AU2016223870B2

AU2016223870B2 - Method for examining sunscreens on the skin

Info

Publication number: AU2016223870B2
Application number: AU2016223870A
Authority: AU
Inventors: Andreas Bleckmann; Ralf Hagens; Thomas Lange; Michael Lessmann; Frank Schwanke
Original assignee: Beiersdorf AG
Current assignee: Beiersdorf AG
Priority date: 2015-02-27
Filing date: 2016-02-09
Publication date: 2020-02-27
Anticipated expiration: 2036-02-09
Also published as: AU2016223870A1; DE102015203509A1; CN107257649A; WO2016134825A1; BR112017016998A2; EP3261519A1

Abstract

A method for examining the UV protective characteristics of individual or multiple UV light protective filters in a cosmetic preparation applied on the skin, characterized in that i) the cosmetic preparation is applied on the skin, ii) the skin treated with the cosmetic preparation is exposed to light, the spectrum of which includes the absorption band of the UV filter to be examined, iii) during this exposure, the image of the skin is recorded using a camera, wherein the camera is equipped with a UV bandpass filter of the wavelength range which likewise corresponds to the absorption band of the UV filter to be examined.

Description

Beiersdorf Aktiengesellschaft Hamburg

Description

Method for studying sunscreen products on the skin

The present invention relates to a method for studying the UV protection properties of indi vidual or multiple UV light protection filters in a cosmetic preparation applied to the skin, characterized in that the cosmetic preparation is applied to the skin, the skin treated using the cosmetic preparation is irradiated using light, the spectrum of which includes the absorp tion bands of the UV filter to be studied, and during this irradiation, the image of the skin is recorded using a camera, wherein the camera is equipped with a UV bandpass filter of the wavelength range which also corresponds to the absorption bands of the UV filter to be stud ied, and the use of the method.

The trend away from aristocratic pallor toward "healthy, sporty brown skin" has been unbro ken for years. To achieve this, humans subject their skin to solar radiation, because it induc es pigment formation in the sense of melanin formation. The ultraviolet radiation of sunlight also has a damaging effect on the skin, however. In addition to acute damage (sunburn), long-term damage occurs, such as an increased risk of suffering from skin cancer in the event of excess irradiation using light from the UVB range (wavelength: 280-320 nm). The excess action of UVB and UVA radiation (wavelength: 320-400 nm) additionally results in weakening of the elastic and collagen fibers of the connective tissue. This results in numer ous phototoxic and photoallergic reactions and results in premature skin aging.

Therefore, an array of light protection filter substances has been developed, which can be used in cosmetic preparations. These UVA and UVB filters are listed in most industrial coun tries in the form of positive list, such as appendix 7 of the German Cosmetics Ordinance.

However, the variety of commercially available sunscreen products should not obscure the fact that these preparations of the prior art have an array of disadvantages. In particular, it has proven to be difficult to determine the effectiveness of individual UV light protection filters (UV filters) after the application on the skin, the distribution thereof on the skin, the storage life thereof, and the duration thereof after physical and/or chemical stress (in particular the water resistance, sweat resistance, and rubbing resistance (for example, upon drying of wet skin treated using sunscreen product by way of a towel after a bath) thereof, the thermal stability and/or UV stability thereof). This is because these properties are not influenced solely by the UV filter substance itself, but rather additionally by the underlying surface to which they are incorporated.

In addition, in vivo methods are applied to determine these properties according to the prior art, which are based on irritating the skin of a test person using UV light until the generation of an erythema. Since the skin of the test subjects experiences a small amount of damage upon each test, it is desirable and required for ethical reasons to develop alternative and less stressful test methods.

It is an object of the present invention to overcome or ameliorate at least one of the disad vantages of the prior art, or to provide a useful alternative.

