When are Challenge Tests Needed and When not?

Antimicrobial preservatives may be added, particularly to aqueous cosmetic preparations, to prevent proliferation or to limit microbial contamination. Microbial contamination during normal conditions of storage and use, particularly for multidose containers, could occur in a product and present a hazard to the customer from infection and spoilage of the preparation.
The efficacy of the preservation of a cosmetic product under development has to be assessed experimentally in order to ensure microbial stability and preservation during storage and use. This is done by challenge testing (Preservation Efficacy test (PET)), which is mandatory for all cosmetic products.
The Challenge test protocol will be presented in detail.
FAQ will be covered like:
-Interpretation of results.
-Has the test to be Validated / Accredited? Can all microbiological laboratories perform the test?
-GMP-Antimicrobial preservatives must not be used as a substitute for good manufacturing practice.
-Biofilm and Challenge test
-Do all cosmetics need Challenge test?
-Frequency of testing and in what conditions there is a need for repetition