Jul 8, 2026 - Cosmetics
New DGK publication on measurement uncertainties in the microbiological testing of cosmetic products
We are pleased that Joelle Nussbaum, Head of Customer Consulting at BAV Institute and Head of the DGK Working Group on Microbiology and Operational Hygiene, has contributed as a co-author to the current DGK publication “Measurement Uncertainties in Microbiological Testing of Cosmetic Products.”
The publication addresses a topic that is of great importance for the quality assurance of cosmetic products: the assessment of measurement uncertainties in microbiological testing. Microbiological tests are used to demonstrate the safety and quality of cosmetic products - for example, in the context of determining the total germ count, detecting specified microorganisms, or testing the effectiveness of preservative systems. Microbiological analyses are naturally subject to biological variations that must be considered when interpreting test results.
The technical article explains the basics of measurement uncertainty in microbiology and shows how it can be assessed and interpreted in practice. Both qualitative and quantitative testing procedures are considered. In addition, the publication addresses proficiency testing as a tool for evaluating laboratory performance and the specifics of the preservative efficacy test (PET or Challenge Test). The aim is to provide laboratories, manufacturers, and experts with a scientific basis for the assessment of microbiological test results.
In the regulatory environment, robust and understandable test results are becoming increasingly important. A sound understanding of measurement uncertainty helps to correctly classify results, avoid misinterpretations, and make informed decisions regarding product safety.
Joelle Nussbaum’s involvement reflects her long-standing commitment to the scientific committee work of the DGK as well as her extensive expertise in the field of cosmetic microbiology. As head of the DGK Working Group on Microbiology and Operational Hygiene, she regularly contributes her experience to the development of practice-relevant scientific recommendations for the cosmetics industry.
The complete technical article “Measurement Uncertainties in Microbiological Testing of Cosmetic Products” is available for download on the DGK website.