SPF Testing

Cosmetics Europe requires samples to be tested to the Standard EN ISO 24443:2012 Cosmetics – Sun protection test methods – In vitro determination of sunscreen UVA photoprotection.

This standard has been published by CEN (June 2012) and replaces the earlier reference method (Colipa Guidelines – Method for in vitro Determination of UVA protection, 2011). The EN ISO test method is now considered as the reference method within the EU. Cosmetics Europe therefore recommends cosmetic manufacturers to use this standard to determine the UVA Protection Factor and the Critical Wavelength. For UVA protection testing, preference is given to the standardised in vitro test method which avoids the need for in vivo testing while delivering equivalent results.

We need 60g of final product and the results are emailed within 4-6 weeks of sample receipt.

In Vivo Testing

When sunscreen products are tested in vivo to determine their Sun Protection Factor (SPF), the procedure generally involves human volunteers. However, not all skin types are typically tested. Instead, the testing focuses on individuals with lighter skin types who are more susceptible to sunburn.

SPF is defined as the ratio of the minimum erythemal dose (MED) on sunscreen-protected skin to the MED on unprotected skin. This refers to the amount of UV radiation required to produce a minimal sunburn or erythema. As lighter skin types burn more easily, they provide a clearer and more immediate indication of the sunscreen’s protective effect.

The Fitzpatrick scale classifies skin types based on their response to UV exposure. The scale ranges from Type I (always burns, never tans) to Type VI (never burns, deeply pigmented). Most in vivo SPF testing is conducted on individuals with Fitzpatrick Skin Types I through III because these are the skin types that burn most easily. Testing on skin types that rarely or never burn would not provide a meaningful measure of the sunscreen’s efficacy in preventing sunburn.

For standardisation and to reduce variability in results, using a narrower range of skin types can be more practical. When different skin types are tested, the results can be more variable due to differences in melanin content and other inherent protective factors.

There are ethical and practical considerations as well. Exposing individuals, especially those with skin types that rarely burn, to the point of erythema could be seen as unnecessary and potentially harmful. It’s also harder to detect erythema in deeply pigmented skin, which can lead to inaccuracies in SPF determination.

While in vivo SPF testing focuses on lighter skin types, it’s important for consumers of all skin types to understand that UV radiation can lead to more than just sunburn. It can cause premature aging, DNA damage, and increase the risk of skin cancer. Therefore, even individuals with darker skin should consider using sunscreen to protect against the broader effects of UV radiation.