Preservative Efficacy Test

Cosmetic products, due to their formulations containing water and natural raw materials, are highly susceptible to microbial contamination. To mitigate this risk, preservatives are added to the formulations. However, whether the preservative used actually protects and preserves the product must be verified with a challenge test.

What is a Challenge Test?

The challenge test is a safety assessment in which a controlled quantity of microorganisms is introduced into a cosmetic product to evaluate the duration and extent to which the product can defend itself against these microorganisms.

This test verifies the following:

• the efficacy of the preservation system,
• the inhibition of microbial proliferation within the product,
• the microbiological safety throughout the product's shelf life,

all of which are scientifically substantiated.

Microorganisms Used for the Test

Strains Used:

• Pseudomonas aeruginosa (ATCC 9027)
• Staphylococcus aureus (ATCC 6538)
• Escherichia coli (ATCC 8739)
• Candida albicans (ATCC 10231)
• Aspergillus brasiliensis (ATCC 16404)

During the test, these microorganisms are added to the product in specified quantities and subsequently enumerated after 7, 14, and 28 days to assess the protective efficacy.

Why is the Challenge Test Required?

• Regulatory Compliance: The European Cosmetics Regulation (EC) No. 1223/2009 mandates that product safety must be demonstrated. The challenge test is a crucial component of this demonstration.
• Consumer Safety: An inadequate preservation system can lead to rapid product spoilage and compromise consumer health.
• Quality Assurance: For manufacturers, the challenge test is a critical assessment for ensuring sustained product quality.

Which products require this test?

• All cosmetic formulations containing water (creams, lotions, shampoos, make-up removers, etc.)
• Products intended to have a long shelf life after packaging
• Products that frequently come into contact with hands or are used communally