Preservative Challenge Test

Preservative Challenge Test

According to ISO 29621, all cosmetics must be free from the numbers and types of microorganisms that could affect product quality and consumer health, as well as to ensure that microorganisms introduced during normal product use will not adversely affect the quality or safety of the product.

Cosmetic products containing a water phase have the ability to support microbial growth and therefore must undergo a preservative challenge test or efficacy test (PET). Basically, the challenge test checks how effective the preservative system of the cosmetic product is and whether it is capable of withstanding various types of contamination during production, from the environment and from direct contact with the human body that the cosmetic product is exposed to, thereby guaranteeing the safety and efficacy of the product during its shelf life. Reference to the results from this test must be made in the cosmetic product safety report (CPSR). This test only needs to be carried out once for each product formulation.


The test ISO 11930 is based on the monitoring of the presence of various pathogens in the cosmetic product when it is produced, followed by the intentional inoculation of a cosmetic product with five different strains of microorganisms:

Staphylococcus aureus (gram-positive bacterium)

Pseudomonas aeruginosa (gram-negative bacterium)

Candida albicans (fungus)

Escherichia coli (gram-negative bacterium)

Aspergillus brasiliensis (fungus)

The remaining concentration of these microorganisms is then determined after 7, 14 and 28 days. The product is considered to pass the preservative efficacy test if the concentrations of the fungi do not increase over the testing period and if the concentrations of the bacteria are reduced sufficiently by day 14 and do not increase from that time until the end of the test.

Quantity of test sample required: 150 g
Total Test Time: 35 days

Written reports are issued on completion of the test. Full results with the recovery of each organisms at each time point will be given along with a Pass/Fail result. Early warnings will be given if the product fails to meet any test criteria at earlier time points.

Contact Us to book your sample for testing:

Total Viable Count (TVC)

A further requirement of the regulations, this quality control test gives you a ‘Certificate of Analysis’ for products and the peace of mind that comes with knowing your product is free from contamination. The test can also help to identify potential problems early and prevent possible product recalls. We can help you find the most appropriate frequency of testing that will maintain your quality assurance in the most cost effective manner. This quick and low cost test would typically be carried out on each batch of product as you make it.
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