Gastrointestinal bacteria growth inhibition by a toilet sanitary good for disaster shelter.

Abstract

Japan has experienced several large earthquakes in the past 30 years. Emergency evacuation shelters become overcrowded immediately after disasters. Deteriorating sanitary conditions in toilets are associated with a higher risk of infectious pathogen transmission. "Ho!Toilet" is a toilet sanitary good for emergency evacuation shelters. Its main ingredients are calcium hydroxide, superabsorbent polymer (SAP), and zeolite. SAP absorbs water and solidifies waste for proper disposal. Zeolites are deodorizers. Calcium hydroxide, which inactivates microorganisms, can reduce the risk of infectious diseases in evacuation shelters. In this study, we designed experiments to confirm the antimicrobial effects of the Ho!Toilet. Escherichia coli (E.coli), Vibrio cholerae (V. cholerae), and Clostridioides difficile (C. difficile) were selected as the microorganisms for this study. Two strains of E.coli and two strains of V. cholerae were inactivated, whereas, C. difficile was not. After the Ho!Toilet powder and bacterial solutions were mixed and stirred, the mixture was separated into a gel and a liquid phase. The pH values in the gel and the liquid phase were 12.0 and 9.3, respectively. After centrifugation of these mixtures, the supernatants were cultured with bacteria at pH 10.7. Ho!Toilet inactivates bacteria other than C. difficile in this study. These effects are mainly achieved under alkaline conditions using calcium hydroxide. Considering the additional effects of the ingredients in Ho!Toilet, SAP, and Zeolite, these products would be useful in toilets with poor sanitary conditions, such as evacuation shelters, to prevent the transmission of infectious diseases.