It was therefore the object of particular embodiments of the present invention to develop a method, using which the effectiveness of individual UV light protection filters (UV filters) after the application on the skin, the distribution thereof on the skin, the storage life thereof, and the duration thereof after physical and/or chemical stress (in particular the water resistance, sweat resistance, and rubbing resistance (for example, upon drying of wet skin treated using sunscreen product by way of a towel after a bath) thereof, the thermal stability and/or UV stability thereof) is to be determined, without having to irritate the skin of the test persons until the occurrence of an erythema.

The object is surprisingly achieved by a method for studying the UV protection properties of individual or multiple UV light protection filters and a cosmetic preparation applied to the skin, wherein (i) the cosmetic preparation is applied to the skin, (ii) the skin treated using the because medic preparation is irradiated using light, the spec trum of which includes the absorption bands of the UV filter to be studied, (iii) during this irradiation, the image of the skin is recorded using a camera, wherein the camera is equipped with a UV bandpass filter of the wavelength range, which also corre sponds to the absorption bands of the UV filter to be studied, and wherein the brightness of the images (or image details) recorded using the camera is set in relation to the brightness of images (or image details) of untreated skin which were obtained according to method steps ii) and iii) and/or to images (or image details) in which the UV light was completely absorbed, and it is also advantageous to calculate the differences of both image series to determine the absorption in percent in comparison to the standard (untreated skin or total absorption, re spectively).

It is advantageous in the meaning of the method according to the invention if after the record ing of the first difference measurement, the skin is subjected to a physical and/or chemical, reproducible stress.

In this case, the method according to the invention is advantageously characterized in that a rinsing or bathing process, a rubbing process, irradiation using UV light, heat, or cold, or the production of body sweat is used as the stress.

For this purpose, the already known stress tests for determining the water resistance, sweat resistance, etc. may also be used (see, for example, Schrader, K., Schrader, A., Die Son nenschutzfaktorbestimmung: Prfung der Wasserresistenz [the sun protection factor deter mination: checking the water resistance], Akt. Dermatol. (20), 130 (1994)).

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

According to the invention, the method according to the invention is advantageously charac terized in that after the stress process, the measurement procedure corresponding to method steps ii) and iii) is repeated and the difference of the two measurements, before and after the physical and/or chemical, reproducible stress, is calculated, to determine the loss of the UV light protection filter or filters on the skin due to the stress process.

This means that the skin treated using the cosmetic preparation is again irradiated after the stress using light, the spectrum of which includes the absorption bands of the UV filter to be studied, and during this irradiation, the image of the skin is recorded using a camera, wherein the camera is equipped with the UV bandpass filter of the wavelength range, which also cor responds to the absorption bands of the UV filter to be studied.

Advantageous embodiments according to the invention of the method according to the inven tion are characterized in that the UV bandpass filter permits UV radiation to pass in the wavelength range from 300 nm to 400 nm.

For example, the UV bandpass filter Baader U from Baader Planetarium GmbH (HWB 60 nm, central wavelength 350 nm), can be used in combination with the camera EOS1200D from Canon for the measurements. To enable a detection of UV radiation, the antialiasing filter in front of the camera sensor has to be removed in this camera. In addition, the camera is set in the image mode monochromatic.

The determination of the grayscale tones of the recordings (i.e., the brightness of the images or image details) and the differences thereof can advantageously be carried out according to the invention by image analysis with the aid of the program ImageJ (platform-independent image editing and image processing program, program and source text are in the public do main).

Advantageous embodiments according to the invention of the method according to the inven tion are characterized in that the luminosity of the light on the skin is from 0.25 Wm-2 to 40 Wm-2.

It is advantageous according to the invention if the quantity of the sunscreen product applied 2 before the physical and/or chemical stress is 0.8 to 2.0mg/cm .

The use of the method according to the invention for determining the UVA protection, the UVB protection, the water resistance, the rubbing resistance, the sweat resistance, the ther mal stability, and/or UV stability of cosmetic sunscreen products on the skin is not least ac cording to the invention.

