Difference between ISO 11930 vs. USP 51 Testing

What is ISO 11930 Test

ISO 11930 is an international standard established to determine the antimicrobial activity of cosmetics. This test is essential for manufacturers of personal care products to ensure that their finished formulas are safe as well as effective throughout the shelf life proposed.

The ISO 11930 test evaluates how much a product can resist microbial contamination under varied conditions that simulate actual use. Complying with this standard helps manufacturers demonstrate legal compliance and assure consumers about the safety of their products.

Microorganisms Tested

The primary organisms included in the testing process are:

• Staphylococcus aureus: A gram-positive bacterium known for its potential to cause skin infections.
• Pseudomonas aeruginosa: A gram-negative bacterium that can lead to serious infections, particularly in immunocompromised individuals.
• Escherichia coli: Another gram-negative bacterium often associated with contamination and foodborne illnesses.
• Candida albicans: A yeast that can cause infections, especially in individuals with weakened immune systems.

Sampling Criteria for ISO 11930

Sampling in the ISO 11930 test follows very strict procedural guidelines. The samples must be representative of the product batch and are typically obtained from the process of manufacture. Samples taken must be stored under conditions analogous to those of the actual environment so that one understands how the product will behave after some time. It ensures that these antimicrobial efficacy tests are performed under appropriate conditions relevant to the antimicrobial efficacy of the product by sampling at appropriate stages of the shelf life of the product. While comparing ISO 11930 Vs USP 51, one should note that tests demand strict sampling procedures for ensuring products’ safety as well as compliance with standards.

Methodology:

 The key procedure involves the following:

1. Cosmetic Product Formulation

The test shall be conducted on the finished formulation of the product in its recommended package. The product shall be exposed to storage and handling conditions that closely simulate its use and shelf life.

2. Inoculation of the Cosmetic Product

The product is inoculated with known concentration of each of the test microorganisms. The initial microbial concentration ranges from 10^5 to 10^6 CFU/mL or g (colony-forming units per milliliter or gram).

3. Incubation Period

Following inoculation, the product is incubated at controlled environmental conditions usually at 20-25°C. This allows microorganisms in contact with the preservative system of the product to grow.

4. Sampling and Enumeration

At defined time points, the microbial counts are obtained to assess the decrease in microbial load. Typically, the following time points are employed.

T0: immediately after inoculation

T7: on day 7

T14: on day 14

T28: on day 28

For each of the time points, the inoculated product samples are taken, plated on agar media, and counted for the surviving microorganisms from colony-forming units.

5. Pass/Fail criteria

The product is evaluated based on the reduction of microbial load over time while being subjected to the following criteria:

For Bacteria: A ≥ 3-log reduction (99.9%) of CFU at day 7, with no subsequent increase at day 28.

For Yeast and Mold: A ≥ 1-log reduction (90%) in CFU at day 7, with no subsequent increase at day 28

6. Results Interpretation

The result of the challenge test is verified to ensure continued adequate preservation of the product over time. If microbial criteria are not achieved, reformulation or improvement of the preservative system may be required.

ISO 11930 Acceptance Criteria

The acceptance criteria for ISO 11930 are based on the ability of the product to reduce and maintain low levels of microbial contamination over time. Specific requirements include:

Reduces Bacteria: Significant reduction (typically 3 log reduction) of bacterial populations (e.g., Staphylococcus aureus and Pseudomonas aeruginosa after 14 days.

Reduction of Yeast and Mold: A reduction of at least 2 logs for yeast and mold such as Aspergillus brasiliensis and Candida albicans shall be obtained within 14 days.

Maintenance: The microbial population should not increase more than 28 days of incubation for bacteria or fungi.

Importance of ISO 11930 Test

The significance of the ISO 11930 test extends beyond regulatory compliance. Here are some key reasons why this test is vital:

1. Consumer Safety: ISO 11930 measures the preservative efficacy of a product, ensuring it is protected against microbial contamination over its shelf life. 
2. Regulatory Compliance: Different countries and regions have safety standards that manufacturers must adhere to when producing cosmetics. The ISO 11930 test provides a standard methodology to test the effectiveness of a preservative in preserving the product, thus enabling compliance with regulatory standards by manufacturers.
3. Product Integrity: Microbial contamination can alter the quality of the product to such an extent that it may change its texture, color, and efficacy. In this respect, ISO 11930 will ensure that the product does not deteriorate in usability during its shelf life, giving assurance to the consumer and protection for the brand.

What is USP 51 Testing

USP 51 is an antimicrobial effectiveness test developed by United States Pharmacopeia to be applied in testing the preservative efficacy of all products, such as pharmaceuticals, cosmetics, and personal care products. This test ensures that the type of product released into the market contains preservatives with which harmful microorganisms can be controlled during storage and usage. Preservatives are the critical constituents of a product that prevent contamination, thereby affecting the product’s safety, efficacy, and quality. If we compare ISO 11930 vs USP 51, USP 51 is more widely applicable across various industries, while ISO 11930 is specifically for cosmetic products.

