Whether at home, in the canteen or restaurant - the question remains as to whether the novel coronavirus SARS-CoV-2 can also be transmitted via dishes or drinking glasses. In general, infections with coronavirus are transmitted directly from person to person via droplets and aerosols. Although smear infections cannot be ruled out, there is still no reliable evidence of indirect transmission of the virus via contaminated objects and surfaces. Nevertheless, drinking glasses deserve special consideration because they come into direct contact with the mouth and oral cavity. A research project by the German Federal Institute for Risk Assessment (BfR) now offers new insights. "Coronaviruses are relatively stable on glass - our studies confirm this. Sufficient cleaning of drinking glasses is therefore important," says BfR President Professor Dr. Dr. Andreas Hensel. "Our data shows that commercial dish washing detergents and manual glass washers can effectively remove coronaviruses from drinking glasses."
The study was published in the scientific journal Food Microbiology on April 6, 2022:
The human coronavirus 229E, which can lead to mild respiratory diseases in humans, was used in the investigations. This virus is related to SARS-CoV-2 and often used as a model virus for human coronaviruses. The results show that after drying on glass, coronaviruses can remain infectious for days to weeks. The presence of light is a major factor in this regard. Infectious coronaviruses could be detected for up to seven days when stored in daylight and up to 21 days in the dark. As enveloped viruses whose genetic material is surrounded by a lipid layer, coronaviruses are sensitive to substances that dissolve lipids such as alcohol and surfactants, which are contained in soaps and dish washing detergents as fat solvents. The investigations at BfR showed that most commercially available dish washing detergents inactivate coronaviruses sufficiently within 15 seconds in dish washing water at a temperature of 23 degrees Celsius. A higher temperature of 43 degrees Celsius and a longer exposure time of 60 seconds was only necessary for one detergent with a lower total content of surfactants. A manual glass washer that complies with DIN 6653-3 could effectively remove coronaviruses from glasses even when using cold water.
The results of the BfR study show that coronaviruses can be sufficiently removed from drinking glasses both when washing by hand and when using manual glass washers. This requires proper rinsing, which includes, among other things, sufficiently frequent change of water, use of detergent concentrations as recommended by the manufacturer and manual scrubbing sufficient to remove dirt.
About the BfR
The German Federal Institute for Risk Assessment (BfR) is a scientifically independent institution within the portfolio of the Federal Ministry of Food and Agriculture (BMEL) in Germany. The BfR advises the Federal Government and the States ('Laender') on questions of food, chemicals and product safety. The BfR conducts independent research on topics that are closely linked to its assessment tasks.