Overview
CEN ISO/TR 19838:2016 - Microbiology - Cosmetics - Guidelines for the application of ISO standards on Cosmetic Microbiology - is a technical report that explains how to apply ISO cosmetic microbiology standards depending on the testing objective (e.g., in‑market control, product development, stability) and the type of product. It provides practical guidance to assess microbial content and antimicrobial preservation and can be used to fulfil the microbiological limits requirement of ISO 17516.
Key topics and requirements
- Scope and purpose: Guidance on selecting and applying ISO methods for finished cosmetic products and formulations based on risk and test objective.
- Microbial content assessment: Describes when to use quantitative (enumeration) methods versus qualitative (detection) methods and how results are reported (cfu/g or cfu/ml for aerobic mesophilic bacteria, yeasts and moulds).
- Specified microorganism detection: Procedures for checking the presence or absence of target organisms important for consumer safety.
- Antimicrobial preservation: Guidance on evaluating preservation of formulations and finished products (preservation efficacy / challenge testing) to ensure products resist microbial proliferation during normal use.
- Neutralization requirement: Emphasizes that any antimicrobial activity of the sample must be neutralized and that neutralization methods must be validated before testing.
- Risk‑based approach: Recommends microbiological risk assessment (see ISO 29621) to determine if testing is necessary - some “hostile” or low‑risk products may not require routine microbial testing.
- Informative annexes: Includes relationships between ISO cosmetic microbiology standards, interpretation examples, and worked examples (e.g., mascara, face cream, shampoo).
Practical applications
- Use this report to:
- Choose appropriate ISO microbiological methods for in‑market control, release testing and product development.
- Interpret microbial content and challenge test results in compliance with ISO 17516 limits.
- Design neutralization studies and validate laboratory methods for cosmetic matrices (including water‑immiscible products).
- Conduct preservation efficacy testing during formulation development to demonstrate consumer safety.
Who should use this standard
- Cosmetic manufacturers and formulation scientists
- Quality control and microbiology laboratories
- Regulatory affairs and compliance teams
- Contract testing laboratories and auditors
Related standards
CEN ISO/TR 19838:2016 is a practical, risk‑based companion for applying ISO cosmetic microbiology standards-helpful for ensuring product safety, regulatory compliance and consistent laboratory practice.
