Testing of hand disinfectants

Admission of biocidal product to the European Union market is possible only after prior registration at the Office Registration of Medicinal Products, Medical Devices and Biocides. One of the requirements for approving the product for sale is the confirmation of the effectiveness declared by the manufacturer. Analysis of action disinfection products is carried out according to ISO standard methodologies. Regulation of the methodology of the conducted research allows for an objective assessment of the effectiveness of the biocide.

Types of products intended for hand disinfection

The current epidemiological situation results in a significant increase in the amount of agents intended for hand disinfection on the market. Among the ISO standards, three basic methodologies for the analysis of the biocidal effectiveness of such products can be distinguished. They allow to determine the effectiveness of surgical disinfection (PN-EN 12791 + A1: 2017-12), hygienic disinfection (PN­-EN 1500:2013­ 07E), and hygienic handwashing (PN-EN 1499: 2013 07E).

It is worth noting that a manufacturer who wants to formulate products with the above-described effects is not required to make three separate preparations. A product with appropriately selected active ingredients may demonstrate biocidal efficacy within all of the aforementioned standards.

A common feature of the analysis of the biocidal effectiveness of hand disinfectants is the conduct of tests on probands. Methodologies differ in the number of volunteers required to complete the test. Another difference is the amount of the product to be analysed and the criteria for accepting the biocidal product as effective.

Surgical hand disinfection according to the EN 12791 + A1: 2017-12

The test is performed with the participation of 23-28 probands. The effects of the product are assessed against the natural microflora of the hands of volunteers taking part in testing, therefore the test is preceded by taking swabs of hands. Then, an appropriate amount of reference agent, which is an isopropanol solution, is applied to the hands of the probands. Hands swabs are carried out after three minutes, and after three hours of hand contact with the product. After the time allowed for the reconstruction of the microflora of the hands, parts of the test with the use of the analyzed biocide can be completed. Afterwards, once again swabs are taken from the probands’ hands without any contact with the disinfectant. Then, the microflora of the hands is exposed to the tested product, and after 3 minutes and 3 hours later, a swab of hand is made in a suitable medium. The interpretation of the results is based on a static analysis by performing the Wilcoxon Test. The biocidal effectiveness of the tested product is compared to the antimicrobial activity of the reference preparation for each of the probands. The method allows to confirm the long-term biocidal effectiveness of the product.

Hygienic hand disinfection by rubbing according to the EN 1500: 2013 07E

The test is performed with 18 to 22 probands whose hands are contaminated with a properly prepared suspension of the reference strain of Escherichia coli. The test begins by taking a hand swab from the subjects’ hands after contact with the bacterial suspension. The microorganisms presented on the hands are then treated with a reference product and handprint is retaken. The last stage of testing begins with the contamination of the probands’ hands in a manner analogous to the previous one. Afterwards, the microorganisms are exposed to the tested product and swab of hand is taken one more time. As in the method performed above, the calculation of the results involves static analysis by performing the Wilcoxon Test for pairs of observations. The efficacy of the tested product is compared to that of the reference preparation. The product, which effectiveness is confirmed by the conducted test, can be used for hand disinfection both in shopping malls, grocery stores, as well as in schools, kindergartens or hospitals.

Hygienic handwashing according to the EN 1499: 2013 07E

This method is analogous to that described above. The test is performed with 12 to 15 probands. The test begins with contaminating their hands with a suspension of the E. coli strain and taking hands swabs from them. Hands of surveyed persons are contaminated again, and then treated with reference soap, washed with water. The final step of the method is another contamination of the hands, the use of a tested washing agent, and the taking of a fingerprint from the proband’s fingertips. For the calculation of the results, a comparison of the reduction in the amount of microorganisms remaining on the hands after contact with the reference product and with the test product is used for each participant. Testing the effectiveness of washing preparations for hygienic handwashing is especially recommended for products used in hospitals, dentists’ offices, nurseries and kindergartens.

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