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Preservative Challenge Test

(also called a Preservative Efficacy Test, Challenge Test or PET)

By adding micro-organisms to your product and monitoring their reduction in numbers we can determine the effectiveness of your preservative system.

There are two standard methods that are commonly applied to cosmetic products, both satisfy the requirements of the new regulations.


i) The test of the European Pharmacopoeia.

This has been used as an industry standard test for many years, largely because no other more suitable method existed.


ii) ISO 11930:2012 Efficacy Test and Evaluation of the Preservation of a Cosmetic Product.

This test started to be used in 2012 and is very specifically aimed at cosmetic products.

Generally this method would be the most appropriate for new cosmetic products.


Testing using these methods involves the inoculation of products with;


Staphylococcus aureus

Pseudomonas aeruginosa

E coli

Aspergillus brasiliensis

Candida albicans


Over time we assess how quickly the numbers of these organisms are reduced by your product.  We compare this reduction with the specific criteria of the test method.


Along with the routinely used test organisms we can also include a combination of environmental isolates that have been shown to exploit weak preservative systems.  You can be certain that a product that passes this test truly is suitably preserved.


For further information and technical details please see our Test Data Sheet.