Effects of Whole-Body VX Vapor Exposure on Lethality in Rats

Much of what is known of the effects of VX on whole animals is derived from studies administering vx percutaneously, subcutaneously, or as an aerosol. Major gaps exist in our understanding of the effects of VX vapor. This study exposed rats to VX vapor in a 1000 L inhalation chamber and established LCT50's and ECT50's (for severe effects) at exposure durations of 10, 60, and 240 min. The values were derived from data collected 24 hr post exposure. A potency comparison with GB and GF shows that VX is approximately 4 to 25 times more potent than GB and 5 to 15 times more potent than GF. Gender differences in the LCT50 values were not significant. An empirical toxic load model was developed, and the toxic exponent for lethality (n) in the equation C(product) x T = k was determined to be n = 0.92. There was a significant depression of AChE of at least 85% at all concentrations tested. Elevated levels of VX-G analog were found in blood plasma at 1 hr post exposure. Prepared in collaboration with Science Applications International Corporation, Abingdon, MD. The original document contains color images.