Relationship between the Dose-response Curves for Lethality and Severe Effects for Chemical Warfare Nerve Agents

The U.S. Environmental Protection Agency has developed a categorical logistic regression approach for regressing ordered response categories on one or more factors due to toxicant exposures. This approach can also be used in analyzing chemical warfare agent toxicity. Towards this end, three previous mammalian studies (involving acute inhalation exposures to G-type nerve agents) were reviewed and analyzed. For all three studies, slightly more than one standard deviation separated an effective concentration (ECXX) for severe effects from a lethal concentration (LCXX) for XX% affected. Such knowledge can be used to better estimate threshold lethality and characterize the dose-response curves.