The Challenge Test, also known as the Preservative Efficacy Test, is a mandatory microbiological safety requirement for most cosmetic products that contain water. Water-based formulations carry a higher risk of microbial contamination during storage and consumer use.
However, not all cosmetic products require this test. Products that are inherently resistant to microbial growth may qualify for a Challenge Test Exemption. Regulators classify these products as microbiologically low risk due to their formulation characteristics or packaging design.
A Challenge Test Exemption confirms that the product remains microbiologically safe without the need for preservatives or preservative efficacy testing.
Regulatory Basis: ISO 29621
The scientific and regulatory framework for Challenge Test Exemptions is defined in ISO 29621: Cosmetics — Microbiology — Guidelines for the risk assessment and identification of microbiologically low-risk products.
This international standard outlines how manufacturers can demonstrate that a cosmetic product does not support microbial survival or growth. The assessment focuses on formulation chemistry, water availability, pH, alcohol content, and packaging protection.
ISO 29621 provides the documented justification required for regulators and safety assessors to accept the exemption.
Formulation Characteristics That Define Low-Risk Products
The most important factor in determining microbiological risk is the formulation itself. Products must actively prevent microbial growth through their physical or chemical properties.
Water activity (aw) plays a critical role. Water activity measures the amount of free water available for microorganisms. When the water activity is equal to or below 0.75, microorganisms cannot grow. Anhydrous products such as body oils, lip balms, pressed powders, and solid sticks typically meet this criterion.
Extreme pH levels also create hostile environments for microorganisms. Products with a pH of 3.0 or lower, or 10.0 or higher, rapidly destroy microbial cell structures and prevent survival.
High concentrations of certain ingredients provide additional protection. Products containing 20 percent or more alcohol, such as perfumes and tonics, are considered microbiologically stable. Raw materials with inherent antimicrobial properties, including strong oxidizing agents, also contribute to low-risk classification.
Packaging and Manufacturing Conditions Supporting Exemption
Packaging design can significantly reduce contamination risk during consumer use. Products that prevent air or finger contact with the formula are considered low risk.
Single-dose units, sealed capsules, and unit-dose sachets eliminate repeated exposure. Airless pump systems also restrict microbial ingress and support exemption claims.
Manufacturing processes may further justify exemption. Filling products at temperatures of 65°C or higher effectively destroys vegetative microorganisms. When combined with protective packaging, this thermal process supports microbiological safety without preservatives.
Documentation Requirements for Challenge Test Exemption
A Challenge Test Exemption must be supported by clear scientific documentation. Manufacturers must demonstrate that the product remains microbiologically safe throughout its shelf life under normal conditions of use.
The justification should align with ISO 29621 principles and include data on formulation composition, water activity, pH, alcohol content, packaging type, and manufacturing controls.
When properly documented, a Challenge Test Exemption eliminates the need for preservative efficacy testing while maintaining full regulatory compliance and consumer safety.
The mandatory label elements in full
Article 19 of Regulation (EC) No 1223/2009 sets out what every cosmetic label must carry. Working through it as a checklist is the fastest way to catch omissions before artwork is signed off:
- The name and address of the Responsible Person, established in the EU
- The country of origin, for products imported into the EU
- The nominal content by weight or volume at the time of packaging
- The date of minimum durability, or the Period After Opening where durability exceeds 30 months
- Particular precautions for use, including any warnings required by the Annexes
- The batch number or other identification allowing the batch to be traced
- The function of the product, unless it is obvious from presentation
- The ingredient list, headed “Ingredients” and given in INCI nomenclature in descending order
All of it must be indelible, easily legible and clearly visible. The two elements most often missed are the function — obvious for a shampoo, not obvious for an unlabelled white jar of cream — and the batch number, which is sometimes applied only to the outer carton and lost when the carton is discarded.
Language requirements across the EU
The Regulation is harmonised, but language is not. Each Member State determines the language in which the consumer-facing information must appear on products sold in its territory, which is why a single pan-European label rarely works without adaptation.
The split is straightforward once understood. The ingredient list stays in INCI in every country, because INCI is a standardised nomenclature rather than a language. Everything a consumer needs to understand — the function, precautions and warnings, instructions for use, and the “best used before” wording — must be given in the language required by the country of sale.
In practice brands either produce multilingual artwork covering their target markets, or use a common base label with country-specific overlabels. Belgium and Luxembourg are worth flagging early in artwork planning, since multiple official languages may be required on the same pack.
Claims on the label
Anything you say about what the product does is a claim, and claims are regulated separately by Regulation (EU) No 655/2013, which sets six common criteria: legal compliance, truthfulness, evidential support, honesty, fairness, and enabling informed decision-making.
Two of these cause most of the problems. Evidential support means every claim needs documented evidence held in the Product Information File before launch — instrumental measurement, a consumer perception study, clinical data or defensible scientific literature. Fairness prohibits claiming an advantage that is simply compliance with the law, which is why “paraben-free”, “not tested on animals” and similar denigrating or self-evident claims are treated as misleading.
Claims also determine classification. A statement that the product treats or prevents a condition presents it as a medicinal product and moves it out of the cosmetics framework entirely — so claim wording should be reviewed before it is set in artwork, not after.
Frequently asked questions
Can I put the mandatory information on the outer carton only?
No. The consumer must still have access to the information once the carton is discarded, so the immediate container needs to carry it too. Where space genuinely does not allow, the enclosed-information route with the hand-and-book symbol is the permitted alternative.
Does the ingredient list need translating?
No. INCI names are identical across all Member States. Only the consumer-facing text — function, warnings, precautions and instructions — needs to be in the local language.
Where does the batch number have to appear?
On the packaging in a way that allows the batch to be identified. If it appears only on an outer box that is thrown away, traceability is lost and the requirement is not met. It is normally printed or laser-coded onto the primary container.
Is “dermatologically tested” allowed?
Only if you hold the evidence. It implies a dermatological study was carried out on the finished product, so the study report must exist in the Product Information File. Used without that evidence it breaches the evidential-support criterion.
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