SPF testing
The protection against UVB radiation is determined by measuring the sun protection factor (SPF). SPF is only a part of UVB – ultra-violet energy coming from the Sun. UVB energy causes skin redness and sunburn.
A SPF test is performed on a panel of 10 to 15 human testers. It is measured how long it takes before UVB rays make unprotected skin go red. If redness appears on unprotected skin after 10 minutes – SPF 30 means that it will take 30 times as long for the same symptoms to appear on the skin. The protection against UVA rays is just as important. Although UVA energy does not cause so much redness or sunburn it destroys skin genes, which may cause mutations and - in the worst case scenario – cancer. This type of radiation accelerates skin aging (wrinkles, lines and saggy skin) and may also cause pigmentation. UVA radiation penetrates into the deepest skin layers. We are exposed to it all day round, even when it is not sunny.
UVA sunscreens are now available on the market. There are also tests whose purpose is to create a UVA “protection factor”. Unfortunately, unlike SPF, they have not been globally standardized. Hence, several different methods are used:
a) ISO 24442 - an in-vivo method recommended by Cosmetics Europe, applied in Asia and in Europe. Its result is the PPD factor (Persistent Pigment Darkening). ISO 24442 determines an in-vivo method for the evaluation of the UVA protection factor (UVAPF) for sun protection products. It is the basis for the evaluation of products containing sunscreens aimed to protect human skin against UVA radiation from the sun and other sources of light.
b) ISO 24443 – an in-vitro method recommended by Cosmetics Europe and standardized in Europe. This procedure does not involve any tests on humans. The UVAPF is determined by measuring the amount of UVA energy passing through a layer of sunscreen.
c) PA Method (Protection Grade of UVA) – a method applied in several Asian countries such as Japan and South Korea. It is basically a copy of the ISO 24442 method with an extra classification from 2-16 and over 16 (PA++++). It does not allow for differentiating between products with PPD 20 and PPD 30, which means that they are labelled in the same way.
d) Broad Spectrum Method – a method applied in the USA and Canada (FDA). It is the easiest one to confirm but does not show to what extent our skin is protected against the damage caused by UVA radiation. It should be emphasized that the sun protection products to be launched on the US and Canadian market may only be tested by one laboratory, which is approved by the FDA (Food and Drug Agency).
Ideally, SPF (UVB) and UVA protection provided by a given product should be the same or similar. It is crucial to remember that sunscreen should be used and that it should be applied repeatedly. In our laboratory, we conduct tests and trials with reference to all of the above mentioned standards. Our equipment is calibrated each year, which is confirmed by applicable certificates. For our tests, we also use certified control products required by the said standard: P2, P3, S1, S2 control samples and HD6 plates for in-vitro tests.
Our laboratory's equipped with the following instruments and devices:
a) Labsphere UV 2000;
b) SolarLight simulators: Model 16S-150-1.2 and Model 601 Multiport with PMA 2100 radiometer and PMA sensors;
c) Suntest CPS+ device
