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COSMETICS
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Labderma — laboratory journal13th of September, 202646.05°N · 14.51°E · Ljubljana, SI · Est. 2024
Challenge test
— the preservative system under load
Challenge testing for cosmetic products
A preservative efficacy test assesses how a cosmetic formulation controls a defined microbial challenge after deliberate inoculation with selected microorganisms.
Measurement
What the test measures
The product is inoculated with defined microorganisms and the microbial population is measured at specified time points. The result is assessed against the reduction and acceptance criteria of the method used, for example ISO 11930 where appropriate.
The difference
Challenge testing vs microbiological quality testing
Microbiological quality testing describes the condition of the sample at the time of analysis. A challenge test deliberately stresses the formulation and assesses how effectively its preservative system controls contamination over time. The two tests answer different questions.
When
When is it relevant?
The need for a challenge test depends on the formulation and its microbiological risk. It is particularly relevant for water-containing products and products that are repeatedly exposed to the user or the environment during normal use.
Questions
What clients ask most
Does every microorganism have to be reduced to zero?
No. The result is evaluated according to the reduction and control criteria of the method at defined time points.
Does the challenge test determine PAO?
Not by itself. It can contribute to the PAO justification together with stability, microbiological quality, packaging and the overall safety assessment.
Next step
Write to us
Ask about challenge testing
Send us the formulation, preservative system, water content and packaging concept. We can then assess the appropriate microbiological testing route. Related: Stability testing · PIF and CPSR