Many thanks to all who replied to my question with insightful comments. It seems that the benefit of "questioning hand-washing practice" is considered questionable. :-) At least I have found a good example of how a certain health practice could be well justified without documented evidence for the benefit. I'd like to thank Liz Waters for the following reference which might be worth sharing: <... a book about creating a market for soap in 20th century Zimbabwe that discusses gender and marketing and the differential...> Timothy Burke; Lifebuoy men, lux women: commodification, consumption, and cleanliness in modern Zimbabwe. Durham: Duke University Press, 1996. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%