Cosmetics Preservative Efficacy and Cosmetics Challenge Test

Preservative efficacy testing, also referred to as a “challenge test” is a procedure for evaluating the antimicrobial protection of a cosmetic product in accordance with ISO 11930 and other recognised standards. Challenge testing of cosmetic preservative systems helps minimise the risk of microbial growth during normal storage and consumer use conditions over the expected shelf-life. Demonstrating the efficacy of preservatives in cosmetics is a regulatory requirement.

What are preservatives in cosmetics?

Preservatives are included in most cosmetic product formulations to protect them from microbiological contamination. They can be natural or synthetic ingredients and may have different properties, such as their minimum inhibitory concentration (MIC), target organisms, and mechanism of action. Preservatives must undergo safety assessments and quality testing to make sure that they are safe for use. 

In Europe, the European Commission ensures an updated list of scientifically evaluated safe preservatives for use in cosmetic products on the EU market (Cosmetic Products Regulation (EC) No. 1223/2009/EC, Annex V). The list contains maximum concentration limits and other restrictions. It also includes special labelling requirements, which outline conditions of use and warnings.

Cosmetics Challenge Test

During preservative efficacy testing studies, the cosmetic product is deliberately challenged to resist microbial growth. This typically involves incubation for 28 days at 32.5°C to represent its shelf life and time-in-use scenarios best. Microorganisms are introduced to the formulation under controlled conditions, and then at regular and defined intervals, analysis is carried out according to a validated protocol to determine the efficacy of the preservative system. For the product to pass testing, its preservation system must demonstrate effectiveness in reducing the level of microorganisms to predefined acceptable limits. 

Our Challenge Test Cosmetics Expertise

Wide Scope of Preservative Challenge Test Experience: Including United States Pharmacopoeia (USP), ISO 11930, European Pharmacopoeia (EP) and Cosmetic, Toiletry and Fragrance Association (CTFA) Microbiology Guidelines.
Centre of Excellence: Over 20+ years of experience
Global Regulatory Knowledge: Helping you to comply with key cosmetic regulations (e.g., EU Regulation 1223/2009). This includes full documentation and interpretation of results in line with ISO acceptance criteria.
Accredited Testing: The laboratory holds ISO 9001 and ISO 17025 (COFRAC (n°1-2411). Scope is available on www.cofrac.fr.), assuring competence, quality of testing results.
Confidence to Innovate: Our ISO 11930 preservative efficacy testing for cosmetic products ensures microbiological safety throughout shelf life and use, so you have the confidence you need in formulation design and production controls.

ISO 11930 Preservative Efficacy Test - Cosmetics

Our European centre of excellence for cosmetics testing, LaCoMeD, is located near Chalon-sur-Saône in France, and this team conducts preservative efficacy testing according to the ISO 11930 standard - Evaluation of the antimicrobial protection of a cosmetic product) using both the reference (manual) method and an internally validated automated method (TEMPO CT).

Microorganisms used for the ISO 11930 cosmetics preservation challenge test include: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus brasiliensis. Additional microorganisms can be included if the product-specific risk assessments require it. 

Total Quality Assurance

Bringing quality and safety to life, we offer a toolbox of Total Quality Assurance Solutions for cosmetics, supporting you across product innovation, raw materials qualification, stability studies, microbial quality and regulatory guidance. We offer a wide breadth of sector-dedicated technical solutions underpinned by 20 years of proven expertise in cosmetics testing delivered from our centres of excellence.

What does ISO ISO 11930 involve?

ISO 11930:2019 Cosmetics — Microbiology — Evaluation of the antimicrobial protection of a cosmetic product, defines the scientific approach to assessing a product's antimicrobial protection. This includes the preservative system, formulation and packaging design.

The ISO 11930 cosmetics preservation challenge test involves, for each test microorganism, inoculating the product with calibrated microorganisms and measuring microbial reductions at defined time intervals. Data generated by the risk assessment (see ISO 29621), the preservation efficacy test, or both, are used to establish the level of antimicrobial protection required to minimize user risk. 

What are examples of preservatives for cosmetics?

Common preservatives include 5-chloro-2-(2,4-dichlorophenoxy) phenol, also known as triclosan, which is allowed for use in nail products for cleaning the fingernails and toenails before the application of artificial nail systems, face powders and blemish concealers, body soap/shower gel, non-spray deodorants, mouthwashes, toothpaste and hand soap as per Annex V. Other preservatives include benzalkonium chloride (used in skincare and other products such as shampoos, body washes), isothiazolinones, such as methylisothiazolinone and also organic acids, such as benzoic acid, salicylic acid, or formic acid which help to safeguard against fungi and some bacteria.