Disinfection of textiles in the washing process (including clothes) is the process of removing microorganisms such as bacteria, fungi, viruses, mycobacteria, spores with the use of biocidal preparations intended for this purpose, using automatic washing machines.
We have been washing clothes and textiles for hundreds of years. The first records of washing with the use of laundry machine come from 1851, when the first washing machine was built by the American- James King. This invention was a worldwide phenomenon, and its creation was intended to speed up and improve the work associated with cleaning materials. However, this device was significantly different from the automatic washing machines that are known nowadays. The basic purpose of the laundry process is to refresh textiles and also to remove stains that have formed during use. Over the years, however, the definition of laundry has evolved considerably. It is no longer a process used only to refresh clothes. What is more, the broadly understood washing process has been enriched with a new function, which is thermal disinfection.
Over the years, awareness of the bacteria, fungi and viruses present in the environment has increased significantly. Currently, scientists are aware of a number of pathogens characterized by a high tolerance to temperature changes. Hence, showing resistance to high temperatures. So what if high temperature is not enough? Products for chemical-thermal disinfection, i.e. washing powders or liquids with the addition of a biocide, come to the rescue.
Biocidal products in the washing process
The market for biocidal products is constantly evolving. In addition to the most popular type of preparations, i.e. hand and surface spray disinfectants, there are new ones, including the above-mentioned products for chemical-thermal disinfection. Products of this type are most often in the form of a liquid, powder, gel or capsules. However, it is not the form that is crucial here, but the addition of an active substance whose purpose is to remove harmful microorganisms from the surface of the fabric. Among the substances added to washing liquids, for example, compounds from the group of quaternary ammonium salts (DDAC / ABDAC) are highly popular. Due to their delicacy, and at the same time the effectiveness of disinfection, they are an efficient combination with non-ionic and anionic surfactants used in regular powders.
Test standard
In 2015, a research methodology was developed to assess the effectiveness of the chemical-thermal disinfection process for textiles. The PN-EN 16616 standard is a carrier methodology that describes the procedure of testing biocides in terms of elimination of deleterious pathogens during the laundry process. The main aim of the methodology is to evaluate whether a given active substance present in a washing product is effective in the assumed disinfection process. The second crucial element is the practical conditions of using the washing agent, which should be reflected in a laboratory test.
During this stage, temperature, contact time, and the presence of loading substances should be taken into account, which is to simulate real conditions. The washing machine on which the tests are performed must comply with the requirements strictly defined in the methodology (point 5.3.2.18 Washing machine and machine preparation) “Chemical-thermal disinfection of textiles – Test method and requirements (phase 2, stage 2).”
If the actual conditions of use of the product differ from the requirements contained in the methodology, the manufacturer’s task is to determine the effective dose of the disinfectant during the test.
Application of the methodology
Chemical-thermal disinfection of textiles can be applied wherever a high level of hygiene is particularly important. That is, in places such as hospitals, health care facilities, rehabilitation offices, nursing homes or clinics. It is also important for nurseries, kindergartens, schools and the entire industrial area to pay attention to the disinfection process. Including maintaining the sterility of clothes of employees working with food, dietary supplements or pharmaceutical technologies. That is because a standard laundry process using products without a biocidal substance in the formulation might not be sufficient.
Registration requirements for biocidal products
In accordance with the requirements of the Office Registration of Medicinal Products, Medical Devices and Biocides in Poland, a biocidal product for disinfecting laundry, which is registered in the national registration, should have tests according to of the discussed methodology PN-EN 16616 and optionally according to PN-EN 14476 “Chemical disinfectants and antiseptics. Quantitative suspension method for determining the virucidal activity of chemical disinfectants and antiseptics used in the medical field. Test method and requirements “, as well as PN-EN 14348 “Chemical disinfectants and antiseptics – Quantitative suspension method for determining the mycobactericidal activity of chemical disinfectants and aseptics used in the medical field, including agents for disinfecting tools. Test method and requirements”.
The European procedure is characterized by slightly broader requirements described by the European Chemicals Agency (ECHA) in “Guidance on the Biocidal Products Regulation Volume II Efficacy – Assessment and Evaluation (Parts B + C) Version 3.0 April 2018”. In the case of the European procedure, in addition to the PN-EN 16616 methodology, the product should have tests according to PN-EN 13727, PN-EN 13624, PN-EN 14348 and regarding the declaration of virucidal effectiveness according to PN-EN 14476.
Reference strains and test procedure
The reference strains indicated in the methodology are: Pseudomonas aeruginosa, Escherichia coli (K12), Staphylococcus aureus, Enterococcus hirae, Enterococcus faecium for bacteria; Candida albicans, Aspergillus brasiliensis for fungi, and Mycobacterium avium and Mycobacterium terrae in the context of the study of mycobactericidal efficacy. There is also the possibility of using optional strains, e.g. viruses. However, it should be remembered that if additional microorganisms are used, they should be incubated under optimal growth conditions (temperature, time, atmosphere, medium).
The research procedure consists in preparing a carrier made of cotton fabric. Then the carrier is covered with pathogenic microorganisms with the presence of centrifuged sheep blood, dried, and then placed in cotton bags. After placing them in the washing machine, they are ready for the disinfection process. The process is carried out at a temperature of <60 ° C or ≥ 60 °C and is only relevant for the actual stage. It is also possible to perform pre-washing / pre-soaking test to pre-clean the tested textiles. However, this requires specific information in the instructions for use of the product. When the washing step is complete, the carriers are transferred to test tubes, and then the actual assay part of the test is conducted. Once the analyses are finished, we calculate the reduction factor. Products tested at <60 ° C are considered effective when the log reduction of bacteria and mycobacteria is more than 7 logarithms after three test replications. Both for strains of bacteria, fungi and mycobacteria, as well as additional test microorganisms adapted to the practical function of the product. Moreover, no microorganisms should be detected in 100 ml of washing / disinfecting liquid.
Summary
Research according to PN-EN 16616 methodology requires the use of a special laundry machine, as well as the participation of specialized laboratory staff. This test represents a niche in the market of laboratory services due to the need for qualified personnel. Laboratories with technical facilities and offering specific tests will help in selecting the research spectrum that is necessary for the manufacturer’s needs.