Study for Effectiveness of Washing Hand with Various Soaps and Disinfectants

Abstract

In April, 1997, the Ministry of Health and Welfare published the manual “Six Points for Prevention against Food Poisoning at Home” based on a new approach called HACCP. This manual, however, did not explain the various actual methods of washing hand. In order to determine the most effective method of washing hand in domestic kitchens, we investigated the survival rates of Escherichia coli (E. coli) on hands that had been washed several ways. The hands were first smeared with a mixture of beef paste and non-pathogenic E. coli, simulating the preparation of hamburger. The glove juice technique was used to collect the bacteria from the hand surface. As a result, we found a certain effectiveness in the use of medicated liquid soap with detergent activity and in duplicated use of non-medicated liquid soap. We further found that spraying ethanol onto hands after both using liquid soap and drying hands was more effective. The most effective method was rubbing hands with undiluted invert soap (10% w/v) for 30 seconds after washing with liquid soap. The method of washing hand should be chosen depending on how heavily the hands are contaminated with bacteria.