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REVIEW OF ACUTE HUMAN-TOXICITY ESTIMATES FOR GD (SOMAN) 40 CONCLUSIONS AND RECOMMENDATIONS The subcommittee's conclusions concerning CDEPAT's proposed estimates for GD are summarized in Table 4-1. Of the seven human-toxicity estimates for GD proposed by CDEPAT to protect soldiers from the toxic effects of CW agents, the subcommittee agrees that one estimate is scientifically valid. The subcommittee recommends that two of the estimates be lowered, and three be considered interim estimates. It also concludes that one estimate should be raised.
TABLE 4-1 Evaluation of Human-Toxicity Estimates for GD Human-Toxicity Estimates for GB Toxicity Route and Form Existing CDEPAT's Subcommittee's Rationale for Subcommittee's Evaluation Type of Exposure Estimates Proposed Evaluation of Proposed Estimates Estimates for GB LCt50 a Percutaneous, None 2,500 mg- Proposed estimate is Proposed estimate based on assumption that GD is 4 vapor min/m3 scientifically valid times more toxic than GB for percutaneous exposure Inhalation, 70 mg-min/ 35 mg-min/ Proposed estimate should Proposed estimate based on the assumption that GD and vapor m3 m3 be lowered GB are equipotent via this route; subcommittee recommends that LCt50 estimate for GD be lowered to correspond to lowered estimate for GB; further research recommended ECt50 b Threshold Percutaneous, None 300 mg-min/ Proposed estimate should In the absence of adequate human or animal data, effects vapor m3 serve as an interim value proposed estimate based on assumption that GD is 4 times more toxic than GB for percutaneous exposure; further research recommended Severe Inhalation, 35 mg-min/ 25 mg-min/ Proposed estimate should In the absence of adequate human or animal data, effects vapor m3 m3 be lowered proposed estimate based on assumption that potenies of GD and GB are comparable; ECt 50 estimate for GD should be lowered to correspond to the lowered estimate REVIEW OF ACUTE HUMAN-TOXICITY ESTIMATES FOR GD (SOMAN) for GB; further research recommended Mild effects Inhalation, None 0.2 mg-min/ Proposed estimate should In the absence of adequate human or animal data, vapor m3 be raised proposed estimate based on assumption that GD is 2.5 times more potent than GB for miotic effects; subcommittee recommends that the LCt50 estimate for GD be raised to correspond to the recommended raised estimate for GB; further research recommended 41
Human-Toxicity Estimates for GB Toxicity Route and Form Existing CDEPAT's Subcommittee's Rationale for Subcommittee's Evaluation Type of Exposure Estimates Proposed Evaluation of Proposed Estimates Estimates for GB LD50 c Percutaneous, 350 mg for 350 mg for Proposed estimate should Because of wide range of LD50 values in animals, liquid 70-kg man 70-kg man serve as an interim value subcommittee's confidence in the proposed estimate is low; CDEPAT's proposed estimate of 350 mg for 70-kg man should serve as an interim value; further research recommended ED50 d Severe Percutaneous, None 200 mg for Proposed estimate should In the absence of adequate human or animal data, effects liquid 70-kg man serve as an interim value proposed estimate was derived using the ID50 e/LD50 ratio of 0.6; the subcommittee recommends that CDEPAT's proposed estimate serve as an interim value; further research recommended a LCt : Vapor exposure that produces lethality in 50% of the exposed animals. Ct refers to the product of concentration (c) and exposure time (t). Note that Ct is not 50 necessarily a constant. b ECt : Percutaneous vapor exposure or inhalation vapor exposure causing a defined effect (e.g., incapacitation, severe effects, mild effects, threshold effects). 50 c LD : Liquid dose causing lethality in 50% of the exposed animals. 50 d ED : Liquid dose causing a defined effect in 50% of the exposed animals. 50 e ID : Liquid dose causing incapacitation in 50% of the exposed population. 50 REVIEW OF ACUTE HUMAN-TOXICITY ESTIMATES FOR GD (SOMAN) 42
