Currently, the promotion of UVA protection or broad-spectrum sun protection is becoming more and more common in sunscreen cosmetics. Among them, human tests for the PFA or PA+~PA++++ expression on the label of sunscreen cosmetics are commonly used and have been recognized by most countries, cosmetics enterprises, and consumers in the world.
This article aims to introduce the test method for PFA (Protection Factor of UVA) of sunscreen cosmetics in the Safety and Technical Standards for Cosmetics (2015 edition).
MPPD: Minimal persistent pigment darkening dose
PFA (protection factor of UVA): MPPD of skin protected with sunscreen cosmetics/MPPD of unprotected skin
Step 1: The sample is applied accurately and evenly to the skin of the test site. To reduce the error, the area of sample application or the total amount of sample should be expanded as much as possible. The sample application area should be not less than 30 square centimeters.
Step 2: After applying the sample, wait for 15 to 30 minutes, and then use a xenon arc lamp as the light source to irradiate the human skin with ultraviolet light within the range of 320 to 400 nm. Observe the skin MPPD after 2-4 hours of irradiation.
Step 3: By calculating the PFA, which is the MPPD of skin protected with sunscreen cosmetics/MPPD of unprotected skin, the UVA protection effect of sunscreen products can be determined.
The labeling of the UVA protection effect should be based on the actual measurement result of PFA, and the UVA protection grade (PA) should be marked on the product label. When the PFA is less than 2, the UVA protection effect shall not be marked; when the PFA is 2 to 3, the UVA protection effect shall be marked with PA+; when the PFA is 4 to 7, PA++ shall be marked; when the PFA is 8 to 15, PA+++ shall be marked; when the PFA is greater than or equal to 16, PA ++++ shall be marked.
Also, you can follow us on LinkedIn for the latest cosmetic and toothpaste compliance information.