Exemplary Embodiment The present exemplary embodiment is to explain the method according to the invention with out restricting it: An experimental setup for determining different light protection factors of sunscreen products consists of: - a special DSLR camera, in which the antialiasing filter was removed (for example, Canon 1200D) - an objective lens (for example, Canon Macro Lens EF 100mm) - a UV bandpass filter (for example, Baader U-Filter 320-380 nm) - two UV illumination sources (for example, EUROLITE LED IP FL-30 COB UV) - a copy stand (for example, Kaiser Reprostander RSX having Reproarm RTX 5512)

The setup provides that the illumination units are attached on the left and right on the stand having an alignment on the center of the stand plate. The distance of the lights from the test area is approximately 35 cm in each case. The camera having objective lens and UV band pass filter is attached to the camera arm and is approximately 55 cm from the test area.

The following products were tested in this experimental setup: - NIVEA SUN Protect & Bronze Lotion SPF 10 - NIVEA SUN Protect & Bronze Lotion SPF 50

One 5 x 5 cm 2 field on the underarm inner side per product is delineated as the test area. A quantity of 2 mg/cm 2 of the respective product is applied to each test area and distributed uniformly using a finger protected by a finger cot. The products each act for 30 seconds thereafter.

The recordings of the respective test areas are carried out with 1/60 exposure time, f4.0, and ISO6400.

The mean grayscale value of the photographed area represents a measure of the light pro tection factor of the respective product. An image editing program (for example, ImageJ) is used to quantify the grayscale values in an image. For this purpose, a defined area is ana lyzed which corresponds to a real area of approximately 4 x 4 cm 2 . Recordings are made in each case before the application (time tO), after the application (time t1), and after a towel rubbing (time t2). The towel rubbing was carried out using a standard towel, wherein 12 rubs (three in each direction) were executed on the dry skin in each area. The results of this ex perimental setup are shown in Figure 1.

Claims

Patent Claims

1. A method for studying the UV protection properties of individual or multiple UV light protection filters in a cosmetic preparation applied to the skin, wherein i) the cosmetic preparation is applied to the skin, ii) the skin treated using the cosmetic preparation is irradiated using light, the spectrum of which contains the absorption bands of the UV filter to be studied, iii) the image of the skin is recorded using a camera during this irradiation, wherein the camera is equipped with a UV bandpass filter of the wavelength range, which also cor responds to the absorption bands of the UV filter to be studied; and wherein

. the brightness of the images (or image details) recorded using the camera is set in relation to the brightness of images (or image details) of untreated skin which were obtained af ter method steps ii) and iii) and/or to images (or image details) in which the UV light was completely absorbed, and differences are calculated of both image series to de termine the absorption in percent in comparison to the standard (untreated skin or total absorption).

2. The method as claimed in claim 1, wherein after recording the first difference meas urement, the skin is subjected to a physical and/or chemical, reproducible stress.

3. The method as claimed in claim 2, wherein a rinsing or bathing process, a rubbing pro cess, irradiation using UV light, heat, or cold, or the production of body sweat is used as the stress.

4. The method as claimed in any one of the preceding claims, wherein after the stress process, the measurement procedure is repeated similarly to ii) and iii) and the differ ence of the two measurements, before and after the physical and/or chemical, repro ducible stress is calculated, to determine the loss of the UV light protection filter or fil ters on the skin due to the stress process.

5. The method as claimed in any one of the preceding claims, wherein the UV bandpass filter permits UV radiation to pass in the wavelength range from 280 nm to 320 nm or 320 nm to 400 nm.

6. The method as claimed in any one of the preceding claims, wherein the luminosity of the light on the skin is from 0.25 Wm-2 to 40 Wm-2.

7. The method as claimed in any one of the preceding claims, wherein the quantity of the sunscreen product applied before the physical and/or chemical stress is 0.8 to 2.0 mg/cm 2 .

8. A use of a method as claimed in any one of the preceding claims for determining the UVA protection, the UVB protection, the water resistance, the rubbing resistance, the sweat resistance, the thermal stability, and/or the UV stability of cosmetic sunscreen products on the skin.