Use of an Approximate Lethal Exposure Method for Examining the Acute Inhalation Toxicity of Combustion Products

An approximate lethal exposure (ALE) method for acute inhalation toxicity testing of thermal decomposition products was developed and evaluated. In comparison to "traditional" LC ₅₀ calculation methods, the ALE method re quired 70% fewer animals and 50% fewer test runs. The ALE procedure relied on analysis of combustion gases and their limited animal testing (F-344 rats). The procedure was used to evaluate eight materials under flaming (5.0 W/cm ² ) and nonflaming (2.5 W/cm ² ) conditions. The complete 30-minute L(Ct) _50's were also calculated for five of those eight materials and compared to the ALE's. The ALE's were within eleven percent of the calculated L(Ct) _50's at 5.0 W/cm ² and ranged within thirteen to fifty-five percent of the L(Ct) _50's at 2.5 W/cm ² . A microcomputer data acquisition and control system to improve data collection and Ct product calculation is also described for the radiant furnace test method for improved data collection and concentration-time product calculation.