To ensure consumer safety, laboratories evaluate cosmetic products against internationally recognised microbiological limits. These limits help manufacturers determine whether a product meets acceptable quality standards before it is placed on the European market.
Understanding what these limits mean—and why they exist—helps manufacturers interpret laboratory reports correctly and support compliance with Regulation (EC) No 1223/2009.
Why are microbiological limits necessary?
Microorganisms are naturally present in the environment. Raw materials, manufacturing equipment, packaging and even normal consumer use can introduce bacteria, yeasts or moulds into cosmetic products.
Most cosmetic formulations include measures to minimise this risk, such as good manufacturing practices, appropriate preservation systems and suitable packaging. Even so, manufacturers need objective laboratory evidence that finished products meet acceptable microbiological quality criteria.
Microbiological limits provide those criteria by defining the maximum levels of contamination considered acceptable for different types of cosmetic products.
Are microbiological limits defined by EU legislation?
Regulation (EC) No 1223/2009 requires cosmetic products to be safe but does not specify numerical microbiological limits.
Instead, European manufacturers generally rely on internationally recognised guidance, particularly ISO 17516:2014 – Cosmetics — Microbiology — Microbiological limits. This standard establishes recommended acceptance criteria for finished cosmetic products and is widely used by laboratories, manufacturers and cosmetic safety assessors.
Although ISO 17516 is not legally mandatory, it represents the accepted scientific reference for evaluating the microbiological quality of cosmetics within the European market.
Two categories of cosmetic products
ISO 17516 recognises that not all cosmetic products present the same level of risk.
Products intended for higher-risk users or sensitive areas are subject to stricter microbiological limits. This category includes:
- Products intended for children under three years of age
- Products used around the eyes
- Products intended for mucous membranes
All other cosmetic products fall into the general category, where slightly higher microbial counts may be considered acceptable while still ensuring consumer safety.
The different limits reflect the varying susceptibility of different consumer groups and anatomical areas.
Typical microbiological limits
The standard establishes acceptance criteria for the total aerobic microbial count (TAMC) and the total yeast and mould count (TYMC).
For higher-risk cosmetic products, the acceptable limits are:
- TAMC: not more than 100 colony-forming units (CFU) per gram or millilitre
- TYMC: not more than 10 CFU per gram or millilitre
For other cosmetic products, the limits are:
- TAMC: not more than 1,000 CFU per gram or millilitre
- TYMC: not more than 100 CFU per gram or millilitre
These values represent maximum acceptable contamination levels rather than target values. In practice, many well-manufactured cosmetic products show considerably lower microbial counts.
Specified microorganisms must be absent
In addition to total microbial counts, certain microorganisms must not be detected in cosmetic products because of their potential to cause infection or spoilage.
ISO 17516 specifies the absence of:
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Candida albicans
- Escherichia coli must also be absent.
The presence of any of these microorganisms generally indicates that the product does not meet acceptable microbiological quality standards and requires further investigation.
How are these limits evaluated?
Laboratories perform microbiological quality testing using recognised analytical methods to determine whether the finished product complies with the applicable acceptance criteria.
The analysis typically measures the total number of viable microorganisms present and investigates whether any specified pathogenic species can be detected.
The results are then compared with the relevant microbiological limits according to the product category.
This testing provides a snapshot of the microbiological condition of the product at the time of analysis.
Do microbiological limits guarantee long-term safety?
Not on their own.
A product that complies with microbiological limits today may still become contaminated during storage or consumer use if the preservation system is not effective.
For this reason, microbiological quality testing and preservative efficacy testing evaluate different aspects of product safety.
Routine microbiological testing confirms that the finished product is microbiologically acceptable at the moment it is tested, whereas preservative efficacy testing evaluates whether microorganisms introduced during normal use can be effectively controlled throughout the product’s lifetime.
Together, these studies provide complementary evidence supporting microbiological safety.
What happens if a product exceeds the limits?
Exceeding the recommended microbiological limits does not necessarily identify the underlying cause of contamination, but it clearly indicates that further investigation is required.
Possible causes include inadequate manufacturing hygiene, contaminated raw materials, insufficient preservation, packaging problems or contamination introduced during production.
The manufacturer should identify and correct the root cause before placing the product on the market. Depending on the findings, reformulation, manufacturing improvements or additional laboratory testing may be necessary.
Simply repeating the microbiological analysis without addressing the cause is unlikely to resolve the problem.
