Inhalation Toxicologic Procedures for Exposure of Small Laboratory Animals to Highly Toxic Materials: Part B: Exposures to Aerosols with Notes on Toxicity of Ricin

摘要

The estimation of military hazard from toxic materials usually requires an estimate of the human toxicity. With expensive, rare and highly toxic substances, only small amounts of substance may be available for testing or safety considerations may restrict the amounts of material that may be used at one time. A functional modular system has been developed for the exposure of mice, rats and guinea pigs to highly toxic liquid, gas or aerosol test materials that requires a minimum of trial material. The total system is described in this aerosol centered report and in companion reports which describe methods for use with gasses. The aerosol exposure system is operated dynamically in a chamber with a very small volume. Provision is made to continuously monitor the concentration and composition of the aerosol in the test atmospheres and grab samples are taken to establish the exposure concentrations. Respiration of the subjects may be continuously monitored during the exposures but because of the restraint of the animals required by the nose only configuration, observations of behavior during the exposures are not possible. The development and validation of this configuration are described and toxicity studies with Ricin are used as examples. The observed nose only inhalation toxicity of Ricin to rats was 4 mg.min/cu m. Times-to-death were generally 24 - 48 hr following significant weight loss. Toxicity values from other laboratories range from 2 to 4 mg.min/cu m.