Instituto Valenciano de Microbiología
(IVAMI)

Masía El Romeral
Ctra. de Bétera a San Antonio Km. 0.3
46117 Bétera (Valencia)
Phone. 96 169 17 02
Fax 96 169 16 37
Email: 
www.ivami.com
CIF B-96337217

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Cosmetics testing - Preservative efficacy tests - Challenge test (EN ISO 11930: 2019 + A1: 2022 and European Pharmacopoeia).

Cosmetics Preservative Efficacy Tests – Challenge tests

Test accredited in our laboratory by ENAC (Spanish National Accreditation Entity). 

Test with the Certificate of Good Laboratory Practices (GLPs). 

Assessment of the antimicrobial protection of a cosmetic product - Challenge test of preservatives. EN ISO 11930: 2019 + A1: 2022 Standard. Exposure tests are intended to determine the power of a preservative to prevent bacterial or fungal contamination during its use, so they are mandatory tests for those products that may pose a risk of infection for the user or a deterioration of the product. To perform the exposure test ("Challenge"), an artificial contamination of the sample is carried out with 5 microorganisms, at a concentration established by the standard. The microorganisms used in the efficacy tests are Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Candida albicans and Aspergillus brasiliensis. The cosmetic inoculated with those microorganisms are followed up at 0 hours, 7, 14, and 28 days. The inoculated microorganisms must descend throughout the follow-up, and must reach a certain logarithmic reduction, in order to meet established criteria A or B. In the case of Aspergillus brasiliensis, it should not suffer an increase after 28 days. 

Assessment of the antimicrobial protection of a cosmetic product - Challenge test of preservatives according to the European Pharmacopoeia (5.1.3. Efficacy of Antimicrobial Preservation). Exposure tests are intended to determine the power of a preservative to prevent bacterial or fungal contamination during its use, so they are mandatory tests for those products that may pose a risk of infection for the user or a deterioration of the product. To perform the exposure test ("Challenge"), an artificial contamination is carried out up to the level established by each standard. The microorganisms used in the efficacy tests are Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus brasiliensis. The European Pharmacopoeia allows the use of other microorganisms if it is considered that they can represent possible contaminants for the product. To do this, the cosmetic product is inoculated with the mentioned microorganisms, and the follow-up is carried out at 0 hours and at different subsequent intervals of time, which vary according to the type of product, until the final reading at 28 days. The inoculated microorganisms must descend throughout the follow-up, and must reach a certain logarithmic reduction, in order to meet the A or B criteria established in the European Pharmacopoeia for each type of product (topical, oral, ophthalmic use, etc.). Criteria A expresses the maximum recommended efficacy that must be achieved. In justified cases, when criteria A cannot be reached, for reasons of an increased risk of adverse reactions, criteria B may be sufficient (satisfactory).

Differences between the preservation efficacy test (Challenge Test) according to EN ISO 11930 and European Pharmacopoeia (5.1.3. Efficacy of Antimicrobial Preservation).                                                                       

 EN ISO 11930

(formerly NF T 75-611)

European Pharmacopoeia

Microorganisms: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus brasiliensis.

Microorganisms: Staphylococcus aureus, Peudomonas aeruginosa, Candida albicans and Aspergillus brasiliensis. The guideline advises to include Escherichia coli for products of oral use, so IVAMI will include this strain in this type of products. It also recommends including Zygosaccharomyces rouxi for oral preparations containing a high concentration of sugar. Furthermore, indicates that other strains, which may represent contaminants for the preparation, may be included.

Sampling: Always 0 hours for all microorganisms and also 7 days for bacteria and yeast, 14 days and 28 days for bacteria, yeasts and molds.

Sampling: Always 0 hours for all microorganisms and besides, depending on the type of product, the following sampling will be carried out: For ear, nasal and topical products and preparations for inhalation 2 days, 7 days, 14 days and 28 days, for bacteria, and at 14 and 28 days for molds and yeasts; For parenteral eye, intrauterine and intramammary preparations at 6 hours, 24 hours, 7 days, 14 days and 28 days, for bacteria, and 7 days, 14 days and 28 days for molds and yeasts; For oral, oromucosal and rectal preparations 14 days and 28 days for bacteria, molds and yeasts.

Inoculum: bacteria: 105 /CFU/mL; yeasts: 104 CFU/mL and molds: 103 UFC/mL.

Inoculum: 105 to 106 CFU/mL for all microorganisms.

Assessment criteria: Criteria A considers that the product is protected against microbial proliferation that may present a potential risk to the user. Criteria B considers that the product is protected if the risk analysis demonstrates the existence of control elements not related to the product, indicating that the microbiological risk is acceptable.

Assessment criteria: The acceptance criteria depend on the products uses (parenteral, ophthalmic, oral, topical…etc.) - Criteria A, expresses the effectiveness that must be achieved, but criteria B, can be sufficient (satisfactory), when the criteria A cannot be achieved, for reasons such as increased risk of adverse reactions.

 

IVAMI´s comment: The EN ISO 11930 standard, considers all products, whatever their use, equal with the level of protection they must offer and the European pharmacopoeia establishes interpretation criteria according to the use of the product, so which for some preparations would be less restrictive, and for others prepared more restrictive. From this point of view, the European standard is more restrictive.

Important information: Before performing the test, the detection and count of mesophilic aerobic bacteria and the count of yeasts and moulds must be carried out according to ISO 21149 and ISO 16212 standards. 

Cosmetics Preservative Efficacy Tests with other microorganisms:

We can perform the tests with other microorganisms different from those required by the EN ISO 11930 standard or the European Pharmacopoeia, as those shown below, required occasionally by some clients, as well as with different evaluation times or reinoculations: