Preservative Efficacy Testing - Challenge Test

Creative Biolabs is an extension of your laboratory to provide a variety of products and services especially cosmetic microbiological tests. Now we are proud to provide preservative efficacy testing for our clients all over the world.

Introduction of Preservative Efficacy Testing (Challenge Test)

Preservative efficacy testing, also known as the challenging test, is the process to test the effectiveness of the preservative system in cosmetic products. Preservatives are present as basic ingredients in most cosmetic formulations to avoid microbial contamination. Preservative efficacy testing is necessary to ensure that the risk of microbial growth within the expected shelf life or use conditions of the product can be minimized. Therefore, the purpose of the preservative efficacy test is to prove the efficacy of the preservative system during the shelf life and service life of cosmetics to reduce the safety risks for consumers.

To perform a preservative efficacy test, the first step is to artificially contaminate the finished cosmetic products and then evaluate the contamination to a level that ensures the determination of the microbial limit. The cosmetic products would be challenged, incubated, and examined at 7, 14, and 28 days. To ensure the reproducibility of the test, the microorganisms used in the challenge test will be standardized. For each time and strain, the log reduction value can be calculated and compared to the minimum values required for evaluation.

ISO 11930:2012 Test Procedure

We can follow the ISO 11930:2012 testing procedure which is a reference method to be used for the evaluation of cosmetic products. The standard strains used in this test include:

Pseudomonas aeruginosa
Staphylococcus aureus
Candida albicans
Aspergillus brasiliensis (previously A. niger)

If a significant decrease or no increase in the viable count of micro-organisms can be observed, it means that this cosmetic product passes the challenge test!

USP <51> Challenge Test Procedure

The USP chapter 51 preservative challenge test is also the most common method for preservative effectiveness measurement in cosmetic products and drug products. The standard strains used in this test include:

Staphylococcus aureus
Escherichia coli
Pseudomonas aeruginosa
Candida albicans
Aspergillus brasiliensis

Custom Test Service

For your special products, we can design a challenge study with considered microorganisms. You can choose your time points and the interested microorganisms for us to measure a reduction. What's more, we can match the parameters/conditions depending on whether the product is ingested or used topically.

Equipped with world-leading technology platforms and professional scientific staff, we are pleased to offer the most qualified services and products for our customers all over the world. If you are interested in our products or services, please do not hesitate to contact us for more detailed information.