USP 51 Acceptance Criteria

The acceptance criteria for USP 51  evaluate the effectiveness of a preservative system in controlling microbial contamination in a product over time. It establishes the minimum required reductions of various types of organism populations such that the preservative system can ensure proper maintenance of the safety and stability of the product. While comparing ISO 11930 Vs USP 51, although both tests determine the effectiveness of preservatives, the two tests refer to different product categories and regulatory requirements.f

Strengths of the USP 51 Antimicrobial Effectiveness Test

1. Comprehensive Assessment: USP 51 evaluates a wide range of microorganisms, including bacteria and fungi, providing a detailed assessment of a product’s antimicrobial properties.
2. Regulatory Acceptance:  The USP standard is accepted across several bodies regulating that all products that undergo testing meet the industry’s set standards.
3. Repeatability: The method will ensure that results are consistent from batch to batch; hence, the manufacturers and regulatory agencies can rely on the data generated.

Weaknesses of the USP 51 Antimicrobial Effectiveness Test

1. Time-consuming: The testing process might take weeks, leading to a post-launch delay in the product.
2. Cost Considerations: All the USP 51 steps may be very costly, especially for small manufacturing facilities.
3. Limited Scope: USP 51 is extensive but cannot cover all possible contamination situations presented by daily practice.

Importance of USP 51 Testing

USP 51 testing for pharmaceuticals and cosmetics is important for numerous reasons:

1. Quality Assurance: It will ensure the maintenance of the antimicrobial properties of products throughout the shelf life period, thus preventing or minimizing contamination.
2. Regulatory Compliance: It is an important requirement for most USP-approved items, making this test a vital one for manufacturers in getting market approval.
3. Consumer Confidence: USP 51 testing also gives consumers confidence that the product is safe and also efficient.
4. Market Access: Such products would be accessed more easily in regulated markets.

Main difference between ISO 11930 Vs USP 51 Testing

The first step that manufacturers must take in order to meet the standards to pass the testing and ensure the safety of the product is understanding the difference between ISO 11930 vs USP 51. There are some primary differences:

• Scope of Testing: ISO 11930 standard is used to evaluate Antimicrobial Protection of Cosmetic Products, whereas USP 51 is used to assess Antimicrobial Effectiveness Testing with pharmaceuticals, cosmetics, and personal care products.

• Testing Protocols:

 Microbial Challenge and Inoculum Level:

ISO 11930: Inoculated with 10^5 to 10^6 CFU/mL or g.

USP 51: Typically inoculates with 10^5 CFU/mL or g.

Time Points for Sampling

ISO 11930: T0, T7, T14, T28, optional T21 (21 days).

USP 51: T0, T7, T14, T28. No optional interim.

Pass-Fail Criteria

ISO 11930: Requires a 3-log reduction in bacteria by day 7 and a 1-log reduction in yeast/mold by day 7.

USP 51: Require reduction by 2 logs for bacteria, and 1-log reduction for yeast/mold in 14 days.

• Regulatory Standards: ISO 11930 adheres strictly to international ISO standards on cosmetics, while USP 51 is part of the U.S. Pharmacopeia standards, which have specific regulatory requirements for pharmaceutical products.

Conclusion

Although both ISO 11930 and USP 51 test the effectiveness of preservatives and play very important roles in preserving the safety and efficacy of products, they were designed with a different set of regulatory and industry focuses. Therefore, the choice between these tests primarily depends on the type of product and the specific regulatory requirements that are applicable to the industry.

At Microbe Investigations Switzerland (MIS), we offer comprehensive ISO 11930 and USP 51  testing services to help you meet global standards. Contact us today to learn more about our services.

FAQs

 1. What is ISO 11930?

ISO 11930 is an international standard that measures the preservative efficacy of cosmetic products against microorganisms that may cause microbial contamination during use.

2. What is USP 51?

USP 51 is a standard that determines the effectiveness of preservatives in establishing antimicrobial activity for the safety and stability of pharmaceutical, cosmetic, and personal care products.

3. What industries use ISO 11930 and USP 51?

ISO 11930 is primarily used for the cosmetic industry, while USP 51 is used in pharmaceutical, cosmetic, and personal care.

4. What microorganisms are tested in both ISO 11930 and USP 51?

Both ISO 11930 and USP 51 test microorganisms such as bacteria (e.g., Staphylococcus aureus, Escherichia coli), yeast (e.g., Candida albicans), and molds (e.g., Aspergillus brasiliensis).

5. What is the key difference between ISO 11930 and USP 51?

The difference is that ISO 11930 specifically addresses cosmetic products, whereas USP 51 applies to a wide range of products that include pharmaceuticals, cosmetics, and personal care items.

6. Do both standards test for preservative efficacy?

Yes, both standards test for preservative efficacy.

7. What are the acceptance criteria for ISO 11930?

The acceptance criteria of ISO 11930 require significant microbial count reduction, as they should not increase with time and must comply with definite limits on microbial levels based on the product category.

8. What are the acceptance criteria for USP 51?

The USP 51 acceptance criteria mentions a defined reduction in microbial counts at specified time intervals. 

9. Do both standards test for fungi and bacteria?

Yes, both standards are used to test for fungi and bacteria.