The Period After Opening (PAO) is a critical piece of cosmetic safety information that informs the consumer about the length of time a product can be used safely once its primary packaging has been opened. Unlike a fixed expiry date, which applies whether or not the product is used, the PAO period begins precisely when the product is first exposed to air and potential contaminants.
Visual Representation and Marking
The PAO is visually represented by the “open jar” symbol
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on the cosmetic packaging, which looks like an open jar or container. Inside or beside the jar symbol, a number followed by the letter ‘M’ is displayed (e.g., 6M, 12M, 24M).
- M stands for “Months.” A symbol indicating 12M means the product is safe and effective to use for 12 months after it has been opened for the first time.
- The PAO marking is mandatory in the European Union (EU) and many other jurisdictions for products with a minimum durability (shelf-life) greater than 30 months.
The Science Behind PAO and Cosmetic Stability
The concept of PAO is directly linked to the microbiological integrity and cosmetic stability of the product once its protective seal is broken.
- Microbial Contamination: Once a product is opened, it is exposed to microorganisms from the air, fingers, and applicators. This contamination can degrade the product, reduce the efficacy of the preservative system, and potentially lead to consumer infection. The PAO ensures the product remains microbially safe throughout that indicated period.
- Physical Degradation: Exposure to oxygen and light can cause oxidation of active ingredients (like vitamins or unsaturated fats) and fragrances, altering the color, smell, texture, and efficacy of the product. The PAO reflects the point at which this degradation might compromise product quality.
PAO vs. Expiry Date
It is essential to distinguish between the PAO and the standard expiry date (or “Best Before End” date).
- Fixed Expiry Date: This date is used for products with a shelf life of 30 months or less. It indicates when the product should be used by, regardless of whether it has been opened.
- PAO: This is used for products with a shelf life of more than 30 months. The PAO takes precedence once the product is opened. Even if a product was manufactured yesterday, the user must adhere to the PAO period (e.g., discard after 6M) rather than the original 30+ month shelf life.
In summary, the PAO (Period After Opening) is a critical consumer safety directive designed to protect the user from the risks associated with product degradation and microbial growth following the breaking of the product’s primary seal.
