Abstract
HCN is one of the major toxic gases generated in fire. However, as HCN always accompanies CO, the reaction of man or animals to HCN in fires is not completely understood. To determine the lethal blood cyanide level of rabbits, to study the behavior of rabbits during the HCN exposure and to discuss the possibility of death mainly caused by inhalation of HCN in fires, experiments were made in which rabbits were exposed to HCN of different concentrations.
The results are summarized as follows.
(1) Blood cyanide levels were all 0.70 μg/ml or below when death occurred to rabbits exposed to HCN of approximately 300 ppm or over in concentration. However, there were cases where blood cyanide levels were higher, when rabbits exposed to HCN of lower concentrations did not die. Therefore, it is impossible to obtain the lethal blood cyanide level by determining the blood cyanide level of rabbits killed by inhalation of HCN.
(2) The toxic effects of cyanide appeared to rabbits much faster when they were exposed to HCN than to CO, which indicates that there is a possibility that HCN may be the principal cause to death in gas poisoning in fires, even when HCN concentration is lower than CO concentration in terms of toxicity, if the former is over the lethal level.
