206 Microbes and You 



can probably be attributed to the efficient defense mechanism 

 that the body has at its command to ward off infections. How 

 else can we explain the "relatively few infections" experienced by 

 drug addicts whose practice of asepsis must be questioned? Since 

 chemicals applied as disinfectants to the skin prior to hypodermic 

 injections do not have an opportunity^ to act in the short contact 

 period, some phvsicians prefer to use acetone as a cleansing agent 

 in preference to either alcohol or soap and water. 



At best, ethyl alcohol in a concentration of between 50 and 70% 

 is a mild disinfectant, and its use should be confined to such tech- 

 nics as soaking thermometers which have been previously wiped 

 with cotton to remove the visible organic matter. While a 30- 

 minute contact period with 70% ethyl alcohol may disinfect ther- 

 mometers, other more reliable compounds are available for this 

 and similar procedures. 



FUMIGANTS 



A few decades ago the custom of fumigation of homes in which 

 individuals had been suffering from communicable diseases was a 

 common procedure, but today this practice is largely directed 

 against insects and rodents which might be carriers of disease. 

 Formaldehyde gas, chlorine, and sulfur dioxide were extensively 

 used for terminal disinfection after a patient had recovered from a 

 communicable disease. Strict attention to sanitary practices, 

 coupled with adequate washing of bedding and extensive ventila- 

 tion, are the usual modern treatments for the sickroom. Hydro- 

 cyanic acid gas is a deadly poison for insects as well as for man 

 and lower animals. Military barracks are usually fumigated with 

 this substance to rid the premises of roaches, bedbugs, and vermin. 

 Because the fumes of hydrogen cyanide are so toxic to humans, 

 extreme care must be exercised bv the workers engaged in ex- 

 teiTnination operations. Special canisters must be used with the 

 gas masks to protect workers from the lethal fumes. 



Aerosol mists and vapors, whose active ingredients include 

 pyrethrum, DDT, or one of the glycols, are popular for treatment of 

 air in closed places. Propylene glycol and the superior triethvlene 

 glycol have come into wide use in an attempt to minimize the 



