ISO 29621:2017

Overview

ISO 29621:2017 - Cosmetics - Microbiology: Guidelines for the risk assessment and identification of microbiologically low-risk products provides guidance to cosmetic manufacturers and regulatory bodies on when finished cosmetic products can be considered microbiologically low-risk. The standard explains how to perform a microbiological risk assessment to determine whether full microbiological testing (and application of other cosmetic microbiology International Standards) is necessary. Its focus is on product characteristics, production and packaging factors that create a hostile environment for microbial survival and growth.

Key Topics

• Scope and definitions - clear definition of “microbiologically low-risk product” and the purpose of risk assessment.
• Risk assessment factors - evaluation framework based on:
  • Composition of the product (physico‑chemical characteristics that inhibit growth)
  • Water activity (aw) - available water controls microbial growth; reference points noted (e.g., aw < 0.7 commonly prevents growth; aw > 0.8 can permit proliferation)
  • pH of formulation - acidic or alkaline extremes can be hostile (examples: pH ~5 favors yeasts/moulds, pH < 3 inhibits yeasts; alkaline products such as liquid soaps at pH 9–10 or hair relaxers at ~12 are unfavourable)
  • Raw materials that create hostile environments
  • Production conditions and Good Manufacturing Practices (GMP)
  • Packaging that prevents ingress of microorganisms
  • Combined factors - synergistic effects of multiple hostile parameters
• Identified low-risk products - characteristics that justify omission of routine microbiological testing
• Guidance on testing necessity - when preservative challenge testing and routine microbiological controls may not be required

Applications

• Determine whether a cosmetic formulation requires microbiological testing or can be classified as low-risk.
• Guide formulation decisions (e.g., water activity, pH adjustments) to minimize microbial risk.
• Support quality assurance and regulatory submissions by documenting risk-based rationale.
• Inform GMP and production controls, packaging selection, and sampling strategy.
• Reduce unnecessary preservative challenge testing and routine assays for products meeting hostile-environment criteria.

Who uses this standard

• Cosmetic manufacturers (R&D, QA/QC, regulatory affairs)
• Formulation scientists and microbiologists
• Quality auditors and regulatory authorities
• Contract manufacturers and packaging engineers

Related Standards

• ISO 22716 (cosmetic GMP)
• Cosmetic microbiology standards referenced in ISO 29621: ISO 18415, ISO 18416, ISO 22717, ISO 22718, ISO 21150
• Pharmacopoeial guidance (e.g., USP) referenced for water activity context

Keywords: ISO 29621:2017, cosmetics microbiology, microbiologically low-risk products, risk assessment, water activity, pH, preservative challenge testing, GMP.