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Ad-mo AN EVALUATION OF A SERIES OF NATURAL AND SYNTHETIC MATERIALS BY INCAPACITATION BIOASSAY TESTING: A SPECIAL REPORT TO THE NATIONAL BUREAU OF STANDARDS TOXICOLOGY FILE COPY Return To. R. K. Hinderer D/5456 Cleveland by G. F. Smith BFGoodrich Chemical Division Avon Lake Technical Center Avon Lake, Ohio 44012 September 1977 BFG22052 22625001 1. Introduction During the past few years pressure has been building to control the acceptability of materials on the basis of combustion toxicological performance. This is in response to the high rate of fire deaths in the United States and the NFPCA's stated goal to reduce the fire death rate by 50% within the next generation. Potentially there are many pathways leading to a reduction of the fire death rate such as utilization of fire detection and suppres sion systems, improved fire service and increased public awareness, as well as control of and safe use practices for materials. How ever, building code groups have not been able to begin regulation of materials on the basis of combustion toxicological performance because no accepted test method is available. The National Bureau of Standards is currently.developing a bioassay testing protocol to be used by code groups to control the acceptability of materials on the basis of combustion toxicological performance. At the present time no formal document has been released by the NBS In the absence of any widely accepted bioassay testing pro tocol, BFGoodrich initiated a program to determine some of the characteristics of the combustion toxicological performance of the materials which BFGoodrich produces. This report describes the results of some of this work. This report is being made to the NBS anticipating that it may be useful to the NBS in its efforts to develop a bioassay testing protocol. Incapacitatiorv as measured in the rotating cage experiment, is a bioresponse which is well suited for the evaluation of the combustion toxicological performance of materials. The usefulness of this bioresponse results from the following critical features which it has been found to possess: 1.) The incapacitation bioresponse, as measured in the rotating cage, is very sensitive to the differences of materials. In comparison to the mortality bio response, it has been found that mortality is much less sensitive to the differences of materials than is incapacitation. This is seen in the relative steepness of the incapacitation dose-response curves and the mortality dose-response curves. Furthermore, the susceptability of test animals to develop exposure induced disease which often leads to mortality can con fuse the interpretation of mortality results. Neverthe less, post exposure mortality data provides some measure of post exposure problems. A complete material evaluation must be based on the incapacitation hazard as well as the potential for post exposure problems. BFG22053 2a>0S922 2. 2. ) Incapacitation, as measured in the rotating cage experiment, clearly identifies materials which induce excessive or unusual toxicological responsesuper toxic materials. The utility of a bioresponse for the evaluation of the combustion toxicological performance of materials depends strongly on its capability to detect super toxic materials. 3. ) The incapacitation bioresponse is easily coupled with analytical measurements of the combustion gas atmo sphere to which the test animals are exposed. This makes it possible to determine which components of the combustion atmosphere are most important in induc ing bioresponse. We have found that for many materials, for example wood and PVC, CO is the main incapacitating component of the combustion products. Experimental A diagram of the combustion-inhalation chamber is given in Figure 1. The physical system consists of a 40 liter inhalation chamber and a 20 liter combustion chamber interconnected by an air circulation system. Eight liters per minute of 50% relative humidity fresh air enters the combustion chamber, 16 liters per minute transfers from the combustion to the inhalation chamber, 8 liters per minute returns from the inhalation to the combustion chamber, 8 liters per minute is exhausted. Hie partial recircula tion of the atmosphere which is used in this procedure permits the fulfillment of three critical criteria: 1.) the animals are exposed to air no hotter than 32C; 2.) test animal anoxia is prevented since the % 02 does not go below 18%; and 3.) a pseudo stable atmosphere of combustion products is generated. The dura tion of the exposure is fifteen minutes for each experiment. Since all exposures are of the same duration, meaningful comparisons of post exposure mortality data can be made. The fifteen minute time period of the experiment is important for another reason. During combustion, PVC releases HC1 early, further heating results in the evolution of CO. It is important that the test animals be exposed to the products of all phases of the decomposition process. Ihe fifteen minute exposure allows nearly complete com bustion to occur. In all experiments, thermal decomposition of the sample is carried out at 2.5 watts/cm2 smoldering combustion. The sample heater is built from nichrome ribbon electrical resistant heating elements. Future work will make use of a range of radiant heat flux exposures as well as both smoldering and flaming combustion. BFG22054 C00SZ9Z7.