Inhalation Toxicity of Aerosolized Nerve Agents. 1. VX Revisited

摘要

The estimated inhalation toxicity of VX for humans was re-examined. A literature search was conducted which identified a number of unrelated and inconsistent animal toxicity studies and some varying estimates of the human inhalation toxicity of VX. The human estimates varied between 5 and 100 mg.min/ cu m without the authors identifying the related respiratory parameters in many cases. Nose only inhalation toxicity studies in mice, rats and guinea pigs were carried out using an NaCI aerosol with entrained VX as the toxic moiety. The observed LCt50 values for 12 min exposures of mice, rats and guinea pigs were 72, 67 and 30 mg.min/cu m, respectively. The mouse value agrees with the 71 mg. min/cu m reported previously by this laboratory for 10 min nose only exposures to VX vapor. No nose only values were found for rats in the literature. The literature values for whole body toxicity in rats and mice were significantly lower than the above figures. The guinea pig value in this study was similar to the 10 min, whole body value of 29 mg.min/cu m obtained from the literature. The present values and the literature values for goats, dogs, rabbits, guinea pigs (which represent a mixture of whole body vapor and aerosol exposures at varying times) and the one nose only value for mice were combined with standard minute- volume/body weight data to provide an estimate of human toxicity of 7 mg.min/cu m for a 70 kg human breathing 15 L/min for 10 min. This is the best estimate that can be made from the somewhat disparate animal data currently available. It is recommended that the CF adopt this 7 mg.min/cu m value for inhalation toxicity of VX and that the value by reviewed regularly to incorporate any new information that becomes available. Differences in the exposure times, body weights and breathing rates will produce corresponding changes in the toxicity value.