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ISO 11930: 2019 – Preservative Efficacy Test
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Summary
ISO 11930 is an internationally recognized test method that evaluates the preservative efficacy of a cosmetic product, ensuring safety from microbial contamination during storage and consumer use. In this test, cosmetic products are challenged with microorganisms and incubated for 28 days, measuring the reduction in microbial count in predefined intervals. The data produced by ISO 11930 test helps manufacturers support preservative performance claims and safer products for consumers.
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Quick understanding about test
ISO 11930: 2019 – Preservative Efficacy Test
ISO 11930 is an international test method that evaluates the cosmetic product’s preservative system efficacy, meaning, how well the system protects the product from microbial contamination.
Applicable to cosmetic products which are water-soluble or water-miscible.
- Staphylococcus aureus (ATCC 6538P)
- Escherichia coli (ATCC 8739)
- Pseudomonas aeruginosa (ATCC 15442)
- Candida albicans (MTCC 3017)
- Aspergillus niger (ATCC 16888)
- The test product is inoculated with specific microorganisms, then incubated and the survived microbial population is measured at defined intervals. Log reduction values are calculated and results are compared to check if it meets acceptance criteria.
- Ensures regulatory compliance with global standards.
- Enhances consumer safety by preventing contamination.
Typically takes 4-5 weeks to complete
The number of surviving microorganisms is measured and log reduction values are calculated.
- Bacteria: ≥3 log reduction within 7, 14, and 28 days (Criteria A).
- Yeast and Fungi: No increase or ≥1 log reduction, depending on the interval and criteria.
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What is ISO 11930?
ISO 11930 is a standard method used to evaluate the overall antimicrobial protection of cosmetic products. It’s commonly referred to as the Preservative Efficacy Test (PET) or Challenge Test. It ensures that cosmetic products are free from microbial contamination throughout their shelf life by assessing the effectiveness of their preservative systems. The standard involves testing the product using specific microorganisms such as bacteria, yeast, and mold to verify its safety and efficacy.
The standard includes :
- Preservative efficacy test
- Challenge test to assess antimicrobial protection of cosmetic products that are not considered as microbiologically low-risk products, based on risk assessment described in ISO 29621
ISO 11930 preservative efficacy test test method overview
- Sample preparation
- Before testing, neutralizer efficacy and the microbiological quality of product is determined using USP <61> or equivalent methods.
- Challenging the product with microorganisms
- The product is divided into five containers and then container is each inoculated with one of the 5 specified organisms at a concentration of >1×10⁵ CFU/g or ml.
- Initial microbial counts are determined by dilution and plating, while a separate 1g or 1ml aliquot is placed in neutralization broth for validating neutralization and recovery.
- Incubation
- Inoculated samples are incubated for 28 days
- Sampling and microbial enumeration
- The inoculated product is evaluated for microbial growth at 7, 14 and 28 days.
- Surviving microorganisms are enumerated using standard dilution and plating techniques.
ISO 11930 acceptance criteria
The reduction in microbial count is compared against defined acceptance criteria (A or B) to determine if the preservative system is effective
EN 11930 passing criteria
Test microorganisms | Acceptance criteria A & B* | Log reduction | ||
7 days | 14 days | 28 days | ||
Bacteria | A | ≥ 3 | ≥ 3 | ≥ 3 |
B | – | ≥ 3 | ≥ 3 | |
Yeast (Candida albicans) | A | ≥ 1 | ≥ 1 | ≥ 1 |
B | – | ≥ 1 | ≥ 1 | |
Fungus (Aspergillus niger) | A | – | No increase from the initial count | ≥ 1 |
B | – | No increase from the initial count | No increase from the initial count | |
*Criteria A and B outline different antimicrobial efficacy criteria for bacteria, fungi, and yeast at specified time intervals (days).
Microorganisms used in ISO 11930 testing
The test evaluates the efficacy of preservatives against a number of microorganisms that are commonly found in cosmetic products. They include
- Staphylococcus aureus (ATCC 6538P)
- Escherichia coli (ATCC 8739)
- Pseudomonas aeruginosa (ATCC 15442)
- Candida albicans (MTCC 3017)
- Aspergillus niger (ATCC 16888)
Applications of ISO 11930 testing
This preservative challenge test is primarily intended for water-soluble or water-miscible cosmetic products. It can also be adapted for testing products where water is the internal (discontinuous) phase.
