Assessment of the Relative Toxicity of Materials: Concept of a Limiting Toxicant

Abstract

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.