Estimation of Human Toxicity from Animal Inhalation Toxicity Data: 2 (Abridged). GB Toxicity Reassessed Using Newer Techniques for Estimation of Human Toxicity


  1. Bide, R.W.
  2. Armour, S.J.
  3. Yee, E.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN)
Estimated human inhalation toxicity values for GB were calculated using a new three dimensional, nonlinear dose response (toxicity) model combined with re-evaluated allometric equations relating animal and human respiration. Historical animal studies of GB toxicity containing both exposure and fractional animal response data were used to test the new process. The final data set contained 6621 animals, 762 groups, 37 studies and 7 species. The toxicity of GB for each species was empirically related to exposure concentration (C; mg/m super 3) and exposure time (T; min) through the surface function Y = b sub 0 + b sub 1 Log sub 10 C + b sub 2 Log sub 10 T or Y = b sub 0 + b sub 2 Log sub 10C super n T where Y is the PROBIT, b sub 0, b sub 1 and b sub 2 are constants and n is the “toxic load exponent”. Between exposure times 0.17 and 30 min, the average value for n in 7 species was 1.35 ± 0.15. The near parallel toxic load equations for each species and the linear relationship between minute volume/ body weight ratio and the inhalation toxicity (LCt sub 50) for GB were used to create a pseudo-human data set and then an exposure time/toxicity surface for the human. The calculated n for the human was 1.38 ± 0.01. The pseudo-human data had much more variability at low exposure times. Raising the lower exposure limit to one min did not change the LCt sub 50 but did result in lower variability. Raising the lower value to 2 min was counterproductive. Based on the toxic load model

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Chemical warfare agents;Human estimates;Inhalation toxicity
Report Number
DRDC-SUFFIELD-TR-2004-167 — Technical Report
Date of publication
01 Aug 2004
Number of Pages
Hardcopy;CD ROM

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