ABSORPTION OF HYDROCYANIC ACID. 16 
SUMMARY. 
Hydrocyanic acid gas, widely used as a fumigant against certain 
insects and rats, often comes in contact with materials intended for 
food. The quantity of hydrocyanic acid absorbed and retained by vari- 
ous fumigated foodstuffs has been determined. 
All of the products examined absorbed the fumigant to some ex- 
tent. Hard rinds of vegetables or skins of fruits had a tendency to 
decrease the absorption. Chlorophyll-bearing vegetables, or those 
of a succulent nature, in general, took up large quantitiea of hydro- 
cyanic acid. 
Some of the fruits and vegetables suffered physical injury (wilting, 
softening, or discoloration) because of fumigation to such an extent 
that they were unmarketable. 
In the case of the seeds most of the hydrocyanic acid was rapidly 
dissipated, so that by the fourth day the content usually was not 
more than 5 parts per million. After this there was a slow dissipa- 
tion, a very small quantity of the fumigant being present at the end 
of three months. The flour examined absorbed a large quantity of 
hydrocyanic acid but gave it off so rapidly that by the end of four 
days, or, at the most, a week, no traces of it could be detected. 
Evacuating the chamber after fumigation was not effective in 
removing absorbed hydrocyanic acid. 
The concentration of hydrocyanic acid gas used had, in general, a 
marked effect on the quantity absorbed by the product. This was 
noticeable even at the end of three months. 
The quantities of hydrocyanic acid absorbed by various other 
products were determined also. 
No conclusions as to the safety of fumigated foods for consumption 
are drawn in this bulletin. Chemical observations alone are included. 
Determinations of the quantities of hydrocyanic acid injurious to 
human health lie in the domain of the pharmacologist. 
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