prEN ISO 17516

prEN ISO 17516 is the CEN draft for Cosmetics - Microbiology - Microbiological limits. It specifies acceptable quantitative and qualitative microbiological limits for finished cosmetic products, so manufacturers and laboratories can judge microbiological quality and consumer-safety risk. The standard is aimed at cosmetic manufacturers, test laboratories and other interested parties that assess product microbiology.

What does prEN ISO 17516 specify?

prEN ISO 17516 sets microbiological limits for finished cosmetic products and gives a way to judge whether a product meets them. It applies to cosmetics as a whole and treats them as non-sterile products, but still expects them to stay within defined microbiological limits.

The document is organized into five main clauses, with a normative Annex A and a bibliography.

What are the key requirements of prEN ISO 17516?

prEN ISO 17516 says that cosmetic products are not required to be sterile, but they must not contain microorganisms at levels that could affect product quality or consumer safety. In practice, the standard is used to decide whether a finished product is microbiologically acceptable.

Product risk and routine testing

Clause 1 and the introduction link microbiological testing to risk. Products considered microbiologically low risk may not need routine testing if the manufacturer can still show that they meet the standard. That matters because routine testing is not treated as automatic for every product - the manufacturer has to justify the control approach.

Limit setting for finished products

Clause 5 establishes microbiological limits for finished cosmetics. The standard distinguishes between ordinary products and products specifically intended for children under three years of age, the eye area or mucous membranes. In practice, that means a manufacturer must set specifications with the product’s intended use in mind, not just one global limit for all cosmetics.

Target organisms that must be absent

Clause 4 and Table 1 require the finished product to be free from specified microorganisms, including Escherichia coli, Pseudomonas paraeruginosa - also known as Pseudomonas aeruginosa - Staphylococcus aureus and Candida albicans. For the reader, this means the control plan is not only about total count; it also has to check for organisms that indicate hygienic failure or may pose a safety concern.

Total counts and interpretation

Clause 5 also sets limits for total aerobic mesophilic microorganisms. The document uses colony count results in CFU per gram or millilitre, and it warns that results close to the limit must be interpreted with the natural variability of plate counts in mind. Annex A supports that decision process with a flowchart, so out-of-limit results are assessed consistently rather than by a single isolated reading.

Control of non-specified microorganisms

Clause 5 allows non-specified microorganisms only when they do not have the ability to grow in the product. The standard ties that judgement to risk assessment, including preservation efficacy studies, or to evidence that the product cannot support microbial growth. In practice, this means the manufacturer has to understand how the formulation behaves over shelf life.

Testing methods to use

The introduction points to ISO methods for sample handling, enumeration and organism detection when testing is needed. That matters because prEN ISO 17516 sets the acceptance limits, while the companion methods provide the laboratory procedures for measuring them.

What terms does prEN ISO 17516 define?

• product - the portion of an identified cosmetic product that is received in the laboratory for testing.
• aerobic mesophilic microorganisms - mesophilic bacteria, yeast and mould that grow aerobically under the conditions specified in the related ISO methods.
• specified microorganism - an organism that is undesirable in a cosmetic product because it may cause skin or eye infection or indicate hygienic failure.
• Escherichia coli - a gram-negative, motile rod with smooth colonies.
• Pseudomonas paraeruginosa - the standard’s term for Pseudomonas aeruginosa, a motile gram-negative rod with brown or greenish smooth colonies.
• Staphylococcus aureus - a gram-positive coccus that commonly appears in grape-like clusters.
• Candida albicans - a yeast that forms white to beige, creamy, convex colonies on a selective medium.

Who uses prEN ISO 17516?

prEN ISO 17516 is used by cosmetic manufacturers, quality managers, microbiology laboratories, contract test labs and suppliers involved in raw materials, processing and packaging. They use it to set microbiological specifications, evaluate finished products, investigate failures and support release decisions. It is also relevant when a buyer wants a clear microbiological quality requirement for cosmetic products.

What changed in prEN ISO 17516 from the previous edition?

prEN ISO 17516 replaces ISO 17516:2014. The stated changes are the addition of Clause 2, the renumbering of the following clauses, and an updated bibliography.

Which standards are used with prEN ISO 17516?

prEN ISO 17516 points to related standards that support risk assessment and testing:

• ISO 29621 - helps identify microbiologically low-risk products.
• ISO 22716 - gives Good Manufacturing Practices for cosmetics.
• ISO 21148 - provides general instructions for microbiological examination.
• ISO 21149 - covers enumeration and detection of aerobic mesophilic bacteria.
• ISO 16212 - covers enumeration of yeast and mould.
• ISO 18415 - covers detection of specified and non-specified microorganisms.
• ISO 18416 - covers detection of Candida albicans.
• ISO 21150 - covers detection of Escherichia coli.
• ISO 22717 - covers detection of Pseudomonas aeruginosa.
• ISO 22718 - covers detection of Staphylococcus aureus.
• ISO 11930 - supports evaluation of antimicrobial protection.
• USP Chapter 61 and EP Chapter 2.6.12 - support interpretation of plate-count variability.

What does the prEN ISO 17516 document contain?

prEN ISO 17516 contains a scope, terms and definitions, a principle clause and the microbiological limits clause. Table 1 sets the acceptance criteria for total counts and for specified organisms, while Annex A gives a flowchart for interpreting test results. The bibliography points to the laboratory methods and risk-assessment documents used to carry out the checks in practice.