "The compact UV LEDs provide a good basis for this", Prof. Lademann says. "Finally, we aim at a reliable, user-friendly and cost-effective system that will be used for ISO standardized sun protection factor determination of sunscreens".



Antje Mertsch
Coordination Office ‚Advanced UV for Life’

c/o Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik
Gustav-Kirchhoff-Straße 4, 12489 Berlin
Tel.: +49 30 6392-3397

Prof. Dr. Dr.-Ing. Jürgen Lademann
Center of Experimental and Applied Cutaneous Physiology

Charité – Universitätsmedizin Berlin
Charitéplatz 1, 10117 Berlin
Tel.: +49 30 450518-235


Background information

The Center of Experimental Applied Cutaneus Physiology is an international center of excellence at the Department of Dermatology, Venereology and Allergology at the Charité Universitätsmedizin Berlin. The research activities are focused on investigations of the use of optical and spectroscopic methods for clinical diagnostics and therapy monitoring in dermatology, and the use of UV radiation for therapy, such as wound healing, psoriasis, and atopic dermatitis.

Founded in 1986, Courage + Khazaka electronic GmbH introduced the first scientific measurement tools to objectively quantify parameters on the skin. Until today C+K electronic has always been the world market leader in this field with a complete range of products for the measurement of skin moisture, fat content, pH, color of skin, elasticity and wrinkles, roughness and texture of the skin surface. The devices are not only interesting for research and industry, but also for the dermatologist to determine skin condition and demonstrate successful outcomes. C+K electronic is particularly proud of the significant participation in the test series "SkinB" on the International Space Station, where the changes of skin under space conditions were investigated.

Hans Karrer GmbH is a partner of dermatologists, pharmacies and patients and develops its products according to their needs for care within the classical dermatological indications. Skin diseases and skin problems can change the quality of life. In order to improve the patient’s life and to decrease symptoms of skin diseases by dermatological care, the company uses its experience and the knowledge of modern science. The company emphasizes on diligence in production and selection of ingredients. Research and manufacture in Germany is very important for the products. All cosmetics are produced according to pharmaceutical GMP.

Advanced UV for Life is a consortium of 49 German partners from industry and science developing UV LEDs and bringing them into applications. The focus is on application fields of medicine, environment and life sciences, disinfection, and production. The consortium, led by the Ferdinand-Braun-Institut, is funded by the Federal Ministry of Education and Research within the program “Twenty20 – Partnership for Innovation”.