Effects of whole-body VX vapor exposure on lethality in rats

Male and female rats were whole-body exposed to VX vapor in a 1000-L single-pass exposure chamber. Estimated exposure dosages producing lethal (LCT50) effects in 50% of exposed male and female rats were established for 10, 60, and 240 min exposure durations. A potency comparison with GB and GF shows that VX becomes increasingly more potent than these G agents with increasing exposure duration. VX is approximately 4 - 30 times more potent than GB and 5 - 15 times more potent than GF. Gender differences in the estimated median dosages were not significant at the 10, 60, and 240 min exposure durations. An empirical toxic load model was developed and the toxic load exponent for lethality (n) in the equation C-n x T = k was determined to be n = 0.92. The VX - G regeneration assay was successfully used as a biomarker for the presence of VX in the blood plasma and RBC fractions of the blood 24 h postexposure.