Levin B C
National Institute of Standards and Technology, Gaithersburg, MD.
Toxicol Lett. 1992 Dec;64-65 Spec No:257-64. doi: 10.1016/0378-4274(92)90197-r.
A comprehensive methodology has been developed for obtaining and using smoke toxicity data for fire hazard analysis. This bench-scale method can simulate diverse fire conditions and identify extremely toxic smoke under both pre- and post-flashover conditions. However, incidence data show that most of the fire deaths in the U.S. occur outside the room of fire origin from smoke and toxic gases that are generated from a fire under post-flashover conditions. Therefore, the most relevant real-scale combustion conditions to simulate in the bench-scale apparatus would be the post-flashover conditions which are achieved by using radiant heat, a high heat flux, and correcting the bench-scale carbon monoxide (CO) results to agree with CO yields observed in real-scale post-flashover fires. The number of test animals (Fischer 344 male rats) is minimized by using the N-Gas Model to estimate the LC50 value from the chemical analysis of the smoke. The current N-Gas Model predicts the toxicity of complex fire gas mixtures based on a large data base of experimental results of individual and mixed gases that include CO, CO2, reduced O2, HCN, HCl, HBr, and NOx. The prediction is checked with a small number of animal tests and an approximate LC50 value is determined. The bench-scale results have been validated with full-scale room wall burns of a limited number of materials of widely differing characteristics chosen to challenge the system. The toxic potency values are assessed to determine if the smoke from a material or product is unusually or extremely toxic and can then be used in computations of fire hazard.
已开发出一种综合方法，用于获取和使用烟雾毒性数据进行火灾危险性分析。这种实验室规模的方法可以模拟各种火灾条件，并识别轰燃前和轰燃后条件下的剧毒烟雾。然而，发生率数据表明，美国大多数火灾死亡发生在火灾起源房间之外，是由轰燃后条件下火灾产生的烟雾和有毒气体所致。因此，在实验室规模装置中要模拟的最相关实际燃烧条件将是轰燃后条件，这可通过使用辐射热、高热通量来实现，并对实验室规模一氧化碳（CO）结果进行校正，使其与实际规模轰燃后火灾中观察到的CO产量一致。通过使用N气体模型根据烟雾的化学分析估算LC50值，可将实验动物（Fischer 344雄性大鼠）数量减至最少。当前的N气体模型基于包括CO、CO2、氧气减少、HCN、HCl、HBr和NOx在内的单一气体和混合气体实验结果的大型数据库，预测复杂火灾气体混合物的毒性。通过少量动物试验对预测进行检验，并确定近似的LC50值。已通过对有限数量特性差异很大的材料进行全尺寸房间墙壁燃烧试验来验证实验室规模的结果，这些材料是为挑战该系统而选择的。评估毒性强度值，以确定材料或产品产生的烟雾是否具有异常或剧毒特性，然后可将其用于火灾危险性计算。
