Development of a New Small-Scale Toxicity Test Method and Its Comparison With Full-Scale Fire Tests.
Development of a New Small-Scale Toxicity Test Method
and Its Comparison With Full-Scale Fire Tests.
(4543 K)
Levin, B. C.
Abstract S5/L2;
Abstracts of the 6th International Congress of
Toxicology. June 28-July 3, 1992, Rome, Italy, 1992.
Toxicology Letters, Vol. 64/65, 257-264, Supplement
1992.
Keywords:
toxicity test methods; large scale fire tests;
methodology; fire hazards; hazard analysis; smoke; toxic
gases; rats
Abstract:
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 assesed 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.
