Evaluation of Toxic Potency Values for Smoke from Products and Materials

Abstract

Many devices have been used to generate data on the toxic potency of smoke from burning products and materials. This paper critically reviews those apparatus and sorts them by the combustion conditions (related to a type of fire) producing the smoke, the specimens tested, and the animal effect measured. All the usable data were derived using rats, and the toxicological effects encountered were lethality, represented by an LC50value, and incapacitation, expressed as an IC50 value. The data showed a wide range of toxic potency values for the products and materials tested. For those engineering applications where the mix of combustibles is unknown, generic values of smoke toxic potency were derived. Statistical analysis of the wealth of published data yielded a generic LC50value of 30 g/m3 ± 20 g/m3 (one standard deviation) for 30 minute exposure of rats for smoke from well-ventilated combustion. There are limited data for underventilated combustion, and a value of 15 g/m3 ± 5 g/m3 is suggested. The mean value of the ratios of IC50 values to LC50values is 0.50 ± 0.21, consistent with a prior review. Thus, for well-ventilated fires, a generic 30 minute IC50 value (for rats) would be 15 g/m3 ± 10 g/m3; for underventilated fires, the corresponding number would be 7 g/m3 ± 2 g/m3. There are some materials with appreciably lower potency values, indicating higher smoke toxicity. If materials like these are expected to comprise a large fraction of the fuel load, a lower generic value should be used.