leakages of gas masks should be so small that even men performing heavy work and breathing at high rates should suffer no ill effects. This same reasoning applies to all other protective devices. For all defensive calculations, therefore, the incapacitating exposure (ICt50) for active man should be used.
Although much consideration has been given to the soldier's activity level and resultant respiratory minute volume in developing human toxicity estimates, little consideration has been given to the purpose of many of the existing human-toxicity estimates for CW agents: Many were probably formulated for offensive purposes. Offensive estimates are designed to produce the desired effect in at least the stated percentage of the population and to produce that effect quickly. The time required for CW agents to produce an effect is generally inversely proportional to the dose received. For defensive purposes, those factors (for example, high minute volume or the use of most resistant individuals in developing human toxicity estimates) result in an underestimation of the potency (toxicity) of the agents.
Silver, S.D. 1953. The Estimation of the Toxicity of GB to Man (U), MLRR 23, Chemical Corps Medical Laboratories Research Report, Army Chemical Center, Md., June 1953. Confidential report.