Protective Efficacy Test (Challenge Test)
Cosmetic Analysis

Protective Efficacy Test (Challenge Test)

    Preservative Efficacy Test (Challenge Test)

    The Preservative Efficacy Test (Challenge Test) is an internationally standardized procedure used to assess the effectiveness and stability of preservatives in cosmetic products. This test aims to ensure that products remain safe throughout their shelf life by guarding against potential microbial contamination introduced by consumers.

    What Is a Challenge Test?

    A Challenge Test evaluates how well preservatives in cosmetic products can control microorganisms over the course of the product’s shelf life. During this test, the product is artificially contaminated in a laboratory environment, and the resulting numerical data (microbial count) are monitored at specific intervals.

    Test Procedure

    1. Artificial Contamination

      • The product is contaminated with test microorganisms under controlled laboratory conditions.
    2. Periodic Sampling

      • Samples are taken at specific time intervals (e.g., on days 7, 14, and 28).
      • Microorganism counts are measured and evaluated on a logarithmic scale.
    3. Confirming Preservative Efficacy

      • The effectiveness of the preservative is verified through observed reductions in microbial levels.

    International Standards

    Preservative efficacy tests follow internationally recognized standards, including:

    • ISO 11930: Evaluation of the antimicrobial protection of a cosmetic product and microbial stability testing.
    • USP <51>: Antimicrobial effectiveness testing according to the United States Pharmacopeia.
    • European Pharmacopoeia (EP): Guidelines for testing microbial preservative efficacy.
    • FDA Cosmetic Safety Guidelines: Recommended protocols for safety assessments of cosmetic products in the United States.

    Test Microorganisms

    The Challenge Test employs standardized microorganisms to evaluate product resilience against microbial contamination, typically including:

    • Bacteria

      • Pseudomonas aeruginosa ATCC 9027
      • Staphylococcus aureus ATCC 6538
      • Escherichia coli ATCC 8739
    • Fungi

      • Candida albicans ATCC 10231
      • Aspergillus brasiliensis ATCC 16404

    The test duration is approximately 35 days, during which the product is regularly evaluated against these microorganisms.

    When Is the Challenge Test Not Mandatory?

    Challenge Tests are not required for products that pose minimal microbiological risk, such as:

    • Products with water activity (a_w) ≤ 0.75: Low water activity inhibits microbial growth.
    • Single-use products: No contamination risk after use.
    • Products with ≥20% alcohol: Alcohol naturally exhibits preservative properties.
    • Products with pH ≤ 3: Highly acidic conditions hinder microbial growth.
    • Products with pH ≥ 10: Highly alkaline environments are unsuitable for microorganisms.
    • Oxidative products: Naturally minimize the risk of microbial contamination.

    Prerequisite: Microbiological Analysis

    Before performing a Challenge Test, products must undergo a microbiological analysis. If a product does not meet initial microbiological criteria, it cannot proceed to the Challenge Test. This step is critical to ensuring the test’s reliability and accuracy.

    Challenge Test Steps

    1. Sample Preparation

      • The product is prepared appropriately before the test, and initial microbiological analysis is performed.
    2. Artificial Contamination

      • The product is contaminated with a predetermined concentration of standard microorganisms.
    3. Interval Analyses

      • Day 7: Initial assessment of microbial count.
      • Day 14: Evaluation of changes in microorganism levels.
      • Day 28: Detailed analysis of preservative efficacy.
    4. Reporting

      • The results are provided in a detailed report indicating the product’s preservative efficacy.

    Purpose and Benefits of the Test

    • Consumer Safety: Ensures products are protected from microbial contamination until they reach the end user.
    • Regulatory Compliance: Documents adherence to cosmetic regulations and international standards.
    • Product Stability: Verifies preservative effectiveness throughout the product’s shelf life.

    Advantages of TTS Laboratory Services

    • Accredited Testing: Analysis services that comply with international standards (ISO 11930, USP <51>, EP).
    • Expert Team: Professional staff of experienced microbiologists and chemists.
    • Advanced Technology: Accurate and precise measurements using modern equipment.
    • Fast and Reliable Reporting: Clear, detailed reports on all test results.

    The Challenge Test (Preservative Efficacy Test) is essential for evaluating the microbiological safety of cosmetic products. At TTS Laboratory Services, we offer professional testing services to ensure your products meet international standards and maintain consumer safety.

    As TTS Laboratory Services, we stand by your side with our accredited analysis scope to meet your testing needs.
    Contact us for more information and service requests!