1. Why microorganisms must be controlled in cosmetics
Cosmetics are products applied directly to the skin, hair, lips, or sensitive areas such as the eyes and the genital area. If contaminated with harmful microorganisms, cosmetics can:
- Cause skin irritation, allergy, or infection.
- Reduce product effectiveness as the active ingredients are broken down by bacteria and fungi.
- Shorten shelf life and make storage unsafe.
- Microorganisms can enter cosmetics during production, packaging, or while in use (opening the cap, hand contact...).
2. Microbiological limits in cosmetics under the regulations
Depending on the type of cosmetic and where it is used (normal skin or sensitive areas), the microbiological limits differ. Below are the limits under international and Vietnamese standards (TCVN 6971:2001, the ASEAN Cosmetic Directive, ISO 17516:2014):
* Cosmetics not intended for sensitive areas (normal skin)
* Cosmetics intended for children under 3 or sensitive areas (eyes, lips, genitals)
3. The dangerous microorganisms in cosmetics that must be controlled
- Staphylococcus aureus: causes dermatitis, boils, and infections.
- Pseudomonas aeruginosa: dangerous for the eyes and damaged skin, especially in people with weakened immune systems.
- Candida albicans: a yeast that causes skin and mucous-membrane infections, particularly dangerous in the genital area.
- In addition, E. coli and Salmonella, if present, are signs of severe contamination.
4. Methods for testing microorganisms in cosmetics
The commonly used standards:
- ISO 21149: enumerates aerobic bacteria.
- ISO 16212: enumerates yeast and mold.
- ISO 18415: detects specified unwanted microorganisms.
- ISO 11930: preservation effectiveness testing (challenge test).
* Basic procedure
- Dilute the sample: cosmetics in a suitable diluent (peptone water, physiological saline...).
- Plate onto culture media: selective media (PCA, SDA, MacConkey agar...).
- Incubate: under suitable conditions (30–35°C for bacteria, 20–25°C for fungi).
- Count colonies: after the incubation period to calculate CFU/g.
- Identify pathogens: by biochemical tests, or PCR techniques if needed.
5. How to minimize microorganisms in cosmetics
- Design a clean production process (GMP): use clean raw materials, sterilized tools, and trained staff.
- Use suitable preservatives: phenoxyethanol, formaldehyde releasers...
- Check production batches on a schedule.
- Sealed packaging and pump dispensers: to reduce exposure and contamination during use.
Microbiological limits in cosmetics are a mandatory factor for user safety. Manufacturers must strictly comply with the standards and test on a schedule to prevent risk. Consumers should also be careful to choose products from reputable brands, and not to use cosmetics that have gone off, changed color, or smell strange.
See also Microbiological testing for cosmetics with Compact Dry plates | Shimadzu