64 CIRCULAR 9 7 7, U. S. DEPARTMENT OF AGRICULTURE 



method is especially adaptable for use in portable or other laundry 

 facilities (see pp. 79-80). 



Before either method is used, the approximate amount of solution 

 or emulsion retained in the garments after wringing or spinning 

 should be determined. From 1 to 2 pints is required for a suit of 

 winter- weight underwear. The concentration is then adjusted to 

 give the desired amount of DDT per garment. If the volume is 



2 pints, the recommended dosage would be attained with a 2-percent 

 solution, containing approximately IS grams, or 0.64 ounce. 



Studies have shown that lindane is also effective as a clothing 

 impregnant for louse control, although much less persistent than 

 DDT. A set of winter-weight underwear impregnated with 2.5 to 



3 grams of lindane in about 2 pints of a 0.3-percent solution or emul- 

 sion will give effective control of lice for a week or 10 days. Gar- 

 ments treated with this small amount of lindane are not effective 

 after laundering and must therefore be re-treated. The Army En- 

 vironmental Health Laboratory is investigating the toxicity of lin- 

 dane to humans, but has not. yet approved its use as a clothing 

 impregnant for control of lice. 



Sprays for Louse Control on the Body 



A spray formula (No. 11) developed primarily as a treatment for 

 head and crab lice and scabies is also issued for the control of body lice 

 where it is desirable to eradicate all lice present on groups of personnel 

 in a short period, as at a port of debarkation in the United States in 

 connection with methyl bromide fumigation of the clothing of return- 

 ing troops. 



The formula is an emulsifiable concentrate known as NBIN and 

 contains the following materials (all percents by weight) : Benzyl 

 benzoate 68, DDT 6, benzocaine 12, and Tween 80 (polyoxyalkylene 

 derivative of sorbitan mono-oleate) 14. It is diluted with 5 volumes 

 of water for application. The individuals are stripped, and while 

 their clothing is being deloused by fumigation they are required to 

 take a bath and are then sprayed with the NBIN emulsion with a 

 power compressor and a paint-spray nozzle. The spray is applied 

 to the pubic and anal regions, the armpits, and other hairy parts of 

 the body to destroy body and crab lice, and to the head to destroy 

 head lice. The spray should be kept out of the eyes by covering them 

 with the fingers. Treated persons should not bathe again for at least 

 24 hours. Benzocaine is a very effective ovicide, so that the eggs as 

 well as the active stages are killed. About 20 ml. of finished emulsion 

 is required per individual, or about 5 gallons per 1,000 men. 



HEAD AND CRAB LICE 



Head and crab lice live continuously on the body, and their eggs 

 (nits) are attached to hairs. Eggs of the head louse are found chiefly 

 on the hairs of the head, and those of the crab louse chiefly on the 

 hairs of the pubic region but also occasionally on other hairy parts of 

 the body. The presence of either species can be readily determined 

 by examining for nits. 



The NBIN formula (see above) diluted 1 to 5 in water is highly effec- 

 tive against both species. It ma}' be applied as a spray or for individual 



