A previous paper dealt with the effect of environmental factors on experimental benzene poisoning. The present paper considers the role of host factors, in particular age, in modifying the toxicity of benzene. Experimental animals were male Donryu rats, and ICR-JCL mice of both sexes, which were given benzene in an olive oil mixture subcutaneously on the back for five days.
Young rats, with the exception of baby rats, were found to have more susceptibility to benzene than mature ones. Mice, on the other hand, showed no significan t differ-ence between young and mature animals, though males were found more susceptible to benzene than females.
The method of selection of animals for experiment is stated, and it is indicated that mature rats of over nine weeks of age may be suitable for experimental work in benzene poisoning, and that it may be unnecessary to take age into consideration in mice.