Situational smoke toxicity testing: hazard assessment as the 'front end' of a smoke toxicity test.

Traditionally, the toxic potency of the smoke from a material or product is part of the assessment of the fire hazard in a given scenario. The assessment also requires a knowledge of virtually all the details of the fire environment and, until they are identified, a 'safe' or 'acceptable' level of smoke toxicity is a term without meaning. This paper suggests a method of using the knowledge of these factors to simplify smoke toxicity testing. Faster, cheaper, and better-targeted smoke toxicity tests would result if the rest of the hazard assessment were carried out first. This is accomplished by determining or specifying all the relevant fire properties except the toxic potency, identifying the other environmental conditions (such as those typical of an aircraft cabin interior) and the desired tenability limits (such as the minimum necessary escape time), and then solving the equations for the buildup of toxic conditions in terms of the single remaining unknown, the toxic potency. The result is the greatest toxic potency which would meet the requirements of the analysis. In this approach, a material or product is acceptable if its smoke is no more toxic then the computed result and unacceptable if it is not. It would not be necessary to obtain an EC50 (product concentration which will cause an effect in half the animals) or dose-response profile, only the response at whatever dose is dictated by the analysis. Two sample cases are presented to illustrate the technique.