A Standard Reference Material for Calibration of the Cup Furnace Smoke Toxicity Method for Assessing the Acute Inhalation Toxicity of Combustion Products

A standard reference material (SRM 1048) has been developed for use with the cup furnace smoke toxicity method. This SRM is to be used to calibrate the apparatus and to enable the user to have confidence that the method is being conducted in a correct manner and that the equipment is functioning properly. The toxicological results from this SRM should not be used to compare with those of other materials (i.e., to determine if the combustion products of a test material are more or less toxic than those from this SRM). SRM 1048 is an acrylonitrile-butadiene-styrene (ABS) and is the same as SRM 1007B which is used for calibrating the flaming mode of the Smoke Density Chamber test method (ASTM E-662 and NFPA 258). For the purposes of calibrating the cup furnace smoke toxicity method, LC50 and N-Gas values plus their respective 95% confidence limits have been determined and certified for two combustion modes (flaming and nonflaming) and two observation periods (for the 30 min exposure only and for the 30 min exposure plus a 14 d post-exposure period). The certified LC50 values plus 95% confidence intervals (in g/m3) are 27 ± 3 (30 min, flaming); 25 ± 3 (30 min+ 14 d, flaming); 58 ± 15 (30 min, nonflaming); and 53 + 12 (30 min+ 14 d, nonflaming). The certified N-Gas values plus 95% confidence intervals are 1.4 ± 0.2 (30 min, flaming); 1.5 ± 0.2 (30 min+ 14 d, flaming); 1.2 ± 0.2 (30 min, nonflaming); and 1.4 ± 0.2 (30 min+ 14 d, nonflaming). It is recommended that this SRM be used with the N-Gas approach to calibrate the cup furnace smoke toxicity method rather than to determine the complete LC50 values. The N-Gas approach has the advantage of providing information on the gases responsible for the lethalities as well as the toxic potency of the smoke. In addition, the N-Gas approach reduces the number of experimental animals, the time necessary to complete the calibration, and the expense.