Fire Safety Science Digital Archive

The scientific literature on the toxicity of products of combustion of flexible polyurethane foam is reviewed to assess its potential for use in toxic hazard analysis. Combustion modes examined include pyrolysis/thermal decomposition, smoldering, and open flaming, and under ventilated flaming combustion. The body of work indicates that victims exposed to products of combustion from flaming polyurethane will result in %COHb’s generally consistent with simple CO exposure, despite the clear toxicological role of HCN. The N-gas fractional effective dose methodology for asphyxiant gases is an appropriate methodology for prediction of incapacitation due to exposure to products of combustion from flaming polyurethane. Conversely, there is significant scientific evidence that smoldering polyurethane foam produces as yet unidentified toxic species that results in deaths during the exposure and that the N-gas fractional effective dose methodology is not appropriate for smoldering combustion. Pyrolysis/thermal decomposition results in post-exposure deaths, consistent with irritant gases. The N-gas model is also not appropriate for pyrolysis/thermal decomposition. There are significant limitations in the experimental methods available that have had a negative impact on the study of toxic hazards. Adsorption and transport of toxicants on smoke particles, loss of toxicants to walls, and more chemically complex toxicants tend to be little studied or considered. There is a need to encourage more sophisticated chemical and physical analysis of fire effluents for complex toxic organic species. It can be argued that there is still a place for animal models when analytical methods and our mechanistic understanding of toxicology of complex organic species are lacking.