The Challenge Test, also known as the antimicrobial protection efficacy test, makes it possible to evaluate the ability of a cosmetic product’s preservative system to control the growth of microorganisms under controlled laboratory conditions.

During the test, the product is deliberately inoculated with reference microorganisms, and their evolution is monitored over the period established by the method. The results make it possible to evaluate the efficacy of the formulation’s antimicrobial protection according to the criteria established in the UNE-EN ISO 11930 standard.

How is the Challenge Test performed?

At Alpiguisa Innovación, we perform the Challenge Test in accordance with the UNE-EN ISO 11930 standard. The procedure used involves inoculating the sample with five reference microorganisms and monitoring their evolution at 7, 14 and 28 days. 

The microorganisms evaluated include Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus brasiliensis. 

The results obtained make it possible to assess the efficacy of the product’s preservation system against microbial contamination and form part of the technical information that may be used in the product’s safety assessment and documentation, where applicable.

Why is it important to perform a Challenge Test?

The preservative system is intended to protect certain cosmetic formulations against the growth of microorganisms that may be introduced during the manufacture, storage or use of the product.

The Challenge Test provides experimental evidence of the efficacy of the formulation’s antimicrobial protection and provides relevant information for the assessment of the product’s microbiological safety.

The results may be used as part of the technical documentation and the cosmetic product safety file when relevant to the product assessment.

Which products may require a Challenge Test?

The Challenge Test is particularly relevant for cosmetic formulations susceptible to microbial growth, especially those containing water and requiring a preservation system to maintain their microbiological protection under the intended storage and use conditions.

Products that may require this type of assessment include:

• Creams and emulsions.

• Lotions and body products.

• Gels.

• Shampoos and conditioners.

• Serums and other aqueous formulations.

• Liquid or semi-liquid cosmetic products susceptible to microbial growth.

The need to perform the test should be determined taking into account the specific characteristics of each formulation and its microbiological risk assessment. The ISO 11930 standard considers an approach based both on preservative efficacy testing and on microbiological risk assessment.