Why ISO 11930 testing is important?
Many regulatory bodies such as the European Union’s Cosmetics Regulation (EC) No 1223/2009, require manufacturers to demonstrate the microbiological safety of their products. ISO 11930 testing is a recognized method to fulfill these requirements as it aids in compliance and market approval.
This test helps ensure that cosmetic products remain safe for consumer use by evaluating their ability to resist microbial contamination. By ensuring product efficacy to resist microbial growth, ISO 11930 testing plays a crucial role to prevent adverse health effects from using contaminated products.
ISO 11930 vs USP 51
Parameter | USP <51> (Antimicrobial Effectiveness Test) | ISO 11930 (Preservative Efficacy Test) |
Purpose | To assess the effectiveness of a product’s preservative system in controlling microbial growth in pharmaceutical and cosmetic/personal care products. | To evaluate overall antimicrobial protection and preservative system efficacy of cosmetic products. |
Regulatory recognition | Compendial method under the United States Pharmacopeia; widely accepted for pharmaceuticals, OTC products, and cosmetics. | Internationally recognized; recommended for cosmetic products under EU/UK regulatory frameworks. |
Microorganisms used | Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Aspergillus brasiliensis. | S. aureus, E. coli, P. aeruginosa, C. albicans, A. brasiliensis. |
Scope of application | Aqueous and non-aqueous pharmaceutical dosage forms, cosmetics, and personal care products containing preservatives. | Water-soluble or water-miscible cosmetic products where water is the internal phase. |
Pass / acceptance criteria | Quantitative results expressed as log reductions at defined time points. | Quantitative log reductions; preservative performance classified as Criteria A (robust/strong) or Criteria B (adequate/sufficient). |
Benefits of Testing
1. Regulatory compliance
2. Consumer safety
3. Product stability
4. Brand reputation
Why MIS?
At Microbe Investigations Switzerland (MIS), we specialize in ISO 11930 preservative efficacy testing to ensure your cosmetic products are both safe and effective. Our expert team delivers precise and comprehensive testing to evaluate the antimicrobial protection of your formulations, helping you meet global safety standards.
In addition to preservative efficacy tests, we offer a wide range of cosmetic testing services including, ISO 16212, ISO 21149, USP 51, etc. to support your product development and regulatory compliance.
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Frequently Asked Questions
DR. Martinoz Scholtz
Preservative challenge testing (PET) , also called Challenge test, is used to evaluate how well a product’s preservative system prevents microbial growth during growth and consumer use.
ISO 11930 is designed for cosmetic and personal-care products while USP <51> is primarily intended for pharmaceutical products. ISO 11930 usually has a stricter early log-reduction requirement and includes classifications of preservative performance criteria (Criteria A and B)
ISO 11930 typically takes 4-5 weeks to complete.
ISO 11930 uses Staphylococcus aureus (ATCC 6538P), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 15442), Aspergillus niger (ATCC-16888), and Candida albicans (MTCC 3017).
At MIS, Additional strains can be added on customer’s request.
Criteria A – Stricter antimicrobial performance, requiring faster and greater microbial reduction.
Criteria B – It is considered less stringent and may be acceptable when justified by product characteristics and microbiological risk assessment.
ISO 11930 is not mandatory, but is widely expected by regulatory authorities to validate product microbiological safety under cosmetic regulations.
This test contributes to product safety and compliance by ensuring that cosmetic formulations have adequate antimicrobial protection to prevent microbial contamination.
No. It may only be skipped if a strong scientific justification is provided (e.g., low-risk formulation), but this is rarely accepted without supporting data.
This test is performed for water-soluble cosmetic formulations or where water is used in the internal phase of product development.
If a product fails ISO 11930 testing, it indicates that the preservative system is not adequate to protect the product against microbial contamination. The product formulation may need to be adjusted, or an alternative preservative system may need to be considered for product safety.
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