The products from nonflaming combustion of wood and a trimethylol-propane-based rigid-urethane foam that was not fire-retarded produced elevated carboxyhemoglobin levels but no abnormal neurological effects. However, when this type of foam contained a reactive phosphate fire retardant, the combustion products caused grand mal seizures and death in rats. The toxic combustion product responsible for the seizures has been identified as 4-ethyl-1-phospha-2,6,7-trioxabicyclo(2.2.2.)octane-1-oxide.

Experiments were conducted on male Long-Evans rats instrumented for measurement of vital functions and a conditioned avoidance response. An intra-arterial cannula was used for removal of blood samples. Rats were exposed to combustion products of three polymeric materials. A National Bureau of Standards smoke chamber and a smaller “static” chamber were used for exposures. Material A produced a syndrome of carbon monoxide (CO)-induced anoxia, the severity of which depended only upon the amount of material degraded and not upon the mode of combustion (heat flux, flaming, or nonflaming). Material B produced a syndrome of epilepsy and carboxyhemoglobin levels below 10 percent. Material C produced a metabolic acidosis and mild CO-induced anoxia, the severity of which was related to the amount of material degraded, irrespective of the combustion mode. The combustion products of Materials B and C produced intoxication syndromes distinctly different from the syndrome of CO-induced anoxia produced by Material A. “Limiting” toxicants or substances with high biological activity may be present in combustion products and produce unique intoxication syndromes.

Während die Schwelprodukte von Tannenholz und diejenigen eines auf Trimethylolpropan‐Basis beruhenden Polyurethanhartschaums bei Versuchsratten keine anormalen neurologischen Effekte bewirken, erweist sich der Verbrennungsrauch eines mit Phosphat‐Flammschutzmitteln ausgerüsteten Polyurethanhartschaums als extrem neurotoxigg.