title: Bidet toilet seats with warm-water tanks: residual chlorine, microbial community, and structural analyses.
abstract: Despite the reported health-related advantages of the use of warm water in bidets, there are health-related disadvantages associated with the use of these toilet seats, and the bacterial research is sparse. We conducted a survey on the hygienic conditions of 127 warm-water bidet toilet seats in restrooms on a university campus. The spray water from the toilet seats had less residual chlorine than their tap water sources. However, the total viable microbial count was below the water-quality standard for tap water. In addition, the heat of the toilet seats' warm-water tanks caused heterotrophic bacteria in the source tap water to proliferate inside the nozzle pipes and the warm-water tanks. Escherichia coli was detected on the spray nozzles of about 5% of the toilet seats, indicating that the self-cleaning mechanism of the spray nozzles was largely functioning properly. However, Pseudomonas aeruginosa was detected on about 2% of the toilet seats. P. aeruginosa was found to remain for long durations in biofilms that formed inside warm-water tanks. Infection-prevention measures aimed at P. aeruginosa should receive full consideration when managing warm-water bidet toilet seats in hospitals in order to prevent opportunistic infections in intensive care units, hematology wards, and other hospital locations.
authors.affiliation: Department of Health Sciences, School of Allied Health Sciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan E-mail: iyot.ahs@kitasato-u.ac.jp.
authors.forename: Toru
authors.initials: T
authors.lastname: Iyo
authors.affiliation: Department of Social and Preventive Epidemiology, School of Public Health, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Asakura
authors.affiliation: Departments of Preventive Medicine and Public Health, Kieo University School of Medicine, 35 Shinanomachi, Sinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Nakano
authors.affiliation: Departments of Preventive Medicine and Public Health, Kieo University School of Medicine, 35 Shinanomachi, Sinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Yamada
authors.affiliation: Departments of Preventive Medicine and Public Health, Kieo University School of Medicine, 35 Shinanomachi, Sinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Omae
mesh_terms: D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification; D002713:Chlorine / Q000737:chemistry* / Q000494:pharmacology; D004202:Disinfectants / Q000737:chemistry* / Q000494:pharmacology; D004203:Disinfection / Q000379:methods; D006358:Hot Temperature; D007564:Japan; D014038:Toilet Facilities; D014871:Water Microbiology
chemical_list: D004202:Disinfectants; D002713:Chlorine