ISO 17516 provides the reference framework for microbiological quality in cosmetics. Cosmetic products do not have to be sterile, but they must have adequate microbiological quality to ensure both consumer safety and product quality during use.
ISO 17516:2014 — Cosmetics — Microbiology — Microbiological limits establishes the quantitative and qualitative microbiological limits applicable to finished cosmetic products and provides a framework for assessing their microbiological quality.
The standard differentiates the limits according to the type of product and pays particular attention to products intended for children under three years of age, the eye area or mucous membranes, where microbiological risk requires stricter criteria.
What Does ISO 17516 Establish?
ISO 17516 is based on a fundamental principle: neither cosmetics nor the raw materials from which they are made are required to be sterile.
However, the microorganisms present must not reach levels that could adversely affect consumer safety or product quality during intended or reasonably foreseeable use.
For this reason, the standard establishes both:
- quantitative limits for aerobic mesophilic microorganisms;
- qualitative requirements relating to the absence of certain specified microorganisms.
These criteria apply to finished cosmetic products. However, the standard also considers that certain products classified as having a low microbiological risk, according to ISO 29621, may not require routine microbiological testing.
Microbiological Limits According To ISO 17516
ISO 17516 establishes two main categories of cosmetic products.
Products For Children Under Three Years Of Age, The Eye Area Or Mucous Membranes
For products specifically intended for children under three years of age, the eye area or mucous membranes, the established limit for total aerobic mesophilic microorganisms — bacteria, yeasts and moulds — is:
≤ 1 × 10² CFU/g or ml
Due to the inherent variability of the plate count method, the standard also indicates that a result is considered out of limit when it exceeds 200 CFU/g or ml.
Other Cosmetic Products
For other cosmetic products, the established limit is:
≤ 1 × 10³ CFU/g or ml
In this case, also taking into account the variability of the plate count method, results are considered out of limit when they exceed 2,000 CFU/g or ml.
This distinction makes it possible to apply stricter microbiological criteria to products whose site of application or target population may involve greater vulnerability.
Which Microorganisms Must Be Absent?
In addition to the total microorganism count, ISO 17516 requires the absence of certain specified microorganisms that may compromise consumer safety or indicate a failure in hygienic conditions.
The following must be absent in 1 g or 1 ml of product:
- Escherichia coli
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Candida albicans
This requirement applies both to products intended for children under three years of age, the eye area or mucous membranes and to other cosmetic products.
Therefore, microbiological assessment should not be limited solely to the total number of microorganisms present. The detection of any of these specified microorganisms must be taken into account when assessing product compliance.
What Happens If Other Microorganisms Are Detected?
The presence of microorganisms other than those specified does not necessarily mean that the product is unacceptable.
ISO 17516 indicates that these microorganisms should not be considered objectionable provided that they are unable to proliferate in the product.
To determine this, a risk assessment may be carried out that includes studies on the efficacy of the preservative system, for example in accordance with ISO 11930, or it may be demonstrated that the characteristics of the product do not support microbial growth, in accordance with ISO 29621.
This means that the interpretation of a microbiological result must consider not only the detection of microorganisms, but also the characteristics of the product and its ability to support or prevent their proliferation.
Test Methods Related To ISO 17516
When microbiological testing is necessary, ISO 17516 refers to different specific international standards depending on the microorganism or parameter to be assessed.
These include:
- ISO 21149, for the enumeration and detection of aerobic mesophilic bacteria.
- ISO 16212, for the enumeration of yeasts and moulds.
- ISO 18415, for the detection of specified and non-specified microorganisms.
- ISO 18416, for the detection of Candida albicans.
- ISO 21150, for the detection of Escherichia coli.
- ISO 22717, for the detection of Pseudomonas aeruginosa.
- ISO 22718, for the detection of Staphylococcus aureus.
Selecting the appropriate method is essential to obtain results that allow correct assessment of compliance with the established limits.
Microbiological Quality Throughout The Product Life
Microbiological control of a cosmetic product should not be understood solely as a one-off check.
ISO 17516 states that, to ensure product quality and consumer safety, the number of non-specified microorganisms recovered from the product should remain stable or decrease throughout its shelf life.
Therefore, microbiological quality is closely related to aspects such as raw materials, manufacturing conditions, the preservative system, packaging and the characteristics of the formulation itself.
The standard also highlights the importance of applying the Good Manufacturing Practices described in ISO 22716 and taking the necessary precautions to limit the introduction of microorganisms from raw materials, processing and packaging.
Do All Cosmetics Require Microbiological Testing?
Not necessarily.
ISO 17516 establishes that products considered to be of low microbiological risk may not need to undergo routine microbiological testing.
This consideration should be supported by an appropriate product assessment in accordance with ISO 29621, taking into account the characteristics of the formulation and its ability to support or prevent microbial growth.
Therefore, omitting certain tests should not be an automatic decision, but the result of a technical assessment that justifies that the product meets the applicable microbiological requirements.
How SAHPYPRO Can Help
At SAHPYPRO, we help manufacturers and companies in the cosmetics sector assess the microbiological quality and safety of their products through services tailored to the characteristics of each formulation and the applicable requirements.
An appropriate microbiological control strategy makes it possible to select the necessary tests, correctly interpret the results and obtain technical information that helps demonstrate product safety and quality.
Our team can support you in the microbiological assessment of cosmetic products and in the application of the relevant standards during product development and control.
Conclusion
ISO 17516:2014 provides the criteria needed to assess the microbiological quality of finished cosmetic products.
The standard establishes different limits depending on the type of product, with stricter requirements for cosmetics intended for children under three years of age, the eye area or mucous membranes. It also requires the absence of E. coli, P. aeruginosa, S. aureus and C. albicans in 1 g or 1 ml of product.
However, microbiological control goes beyond checking a CFU value. The ability of microorganisms to proliferate, the characteristics of the formulation, preservation efficacy and manufacturing conditions form part of a broader assessment.
Correctly applying these criteria makes it possible to turn microbiological results into useful information to demonstrate product quality and consumer safety.