The ‘Preservative Efficacy Test’ or ‘Challenge Test’ is a cornerstone of product safety and is a requirement for most products before they can be sold in the UK, EU, or US markets.
As consumers use products, they introduce microorganisms which, if the preservative system is not effective, can result in contamination, spoilage, and risk consumer safety. The challenge test mimics this contamination by introducing a known number of micro-organisms into the product to ‘challenge’ the preservative system. This routine regulatory microbiology testing is performed using a variety of dehydrated culture media, which all have different properties, functions, and nutritional benefits. At various points during the testing, the number of these microorganisms remaining are counted and the product must meet an appropriate standard in order to pass.
Challenge testing is a requirement for products where the formula is not regarded as microbiologically low risk e.g. >20% alcohol. Results of a challenge test or justification for bypassing a challenge test must be reviewed in the Cosmetic Product Safety Report.
Our preferred test method is EN ISO 11930 which is deemed to be the most appropriate for supporting EU cosmetic regulatory assessments. However, we can also perform the following test protocols, all of which are valid Preservative Efficacy Testing (PET) methods from around the world:
•ISO 11930 – Specifically aimed towards cosmetic products, it consists of 3 test time points, 5 organisms are used in a separate 1% inoculum spikes at day 0. Used in conjunction with ISO 29621.
•Risk assessment (ISO 29621) – referenced in ISO 11930, gives guidance when determining if a product is low risk based on information ranging from packaging properties to a product’s chemical properties.
•EU Pharmacopeia – This method can be applied to cosmetic products intended for the European market, however, it is primarily aimed at medical products. It consists of 4 test time points, 4 organisms are used in separate 1% inoculum spikes at day 0.
•US Pharma – This method can be applied to cosmetic products intended for the US market, however, it is primarily aimed at medical products. It consists of 2 test time points, 4 organisms are used in separate 1% inoculum spikes at day 0.
•Japanese Pharma – This method can be applied to cosmetic products intended for the Japanese market, however, it is primarily aimed at medical products. It consists of 2 test time points, 4 organisms are used in separate 1% inoculum spikes at day 0.
•KOKO – Developed to test both preservative efficacy as well as preservative stability, a test sample is spiked 6 times at 1 week intervals and tested before each spike. Spikes quantities make up 4% of the original sample volume. This is a stringent test as samples must achieve less than 2log growth throughout the entire test.
•Reduced – This is an in-house test we use as indication test as to whether samples are classed as hostile to microorganism. The data gathered from this can be used in conjunction with ISO 29621 to determine the outcome of a risk assessment. With a reduced turn-around time of 10 days, this test is useful for formulators to decide if a product is ready to undergo a full test and results are available after 10 days.
•Petra – This method is developed to give an indication as to whether a sample would pass a full preservative efficacy test. The sample is spiked at 2 time points with a 1% spike for 5 separate organisms and then tested 48 hours after. With a reduced turn-around time of 10 days this test is useful for formulators to decide if a product is ready to undergo a full test as it is quicker and cheaper than a full challenge.
•Client-specific – we have extensive experience in adapting Preservative Efficacy Testing to suit a client’s specific requirements as well as providing guidance when deciding which test is appropriate for a specific product.
•VeganSure – an alternative to test the preservative efficacy of Vegan Cosmetic Products using culture medias and neutralisers replacing ALL animal derived ingredients with plant-derived/synthetic alternatives.
By using our in-house laboratory alongside our Responsible Person and Cosmetic Product Safety Report service, you can save time and money. Running the Preservative Efficacy Test alongside the CPSR the process can be sped up significantly allowing you to get your products to market more quickly.
For more information about our microbiological testing service, please contact us.