Microbiological purity of cosmetic products – sources of contamination and microbiological limits

Microbiological purity testing, in addition to stress tests and stability tests, is one of the conditions for allowing a cosmetic product to be sold in the European Union.

The effects of microorganisms on cosmetics

Contamination of a cosmetic product with microorganisms has a number of consequences. As a result of the interaction of microorganisms with the product ingredients, its consistency, pH, color and smell may change. In addition, a microbiologically contaminated product may lose its properties. Most importantly, it poses a threat to human health, causing inflammation, allergic reactions and infections.

Sources of microbiological infections in cosmetic products

Microbiological contamination of a cosmetic may occur during production (primary infections) and during use of the finished product (secondary infections). In order to minimize the risk of cosmetic contamination, the microbiological purity of the production environment is monitored at the stage of its production. It may include an analysis of the cleanliness of production lines, work surfaces and air in the production room. And also the cleanliness of the protective clothing and hands of the staff. Frequent tests of the production environment allow for quick response in the event of contamination. They can be performed by an on-site laboratory or by an external laboratory that offers analysis of swabs, prints and air.

After leaving the production line, the cosmetic is still exposed to contamination during use. Therefore, it should contain appropriate preservatives whose effectiveness is subjected to a stress test. The only exception are cosmetics with a low risk of microbiological contamination, whose properties limit the possibility of infection.

Cosmetics with low and high risk of microbiological contamination

According to the guidelines of the PN-EN ISO 29621:2017-04 standard, products with low microbiological risk are cosmetics with specific physico-chemical properties. First of all, these are products with low water activity (e.g. lip balms), pH value ≤3.0 (e.g. scrubs) or ≥10.0 (e.g. hair straightening products). This group also includes products containing ≥ 20% alcohol (e.g. perfumes). As well as cosmetics based on solvents (e.g. nail polishes). Other important factors influencing the susceptibility of a cosmetic to microbiological infection are the type and size of packaging and packaging conditions. However, the assessment of the risk of product contamination should be carried out individually for each product before refraining from performing load tests. Cosmetics with a high risk of microbiological contamination are considered to be products with a high water content (e.g. milks), reduced preservatives content and natural products.

Criteria for microbiological quality of cosmetic products

In accordance with the Regulation (EC) No. 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products, the cosmetic safety report constituting the basis for introducing it to the market of European Union countries should include information on the microbiological quality of the cosmetic product as well as the results of stress testing. cosmetic. Both the above-mentioned tests and the entire cosmetic safety report are prepared by the Ekolabos Laboratory.

The acceptance criteria for the microbiological purity of cosmetic products in accordance with PN-EN ISO 17516:2014 are summarized in Table 1. In accordance with the requirements presented in this standard, the qualitative examination of the cosmetic should demonstrate the absence of the following opportunistic pathogens: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans in 1 g or 1 ml of cosmetic. In turn, the acceptance criteria for the microbiological purity of cosmetics for quantitative tests depend on the type of product. In the case of children’s cosmetics intended for use around the eyes or on mucous membranes (category I), the maximum allowable amount of aerobic mesophilic bacteria is 100 cfu/g. However, in the case of other cosmetics, the result cannot exceed 1000 cfu/g.

Cosmetics preservation test

The stress test of cosmetic products is intended to demonstrate the effectiveness of the preservative used in it and is not required only in the case of cosmetics with a low risk of microbiological infection. According to the PN-EN ISO 11930:2012 standard, the method involves contaminating the tested sample with given bacterial strains and then checking the degree of contamination of the product in a given period of time after 7, 14 and 28 days.

Table 1. Criteria for accepting the microbiological purity of cosmetic products in accordance with PN-EN ISO 17516:2014