The Effect of Chemicals on Microorganisms 213 



make them safe for human use, but pubhc eating estabhshments 

 should make certain that utensils are sanitized. 



When surgeons and their assistants subject hands to the usual 

 surgical scrub with soap and a stiff brush, they are attempting to 

 reduce the microbial population of their skin by mechanical action. 

 You cannot sterilize the skin with any known compound developed 

 to date without destroying or severely injuring this tissue. Skin 

 is composed of many layers of cells, and while the outer cells may 

 be freed of organisms by a combination of mechanical and chemi- 

 cal procedures, the underlying cells may still harbor potentially 

 dangerous bacteria, especially deep in the pore spaces. 



So-called medicated soaps, while they have value, do not dis- 

 infect the hands with the ease the advertisements would lead you 

 to believe. If such medicated soaps are used to the exclusion of 

 other tvpes of washing preparations, there is evidence that the thin 

 film of soap and its active medication can reduce the bacterial flora 

 to a small fraction of that normally found on the skin. Some 

 surgeons have found that they can materially shorten the length 

 of a surgical scrub if they use selected medicated soaps and no 

 other cleansing preparations on their hands at home, in the office, 

 and in the hospital. The usual minute or less that is devoted to 

 a single washing of the hands by most persons is not going to 

 drastically reduce the bacterial population, whether medicated or 

 non-medicated soaps are employed. Only prolonged exposure to 

 the active germicidal ingredient will effectively do the job that the 

 "ads" would have you believe. 



Wetting and cleaning agents, classified as synthetic deter- 

 gents, have come into prominence in recent years, and the claims 

 that these compounds can clean as well as disinfect in one opera- 

 tion are true only under designated conditions. These soapless- 

 soaps are advocated for use in dishwashing and in clothes-washing 

 machines because of their relative stability in both acid and alka- 

 line solutions and because of their failure to form precipitates in 

 hard water. The low surface tension of detergents gives them 

 the advantage of being able to penetrate and to wet surfaces better 

 than either water or ordinary soaps. 



