Dermatological testing of cosmetics (compatibility testing, patch test)

The scope of the test is to evaluate the irritation potential on the skin, under the control of a dermatologist. The test is applicable for:

• Cosmetic ingredients
• Mixtures of ingredients
• Finished cosmetic products

The principle is based on the application of the test product on the skin of the back of adult volunteers. The product is kept in contact with the skin for 48hrs under occlusive patch. The clinical observation of the effects is carried out by a dermatologist after withdrawal of the patch. The ranking of the irritant potential is assessed according to a determined numerical scale depending on the irritation observed; ranking varies between:

• Not irritant
• Very Slightly Irritant
• Slightly Irritant
• Moderately Irritant
• Irritant
• Very Irritant

The patch test is recommended by SCCNFP/0068/98 as a significant tool for the safety assessor. “It is recommended to undertake compatibility testing on a number of human volunteers before the product is finally marketed”.