Microbiological tests of cosmetics are performed to determine the degree of microbiological purity of products in accordance with the evaluation criteria and microbiological requirements set out in the Regulation of the Minister of Health (Dz. U. of 2003, No. 9, item 107). According to the Regulation, tests are performed to determine the quantity of:
- Total number of aerobic mesophilic microorganisms
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Candida albicans
- Escherichia coli
- Aspergillus brasiliensis
Moreover, microbiological tests of cosmetics aim at determining whether the tested product does not pose a threat to human health. By performing microbiological purity tests of your products, you ensure high quality and safety of their use.
Additionally, thanks to load tests of cosmetics (challenge tests) consisting in multiple contamination of the tested samples, we are able to determine precisely whether the preservative system adapted by you is able to maintain microbiological purity of cosmetic products and whether it is possible to create a product which is safer for the consumer.
Furthermore, it should be noted that according to the Regulation of the Minister of Health, cosmetic products are divided into two categories with regard to the permissible limits:
- category I, according to which the maximum content of the total number of aerobic mesophilic microorganisms may not exceed 5.0 x 10 2 cfu/g or ml, specific microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans) absent in 0.1 g. Category I includes cosmetics intended for children and the eye area.
- Category II, according to which the maximum content of the total number of microorganismsaerobic mesophilic microorganisms shall not exceed 5.0 x 10 3 cfu/g or ml, microorganismsspecific micro-organisms (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans) absent absent in 0.1 g. Category II includes other cosmetics, i.e. creams, lotions, milks, etc.
Water activity test
Water activity test is performed in order to identify the so-called microbiologically insensitive products. These products include all products with trace water content, products with high pH (pH>10 and pH<3), free-flowing products, oil products, etc. The water activity parameter (abbreviated aw) is the ratio of the water vapour pressure above the test sample to that of pure water at the same temperature. Chemically pure water has an aw value of 1, but as the concentration of soluble compounds increases, the water activity (aw) falls below 1. Most microorganisms (e.g. bacteria) can live in an environment where water activity is aw=0.95. Yeast thrives in an environment with aw between 0.60 and 0.88. Below aw=0.60 no growth of microorganisms is observed. The correct aw test result for cosmetic products is considered to be all those below aw=0.75, however additional factors (such as type of packaging used, production technology, raw materials used, pH of the product) should also be taken into consideration.